From 166f04133b2c24e305da8df03d9c06944afb0824 Mon Sep 17 00:00:00 2001 From: David Jansen Date: Wed, 26 Jun 2024 08:14:21 +0000 Subject: [PATCH] Update 'docs' folder with ci_updates and delete old branches. --- docs/ci_updates/index.html | 18 + docs/ci_updates/syntax/HTML_correct_log.txt | 38694 +++++++++--------- docs/ci_updates/syntax/HTML_error_log.txt | 654 +- 3 files changed, 19692 insertions(+), 19674 deletions(-) create mode 100644 docs/ci_updates/index.html diff --git a/docs/ci_updates/index.html b/docs/ci_updates/index.html new file mode 100644 index 0000000000..78c72a52e5 --- /dev/null +++ b/docs/ci_updates/index.html @@ -0,0 +1,18 @@ + + + + + + + Files generated by CI + + +
+
  • ci/result/syntax/HTML_error_log.txt

    • +
  • ci/result/syntax/AixLib_StyleCheckLog.html

    • +
  • ci/result/syntax/HTML_correct_log.txt

    • +
    + + + + \ No newline at end of file diff --git a/docs/ci_updates/syntax/HTML_correct_log.txt b/docs/ci_updates/syntax/HTML_correct_log.txt index b458b57edb..b5d0f04c1a 100644 --- a/docs/ci_updates/syntax/HTML_correct_log.txt +++ b/docs/ci_updates/syntax/HTML_correct_log.txt @@ -1,1234 +1,1317 @@ ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/finiteLineSource_Erfint.mo ---- +---- AixLib/BoundaryConditions/Validation/UsersGuide.mo ---- -------- HTML Code -------- -

    - This function evaluates the integral of the error function, given by: -

    -

    - \"image\" -

    - - - --------- Corrected Code --------

    - This function evaluates the integral of the error function, given by: +The package AixLib.BoundaryConditions.Validation.BESTEST +contains the models that are used for the BESTEST validation ASHRAE 2020 for weather data acquisition and postprocessing.

    -

    - \"image\" +

    +Each model represents a different climate with different days as shown in the tables below. +All examples have a script that runs the simulation according to the specifications and derive the required Json file as reported below. +

    +

    +The weather radiation data has to be provided at different orientations and inclinations.

    +

    Table 2: Azimuth and Slope for Surfaces

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

    Azimuth

    Slope

    Horizontal

    0° from horizontal

    South

    90° from horizontal

    East

    90° from horizontal

    North

    90° from horizontal

    West

    90° from horizontal

    45° East of South

    90° from horizontal

    45° West of South

    90° from horizontal

    East

    30° from horizontal

    South

    30° from horizontal

    West

    30° from horizontal

    + +

    Additional parameters and correlations

    +

    Outputs required

    +

    Annual Outputs

    +

     The following outputs are provided for an annual simulation:

    + +

    Hourly Outputs

    +

    The following outputs are provided for each hour of the days specified for each test case in Table 3:

    + +

    Table 3: Specific Days for Output

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

    Case

    Days

    WD100

    May 4th, July 14th, September 6th

    WD200

    May 24th, August 26th

    WD300

    February 7th, August 13th

    WD400

    January 24th, July 1st

    WD500

    March 1st, September 14th

    WD600

    May 4th, July 14th, September 6th

    +

    Sub-hourly Outputs

    +

    The following outputs are provided at each timestep of the days specified for each test case in Table 3:

    + +

    The following outputs are provided integrated hourly for the days specified for each test case in Table 3:

    + +

    Validation results

    +

    (Not available yet)

    +

    Implementation

    +

    To generate the data shown in this user guide, run

    +
    +cd AixLib/Resources/Data/BoundaryConditions/Validation/BESTEST
+python3 generateResults.py -p
+
    +

    At the beginning of the Python script there are several options that the user can choose, by default the script will: +

    + +

    References

    +

    (Not available yet)

    --------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/BoundaryConditions/Validation/BESTEST/WD500.mo ---- --------- HTML Code -------- - -

    - -

    WD500: Time Zone Case

    -

    Weather data file : WD500.epw

    -

    Table 1: Site Data for Weather file WD500epw

    - - - - - - - - - - - - - - - - -

    Latitude

    28.567° north

    Longitude

    77.103° east

    Altitude

    236.9 m

    Time Zone

    5.5

    - --------- Corrected Code -------- -

    - WD500: Time Zone Case -

    + +-------- Corrected Code --------

    - Weather data file : WD500.epw + The package AixLib.BoundaryConditions.Validation.BESTEST + contains the models that are used for the BESTEST validation ASHRAE + 2020 for weather data acquisition and postprocessing.

    - Table 1: Site Data for Weather file WD500epw + Each model represents a different climate with different days as + shown in the tables below. All examples have a script that runs the + simulation according to the specifications and derive the required + Json file as reported below.

    - + The weather radiation data has to be provided at different + orientations and inclinations. +

    +

    + Table 2: Azimuth and Slope for Surfaces +

    +
    -

    - Latitude + Azimuth

    - 28.567° north + Slope

    - Longitude + Horizontal

    - 77.103° east + 0° from horizontal

    - Altitude + South

    - 236.9 m + 90° from horizontal

    - Time Zone + East

    - 5.5 + 90° from horizontal

    - --------- Errors -------- -line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 - - ----- AixLib/BoundaryConditions/UsersGuide.mo ---- --------- HTML Code -------- - -

    This package contains models to read or compute boundary conditions, such as weather data, solar irradition and sky temperatures. -The calculations follow the description in Wetter (2004), Appendix A.4.2.

    -

    Accessing weather data

    -

    -The model - -AixLib.BoundaryConditions.WeatherData.ReaderTMY3 -can read TMY3 weather data for different locations. -The documentation of that model explains how to add -weather data for locations that are not distributed with the -AixLib library. -

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    +

    + North +

    +     		+

    + 90° from horizontal +

    +
    +

    + West +

    +     		+

    + 90° from horizontal +

    +
    +

    + 45° East of South +

    +     		+

    + 90° from horizontal +

    +
    +

    + 45° West of South +

    +     		+

    + 90° from horizontal +

    +
    +

    + East +

    +     		+

    + 30° from horizontal +

    +
    +

    + South +

    +     		+

    + 30° from horizontal +

    +
    +

    + West +

    +     		+

    + 30° from horizontal +

    +

    -To access these weather data from the graphical model editor, -proceed as follows: + Additional parameters and correlations

    -
      -
    1. +
        +
      • Ground reflectance ρ is set to 0 for cases from WD100 to WD500 + and 0.2 for WD600 +
        • +
      • + Sky + black body temperature calculated using Horizontal radiation or + dew point temperature and sky cover. +
        • +
      • Diffused radiation calculated using + Perez and + Isotropic sky models +
        • +
      +

      + Outputs required +

      -Create an instance of - -AixLib.BoundaryConditions.WeatherData.ReaderTMY3. + Annual Outputs

      -
      2. -

    2. -Create an instance of - -AixLib.BoundaryConditions.WeatherData.Bus. +  The following outputs are provided for an annual + simulation:

      -
      3. -
    3. +
        +
      • Average dry bulb temperature (°C) +
        • +
      • Average relative humidity (%) +
        • +
      • Average dewpoint temperature (°C) +
        • +
      • Average humidity ratio (kg moisture/kg dry air) +
        • +
      • Average wet bulb temperature (°C) +
        • +
      • Sum of total, beam, and diffuse solar radiation incident on each + surface (Wh/m2) +
        • +

      -Draw a connection between these two instances. + Hourly Outputs

      -
      4. -

    4. -Finally, to send weather data to an input connector of a model, -connect the input connector of that model with the instance of - -AixLib.BoundaryConditions.WeatherData.Bus. -Some models connect to the whole weather data bus, such as - -AixLib.BoundaryConditions.SolarGeometry.Examples.IncidenceAngle, -in which case the connection will directly be drawn. -Other models require only an individual signal from the weather data bus, -such as - -AixLib.BoundaryConditions.SkyTemperature.Examples.BlackBody. -In this situation, Modelica modeling environments typically show a window that allows you to -select what data from this weather data bus you want to connect -with your model. + The following outputs are provided for each hour of the days + specified for each test case in Table 3:

      -
      5. -
    -

    Conventions for surface azimuth and tilt

    -

    To compute the solar irradiation, parameters such as the surface azimuth and the surface tilt are defined as shown in the following three figures.

    -

    \"image\"

    -

    \"image\"

    -

    \"image\"

    +

    -For the surface azimuth and tilt, the enumerations - -AixLib.Types.Azimuth -and - -AixLib.Types.Tilt -can be used. + Table 3: Specific Days for Output

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    +

    + Case +

    +     		+

    + Days +

    +
    +

    + WD100 +

    +     		+

    + May 4th, July 14th, September 6th +

    +
    +

    + WD200 +

    +     		+

    + May 24th, August 26th +

    +
    +

    + WD300 +

    +     		+

    + February 7th, August 13th +

    +
    +

    + WD400 +

    +     		+

    + January 24th, July 1st +

    +
    +

    + WD500 +

    +     		+

    + March 1st, September 14th +

    +
    +

    + WD600 +

    +     		+

    + May 4th, July 14th, September 6th +

    +

    -Note that a ceiling has a tilt of 0 - -if they are facing straight upwards. -This is correct because -the solar irradiation on a ceiling construction is on the other-side surface, -which faces upwards toward the sky. Hence, a construction is considered -a ceiling from the view point of a person standing inside a room. -

    - -

    References

    - - --------- Corrected Code -------- -

    - This package contains models to read or compute boundary conditions, - such as weather data, solar irradition and sky temperatures. The - calculations follow the description in Wetter (2004), Appendix A.4.2. + Sub-hourly Outputs

    -

    - Accessing weather data -

    - The model AixLib.BoundaryConditions.WeatherData.ReaderTMY3 - can read TMY3 weather data for different locations. The documentation - of that model explains how to add weather data for locations that are - not distributed with the AixLib library. + The following outputs are provided at each timestep of the days + specified for each test case in Table 3:

    +

    - To access these weather data from the graphical model editor, proceed - as follows: + The following outputs are provided integrated hourly for the days + specified for each test case in Table 3:

    -
      -
    1. -

      - Create an instance of AixLib.BoundaryConditions.WeatherData.ReaderTMY3. -

      -
      2. -
    2. -

      - Create an instance of AixLib.BoundaryConditions.WeatherData.Bus. -

      +
        +
      • Total incident horizontal solar radiation (Wh/m2)
        • -
      • -

        - Draw a connection between these two instances. -

        +
      • Total incident horizontal beam solar radiation (Wh/m2)
        • -
      • -

        - Finally, to send weather data to an input connector of a model, - connect the input connector of that model with the instance of - AixLib.BoundaryConditions.WeatherData.Bus. - Some models connect to the whole weather data bus, such as - - AixLib.BoundaryConditions.SolarGeometry.Examples.IncidenceAngle, - in which case the connection will directly be drawn. Other models - require only an individual signal from the weather data bus, such - as - AixLib.BoundaryConditions.SkyTemperature.Examples.BlackBody. - In this situation, Modelica modeling environments typically show - a window that allows you to select what data from this weather - data bus you want to connect with your model. -

        +
      • Total incident horizontal diffuse solar radiation (Wh/m2)
        • -
    +

    - Conventions for surface azimuth and tilt + Validation results

    - To compute the solar irradiation, parameters such as the surface - azimuth and the surface tilt are defined as shown in the following - three figures. -

    -

    - \"image\" -

    -

    - \"image\" -

    -

    - \"image\" + (Not available yet)

    +

    + Implementation +

    - For the surface azimuth and tilt, the enumerations AixLib.Types.Azimuth and - AixLib.Types.Tilt can be - used. + To generate the data shown in this user guide, run

    +
    +cd AixLib/Resources/Data/BoundaryConditions/Validation/BESTEST
+python3 generateResults.py -p
+

    - Note that a ceiling has a tilt of 0 - if they are facing straight upwards. This is correct because the - solar irradiation on a ceiling construction is on the other-side - surface, which faces upwards toward the sky. Hence, a construction is - considered a ceiling from the view point of a person standing inside - a room. + At the beginning of the Python script there are several options that + the user can choose, by default the script will:

    +

    References

    +

    + (Not available yet) +

    -------- Errors -------- -line 60 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 61 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 62 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 14 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 +line 98 column 1 - Warning: The summary attribute on the
    element is obsolete in HTML5 ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/finiteLineSource.mo ---- +---- AixLib/Utilities/Math/Functions/bicubic.mo ---- -------- HTML Code -------- -

    - This function evaluates the finite line source solution. This solution - gives the relation between the constant heat transfer rate (per unit length) - injected by a line source of finite length H1 buried at a - distance D1 from a constant temperature surface - (T=0) and the average temperature raise over a line of finite length - H2 buried at a distance D2 from the constant - temperature surface. - The finite line source solution is defined by: -

    -

    - \"image\" + This function computes +

    + y = a1 + + a2 x1 + a3 x12 + + a4 x2 + a5 x22 + + a6 x1 x2 + + a7 x1^3 + + a8 x2^3 + + a9 x12 x2 + + a10 x1 x22

    + + + +-------- Corrected Code -------- +This function computes +

    + y = a1 + a2 x1 + a3 + x12 + a4 x2 + + a5 x22 + a6 x1 + x2 + a7 x1^3 + a8 + x2^3 + a9 x12 + x2 + a10 x1 + x22 +

    + + +-------- Errors -------- +line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/ThermalZones/ReducedOrder/RC/OneElement.mo ---- +-------- HTML Code -------- +

    - where ΔT1-2(t,r,H1,D1,H2,D2) - is the temperature raise after a time t of constant heat injection and at - a distance r from the line heat source, Q' is the heat injection - rate per unit length, ks is the soil thermal conductivity and - hFLS is the finite line source solution. + This model merges all thermal masses into one + element, parameterized by the length of the RC-chain + nExt, the vector of the capacities CExt[nExt] that is + connected via the vector of resistances RExt[nExt] and + RExtRem to the ambient and indoor air. + By default, the model neglects all + internal thermal masses that are not directly connected to the ambient. + However, the thermal capacity of the room air can be increased by + using the parameter mSenFac.

    - The finite line source solution is given by: + The image below shows the RC-network of this model.

    - \"image\" -

    -

    - where αs is the ground thermal diffusivity and - erfint is the integral of the error function, defined in - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_erfint. - The integral is solved numerically, with the integrand defined in - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_Integrand. + \"image\"/

    - + -------- Corrected Code --------

    - This function evaluates the finite line source solution. This - solution gives the relation between the constant heat transfer rate - (per unit length) injected by a line source of finite length - H1 buried at a distance D1 from a - constant temperature surface (T=0) and the average temperature - raise over a line of finite length H2 buried at a - distance D2 from the constant temperature surface. - The finite line source solution is defined by: -

    -

    - \"image\" -

    -

    - where - ΔT1-2(t,r,H1,D1,H2,D2) - is the temperature raise after a time t of constant heat - injection and at a distance r from the line heat source, - Q' is the heat injection rate per unit length, - ks is the soil thermal conductivity and - hFLS is the finite line source solution. + This model merges all thermal masses into one element, parameterized + by the length of the RC-chain nExt, the vector of the + capacities CExt[nExt] that is connected via the vector + of resistances RExt[nExt] and RExtRem to + the ambient and indoor air. By default, the model neglects all + internal thermal masses that are not directly connected to the + ambient. However, the thermal capacity of the room air can be + increased by using the parameter mSenFac.

    - The finite line source solution is given by: + The image below shows the RC-network of this model.

    - \"image\" -

    -

    - where αs is the ground thermal diffusivity and - erfint is the integral of the error function, defined in - - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_erfint. - The integral is solved numerically, with the integrand defined in - - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_Integrand. + \"image\"

    -------- Errors -------- -line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 16 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Media/Specialized/Air/PerfectGas.mo ---- +---- AixLib/Utilities/Math/QuadraticLinear.mo ---- -------- HTML Code -------- - Function to set the state for given pressure, enthalpy and species concentration. - - The thermodynamic state record - is computed from density d, temperature T and composition X. - - Saturation pressure of water above the triple point temperature is computed from temperature. It's range of validity is between - 273.16 and 373.16 K. Outside these limits a less accurate result is returned. - - Derivative function of - - AixLib.Media.Specialized.Air.PerfectGas.saturationPressureLiquid - - Pressure is returned from the thermodynamic state record input as a simple assignment. - - Temperature is returned from the thermodynamic state record input as a simple assignment. - - Density is computed from pressure, temperature and composition in the thermodynamic state record applying the ideal gas law. - - Specific entropy is calculated from the thermodynamic state record, assuming ideal gas behavior and including entropy of mixing. Liquid or solid water is not taken into account, the entire water content X[1] is assumed to be in the vapor state (relative humidity below 1.0). - - Temperature as a function of specific enthalpy and species concentration. - The pressure is input for compatibility with the medium models, but the temperature - is independent of the pressure. - -

    - This data record contains the coefficients for perfect gases. -

    +

    Block for function quadraticLinear, which computes

    +

    y = a1 + a2 x1 + a3 x12 + (a4 + a5 x1 + a6 x12) x2

    +-------- Corrected Code -------- +

    + Block for function quadraticLinear, which computes +

    +

    + y = a1 + a2 x1 + a3 x12 + (a4 + a5 x1 + a6 x12) x2 +

    + + +-------- Errors -------- +line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Interfaces/PrescribedOutlet.mo ---- +-------- HTML Code -------- +

    - This package contains a thermally perfect model of moist air. -

    -

    - A medium is called thermally perfect if -

    - -

    - In addition, this medium model is calorically perfect, i.e., the - specific heat capacities at constant pressure cp - and constant volume cv are both constant (Bower 1998). + This model sets the temperature or the water vapor mass fraction + of the medium that leaves port_a + to the value given by the input TSet or X_wSet, + subject to optional limitations on the capacity + for heating and cooling, or limitations on the humidification or dehumidification + moisture mass flow rate. + Also, optionally the model allows to take into account first order dynamics.

    - This medium uses the ideal gas law + If the parameters energyDynamics is not equal to + Modelica.Fluid.Types.Dynamics.SteadyState, + the component models the dynamic response using a first order differential equation. + The time constant of the component is equal to the parameter tau. + This time constant is adjusted based on the mass flow rate using

    - ρ = p ⁄(R T), + τeff = τ |ṁ| ⁄ ṁnom

    where - ρ is the density, - p is the pressure, - R is the gas constant and - T is the temperature. -

    -

    - The enthalpy is computed using the convention that h=0 - if T=0 °C and no water vapor is present. + τeff is the effective time constant for the given mass flow rate + ṁ and + τ is the time constant at the nominal mass flow rate + ṁnom. + This type of dynamics is equal to the dynamics that a completely mixed + control volume would have.

    - Note that for typical building simulations, the media - AixLib.Media.Air - should be used as it leads generally to faster simulation. + This model has no pressure drop. + See + AixLib.Fluid.HeatExchangers.PrescribedOutlet + for a model that instantiates this model and that has a pressure drop.

    -

    References

    - Bower, William B. A primer in fluid mechanics: Dynamics of flows in one - space dimension. CRC Press. 1998. + In case of reverse flow, + the fluid that leaves port_a has the same + properties as the fluid that enters port_b.

    -------- Corrected Code -------- -Function to set the state for given pressure, enthalpy and species -concentration. -The thermodynamic state record is computed from density d, temperature -T and composition X. -Saturation pressure of water above the triple point temperature is -computed from temperature. It's range of validity is between 273.16 and -373.16 K. Outside these limits a less accurate result is returned. -Derivative function of -AixLib.Media.Specialized.Air.PerfectGas.saturationPressureLiquid -Pressure is returned from the thermodynamic state record input as a -simple assignment. -Temperature is returned from the thermodynamic state record input as a -simple assignment. -Density is computed from pressure, temperature and composition in the -thermodynamic state record applying the ideal gas law. -Specific entropy is calculated from the thermodynamic state record, -assuming ideal gas behavior and including entropy of mixing. Liquid or -solid water is not taken into account, the entire water content X[1] is -assumed to be in the vapor state (relative humidity below 1.0). -Temperature as a function of specific enthalpy and species -concentration. The pressure is input for compatibility with the medium -models, but the temperature is independent of the pressure. -

    - This data record contains the coefficients for perfect gases. -

    -

    - This package contains a thermally perfect model of moist air. -

    -

    - A medium is called thermally perfect if -

    - -

    - In addition, this medium model is calorically perfect, i.e., - the specific heat capacities at constant pressure - cp and constant volume cv are - both constant (Bower 1998). + This model sets the temperature or the water vapor mass fraction of + the medium that leaves port_a to the value given by the + input TSet or X_wSet, subject to optional + limitations on the capacity for heating and cooling, or limitations + on the humidification or dehumidification moisture mass flow rate. + Also, optionally the model allows to take into account first order + dynamics.

    - This medium uses the ideal gas law + If the parameters energyDynamics is not equal to + Modelica.Fluid.Types.Dynamics.SteadyState, the component + models the dynamic response using a first order differential + equation. The time constant of the component is equal to the + parameter tau. This time constant is adjusted based on + the mass flow rate using

    - ρ = p ⁄(R T), -

    -

    - where ρ is the density, p is the pressure, R is - the gas constant and T is the temperature. + τeff = τ |ṁ| ⁄ ṁnom

    - The enthalpy is computed using the convention that h=0 if - T=0 °C and no water vapor is present. + where τeff is the effective time constant for the + given mass flow rate ṁ and τ is the time constant at + the nominal mass flow rate ṁnom. This type of + dynamics is equal to the dynamics that a completely mixed control + volume would have.

    - Note that for typical building simulations, the media AixLib.Media.Air should be used as - it leads generally to faster simulation. + This model has no pressure drop. See AixLib.Fluid.HeatExchangers.PrescribedOutlet + for a model that instantiates this model and that has a pressure + drop.

    -

    - References -

    - Bower, William B. A primer in fluid mechanics: Dynamics of flows - in one space dimension. CRC Press. 1998. + In case of reverse flow, the fluid that leaves port_a + has the same properties as the fluid that enters port_b.

    + +-------- Errors -------- +line 18 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/ThermalZones/ReducedOrder/RC/BaseClasses/ExteriorWall.mo ---- +-------- HTML Code -------- + +

    ExteriorWall represents heat conduction and heat storage + within walls. It links a variable number n of thermal resistances + and capacities to a series connection. n thus defines the spatial + discretization of thermal effects within the wall. All effects are considered + as one-dimensional normal to the wall's surface. This model is thought + for exterior wall elements that contribute to heat transfer to the outdoor. + The RC-chain is defined via a vector of capacities CExt[n] and a + vector of resistances RExt[n]. Resistances and capacities are + connected alternately, starting with the first resistance RExt[1], + from heat port_a to heat port_b. RExtRem + is the resistance between the last capacity CExt[end] and the + heat port_b.

    +

    \"image\"/

    + + + +-------- Corrected Code -------- +

    + ExteriorWall represents heat conduction and heat storage + within walls. It links a variable number n of thermal + resistances and capacities to a series connection. n + thus defines the spatial discretization of thermal effects within the + wall. All effects are considered as one-dimensional normal to the + wall's surface. This model is thought for exterior wall elements that + contribute to heat transfer to the outdoor. The RC-chain is defined + via a vector of capacities CExt[n] and a vector of + resistances RExt[n]. Resistances and capacities are + connected alternately, starting with the first resistance + RExt[1], from heat port_a to heat + port_b. RExtRem is the resistance between + the last capacity CExt[end] and the heat + port_b. +

    +

    + \"image\" +

    + -------- Errors -------- -line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 14 column 4 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatExchangers/SensibleCooler_T.mo ---- +---- AixLib/Fluid/Actuators/Valves/ThreeWayTable.mo ---- -------- HTML Code --------

    - Model for an ideal sensible-only cooler that controls its outlet temperature to - a prescribed outlet temperature. -

    -

    - This model forces the outlet temperature at port_b to be - no higher than the temperature of the input signal - TSet, subject to optional limits on the - capacity. - By default, the model has unlimited cooling capacity. -

    -

    - The output signal Q_flow ≤ 0 is the heat added - to the medium if the mass flow rate is from port_a to port_b. - If the flow is reversed, then Q_flow=0. -

    -

    - The outlet conditions at port_a are not affected by this model, - other than for a possible pressure difference due to flow friction. -

    -

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, - the component models the dynamic response using a first order differential equation. - The time constant of the component is equal to the parameter tau. - This time constant is adjusted based on the mass flow rate using -

    -

    - τeff = τ |ṁ| ⁄ ṁnom + Three way valve with table-specified opening characteristics. + A separate characteristic for each flow path is used.

    - where - τeff is the effective time constant for the given mass flow rate - ṁ and - τ is the time constant at the nominal mass flow rate - ṁnom. - This type of dynamics is equal to the dynamics that a completely mixed - control volume would have. + Each flow path uses an instance of the model + + AixLib.Fluid.Actuators.Valves.TwoWayTable. + Therefore, this model needs to be parameterized the same way as + + AixLib.Fluid.Actuators.Valves.TwoWayTable. + Specifically, + the mass flow rate for the fully open valve is determined based + on the value of the parameter CvData. + For the different valve positions y ∈ [0, 1], this nominal flow rate is + scaled by the values of the parameter + flowCharacteristics1 and flowCharacteristics3, respectively. + These parameters declare a table of the form

    +
    + + + + + + +
    y 0 ... 1
    φ l ... 1

    - Optionally, this model can have a flow resistance. - Set dp_nominal = 0 to disable the flow friction calculation. + where l = Kv(y=0)/Kv(y=1) > 0 is the valve leakage. + The first row is the valve opening, and the second row is the + mass flow rate, relative to the mass flow rate of the fully open + valve, under the assumption of a constant pressure difference across the + valve. + A suggested value for the valve leakage is l=0.0001. + If l = 0, then this model will replace it with + l = 10-8 for numerical reasons. + For example, if a valve has Kv=0.5 [m3/h/bar1/2] and + a linear opening characteristics and + a valve leakage of l=0.0001, then one would set

    + 
    +  CvData=AixLib.Fluid.Types.CvTypes.Kv
+  Kv = 0.5
+  flowCharacteristics1(y={0,1}, phi={0.0001,1})
+  flowCharacteristics3(y={0,1}, phi={0.0001,1})
+

    - For a similar model that is a heater, use - - AixLib.Fluid.HeatExchangers.Heater_T. - For a model that uses a control signal u ∈ [0, 1] and multiplies - this with the nominal heating or cooling power, use - - AixLib.Fluid.HeatExchangers.HeaterCooler_u. + Note, however, that + + AixLib.Fluid.Actuators.Valves.ThreeWayLinear provides a more + efficient implementation for this simple case.

    -

    Limitations

    - If the flow is from port_b to port_a, - then the enthalpy of the medium is not affected by this model. + The parameters flowCharacteristics1 and flowCharacteristics3 must meet the following + requirements, otherwise the model stops with an error:

    +

    - This model does not affect the humidity of the air. Therefore, - if used to cool air below the dew point temperature, the water mass fraction - will not change. + This model is based on the partial valve model + + AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. + Check this model for more information, such + as the regularization near the origin.

    -

    Validation

    - The model has been validated against the analytical solution in - the examples - - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet - and - - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic. + For an example that specifies an opening characteristics, see + + AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable.

    + -------- Corrected Code --------

    - Model for an ideal sensible-only cooler that controls its outlet - temperature to a prescribed outlet temperature. + Three way valve with table-specified opening characteristics. A + separate characteristic for each flow path is used.

    - This model forces the outlet temperature at port_b to be - no higher than the temperature of the input signal TSet, - subject to optional limits on the capacity. By default, the model has - unlimited cooling capacity. -

    -

    - The output signal Q_flow ≤ 0 is the heat added to the - medium if the mass flow rate is from port_a to - port_b. If the flow is reversed, then - Q_flow=0. -

    -

    - The outlet conditions at port_a are not affected by this - model, other than for a possible pressure difference due to flow - friction. -

    -

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, the component - models the dynamic response using a first order differential - equation. The time constant of the component is equal to the - parameter tau. This time constant is adjusted based on - the mass flow rate using -

    -

    - τeff = τ |ṁ| ⁄ ṁnom -

    -

    - where τeff is the effective time constant for the - given mass flow rate ṁ and τ is the time constant at - the nominal mass flow rate ṁnom. This type of - dynamics is equal to the dynamics that a completely mixed control - volume would have. + Each flow path uses an instance of the model AixLib.Fluid.Actuators.Valves.TwoWayTable. + Therefore, this model needs to be parameterized the same way as + AixLib.Fluid.Actuators.Valves.TwoWayTable. + Specifically, the mass flow rate for the fully open valve is + determined based on the value of the parameter CvData. + For the different valve positions y ∈ [0, 1], this nominal + flow rate is scaled by the values of the parameter + flowCharacteristics1 and + flowCharacteristics3, respectively. These parameters + declare a table of the form

    + + + + + + + + + + + + + +
    + y + + 0 + + ... + + 1 +
    + φ + + l + + ... + + 1 +

    - Optionally, this model can have a flow resistance. Set - dp_nominal = 0 to disable the flow friction calculation. + where l = Kv(y=0)/Kv(y=1) > 0 is the + valve leakage. The first row is the valve opening, and the second row + is the mass flow rate, relative to the mass flow rate of the fully + open valve, under the assumption of a constant pressure difference + across the valve. A suggested value for the valve leakage is + l=0.0001. If l = 0, then this model will replace it + with l = 10-8 for numerical reasons. For example, + if a valve has Kv=0.5 + [m3/h/bar1/2] and a linear opening + characteristics and a valve leakage of l=0.0001, then one + would set

    +
    +  CvData=AixLib.Fluid.Types.CvTypes.Kv
+  Kv = 0.5
+  flowCharacteristics1(y={0,1}, phi={0.0001,1})
+  flowCharacteristics3(y={0,1}, phi={0.0001,1})
+

    - For a similar model that is a heater, use AixLib.Fluid.HeatExchangers.Heater_T. - For a model that uses a control signal u ∈ [0, 1] and - multiplies this with the nominal heating or cooling power, use - AixLib.Fluid.HeatExchangers.HeaterCooler_u. + Note, however, that AixLib.Fluid.Actuators.Valves.ThreeWayLinear + provides a more efficient implementation for this simple case.

    -

    - Limitations -

    - If the flow is from port_b to port_a, then - the enthalpy of the medium is not affected by this model. + The parameters flowCharacteristics1 and + flowCharacteristics3 must meet the following + requirements, otherwise the model stops with an error:

    +

    - This model does not affect the humidity of the air. Therefore, if - used to cool air below the dew point temperature, the water mass - fraction will not change. + This model is based on the partial valve model AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. + Check this model for more information, such as the regularization + near the origin.

    -

    - Validation -

    - The model has been validated against the analytical solution in the - examples AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet - and - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic. + For an example that specifies an opening characteristics, see + + AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable.

    -------- Errors -------- -line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 21 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 ----- AixLib/Fluid/FMI/ExportContainers/HVACZone.mo ---- +---- AixLib/Fluid/Movers/BaseClasses/Characteristics/pressure.mo ---- -------- HTML Code --------

    - Model that is used as a container for an HVAC system that is - to be exported as an FMU and that serves a single zone. -

    -

    Typical use and important parameters

    -

    - To use this model as a container for an FMU, extend - from this model, rather than instantiate it, - and add your HVAC system. By extending from this model, the top-level - signal connectors on the right stay at the top-level, and hence - will be visible at the FMI interface. - The example - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone - shows how a simple HVAC system can be implemented and exported as - an FMU. - -

    -

    - The conversion between the fluid ports and signal ports is done - in the HVAC adapter hvacAda. - This adapter has a vector of fluid ports called ports. - The supply and return air ducts, including any resistance model for the inlet - diffusor or exhaust grill, need to be connected to these ports. - Also, if a thermal zone has interzonal air exchange or air infiltration, - these flows need to be connected to ports. - This model outputs at the port fluPor the mass flow rate for - each flow that is connected to ports, together with its - temperature, water vapor mass fraction per total mass of the air (not per kg dry - air), and trace substances. These quantities are always as if the flow - enters the room, even if the flow is zero or negative. - If a medium has no moisture, e.g., if Medium.nXi=0, or - if it has no trace substances, e.g., if Medium.nC=0, then - the output signal for these properties are removed. - These quantities are always as if the flow - enters the room, even if the flow is zero or negative. - Thus, a thermal zone model that uses these signals to compute the - heat added by the HVAC system needs to implement an equation such as + This function computes the fan static + pressure raise as a function of volume flow rate and revolution in the form

    - Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), + Δp = rN2   s(V̇/rN, d),

    where - Qsen is the sensible heat flow rate added to the thermal zone, - ṁsup is the supply air mass flow rate from - the port fluPor (which is negative if it is an exhaust), - cp is the specific heat capacity at constant pressure, - Tsup is the supply air temperature and - Tair,zon is the zone air temperature. - Note that without the max(·, ·), the energy - balance would be wrong. -

    -

    - The input signals of this model are the zone radiative temperature. - The the zone air temperature, - the water vapor mass fraction per total mass of the air (unless Medium.nXi=0) - and trace substances (unless Medium.nC=0) are obtained from the connector - fluPor.backward. - The outflowing fluid stream(s) at the port ports will be at the - states obtained from fluPor.backward. - All fluid streams at port ports are at the same - pressure. - For convenience, the instance hvacAda also outputs the - properties obtained from fluPor.backward. These can be used - to connect a controller. The properties are available for each flow path in - fluPor.backward. For a thermal zone with mixed air, these are - all equal, while for a stratified room model, they can be different. + Δp is the pressure rise, + rN is the normalized fan speed, + V̇ is the volume flow rate and + d are performance data for fan or pump power consumption at rN=1.

    - +

    Implementation

    - See - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone - for a model that uses this model. + The function s(·, ·) is a cubic hermite spline. + If the data d define a monotone decreasing sequence, then + s(·, d) is a monotone decreasing function.

    - For models that multiple thermal zones connected to the HVAC system, - use the model - - AixLib.Fluid.FMI.ExportContainers.HVACZones. -

    -

    Assumption and limitations

    -

    - The mass flow rates at ports sum to zero, hence this - model conserves mass. -

    -

    - This model does not impose any pressure, other than setting the pressure - of all fluid connections to ports to be equal. - The reason is that setting a pressure can lead to non-physical system models, - for example if a mass flow rate is imposed and the HVAC system is connected - to a model that sets a pressure boundary condition such as - - AixLib.Fluid.Sources.Outside. - Also, setting a pressure would make it impossible to use multiple instances - of this model (one for each thermal zone) and build in Modelica an airflow network - model with pressure driven mass flow rates. -

    -

    - The model has no pressure drop. Hence, the pressure drop - of an air diffuser or of an exhaust grill needs to be modelled - in models that are connected to ports. + The function allows rN to be zero.

    -------- Corrected Code --------

    - Model that is used as a container for an HVAC system that is to be - exported as an FMU and that serves a single zone. -

    -

    - Typical use and important parameters -

    -

    - To use this model as a container for an FMU, extend from this model, - rather than instantiate it, and add your HVAC system. By extending - from this model, the top-level signal connectors on the right stay at - the top-level, and hence will be visible at the FMI interface. The - example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone shows - how a simple HVAC system can be implemented and exported as an FMU. - -

    -

    - The conversion between the fluid ports and signal ports is done in - the HVAC adapter hvacAda. This adapter has a vector of - fluid ports called ports. The supply and return air - ducts, including any resistance model for the inlet diffusor or - exhaust grill, need to be connected to these ports. Also, if a - thermal zone has interzonal air exchange or air infiltration, these - flows need to be connected to ports. This model outputs - at the port fluPor the mass flow rate for each flow that - is connected to ports, together with its temperature, - water vapor mass fraction per total mass of the air (not per kg dry - air), and trace substances. These quantities are always as if the - flow enters the room, even if the flow is zero or negative. If a - medium has no moisture, e.g., if Medium.nXi=0, or if it - has no trace substances, e.g., if Medium.nC=0, then the - output signal for these properties are removed. These quantities are - always as if the flow enters the room, even if the flow is zero or - negative. Thus, a thermal zone model that uses these signals to - compute the heat added by the HVAC system needs to implement an - equation such as + This function computes the fan static pressure raise as a function of + volume flow rate and revolution in the form

    - Qsen = max(0, ṁsup)   cp   - (Tsup - Tair,zon), -

    -

    - where Qsen is the sensible heat flow rate added to - the thermal zone, ṁsup is the supply air mass flow - rate from the port fluPor (which is negative if it is an - exhaust), cp is the specific heat capacity at - constant pressure, Tsup is the supply air - temperature and Tair,zon is the zone air - temperature. Note that without the max(·, ·), the energy - balance would be wrong. -

    -

    - The input signals of this model are the zone radiative temperature. - The the zone air temperature, the water vapor mass fraction per total - mass of the air (unless Medium.nXi=0) and trace - substances (unless Medium.nC=0) are obtained from the - connector fluPor.backward. The outflowing fluid - stream(s) at the port ports will be at the states - obtained from fluPor.backward. All fluid streams at port - ports are at the same pressure. For convenience, the - instance hvacAda also outputs the properties obtained - from fluPor.backward. These can be used to connect a - controller. The properties are available for each flow path in - fluPor.backward. For a thermal zone with mixed air, - these are all equal, while for a stratified room model, they can be - different. -

    -

    - See - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone for a - model that uses this model. + Δp = rN2   s(V̇/rN, d),

    - For models that multiple thermal zones connected to the HVAC system, - use the model AixLib.Fluid.FMI.ExportContainers.HVACZones. + where Δp is the pressure rise, rN is the + normalized fan speed, V̇ is the volume flow rate and d + are performance data for fan or pump power consumption at + rN=1.

    - Assumption and limitations + Implementation

    - The mass flow rates at ports sum to zero, hence this - model conserves mass. -

    -

    - This model does not impose any pressure, other than setting the - pressure of all fluid connections to ports to be equal. - The reason is that setting a pressure can lead to non-physical system - models, for example if a mass flow rate is imposed and the HVAC - system is connected to a model that sets a pressure boundary - condition such as AixLib.Fluid.Sources.Outside. - Also, setting a pressure would make it impossible to use multiple - instances of this model (one for each thermal zone) and build in - Modelica an airflow network model with pressure driven mass flow - rates. + The function s(·, ·) is a cubic hermite spline. If the data + d define a monotone decreasing sequence, then s(·, d) + is a monotone decreasing function.

    - The model has no pressure drop. Hence, the pressure drop of an air - diffuser or of an exhaust grill needs to be modelled in models that - are connected to ports. + The function allows rN to be zero.

    -------- Errors -------- -line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Chillers/Carnot_y.mo ---- +---- AixLib/Fluid/HeatPumps/Carnot_TCon.mo ---- -------- HTML Code --------

    - This is model of a chiller whose coefficient of performance COP changes + This is a model of a heat pump whose coefficient of performance COP changes with temperatures in the same way as the Carnot efficiency changes. - The input signal y is the control signal for the compressor. + The control input is the setpoint of the condenser leaving temperature, which + is met exactly at steady state if the heat pump has sufficient capacity.

    The model allows to either specify the Carnot effectivness @@ -1242,17 +1325,17 @@ line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5

    ηCarnot,0 = COP0 - ⁄ (Teva,0 ⁄ (Tcon,0-Teva,0)). + ⁄ (Tcon,0 ⁄ (Tcon,0-Teva,0)).

    - The chiller COP is computed as the product + The heat pump COP is computed as the product

    COP = ηCarnot,0 COPCarnot ηPL,

    where COPCarnot is the Carnot efficiency and - ηPL is a polynomial in the cooling part load ratio yPL + ηPL is a polynomial in heating part load ratio yPL that can be used to take into account a change in COP at part load conditions. This polynomial has the form @@ -1269,25 +1352,25 @@ line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5 or steady-state response. The transient response of the model is computed using a first order differential equation for the evaporator and condenser fluid volumes. - The chiller outlet temperatures are equal to the temperatures of these lumped volumes. + The heat pump outlet temperatures are equal to the temperatures of these lumped volumes.

    Typical use and important parameters

    - When using this component, make sure that the evaporator and the condenser have sufficient mass flow rate. - Based on the mass flow rates, the compressor power, temperature difference and the efficiencies, - the model computes how much heat will be added to the condenser and removed at the evaporator. - If the mass flow rates are too small, very high temperature differences can result. + When using this component, make sure that the condenser has sufficient mass flow rate. + Based on the evaporator mass flow rate, temperature difference and the efficiencies, + the model computes how much heat will be removed by to the evaporator. + If the mass flow rate is too small, very low outlet temperatures can result, possibly below freezing.

    - The evaporator heat flow rate QEva_flow_nominal is used to assign + The condenser heat flow rate QCon_flow_nominal is used to assign the default value for the mass flow rates, which are used for the pressure drop calculations. It is also used to compute the part load efficiency. - Hence, make sure that QEva_flow_nominal is set to a reasonable value. + Hence, make sure that QCon_flow_nominal is set to a reasonable value.

    - The maximum cooling capacity is set by the parameter QEva_flow_min, - which is by default set to negative infinity. + The maximum heating capacity is set by the parameter QCon_flow_max, + which is by default set to infinity.

    The coefficient of performance depends on the @@ -1296,13 +1379,14 @@ line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5

    Notes

    - For a similar model that can be used as a heat pump, see - AixLib.Fluid.HeatPumps.Carnot_y. + For a similar model that can be used as a chiller, see + + AixLib.Fluid.Chillers.Examples.Carnot_TEva.

    -------- Corrected Code --------

    - This is model of a chiller whose coefficient of performance COP + This is a model of a heat pump whose coefficient of performance COP changes with temperatures in the same way as the Carnot efficiency - changes. The input signal y is the control signal for the - compressor. + changes. The control input is the setpoint of the condenser leaving + temperature, which is met exactly at steady state if the heat pump + has sufficient capacity.

    The model allows to either specify the Carnot effectivness @@ -1394,18 +1426,18 @@ line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5 effectivness as

    - ηCarnot,0 = COP0 ⁄ (Teva,0 ⁄ + ηCarnot,0 = COP0 ⁄ (Tcon,0 ⁄ (Tcon,0-Teva,0)).

    - The chiller COP is computed as the product + The heat pump COP is computed as the product

    COP = ηCarnot,0 COPCarnot ηPL,

    where COPCarnot is the Carnot efficiency and - ηPL is a polynomial in the cooling part load ratio + ηPL is a polynomial in heating part load ratio yPL that can be used to take into account a change in COP at part load conditions. This polynomial has the form

    @@ -1421,31 +1453,30 @@ line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5 On the Dynamics tag, the model can be parametrized to compute a transient or steady-state response. The transient response of the model is computed using a first order differential equation - for the evaporator and condenser fluid volumes. The chiller outlet + for the evaporator and condenser fluid volumes. The heat pump outlet temperatures are equal to the temperatures of these lumped volumes.

    Typical use and important parameters

    - When using this component, make sure that the evaporator and the - condenser have sufficient mass flow rate. Based on the mass flow - rates, the compressor power, temperature difference and the - efficiencies, the model computes how much heat will be added to the - condenser and removed at the evaporator. If the mass flow rates are - too small, very high temperature differences can result. + When using this component, make sure that the condenser has + sufficient mass flow rate. Based on the evaporator mass flow rate, + temperature difference and the efficiencies, the model computes how + much heat will be removed by to the evaporator. If the mass flow rate + is too small, very low outlet temperatures can result, possibly below + freezing.

    - The evaporator heat flow rate QEva_flow_nominal is used + The condenser heat flow rate QCon_flow_nominal is used to assign the default value for the mass flow rates, which are used for the pressure drop calculations. It is also used to compute the part load efficiency. Hence, make sure that - QEva_flow_nominal is set to a reasonable value. + QCon_flow_nominal is set to a reasonable value.

    - The maximum cooling capacity is set by the parameter - QEva_flow_min, which is by default set to negative - infinity. + The maximum heating capacity is set by the parameter + QCon_flow_max, which is by default set to infinity.

    The coefficient of performance depends on the evaporator and @@ -1456,11 +1487,11 @@ line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5 Notes

    - For a similar model that can be used as a heat pump, see AixLib.Fluid.HeatPumps.Carnot_y. + For a similar model that can be used as a chiller, see AixLib.Fluid.Chillers.Examples.Carnot_TEva.

    -------- Errors -------- -line 16 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 24 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 34 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 17 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 35 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Movers/Data/Pumps/Wilo/Stratos25slash1to6.mo ---- +---- AixLib/Fluid/HeatExchangers/ActiveBeams/BaseClasses/Convector.mo ---- -------- HTML Code -------- -

    Data from - - http://productfinder.wilo.com/en/COM/product/00000018000028040002003a/fc_product_datasheet +

    + In cooling mode, this model adds heat to the water stream. The heat added is equal to: +

    +

    + QBeam = Qrated fΔT fSA fW

    - The nominal rpm is arbitrarily chosen as the rpm of the pump curve - in the data sheet that has the highest rpm, - without being limited by the maximum power limitation - (see dotted curve on figure below). - Pump curves (H(m_flow) and P(m_flow)) from the data sheets - are digitized using - web plot digitizer. + In heating mode, the heat is removed from the water stream.

    -

    Limitations:

    + -

    - The figure below illustrates a digitized pump curve. -

    -

    - \"Pump

    - - -------- Corrected Code --------

    - Data from - http://productfinder.wilo.com/en/COM/product/00000018000028040002003a/fc_product_datasheet + In cooling mode, this model adds heat to the water stream. The heat + added is equal to: +

    +

    + QBeam = Qrated fΔT + fSA fW

    - The nominal rpm is arbitrarily chosen as the rpm of the pump curve in - the data sheet that has the highest rpm, without being limited by the - maximum power limitation (see dotted curve on figure below). Pump - curves (H(m_flow) and P(m_flow)) from the data sheets are digitized - using web plot - digitizer. + In heating mode, the heat is removed from the water stream.

    -

    - Limitations: -

    -

    - The figure below illustrates a digitized pump curve. -

    -

    - \"Pump -

    - -------- Errors -------- -line 27 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Utilities/Math/Functions/bicubic.mo ---- +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/finiteLineSource.mo ---- -------- HTML Code -------- - This function computes -

    - y = a1 - + a2 x1 + a3 x12 - + a4 x2 + a5 x22 - + a6 x1 x2 - + a7 x1^3 - + a8 x2^3 - + a9 x12 x2 - + a10 x1 x22 +

    + This function evaluates the finite line source solution. This solution + gives the relation between the constant heat transfer rate (per unit length) + injected by a line source of finite length H1 buried at a + distance D1 from a constant temperature surface + (T=0) and the average temperature raise over a line of finite length + H2 buried at a distance D2 from the constant + temperature surface. + The finite line source solution is defined by: +

    +

    + \"image\" +

    +

    + where ΔT1-2(t,r,H1,D1,H2,D2) + is the temperature raise after a time t of constant heat injection and at + a distance r from the line heat source, Q' is the heat injection + rate per unit length, ks is the soil thermal conductivity and + hFLS is the finite line source solution. +

    +

    + The finite line source solution is given by: +

    +

    + \"image\" +

    +

    + where αs is the ground thermal diffusivity and + erfint is the integral of the error function, defined in + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_erfint. + The integral is solved numerically, with the integrand defined in + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_Integrand.

    -------- Corrected Code -------- -This function computes -

    - y = a1 + a2 x1 + a3 - x12 + a4 x2 + - a5 x22 + a6 x1 - x2 + a7 x1^3 + a8 - x2^3 + a9 x12 - x2 + a10 x1 - x22 +

    + This function evaluates the finite line source solution. This + solution gives the relation between the constant heat transfer rate + (per unit length) injected by a line source of finite length + H1 buried at a distance D1 from a + constant temperature surface (T=0) and the average temperature + raise over a line of finite length H2 buried at a + distance D2 from the constant temperature surface. + The finite line source solution is defined by: +

    +

    + \"image\" +

    +

    + where + ΔT1-2(t,r,H1,D1,H2,D2) + is the temperature raise after a time t of constant heat + injection and at a distance r from the line heat source, + Q' is the heat injection rate per unit length, + ks is the soil thermal conductivity and + hFLS is the finite line source solution. +

    +

    + The finite line source solution is given by: +

    +

    + \"image\" +

    +

    + where αs is the ground thermal diffusivity and + erfint is the integral of the error function, defined in + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_erfint. + The integral is solved numerically, with the integrand defined in + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource_Integrand.

    -------- Errors -------- -line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/FixedResistances/HydraulicDiameter.mo ---- +---- AixLib/Fluid/Movers/Validation/PowerExact.mo ---- -------- HTML Code --------

    - This is a model of a flow resistance with a fixed flow coefficient. - The mass flow rate is computed as -

    -

    - ṁ = k - √ΔP, -

    -

    - where - k is a constant and - ΔP is the pressure drop. - The constant k is equal to - k=m_flow_nominal/sqrt(dp_nominal), - where m_flow_nominal is a parameter. -

    -

    Assumptions

    -

    - In the region - abs(m_flow) < m_flow_turbulent, - the square root is replaced by a differentiable function - with finite slope. - The value of m_flow_turbulent is - computed as - m_flow_turbulent = eta_nominal*dh/4*π*ReC, - where - eta_nominal is the dynamic viscosity, obtained from - the medium model. The parameter - dh is the hydraulic diameter and - ReC=4000 is the critical Reynolds number, which both - can be set by the user. -

    -

    Important parameters

    -

    - By default, the pressure drop at nominal flow rate is computed as -

    - 
    - dp_nominal = fac * dpStraightPipe_nominal,
-
    -

    - where dpStraightPipe_nominal is a parameter that is automatically computed - based on the - nominal mass flow rate, hydraulic diameter, pipe roughness and medium properties. - The hydraulic diameter dh is by default - computed based on the flow velocity v_nominal and the nominal - mass flow rate m_flow_nominal. Hence, users should change the - default values of dh or v_nominal - if they are not applicable for their model. -

    -

    - The factor fac takes into account additional resistances such as - for bends. The default value of 2 can be changed by the user. -

    -

    - The parameter from_dp is used to determine - whether the mass flow rate is computed as a function of the - pressure drop (if from_dp=true), or vice versa. - This setting can affect the size of the nonlinear system of equations. -

    -

    - If the parameter linearized is set to true, - then the pressure drop is computed as a linear function of the - mass flow rate. -

    -

    - Setting allowFlowReversal=false can lead to simpler - equations. However, this should only be set to false - if one can guarantee that the flow never reverses its direction. - This can be difficult to guarantee, as pressure imbalance after - the initialization, or due to medium expansion and contraction, - can lead to reverse flow. -

    -

    - If the parameter - show_T is set to true, - then the model will compute the - temperature at its ports. Note that this can lead to state events - when the mass flow rate approaches zero, - which can increase computing time. -

    -

    Notes

    -

    - For more detailed models that compute the actual flow friction, - models from the package - - Modelica.Fluid - can be used and combined with models from the - AixLib library. + This example is identical to + + AixLib.Fluid.Movers.Validation.PowerSimplified, except that the + performance data for the flow controlled pumps + pump_dp and pump_m_flow contain + the pressure curves and efficiency curves. + The plot below shows that this leads to a computation of the power consumption + that is identical to the one from the speed controlled pump pump_Nrpm.

    -

    - For a model that uses dp_nominal as a parameter rather than - geoemetric data, use - - AixLib.Fluid.FixedResistances.PressureDrop. +

    + \"image\"

    -

    Implementation

    + + + +-------- Corrected Code -------- +

    + This example is identical to AixLib.Fluid.Movers.Validation.PowerSimplified, + except that the performance data for the flow controlled pumps + pump_dp and pump_m_flow contain the + pressure curves and efficiency curves. The plot below shows that this + leads to a computation of the power consumption that is identical to + the one from the speed controlled pump pump_Nrpm. +

    +

    + \"image\" +

    + + +-------- Errors -------- +line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp.mo ---- +-------- HTML Code -------- +

    - The pressure drop is computed by calling a function in the package - - AixLib.Fluid.BaseClasses.FlowModels, - This package contains regularized implementations of the equation + Function that computes the pressure drop of flow elements as

    m = sign(Δp) k √ Δp  

    - and its inverse function. + with regularization near the origin. + Therefore, the flow coefficient is +

    +

    + k = m ⁄ √ Δp  

    - To decouple the energy equation from the mass equations, - the pressure drop is a function of the mass flow rate, - and not the volume flow rate. - This leads to simpler equations. + The input m_flow_turbulent determines the location of the regularization.

    - --------- Corrected Code -------- -

    - This is a model of a flow resistance with a fixed flow coefficient. - The mass flow rate is computed as -

    -

    - ṁ = k √ΔP, -

    -

    - where k is a constant and ΔP is the pressure drop. The - constant k is equal to - k=m_flow_nominal/sqrt(dp_nominal), where - m_flow_nominal is a parameter. -

    -

    - Assumptions -

    -

    - In the region abs(m_flow) < m_flow_turbulent, the - square root is replaced by a differentiable function with finite - slope. The value of m_flow_turbulent is computed as - m_flow_turbulent = eta_nominal*dh/4*π*ReC, where - eta_nominal is the dynamic viscosity, obtained from the - medium model. The parameter dh is the hydraulic diameter - and ReC=4000 is the critical Reynolds number, which both - can be set by the user. -

    -

    - Important parameters -

    -

    - By default, the pressure drop at nominal flow rate is computed as -

    -
    - dp_nominal = fac * dpStraightPipe_nominal,
-
    -

    - where dpStraightPipe_nominal is a parameter that is - automatically computed based on the nominal mass flow rate, hydraulic - diameter, pipe roughness and medium properties. The hydraulic - diameter dh is by default computed based on the flow - velocity v_nominal and the nominal mass flow rate - m_flow_nominal. Hence, users should change the default - values of dh or v_nominal if they are not - applicable for their model. -

    -

    - The factor fac takes into account additional resistances - such as for bends. The default value of 2 can be changed - by the user. -

    -

    - The parameter from_dp is used to determine whether the - mass flow rate is computed as a function of the pressure drop (if - from_dp=true), or vice versa. This setting can affect - the size of the nonlinear system of equations. -

    -

    - If the parameter linearized is set to true, - then the pressure drop is computed as a linear function of the mass - flow rate. -

    -

    - Setting allowFlowReversal=false can lead to simpler - equations. However, this should only be set to false if - one can guarantee that the flow never reverses its direction. This - can be difficult to guarantee, as pressure imbalance after the - initialization, or due to medium expansion and contraction, can lead - to reverse flow. -

    -

    - If the parameter show_T is set to true, - then the model will compute the temperature at its ports. Note that - this can lead to state events when the mass flow rate approaches - zero, which can increase computing time. -

    -

    - Notes -

    -

    - For more detailed models that compute the actual flow friction, - models from the package Modelica.Fluid can be used and - combined with models from the AixLib library. -

    -

    - For a model that uses dp_nominal as a parameter rather - than geoemetric data, use AixLib.Fluid.FixedResistances.PressureDrop. -

    -

    - Implementation -

    +
  • + May 1, 2017, by Filip Jorissen:
    + Revised implementation such that + basicFlowFunction_dp + is C2 continuous. + See #725. +
    • +
  • + March 19, 2016, by Michael Wetter:
    + Added abs function for + AixLib.Fluid.FixedResistances.Validation.PressureDropsExplicit + to work in OpenModelica. + See + OpenModelica ticket 3778. +
    • +
  • + January 22, 2016, by Michael Wetter:
    + Corrected type declaration of pressure difference. + This is + for #404. +
    • +
  • + July 28, 2015, by Michael Wetter:
    + Removed double declaration of smooth(..) and smoothOrder + and changed Inline=true to LateInline=true. + This is for + issue 301. +
    • +
  • + July 15, 2015, by Filip Jorissen:
    + New, more efficient implementation based on regularisation using simple polynomial. + Expanded common subexpressions for function inlining to be possible. + Set Inline=true for inlining to occur. + This is for + #279. +
    • +
  • + January 9, 2014, by Michael Wetter:
    + Correct revision section, of which there were two. +
    • +
  • + August 10, 2011, by Michael Wetter:
    + Removed if-then optimization that set m_flow=0 if dp=0, + as this causes the derivative to be discontinuous at dp=0. +
    • +
  • + August 4, 2011, by Michael Wetter:
    + Removed option to use a linear function. The linear implementation is now done + in models that call this function. With the previous implementation, + the symbolic processor may not rearrange the equations, which can lead + to coupled equations instead of an explicit solution. +
    • +
  • + March 29, 2010 by Michael Wetter:
    + Changed implementation to allow k=0, which is + the case for a closed valve with no leakage +
    • +
  • + April 13, 2009, by Michael Wetter:
    + First implementation. +
    • + + +-------- Corrected Code --------

    - The pressure drop is computed by calling a function in the package - AixLib.Fluid.BaseClasses.FlowModels, - This package contains regularized implementations of the equation + Function that computes the pressure drop of flow elements as

    m = sign(Δp) k √ Δp  

    - and its inverse function. + with regularization near the origin. Therefore, the flow coefficient + is +

    +

    + k = m ⁄ √ Δp +  

    - To decouple the energy equation from the mass equations, the pressure - drop is a function of the mass flow rate, and not the volume flow - rate. This leads to simpler equations. + The input m_flow_turbulent determines the location of + the regularization.

    -------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 104 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatPumps/Carnot_y.mo ---- +---- AixLib/Fluid/Chillers/Carnot_y.mo ---- -------- HTML Code --------

    - This is model of a heat pump whose coefficient of performance COP changes + This is model of a chiller whose coefficient of performance COP changes with temperatures in the same way as the Carnot efficiency changes. The input signal y is the control signal for the compressor.

    @@ -1952,17 +1975,17 @@ line 104 column 2 - Warning:

    attribute "align" not allowed for HTML5

    ηCarnot,0 = COP0 - ⁄ (Tcon,0 ⁄ (Tcon,0-Teva,0)). + ⁄ (Teva,0 ⁄ (Tcon,0-Teva,0)).

    - The heat pump COP is computed as the product + The chiller COP is computed as the product

    COP = ηCarnot,0 COPCarnot ηPL,

    where COPCarnot is the Carnot efficiency and - ηPL is a polynomial in the heating part load ratio yPL + ηPL is a polynomial in the cooling part load ratio yPL that can be used to take into account a change in COP at part load conditions. This polynomial has the form @@ -1971,14 +1994,15 @@ line 104 column 2 - Warning:

    attribute "align" not allowed for HTML5 ηPL = a1 + a2 yPL + a3 yPL2 + ...

    - where the coefficients ai are declared by the parameter a. + where the coefficients ai + are declared by the parameter a.

    On the Dynamics tag, the model can be parametrized to compute a transient or steady-state response. The transient response of the model is computed using a first order differential equation for the evaporator and condenser fluid volumes. - The heat pump outlet temperatures are equal to the temperatures of these lumped volumes. + The chiller outlet temperatures are equal to the temperatures of these lumped volumes.

    Typical use and important parameters

    @@ -1988,15 +2012,15 @@ line 104 column 2 - Warning:

    attribute "align" not allowed for HTML5 If the mass flow rates are too small, very high temperature differences can result.

    - The condenser heat flow rate QCon_flow_nominal is used to assign + The evaporator heat flow rate QEva_flow_nominal is used to assign the default value for the mass flow rates, which are used for the pressure drop calculations. It is also used to compute the part load efficiency. - Hence, make sure that QCon_flow_nominal is set to a reasonable value. + Hence, make sure that QEva_flow_nominal is set to a reasonable value.

    - The maximum heating capacity is set by the parameter QCon_flow_max, - which is by default set to infinity. + The maximum cooling capacity is set by the parameter QEva_flow_min, + which is by default set to negative infinity.

    The coefficient of performance depends on the @@ -2005,13 +2029,13 @@ line 104 column 2 - Warning:

    attribute "align" not allowed for HTML5

    Notes

    - For a similar model that can be used as a chiller, see - AixLib.Fluid.Chillers.Carnot_y. + For a similar model that can be used as a heat pump, see + AixLib.Fluid.HeatPumps.Carnot_y.

    + + + + + + +
    Correct use + \"image\" +
    Not recommended + \"image\" +
    +

    - Models that extend from this partial model need to provide an - assignment for UA. +Except for the mass flow rate sensor, +all sensors with two ports can be +configured as dynamic sensors or as steady-state sensor. +The list below advices on how to configure sensors.

    +

    +The table below summarizes the recommendations for the use of sensors. +

    + + + + + + + + + + + + + + + + + + + + + + + +
    Measured quantityOne port sensorTwo port sensor
    steady-state (tau=0)dynamic (tau > 0)
    temperature
    + relative humidity
    + mass fraction
    + trace substances
    + specific enthalpy
    + specific entropy    		use only if connected to a volumeavoidrecommended
    volume flow rate
    + enthalpy flow rate
    + entropy flow rate    		-recommendedrecommended
    pressurerecommendedrecommendedrecommended
    --------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/HeatExchangers/ActiveBeams/BaseClasses/Convector.mo ---- --------- HTML Code -------- - -

    - In cooling mode, this model adds heat to the water stream. The heat added is equal to: -

    -

    - QBeam = Qrated fΔT fSA fW -

    -

    - In heating mode, the heat is removed from the water stream. -

    - - - --------- Corrected Code -------- +

    Sensor Dynamics

    +
    Dynamic response to fluid flowing through the sensor

    - In cooling mode, this model adds heat to the water stream. The heat - added is equal to: +If a sensor is configured as a dynamic sensor by setting tau > 0, +then the measured quantity, say the temperature T, is +computed as

    - QBeam = Qrated fΔT - fSA fW + τ   dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T),

    - In heating mode, the heat is removed from the water stream. +where τ is a user-defined time constant of the sensor (a suggested value is around 10 seconds, +which is the default setting for the components), +dT ⁄ dt is the time derivative of the sensor output signal, +|ṁ| is the absolute value of the mass flow rate, +ṁ0 is the user-specified nominal value of the mass flow rate and +θ is the temperature of the medium inside the sensor. +An equivalent physical model of such a sensor would be a perfectly mixed volume +with a sensor that outputs the temperature of this volume. In this situation, the size of the volume would +be V=τ   ṁ0 ⁄ ρ, where +ρ is the density of the fluid.

    - - --------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/FixedResistances/Junction.mo ---- --------- HTML Code -------- - -

    - Model of a flow junction with an optional fixed resistance in each flow leg - and an optional mixing volume at the junction. -

    -

    - The pressure drop is implemented using the model - - AixLib.Fluid.FixedResistances.PressureDrop. - If its nominal pressure drop is set to zero, then the pressure drop - model will be removed. - For example, the pressure drop declaration -

    - 
    -   m_flow_nominal={ 0.1, 0.1,  -0.2},
-   dp_nominal =   {500,    0, -6000}
-
    -

    - would model a flow mixer that has the nominal flow rates and associated pressure drops - as shown in the figure below. Note that port_3 is set to negative values. - The negative values indicate that at the nominal conditions, fluid is leaving the component. -

    -

    - \"image\" -

    -

    - If - energyDynamics <> Modelica.Fluid.Types.Dynamics.SteadyState, - then at the flow junction, a fluid volume is modeled. - The fluid volume is implemented using the model - - AixLib.Fluid.Delays.DelayFirstOrder. - The fluid volume has the size -

    - 
    -   V = sum(abs(m_flow_nominal[:])/3)*tau/rho_nominal
-
    -

    - where tau is a parameter and rho_nominal is the density - of the medium in the volume at nominal condition. - Setting energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial - can help reducing the size of the nonlinear - system of equations. -

    - - - --------- Corrected Code -------- +
    Dynamic response to ambient temperature

    - Model of a flow junction with an optional fixed resistance in each - flow leg and an optional mixing volume at the junction. +For the sensor + +AixLib.Fluid.Sensors.TemperatureTwoPort, +by setting transferHeat = true, heat transfer to a +fixed ambient can be approximated. The heat transfer is computed as +

    +

    + τHeaTra   dT ⁄ dt = (TAmb-T),

    - The pressure drop is implemented using the model AixLib.Fluid.FixedResistances.PressureDrop. - If its nominal pressure drop is set to zero, then the pressure drop - model will be removed. For example, the pressure drop declaration +where τHeaTra is a fixed time constant and +TAmb is a fixed ambient temperature. +Setting transferHeat = true is useful if the sensor output T +is used to switch the mass flow rate on again. If transferHeat = false, +then the sensor output T remains constant if the mass flow rate is zero +and hence a fan or pump controller that uses this signal may never switch the device +on again. +If the sensor output T is not used to switch on the mass flow rate, then +in general one can use transferHeat=false.

    -
    -   m_flow_nominal={ 0.1, 0.1,  -0.2},
-   dp_nominal =   {500,    0, -6000}
-

    - would model a flow mixer that has the nominal flow rates and - associated pressure drops as shown in the figure below. Note that - port_3 is set to negative values. The negative values - indicate that at the nominal conditions, fluid is leaving the - component. +Note that since in practice the heat transfer is due to a combination of ambient +temperature and upstream or downstream fluid temperature, for example by two-way +buoyancy-driven flow inside the duct or pipe, the model uses as an approximation +a fixed ambient temperature. +Since the sensor is not affecting the temperature of the medium, this approximation +of the heat transfer does not add or remove heat from the fluid.

    -

    - \"image\" +

    Combined dynamic response
    +

    +For the sensor + +AixLib.Fluid.Sensors.TemperatureTwoPort, +if both dynamic effects are enabled, then +the output T is computed as

    +

    +dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T) ⁄ τ + +(TAmb-T) ⁄ τHeaTra. +

    +

    Implementation

    - If energyDynamics <> - Modelica.Fluid.Types.Dynamics.SteadyState, then at the flow - junction, a fluid volume is modeled. The fluid volume is implemented - using the model AixLib.Fluid.Delays.DelayFirstOrder. - The fluid volume has the size +The above equation is implemented in such a way that it is differentiable in the mass flow rate.

    -
    -   V = sum(abs(m_flow_nominal[:])/3)*tau/rho_nominal
-

    - where tau is a parameter and rho_nominal is - the density of the medium in the volume at nominal condition. Setting - energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial - can help reducing the size of the nonlinear system of equations. +Note that the implementation of the dynamic sensors does not use the model + +AixLib.Fluid.MixingVolumes. +The reason is that depending on the selected medium model, the +mixing volume may introduce states for the pressure, species concentration, +trace substance, specific enthalpy and specific entropy. Not all states are typically needed to +model the dynamics of a sensor. Moreover, in many building system applications, +the sensor dynamics is not of concern, but is rather used here to avoid numerical +problems that steady-state models of sensors cause when flow rates are +very close to zero.

    - - --------- Errors -------- -line 23 column 2 - Warning:

    attribute "align" not allowed for HTML5 - ----- AixLib/Media/Water.mo ---- --------- HTML Code -------- - -

    - Model with basic thermodynamic properties. -

    -

    - This base properties model is identical to - - Modelica.Media.Water.ConstantPropertyLiquidWater, - except that the equation - u = cv_const*(T - reference_T) - has been replaced by u=h because - cp_const=cv_const. -

    -

    - This model provides equation for the following thermodynamic properties: -

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    VariableUnitDescription
    TKtemperature
    pPaabsolute pressure
    dkg/m3density
    hJ/kgspecific enthalpy
    uJ/kgspecific internal energy
    Xi[nXi]kg/kgindependent mass fractions m_i/m
    RJ/kg.Kgas constant
    Mkg/molmolar mass
    - -

    - Enthalpy of the water. -

    - - - -

    - This medium package models liquid water. -

    -

    - The mass density is computed using a constant value of 995.586 kg/s. - For a medium model in which the density is a function of temperature, use - - AixLib.Media.Specialized.Water.TemperatureDependentDensity which may have considerably higher computing time. -

    -

    - For the specific heat capacities at constant pressure and at constant volume, - a constant value of 4184 J/(kg K), which corresponds to 20°C - is used. - The figure below shows the relative error of the specific heat capacity that - is introduced by this simplification. -

    -

    - \"Relative -

    -

    - The enthalpy is computed using the convention that h=0 - if T=0 °C. -

    -

    Limitations

    -

    - Density, specific heat capacity, thermal conductivity and viscosity are constant. - Water is modeled as an incompressible liquid. - There are no phase changes. -

    - - - -------- Corrected Code --------

    - Model with basic thermodynamic properties. + This package contains models of sensors. There are models with one + and with two fluid ports.

    +

    + Selection and parameterization of sensor models +

    - This base properties model is identical to Modelica.Media.Water.ConstantPropertyLiquidWater, - except that the equation u = cv_const*(T - reference_T) - has been replaced by u=h because - cp_const=cv_const. + When selecting a sensor model, a distinction needs to be made whether + the measured quantity depends on the direction of the flow or not, + and whether the sensor output signal is the product of the mass flow + rate and a medium property.

    - This model provides equation for the following thermodynamic - properties: + Output signals that depend on the flow direction and are not + multiplied by the mass flow rate are temperature, relative humidity, + water vapor concentration X, trace substances C and + density. For such quantities, sensors with two fluid ports need to be + used. An exception is if the quantity is measured directly in a fluid + volume, which is the case for models from the package AixLib.Fluid.MixingVolumes. + Therefore, to measure for example the outlet temperature of a heat + exchanger, the configuration labelled correct use in the + figure below should be used, and not the configuration labelled + not recommended. For an explanation, see + Modelica.Fluid.Examples.Explanatory.MeasuringTemperature.

    - - - - - - +
    - Variable - - Unit - - Description -
    - - - + - - - - - - - - + +
    - T - - K - - temperature + + Correct use + + \"image\"
    - p - - Pa - - absolute pressure -
    - d - - kg/m3 - - density + + Not recommended + + \"image\"
    +

    + Except for the mass flow rate sensor, all sensors with two ports can + be configured as dynamic sensors or as steady-state sensor. The list + below advices on how to configure sensors. +

    + +

    + The table below summarizes the recommendations for the use of + sensors. +

    + - - - + + + - - - - - - + - - - + - - - +
    - h - - J/kg - - specific enthalpy - + Measured quantity + + One port sensor + + Two port sensor +
    - u - - J/kg + + steady-state (tau=0) - specific internal energy + + dynamic (tau > 0)
    - Xi[nXi] + + temperature
    + relative humidity
    + mass fraction
    + trace substances
    + specific enthalpy
    + specific entropy     		- kg/kg + + use only if connected to a volume - independent mass fractions m_i/m + + avoid + + recommended
    - R + + volume flow rate
    + enthalpy flow rate
    + entropy flow rate     		- J/kg.K + + - - gas constant + + recommended + + recommended
    - M + + pressure - kg/mol + + recommended - molar mass + + recommended + + recommended
    +

    + Sensor Dynamics +

    +
    + Dynamic response to fluid flowing through the sensor +

    - Enthalpy of the water. + If a sensor is configured as a dynamic sensor by setting tau + > 0, then the measured quantity, say the temperature + T, is computed as +

    +

    + τ   dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T),

    -

    - This medium package models liquid water. + where τ is a user-defined time constant of the sensor (a + suggested value is around 10 seconds, which is the default setting + for the components), dT ⁄ dt is the time derivative of the + sensor output signal, |ṁ| is the absolute value of the mass + flow rate, ṁ0 is the user-specified nominal value + of the mass flow rate and θ is the temperature of the medium + inside the sensor. An equivalent physical model of such a sensor + would be a perfectly mixed volume with a sensor that outputs the + temperature of this volume. In this situation, the size of the volume + would be V=τ   ṁ0 ⁄ ρ, where ρ is the + density of the fluid.

    +
    + Dynamic response to ambient temperature +

    - The mass density is computed using a constant value of 995.586 - kg/s. For a medium model in which the density is a function of - temperature, use - AixLib.Media.Specialized.Water.TemperatureDependentDensity which - may have considerably higher computing time. + For the sensor AixLib.Fluid.Sensors.TemperatureTwoPort, + by setting transferHeat = true, heat transfer to a fixed + ambient can be approximated. The heat transfer is computed as +

    +

    + τHeaTra   dT ⁄ dt = (TAmb-T),

    - For the specific heat capacities at constant pressure and at constant - volume, a constant value of 4184 J/(kg K), which corresponds - to 20°C is used. The figure below shows the relative error of - the specific heat capacity that is introduced by this simplification. + where τHeaTra is a fixed time constant and + TAmb is a fixed ambient temperature. Setting + transferHeat = true is useful if the sensor output + T is used to switch the mass flow rate on again. If + transferHeat = false, then the sensor output T + remains constant if the mass flow rate is zero and hence a fan or + pump controller that uses this signal may never switch the device on + again. If the sensor output T is not used to switch on the + mass flow rate, then in general one can use + transferHeat=false.

    -

    - - +

    + Note that since in practice the heat transfer is due to a combination + of ambient temperature and upstream or downstream fluid temperature, + for example by two-way buoyancy-driven flow inside the duct or pipe, + the model uses as an approximation a fixed ambient temperature. Since + the sensor is not affecting the temperature of the medium, this + approximation of the heat transfer does not add or remove heat from + the fluid.

    +
    + Combined dynamic response +

    - The enthalpy is computed using the convention that h=0 if - T=0 °C. + For the sensor AixLib.Fluid.Sensors.TemperatureTwoPort, + if both dynamic effects are enabled, then the output T is + computed as +

    +

    + dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T) ⁄ τ + + (TAmb-T) ⁄ τHeaTra.

    - Limitations + Implementation

    - Density, specific heat capacity, thermal conductivity and viscosity - are constant. Water is modeled as an incompressible liquid. There are - no phase changes. -

    - - --------- Errors -------- -line 17 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 - - -line 18 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Actuators/BaseClasses/exponentialDamper.mo ---- --------- HTML Code -------- - -

    - This function computes the opening characteristics of an exponential damper. -

    - The function is used by the model - - AixLib.Fluid.Actuators.Dampers.Exponential. -

    - For yL < y < yU, the damper characteristics is -

    -

    - kd(y) = exp(a+b (1-y)). -

    -

    - Outside this range, the damper characteristic is defined by a quadratic polynomial. -

    -

    - Note that this implementation returns sqrt(kd(y)) instead of kd(y). - This is done for numerical reason since otherwise kd(y) may be an iteration - variable, which may cause a lot of warnings and slower convergence if the solver - attempts kd(y) < 0 during the iterative solution procedure. -

    - - - --------- Corrected Code -------- -

    - This function computes the opening characteristics of an exponential - damper. -

    -

    - The function is used by the model AixLib.Fluid.Actuators.Dampers.Exponential. -

    -

    - For yL < y < yU, the damper characteristics is -

    -

    - kd(y) = exp(a+b (1-y)). + The above equation is implemented in such a way that it is + differentiable in the mass flow rate.

    - Outside this range, the damper characteristic is defined by a - quadratic polynomial. -

    -

    - Note that this implementation returns sqrt(kd(y)) - instead of kd(y). This is done for numerical reason - since otherwise kd(y) may be an iteration variable, - which may cause a lot of warnings and slower convergence if the - solver attempts kd(y) < 0 during the iterative - solution procedure. + Note that the implementation of the dynamic sensors does not use the + model AixLib.Fluid.MixingVolumes. + The reason is that depending on the selected medium model, the mixing + volume may introduce states for the pressure, species concentration, + trace substance, specific enthalpy and specific entropy. Not all + states are typically needed to model the dynamics of a sensor. + Moreover, in many building system applications, the sensor dynamics + is not of concern, but is rather used here to avoid numerical + problems that steady-state models of sensors cause when flow rates + are very close to zero.

    - -------- Errors -------- -line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 32 column 1 - Warning: The summary attribute on the

    element is obsolete in HTML5 +line 105 column 1 - Warning: The summary attribute on the
    element is obsolete in HTML5 +line 33 column 5 - Warning:
    attribute "align" not allowed for HTML5 +line 38 column 5 - Warning: attribute "align" not allowed for HTML5 +line 144 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 167 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 197 column 1 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Movers/BaseClasses/Characteristics/efficiency.mo ---- +---- AixLib/Fluid/FMI/UsersGuide.mo ---- -------- HTML Code -------- -

    - This function computes the fan or pump efficiency for given normalized volume flow rate - and performance data. The efficiency is -

    -

    - η = s(V̇/rN, d), -

    -

    - where - η is the efficiency, - rN is the normalized fan speed, - V̇ is the volume flow rate, and - d are performance data for fan or pump efficiency. -

    -

    Implementation

    -

    - The function s(·, ·) is a cubic hermite spline. - If the data d define a monotone decreasing sequence, then - s(·, d) is a monotone decreasing function. -

    - -
      -
    • - December 2, 2016, by Michael Wetter:
      - Removed min attribute as otherwise numerical noise can cause - the assertion on the limit to fail.
      - This is for - #606. -
      • -
    • - November 22, 2014, by Michael Wetter:
      - Corrected documentation as curve uses V̇ - as an independent variable. -
      • -
    • - September 30, 2014, by Filip Jorissen:
      - Changed polynomial to be evaluated at V_flow - instead of r_V. -
      • -
    • - April 19, 2014, by Filip Jorissen:
      - Changed polynomial to be evaluated at r_V/r_N - instead of r_V to properly account for the - scaling law. See - #202 - for a discussion and validation. -
      • -
    • - September 28, 2011, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code --------

    - This function computes the fan or pump efficiency for given - normalized volume flow rate and performance data. The efficiency is -

    -

    - η = s(V̇/rN, d), +This user's guide describes the FMI package (Wetter et al., 2015). +The FMI package has been implemented to facilitate the export +of thermofluid flow models such as HVAC components, HVAC systems +and thermal zones as Functional Mockup Units (FMUs). +This allows to export thermofluid flow models as FMUs so that they can be +imported in other simulators. +To export thermofluid flow components, a Modelica block is needed +in order for the model to only have input and output signals +rather than fluid connectors, as fluid connectors do not impose any causality +on the signal flow. +This package implements such blocks and its connectors.

    - where η is the efficiency, rN is the - normalized fan speed, V̇ is the volume flow rate, and d - are performance data for fan or pump efficiency. +The main packages are as follows:

    -

    - Implementation -

    -

    - The function s(·, ·) is a cubic hermite spline. If the data - d define a monotone decreasing sequence, then s(·, d) - is a monotone decreasing function. + + + + + + + + + + + + + + + + + + + + +
    PackageDescription
    + + AixLib.Fluid.FMI.ExportContainers + +

    + Package with blocks to export thermofluid flow components and systems. +

    +

    + To export an HVAC component or system with a single inlet and outlet port, instantiate + + AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort + with a replaceable model, + or extend from + + AixLib.Fluid.FMI.ExportContainers.PartialTwoPort + and add components.
    + See + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.Fan + and + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ResistanceVolume. +

    +

    + To export an HVAC system that serves a single thermal zone, extend from + + AixLib.Fluid.FMI.ExportContainers.HVACZone + and add the HVAC system.
    + See + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone. +

    +

    + To export an HVAC system that serves multiple thermal zones, extend from + + AixLib.Fluid.FMI.ExportContainers.HVACZones + and add the HVAC system.
    + See + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones. +

    +

    + To export a single thermal zone, extend from + + AixLib.Fluid.FMI.ExportContainers.ThermalZone + and add the thermal zone.
    + See + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. +

    +

    + To export multiple thermal zones, extend from + + AixLib.Fluid.FMI.ExportContainers.ThermalZones + and add the thermal zone models.
    + See + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones. +

    +
    + + AixLib.Fluid.FMI.Adaptors + +

    + Package with adaptors to connect models with fluid ports to blocks that + have input and output signals. +

    +
    +

    + + AixLib.Fluid.FMI.Conversion +

    +    		 +

    + Package with blocks that convert between the signal connectors of + + AixLib.Fluid.FMI.Interfaces + and the real input and output signal connectors of the Modelica Standard Library. +

    +
    + + AixLib.Fluid.FMI.Interfaces + +

    + Package with composite connectors that have different input and output + signals. These connectors are used to export FMUs, and they contain + quantities such as mass flow rate, temperature, optional pressure, etc. +

    +
    +

    +The package + +AixLib.Fluid.FMI.ExportContainers.Examples.FMUs +contains various examples in which HVAC components, HVAC systems +and thermal zones are exported as an FMU.

    -
      -
    • December 2, 2016, by Michael Wetter:
      - Removed min attribute as otherwise numerical noise can - cause the assertion on the limit to fail.
      - This is for #606. -
      • -
    • November 22, 2014, by Michael Wetter:
      - Corrected documentation as curve uses V̇ as an independent - variable. -
      • -
    • September 30, 2014, by Filip Jorissen:
      - Changed polynomial to be evaluated at V_flow instead - of r_V. -
      • -
    • April 19, 2014, by Filip Jorissen:
      - Changed polynomial to be evaluated at r_V/r_N instead - of r_V to properly account for the scaling law. See - #202 - for a discussion and validation. -
      • -
    • September 28, 2011, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/HeatExchangers/ActiveBeams/Data/BaseClasses/TemperatureDifference.mo ---- --------- HTML Code -------- - -

    - Data record for performance data that describe the normalized - temperature difference - versus the change in the rate of heating or cooling. - The normalized temperature difference is defined as -

    -

    - rΔTi= - ΔTi ⁄ ΔTnominal - = - (Twi-Tz) - ⁄ - (Tw,nominal-Tz), -

    -

    - where - Twi is the water inlet temperature, - Tz is the zone air temperature and - Tw,nominal is the nominal water inlet temperature. -

    -

    - The normalized temperature difference rΔT must be strictly increasing, i.e., - rΔTi < rΔTi+1. - Both vectors, rΔT and f - must have the same size. -

    - -
      -
    • - June 13, 2016, by Michael Wetter:
      - Revised implementation. -
      • -
    • - May 20, 2016, by Alessandro Maccarini:
      - First implementation. -
      • -
    - --------- Corrected Code -------- +

    Typical use

    - Data record for performance data that describe the normalized - temperature difference versus the change in the rate of heating or - cooling. The normalized temperature difference is defined as +Users who want to export a single thermofluid flow component, or a +subsystem of thermofluid flow components, can use the block + +AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort. +This block has a fluid inlet, a fluid outlet, and a replaceable +component that can be replaced with an HVAC component or system that +has an inlet and outlet fluid port.

    -

    - rΔTi= ΔTi ⁄ ΔTnominal = - (Twi-Tz) ⁄ - (Tw,nominal-Tz), +

    +Users who want to export a whole HVAC system that serves a single thermal zone +can do so by extending the partial block + +AixLib.Fluid.FMI.ExportContainers.HVACZone. +The example + +AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone +illustrates how this can be accomplished.
    +Similar export containers and examples are implemented for HVAC systems that serve multiple thermal zones.

    - where Twi is the water inlet - temperature, Tz is the zone air temperature and - Tw,nominal is the nominal water inlet temperature. +Conversely, to export a thermal zone, users can extend the partial block + +AixLib.Fluid.FMI.ExportContainers.ThermalZone. +The example + +AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone +illustrates how this can be accomplished.
    +Similar export containers and examples are implemented for models of multiple thermal zones.

    - The normalized temperature difference rΔT must be - strictly increasing, i.e., rΔTi < - rΔTi+1. Both vectors, rΔT - and f must have the same size. +Each example and validation model has a Dymola script that +either simulates the model, or exports the model as an FMU. +The script can be invoked from the pull +down menu Commands -> Export FMU.

    -
      -
    • June 13, 2016, by Michael Wetter:
      - Revised implementation. -
      • -
    • May 20, 2016, by Alessandro Maccarini:
      - First implementation. -
      • -
    - --------- Errors -------- -line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/FixedResistances/BaseClasses/PlugFlow.mo ---- --------- HTML Code -------- - -

      -
    • - October 20, 2017, by Michael Wetter:
      - Deleted various parameters and variables that were not used. -
      - Revised documentation to follow the guidelines. -
      • -
    • - May 19, 2016 by Marcus Fuchs:
      - Remove condition on show_V_flow for calculation of - V_flow to conform with pedantic checking. -
      • -
    • - October 10, 2015 by Marcus Fuchs:
      - Copy Icon from KUL implementation and rename model. -
      • -
    • - June 23, 2015 by Marcus Fuchs:
      - First implementation. -
      • -
    - -

    - Model that computes the temperature propagation of - a fluid flow through a pipe, idealized as a plug flow. -

    -

    Main equation

    -

    - The transport delay is computed using the one-dimensional wave equation - without source or sink terms, -

    - ∂z(x,t)/∂t + v(t) ∂z(x,t)/∂x = 0, -

    -

    where z(x,t) is the spatial distribution as a function of time of any - property z of the fluid. - For the temperature propagation, z will be replaced by T. -

    -

    Assumptions

    -

    - This model is based on the following assumptions: -

    -
      -
    • - Axial diffusion in water is assumed to be negligibe. -
      • -
    • - The water temperature is assumed uniform in a cross section. -
      • -
    - --------- Corrected Code -------- -
      -
    • October 20, 2017, by Michael Wetter:
      - Deleted various parameters and variables that were not used.
      - Revised documentation to follow the guidelines. -
      • -
    • May 19, 2016 by Marcus Fuchs:
      - Remove condition on show_V_flow for calculation of - V_flow to conform with pedantic checking. -
      • -
    • October 10, 2015 by Marcus Fuchs:
      - Copy Icon from KUL implementation and rename model. -
      • -
    • June 23, 2015 by Marcus Fuchs:
      - First implementation. -
      • -
    +

    Options

    - Model that computes the temperature propagation of a fluid flow - through a pipe, idealized as a plug flow. +In the +AixLib.Fluid package, +most models have a boolean parameter called allowFlowReversal. +If set to true, then the flow can be in either direction, +otherwise it needs to be from the inlet to the outlet port. +This parameter is also used in the +AixLib.Fluid.FMI package. +The package was designed in such a way that an FMU, +if exported with allowFlowReversal=false +has as input the mass flow rate, +pressure and fluid properties of the inflowing fluid. The outputs +are the outlet mass flow rate, outlet pressure and the fluid +properties of the outflowing medium. This allows simulators +such as Ptolemy II +to evaluate the FMUs in the direction of the mass flow by first +setting all inputs, then evaluating the model equations, +and finally retrieving the +outputs before proceeding the simulation with the next downstream +component. +If allowFlowReversal=true, then the connectors have additional +signals for the properties of the fluid if it flows backwards.

    -

    - Main equation -

    - The transport delay is computed using the one-dimensional wave - equation without source or sink terms, +Most components have a boolean parameter use_p_in. +If use_p_in=true, then the pressure is used from the +connector, and based on the mass flow rate, the outlet pressure +is computed and assigned to the outlet connectors. +If use_p_in=false, then the pressure as declared +by the constant p_default of the medium model is +used, and the component computes no pressure drop. +Setting use_p_in=false therefore leads to fewer +equations, but it requires a component that specifies the mass +flow rate, such as + +AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.IdealSource_m_flow.

    -

    - ∂z(x,t)/∂t + v(t) ∂z(x,t)/∂x = 0, +

    Notes

    +

    +Note the following when exporting HVAC component models as an FMU:

    +
      +

    1. - where z(x,t) is the spatial distribution as a function of time - of any property z of the fluid. For the temperature - propagation, z will be replaced by T. +For models with control volumes, +the mass balance must be configured using +massDynamics=Modelica.Fluid.Types.Dynamics.SteadyState +when used with the media + +AixLib.Media.Air. +Otherwise, the translation stops with the error

      -

      - Assumptions -

      +
      +The model requires derivatives of some inputs as listed below:
+1 inlet.p
+

      - This model is based on the following assumptions: +The reason is that for + +AixLib.Media.Air, +mass is proportional to pressure and pressure is proportional +to density. Hence, dm/dt requires dp/dt, +but the time derivative of the pressure is not an input to the model. +

      +

      +For +AixLib.Media.Water, this setting is not needed +as the mass is independent of pressure. +

      +
      2. +
    2. +

      +The model + +AixLib.Fluid.Movers.FlowControlled_m_flow +cannot be exported as an FMU. +This is because it assignes the mass flow rate. +However, the input connector + +AixLib.Fluid.FMI.Interfaces.Inlet +already declares the mass flow rate as an input. +Therefore, the mass flow rate is overdetermined. +As a fall back, if a user needs to set the mass flow rate, he/she can +do so by using + +AixLib.Fluid.FMI.Source_T, +which takes as an input signal the mass flow rate. +

      +
      3. +
    +

    +When connecting fluid flow components in a loop, +be careful to avoid circular assignments for example for the temperature, +as these can of course not be simulated. +An example of such an ill-posed problem is to connect the outlet of + +AixLib.Fluid.FixedResistances.PressureDrop +to its inlet. In this situation, neither pressure, nor mass flow rate or temperature +can be computed. To model such loops, a control volume with a dynamic energy +balance must be presented, and the medium needs to be compressible. +

    +

    References

    +

    +Michael Wetter, Marcus Fuchs and Thierry Stephane Nouidui.
    + +Design choices for thermofluid flow components and systems that are exported as Functional Mockup Units.
    +Proc. of the 11th International Modelica Conference, + p. 31-41, + Versailles, France, September 2015.

    -
      -
    • Axial diffusion in water is assumed to be negligibe. -
      • -
    • The water temperature is assumed uniform in a cross section. -
      • -
    - --------- Errors -------- -line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/FMI/ExportContainers/HVACZones.mo ---- --------- HTML Code -------- -

    - Model that is used as a container for an HVAC system that is - to be exported as an FMU and that serves multiple zones. -

    -

    Typical use and important parameters

    -

    - To use this model as a container for an FMU, simply extend - from this model, rather than instantiate it, - and add your HVAC system. By extending from this model, the top-level - signal connectors on the right stay at the top-level, and hence - will be visible at the FMI interface. - The example - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones - shows how a simple HVAC system that serves two rooms can be implemented and exported as - an FMU. - -

    -

    - The following two parameters need to be assigned by the user: - Set nZon to the number of thermal zones to which the - FMU will be connected. - Set nPorts to the largest number of fluid ports - that the thermal zones has. For example, - if nZon=2 and zone 1 has one inlet and one outlet - (hence it has 2 ports), - and zone 2 has one inlets and two outlets - (hence it has 3 ports), then - set nPorts=3. This will add more fluid ports than are needed - for zone 1, but this causes no overhead if they are not connected. -

    -

    - The conversion between the fluid ports and signal ports is done - in the HVAC adapter hvacAda. - This adapter has a vector of fluid ports called ports. - The supply and return air ducts, including any resistance model for the inlet - diffusor or exhaust grill, need to be connected to these ports. - Also, if a thermal zone has interzonal air exchange or air infiltration, - these flows need to be connected to ports. - This model outputs at the port fluPor the mass flow rate for - each flow that is connected to ports, together with its - temperature, water vapor mass fraction per total mass of the air (not per kg dry - air), and trace substances. These quantities are always as if the flow - enters the room, even if the flow is zero or negative. - If a medium has no moisture, e.g., if Medium.nXi=0, or - if it has no trace substances, e.g., if Medium.nC=0, then - the output signal for these properties are removed. - These quantities are always as if the flow - enters the room, even if the flow is zero or negative. - Thus, a thermal zone model that uses these signals to compute the - heat added by the HVAC system need to implement an equation such as -

    -

    - Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), -

    -

    - where - Qsen is the sensible heat flow rate added to the thermal zone, - ṁsup is the supply air mass flow rate from - the port fluPor (which is negative if it is an exhaust), - cp is the specific heat capacity at constant pressure, - Tsup is the supply air temperature and - Tair,zon is the zone air temperature. - Note that without the max(·, ·), the energy - balance would be wrong. -

    - -

    - The input signals of this model are the radiative temperature of each zone. - The the zone air temperatures, - the water vapor mass fractions per total mass of the air (unless Medium.nXi=0) - and trace substances (unless Medium.nC=0) are obtained from the connector - fluPor.backward. - The outflowing fluid stream(s) at the port ports will be at the - states obtained from fluPor.backward. - For any given izon ∈ {1, ..., nzon}, - for each iports ∈ {1, ..., nports} - all fluid streams at port ports[izon, iports] are at the same - pressure. - For convenience, the instance hvacAda also outputs the - properties obtained from fluPor.backward. These can be used - to connect a controller. The properties are available for each flow path in - fluPor.backward. For a thermal zone with mixed air, these are - all equal, while for a stratified room model, they can be different. -

    -

    - See - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones - for a model that uses this model. -

    -

    - For models that only have one thermal zone connected to the HVAC system, - use the simpler model - - AixLib.Fluid.FMI.ExportContainers.HVACZone. -

    -

    Assumption and limitations

    -

    - The mass flow rates at ports sum to zero, hence this - model conserves mass for each thermal zone. -

    -

    - This model does not impose any pressure, other than, - for any given izon ∈ {1, ..., nzon} and - for each j,k ∈ {1, ..., nports}, - setting the pressure of ports[izon, j].p = ports[izon, k].p - to be the same. - The reason is that setting a pressure can lead to non-physical system models, - for example if a mass flow rate is imposed and the HVAC system is connected - to a model that sets a pressure boundary condition such as - - AixLib.Fluid.Sources.Outside. - Also, setting a pressure would make it impossible to use multiple instances - of this model (one for each thermal zone) and build in Modelica an airflow network - model with pressure driven mass flow rates. -

    -

    - The model has no pressure drop. Hence, the pressure drop - of an air diffuser or of an exhaust grill needs to be modelled - in models that are connected to ports. -

    - -
      -
    • - January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air only. - See #1050. -
      • -
    • - May 25, 2016, by Michael Wetter:
      - First implementation. -
      • -
    - -------- Corrected Code --------

    - Model that is used as a container for an HVAC system that is to be - exported as an FMU and that serves multiple zones. + This user's guide describes the FMI package (Wetter et al., 2015). + The FMI package has been implemented to facilitate the export of + thermofluid flow models such as HVAC components, HVAC systems and + thermal zones as Functional Mockup Units (FMUs). This allows to + export thermofluid flow models as FMUs so that they can be imported + in other simulators. To export thermofluid flow components, a + Modelica block is needed in order for the model to only have input + and output signals rather than fluid connectors, as fluid connectors + do not impose any causality on the signal flow. This package + implements such blocks and its connectors. +

    +

    + The main packages are as follows: +

    + + + + + + + + + + + + + + + + + + + + + +
    + Package + + Description +
    + AixLib.Fluid.FMI.ExportContainers + +

    + Package with blocks to export thermofluid flow components and + systems. +

    +

    + To export an HVAC component or system with a single inlet and + outlet port, instantiate + AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort with a + replaceable model, or extend from AixLib.Fluid.FMI.ExportContainers.PartialTwoPort + and add components.
    + See + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.Fan and + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ResistanceVolume. +

    +

    + To export an HVAC system that serves a single thermal zone, + extend from AixLib.Fluid.FMI.ExportContainers.HVACZone + and add the HVAC system.
    + See + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone. +

    +

    + To export an HVAC system that serves multiple thermal zones, + extend from AixLib.Fluid.FMI.ExportContainers.HVACZones + and add the HVAC system.
    + See + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones. +

    +

    + To export a single thermal zone, extend from AixLib.Fluid.FMI.ExportContainers.ThermalZone + and add the thermal zone.
    + See + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. +

    +

    + To export multiple thermal zones, extend from AixLib.Fluid.FMI.ExportContainers.ThermalZones + and add the thermal zone models.
    + See + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones. +

    +
    + AixLib.Fluid.FMI.Adaptors + +

    + Package with adaptors to connect models with fluid ports to + blocks that have input and output signals. +

    +
    +

    + AixLib.Fluid.FMI.Conversion +

    +     		+

    + Package with blocks that convert between the signal connectors + of AixLib.Fluid.FMI.Interfaces + and the real input and output signal connectors of the Modelica + Standard Library. +

    +
    + AixLib.Fluid.FMI.Interfaces + +

    + Package with composite connectors that have different input and + output signals. These connectors are used to export FMUs, and + they contain quantities such as mass flow rate, temperature, + optional pressure, etc. +

    +
    +

    + The package AixLib.Fluid.FMI.ExportContainers.Examples.FMUs + contains various examples in which HVAC components, HVAC systems and + thermal zones are exported as an FMU.

    - Typical use and important parameters + Typical use

    - To use this model as a container for an FMU, simply extend from this - model, rather than instantiate it, and add your HVAC system. By - extending from this model, the top-level signal connectors on the - right stay at the top-level, and hence will be visible at the FMI - interface. The example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones shows - how a simple HVAC system that serves two rooms can be implemented and - exported as an FMU. + Users who want to export a single thermofluid flow component, or a + subsystem of thermofluid flow components, can use the block AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort. + This block has a fluid inlet, a fluid outlet, and a replaceable + component that can be replaced with an HVAC component or system that + has an inlet and outlet fluid port.

    - The following two parameters need to be assigned by the user: Set - nZon to the number of thermal zones to which the FMU - will be connected. Set nPorts to the largest number of - fluid ports that the thermal zones has. For example, if - nZon=2 and zone 1 has one inlet and one outlet - (hence it has 2 ports), and zone 2 has one inlets and two - outlets (hence it has 3 ports), then set nPorts=3. This - will add more fluid ports than are needed for zone 1, but this - causes no overhead if they are not connected. + Users who want to export a whole HVAC system that serves a single + thermal zone can do so by extending the partial block AixLib.Fluid.FMI.ExportContainers.HVACZone. + The example + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone + illustrates how this can be accomplished.
    + Similar export containers and examples are implemented for HVAC + systems that serve multiple thermal zones.

    - The conversion between the fluid ports and signal ports is done in - the HVAC adapter hvacAda. This adapter has a vector of - fluid ports called ports. The supply and return air - ducts, including any resistance model for the inlet diffusor or - exhaust grill, need to be connected to these ports. Also, if a - thermal zone has interzonal air exchange or air infiltration, these - flows need to be connected to ports. This model outputs - at the port fluPor the mass flow rate for each flow that - is connected to ports, together with its temperature, - water vapor mass fraction per total mass of the air (not per kg dry - air), and trace substances. These quantities are always as if the - flow enters the room, even if the flow is zero or negative. If a - medium has no moisture, e.g., if Medium.nXi=0, or if it - has no trace substances, e.g., if Medium.nC=0, then the - output signal for these properties are removed. These quantities are - always as if the flow enters the room, even if the flow is zero or - negative. Thus, a thermal zone model that uses these signals to - compute the heat added by the HVAC system need to implement an - equation such as -

    -

    - Qsen = max(0, ṁsup)   cp   - (Tsup - Tair,zon), -

    -

    - where Qsen is the sensible heat flow rate added to - the thermal zone, ṁsup is the supply air mass flow - rate from the port fluPor (which is negative if it is an - exhaust), cp is the specific heat capacity at - constant pressure, Tsup is the supply air - temperature and Tair,zon is the zone air - temperature. Note that without the max(·, ·), the energy - balance would be wrong. + Conversely, to export a thermal zone, users can extend the partial + block AixLib.Fluid.FMI.ExportContainers.ThermalZone. + The example + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone + illustrates how this can be accomplished.
    + Similar export containers and examples are implemented for models of + multiple thermal zones.

    - The input signals of this model are the radiative temperature of each - zone. The the zone air temperatures, the water vapor mass fractions - per total mass of the air (unless Medium.nXi=0) and - trace substances (unless Medium.nC=0) are obtained from - the connector fluPor.backward. The outflowing fluid - stream(s) at the port ports will be at the states - obtained from fluPor.backward. For any given - izon ∈ {1, ..., nzon}, for each - iports ∈ {1, ..., nports} all fluid - streams at port ports[izon, - iports] are at the same pressure. For convenience, - the instance hvacAda also outputs the properties - obtained from fluPor.backward. These can be used to - connect a controller. The properties are available for each flow path - in fluPor.backward. For a thermal zone with mixed air, - these are all equal, while for a stratified room model, they can be - different. + Each example and validation model has a Dymola script that either + simulates the model, or exports the model as an FMU. The script can + be invoked from the pull down menu Commands -> Export + FMU.

    +

    + Options +

    - See - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones for a - model that uses this model. + In the AixLib.Fluid package, + most models have a boolean parameter called + allowFlowReversal. If set to true, then the + flow can be in either direction, otherwise it needs to be from the + inlet to the outlet port. This parameter is also used in the AixLib.Fluid.FMI package. The + package was designed in such a way that an FMU, if exported with + allowFlowReversal=false has as input the mass flow rate, + pressure and fluid properties of the inflowing fluid. The outputs are + the outlet mass flow rate, outlet pressure and the fluid properties + of the outflowing medium. This allows simulators such as Ptolemy II + to evaluate the FMUs in the direction of the mass flow by first + setting all inputs, then evaluating the model equations, and finally + retrieving the outputs before proceeding the simulation with the next + downstream component. If allowFlowReversal=true, then + the connectors have additional signals for the properties of the + fluid if it flows backwards.

    - For models that only have one thermal zone connected to the HVAC - system, use the simpler model AixLib.Fluid.FMI.ExportContainers.HVACZone. + Most components have a boolean parameter use_p_in. If + use_p_in=true, then the pressure is used from the + connector, and based on the mass flow rate, the outlet pressure is + computed and assigned to the outlet connectors. If + use_p_in=false, then the pressure as declared by the + constant p_default of the medium model is used, and the + component computes no pressure drop. Setting + use_p_in=false therefore leads to fewer equations, but + it requires a component that specifies the mass flow rate, such as + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.IdealSource_m_flow.

    - Assumption and limitations + Notes

    - The mass flow rates at ports sum to zero, hence this - model conserves mass for each thermal zone. + Note the following when exporting HVAC component models as an FMU:

    +
      +
    1. +

      + For models with control volumes, the mass balance must be + configured using + massDynamics=Modelica.Fluid.Types.Dynamics.SteadyState + when used with the media AixLib.Media.Air. Otherwise, + the translation stops with the error +

      + 
      +The model requires derivatives of some inputs as listed below:
+1 inlet.p
+
      +

      + The reason is that for AixLib.Media.Air, mass is + proportional to pressure and pressure is proportional to density. + Hence, dm/dt requires dp/dt, but the time + derivative of the pressure is not an input to the model. +

      +

      + For AixLib.Media.Water, this + setting is not needed as the mass is independent of pressure. +

      +
      2. +
    2. +

      + The model AixLib.Fluid.Movers.FlowControlled_m_flow + cannot be exported as an FMU. This is because it assignes the + mass flow rate. However, the input connector AixLib.Fluid.FMI.Interfaces.Inlet + already declares the mass flow rate as an input. Therefore, the + mass flow rate is overdetermined. As a fall back, if a user needs + to set the mass flow rate, he/she can do so by using AixLib.Fluid.FMI.Source_T, + which takes as an input signal the mass flow rate. +

      +
      3. +

    - This model does not impose any pressure, other than, for any given - izon ∈ {1, ..., nzon} and for each - j,k ∈ {1, ..., nports}, setting the pressure of - ports[izon, j].p = ports[izon, - k].p to be the same. The reason is that setting a pressure can - lead to non-physical system models, for example if a mass flow rate - is imposed and the HVAC system is connected to a model that sets a - pressure boundary condition such as AixLib.Fluid.Sources.Outside. - Also, setting a pressure would make it impossible to use multiple - instances of this model (one for each thermal zone) and build in - Modelica an airflow network model with pressure driven mass flow - rates. + When connecting fluid flow components in a loop, be careful to avoid + circular assignments for example for the temperature, as these can of + course not be simulated. An example of such an ill-posed problem is + to connect the outlet of AixLib.Fluid.FixedResistances.PressureDrop + to its inlet. In this situation, neither pressure, nor mass flow rate + or temperature can be computed. To model such loops, a control volume + with a dynamic energy balance must be presented, and the medium needs + to be compressible.

    +

    + References +

    - The model has no pressure drop. Hence, the pressure drop of an air - diffuser or of an exhaust grill needs to be modelled in models that - are connected to ports. + Michael Wetter, Marcus Fuchs and Thierry Stephane Nouidui.
    + + Design choices for thermofluid flow components and systems that are + exported as Functional Mockup Units.
    + Proc. of the 11th International Modelica Conference, p. 31-41, + Versailles, France, September 2015.

    -
      -
    • January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air only. See #1050. -
      • -
    • May 25, 2016, by Michael Wetter:
      - First implementation. -
      • -
    -------- Errors -------- -line 60 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 18 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 ----- AixLib/Fluid/HeatPumps/Carnot_TCon.mo ---- +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/infiniteLineSource.mo ---- -------- HTML Code --------

    - This is a model of a heat pump whose coefficient of performance COP changes - with temperatures in the same way as the Carnot efficiency changes. - The control input is the setpoint of the condenser leaving temperature, which - is met exactly at steady state if the heat pump has sufficient capacity. -

    -

    - The model allows to either specify the Carnot effectivness - ηCarnot,0, or - a COP0 - at the nominal conditions, together with - the evaporator temperature Teva,0 and - the condenser temperature Tcon,0, in which - case the model computes the Carnot effectivness as + This function evaluates the infinite line source solution. This solution gives + the relation between the constant heat transfer rate (per unit length) injected + by a line heat source of infinite length and the temperature raise in the + medium. The infinite line source solution is defined by

    -

    - ηCarnot,0 = - COP0 - ⁄ (Tcon,0 ⁄ (Tcon,0-Teva,0)). +

    + \"image\"

    - The heat pump COP is computed as the product -

    -

    - COP = ηCarnot,0 COPCarnot ηPL, + where ΔT(t,r) is the temperature raise after a time t of + constant heat injection and at a distance r from the line source, + Q' is the heat injection rate per unit length, ks is + the soil thermal conductivity and hILS is the infinite line + source solution.

    - where COPCarnot is the Carnot efficiency and - ηPL is a polynomial in heating part load ratio yPL - that can be used to take into account a change in COP at part load - conditions. - This polynomial has the form -

    -

    - ηPL = a1 + a2 yPL + a3 yPL2 + ... + The infinite line source solution is given by the exponential integral

    -

    - where the coefficients ai - are declared by the parameter a. +

    + \"image\"

    - On the Dynamics tag, the model can be parametrized to compute a transient - or steady-state response. - The transient response of the model is computed using a first - order differential equation for the evaporator and condenser fluid volumes. - The heat pump outlet temperatures are equal to the temperatures of these lumped volumes. -

    -

    Typical use and important parameters

    -

    - When using this component, make sure that the condenser has sufficient mass flow rate. - Based on the evaporator mass flow rate, temperature difference and the efficiencies, - the model computes how much heat will be removed by to the evaporator. - If the mass flow rate is too small, very low outlet temperatures can result, possibly below freezing. -

    -

    - The condenser heat flow rate QCon_flow_nominal is used to assign - the default value for the mass flow rates, which are used for the pressure drop - calculations. - It is also used to compute the part load efficiency. - Hence, make sure that QCon_flow_nominal is set to a reasonable value. -

    -

    - The maximum heating capacity is set by the parameter QCon_flow_max, - which is by default set to infinity. -

    -

    - The coefficient of performance depends on the - evaporator and condenser leaving temperature - since otherwise the second law of thermodynamics may be violated. -

    -

    Notes

    -

    - For a similar model that can be used as a chiller, see - - AixLib.Fluid.Chillers.Examples.Carnot_TEva. + where αs is the ground thermal diffusivity. The + exponential integral is implemented in + AixLib.Utilities.Math.Functions.exponentialIntegralE1.

    • - January 3, 2017, by Michael Wetter:
      - Removed parameters - effInpEva and effInpCon - and updated documentation. - This is for - - issue 497. -
      • -
    • - August 8, 2016, by Michael Wetter:
      - Changed default temperature to compute COP to be the leaving temperature as - use of the entering temperature can violate the 2nd law if the temperature - lift is small.
      - This is for - - Annex 60, issue 497. -
      • -
    • - November 25, 2015 by Michael Wetter:
      + March 22, 2018 by Massimo Cimmino:
      First implementation.
    -------- Corrected Code --------

    - This is a model of a heat pump whose coefficient of performance COP - changes with temperatures in the same way as the Carnot efficiency - changes. The control input is the setpoint of the condenser leaving - temperature, which is met exactly at steady state if the heat pump - has sufficient capacity. -

    -

    - The model allows to either specify the Carnot effectivness - ηCarnot,0, or a COP0 at the - nominal conditions, together with the evaporator temperature - Teva,0 and the condenser temperature - Tcon,0, in which case the model computes the Carnot - effectivness as -

    -

    - ηCarnot,0 = COP0 ⁄ (Tcon,0 ⁄ - (Tcon,0-Teva,0)). -

    -

    - The heat pump COP is computed as the product -

    -

    - COP = ηCarnot,0 COPCarnot ηPL, -

    -

    - where COPCarnot is the Carnot efficiency and - ηPL is a polynomial in heating part load ratio - yPL that can be used to take into account a change - in COP at part load conditions. This polynomial has the form -

    -

    - ηPL = a1 + a2 yPL + - a3 yPL2 + ... -

    -

    - where the coefficients ai are declared by the - parameter a. -

    -

    - On the Dynamics tag, the model can be parametrized to - compute a transient or steady-state response. The transient response - of the model is computed using a first order differential equation - for the evaporator and condenser fluid volumes. The heat pump outlet - temperatures are equal to the temperatures of these lumped volumes. + This function evaluates the infinite line source solution. This + solution gives the relation between the constant heat transfer rate + (per unit length) injected by a line heat source of infinite length + and the temperature raise in the medium. The infinite line source + solution is defined by

    -

    - Typical use and important parameters -

    -

    - When using this component, make sure that the condenser has - sufficient mass flow rate. Based on the evaporator mass flow rate, - temperature difference and the efficiencies, the model computes how - much heat will be removed by to the evaporator. If the mass flow rate - is too small, very low outlet temperatures can result, possibly below - freezing. +

    + \"image\"

    - The condenser heat flow rate QCon_flow_nominal is used - to assign the default value for the mass flow rates, which are used - for the pressure drop calculations. It is also used to compute the - part load efficiency. Hence, make sure that - QCon_flow_nominal is set to a reasonable value. + where ΔT(t,r) is the temperature raise after a time t + of constant heat injection and at a distance r from the line + source, Q' is the heat injection rate per unit length, + ks is the soil thermal conductivity and + hILS is the infinite line source solution.

    - The maximum heating capacity is set by the parameter - QCon_flow_max, which is by default set to infinity. + The infinite line source solution is given by the exponential + integral

    -

    - The coefficient of performance depends on the evaporator and - condenser leaving temperature since otherwise the second law of - thermodynamics may be violated. +

    + \"image\"

    -

    - Notes -

    - For a similar model that can be used as a chiller, see AixLib.Fluid.Chillers.Examples.Carnot_TEva. + where αs is the ground thermal diffusivity. The + exponential integral is implemented in AixLib.Utilities.Math.Functions.exponentialIntegralE1.

      -
    • January 3, 2017, by Michael Wetter:
      - Removed parameters effInpEva and - effInpCon and updated documentation. This is for - issue - 497. -
      • -
    • August 8, 2016, by Michael Wetter:
      - Changed default temperature to compute COP to be the leaving - temperature as use of the entering temperature can violate the 2nd - law if the temperature lift is small.
      - This is for Annex 60, - issue 497. -
      • -
    • November 25, 2015 by Michael Wetter:
      +
    • March 22, 2018 by Massimo Cimmino:
      First implementation.
    -------- Errors -------- -line 17 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 35 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 21 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Sources/Outside_CpData.mo ---- +---- AixLib/BoundaryConditions/Validation/BESTEST/WD400.mo ---- -------- HTML Code -------- -

    - This model describes boundary conditions for - pressure, enthalpy, and species concentration that can be obtained - from weather data. The model is identical to - - AixLib.Fluid.Sources.Outside, - except that it adds the wind pressure to the - pressure at the fluid ports ports. -

    -

    - The pressure p at the fluid ports is computed as: -

    -

    - p = pw + Cp,act Cs v2 ρ ⁄ 2, -

    -

    - where pw is the atmospheric pressure from the weather bus, - v is the wind speed from the weather bus, and - ρ is the fluid density. -

    -

    - The wind pressure coefficient Cp,act is a function of the surface wind incidence - angle and is defined relative to the surface azimuth (normal to the surface is 0). - The wind incidence angle incAng is computed from the wind direction obtained from the weather file - with the surface azimuth azi as the base of the angle. - The relation between the wind pressure coefficient Cp,act and the incidence angle incAng - is defined by a cubic hermite interpolation of the users table input. - Typical table values can be obtained from the "AIVC guide to energy efficient ventilation", - appendix 2 (1996). The default table is appendix 2, table 2.2, face 1. -

    -

    - The wind speed modifier Cs can be used to incorporate the effect of the surroundings on the local wind speed. -

    -

    Definition of angles

    -

    - The angles incAngSurNor for the wind incidence angle relative to the surface normal - are measured counter-clock wise. - The figure below shows an example entry, which is also used in the model - - AixLib.Fluid.Sources.Examples.Outside_CpData_Specification. -

    -

    \"image\"

    - -

    - The wind incidence angle and surface azimuths are defined as follows: - The wind indicience angle is obtained directly from the weather data bus weaBus.winDir. - This variable contains the data from the weather data file that was read, such as a TMY3 file. - In accordance to TMY3, the data is as shown in the table below. -

    -
    - - - - -
    Value of winDir if the wind blows from different directions.
    Wind from North:
    0
    0°
    Wind from West:
    3π/2
    270°    		 Wind from East:
    π/2
    90°
    Wind from South:
    π
    180°
    -

    - For the surface azimuth azi, the specification from - AixLib.Types.Azimuth is - used, which is as shown in the table below. -

    - - - - - - -
    Value of azi if the exterior wall faces in the different directions.
    Wall facing north:
    π
    180°
    Wall facing West:
    π/2
    90°    		 Wall facing east:
    3π/2
    270°
    Wall facing South:
    0;
    0°
    - -

    Related model

    -

    - This model differs from - AixLib.Fluid.Sources.Outside_CpLowRise by the calculation of the wind pressure coefficient - Cp,act. - The wind pressure coefficient is defined by a user-defined table instead of a generalized equation - such that it can be used for all building sizes and situations, for shielded buildings, - and for buildings with non-rectangular shapes. -

    -

    - References -

    -
      -
    • M. W. Liddament, 1996, A guide to energy efficient ventilation. AIVC Annex V.
      • -
    -
    • - February 2, 2022, by Michael Wetter:
      - Revised implementation.
      + September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the weather data bus.
      This is for - IBPSA, #1436. + IBPSA, #1477.
    • - Apr 6, 2021, by Klaas De Jonge:
      + March 11, 2020, by Ettore Zanetti:
      First implementation.
      • -
    - --------- Corrected Code -------- -

    - This model describes boundary conditions for pressure, enthalpy, and - species concentration that can be obtained from weather data. The - model is identical to AixLib.Fluid.Sources.Outside, - except that it adds the wind pressure to the pressure at the fluid - ports ports. -

    -

    - The pressure p at the fluid ports is computed as: -

    -

    - p = pw + Cp,act Cs v2 ρ ⁄ - 2, -

    -

    - where pw is the atmospheric pressure from the - weather bus, v is the wind speed from the weather bus, and - ρ is the fluid density. -

    -

    - The wind pressure coefficient Cp,act is a function - of the surface wind incidence angle and is defined relative to the - surface azimuth (normal to the surface is 0). The wind - incidence angle incAng is computed from the wind - direction obtained from the weather file with the surface azimuth - azi as the base of the angle. The relation between the - wind pressure coefficient Cp,act and the incidence - angle incAng is defined by a cubic hermite interpolation - of the users table input. Typical table values can be obtained from - the \"AIVC guide to energy efficient ventilation\", appendix 2 (1996). - The default table is appendix 2, table 2.2, face 1. -

    -

    - The wind speed modifier Cs can be used to - incorporate the effect of the surroundings on the local wind speed. -

    +
  • + April 14, 2020, by Ettore Zanetti:
    + Rework after comments from pull request + #1339. +
    • +
  • + May 2, 2021, by Ettore Zanetti:
    + Updated weather file as explained in #1478. +
    • + + +

    WD400: High Latitude Case

    +

    Weather data file : WD400.epw

    +

    Table 1: Site Data for Weather file WD400.epw

    + + + + + + + + + + + + + + + + +

    Latitude

    71.286° north

    Longitude

    156.767° west

    Altitude

    10 m

    Time Zone

    -9

    + +-------- Corrected Code -------- +
      +
    • September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the + weather data bus.
      + This is for IBPSA, + #1477. +
      • +
    • March 11, 2020, by Ettore Zanetti:
      + First implementation. +
      • +
    • April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request #1339. +
      • +
    • May 2, 2021, by Ettore Zanetti:
      + Updated weather file as explained in #1478. +
      • +

    - Definition of angles + WD400: High Latitude Case

    - The angles incAngSurNor for the wind incidence angle - relative to the surface normal are measured counter-clock wise. The - figure below shows an example entry, which is also used in the model - - AixLib.Fluid.Sources.Examples.Outside_CpData_Specification. -

    -

    - \"image\" + Weather data file : WD400.epw

    - The wind incidence angle and surface azimuths are defined as follows: - The wind indicience angle is obtained directly from the weather data - bus weaBus.winDir. This variable contains the data from - the weather data file that was read, such as a TMY3 file. In - accordance to TMY3, the data is as shown in the table below. + Table 1: Site Data for Weather file WD400.epw

    - - - - - - - +
    - Value of winDir if the wind blows from different - directions. -
    - Wind from North:
    - 0
    - 0° -
    - - - - - - - -
    - Wind from West:
    - 3π/2
    - 270° +     		+

    + Latitude +

    		- Wind from East:
    - π/2
    - 90° +     		+

    + 71.286° north +

    - Wind from South:
    - π
    - 180° +     		+

    + Longitude +

    -

    - For the surface azimuth azi, the specification from - AixLib.Types.Azimuth is - used, which is as shown in the table below. -

    - - - - - - - - - - - + -
    - Value of azi if the exterior wall faces in the - different directions. -
    - Wall facing north:
    - π
    - 180° +     		+

    + 156.767° west +

    - Wall facing West:
    - π/2
    - 90° +     		+

    + Altitude +

    		- Wall facing east:
    - 3π/2
    - 270° +     		+

    + 10 m +

    - Wall facing South:
    - 0;
    - 0° +     		+

    + Time Zone +

    +     		+

    + -9 +

    -

    - Related model -

    -

    - This model differs from AixLib.Fluid.Sources.Outside_CpLowRise - by the calculation of the wind pressure coefficient - Cp,act. The wind pressure coefficient is defined by - a user-defined table instead of a generalized equation such that it - can be used for all building sizes and situations, for shielded - buildings, and for buildings with non-rectangular shapes. -

    -

    - References -

    -
      -
    • M. W. Liddament, 1996, A guide to energy efficient - ventilation. AIVC Annex V. -
      • -
    -
      -
    • February 2, 2022, by Michael Wetter:
      - Revised implementation.
      - This is for IBPSA, - #1436. -
      • -
    • Apr 6, 2021, by Klaas De Jonge:
      - First implementation. -
      • -
    -------- Errors -------- -line 51 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 -line 63 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 -line 14 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 43 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 5 column 2 - Warning: The summary attribute on the

    element is obsolete in HTML5 ----- AixLib/BoundaryConditions/Validation/BESTEST/WD100.mo ---- +---- AixLib/Fluid/Movers/BaseClasses/Characteristics/power.mo ---- -------- HTML Code -------- -

    WD100: Base Case

    -

    Weather data file : WD100.epw

    -

    Table 1: Site Data for Weather file WD100.epw

    -
    - - - - - - - - - - - - - - - -

    Latitude

    39.833° north

    Longitude

    104.65° west

    Altitude

    1650 m

    Time Zone

    -7

    -

    This model is a template for all the other test cases. - It allows to extrapolate all the weather data from the Reader TMY3 for a specific location, incliation and azimuth. - The model - AixLib.BoundaryConditions.Validation.IsotropicAndPerezDiffuseRadiation - outputs radiation data using the available Isotropic and Perez methodlogies. - The sky temperature is calculated using both the Horizontal radiation model, - from data reader weaBusHorRad and the dew point temperature plus sky cover model from the datareader weaBusSkyCovDewTem.

    +

    + This function computes the fan power consumption for given volume flow rate, + speed and performance data. The power consumption is +

    +

    + P = rN3   s(V̇/rN, d), +

    +

    + where + P is the power consumption, + rN is the normalized fan speed, + V̇ is the volume flow rate and + d are performance data for fan or pump power consumption at rN=1. +

    +

    Implementation

    +

    + The function s(·, ·) is a cubic hermite spline. + If the data d define a monotone decreasing sequence, then + s(·, d) is a monotone decreasing function. +

    • - September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the weather data bus.
      - This is for - IBPSA, #1477. + February 26, 2014, by Filip Jorissen:
      + Changed polynomial to be evaluated at V_flow/r_N + instead of V_flow to properly account for the + scaling law. See + #202 + for a discussion and validation.
    • - March 11, 2020, by Ettore Zanetti:
      + September 28, 2011, by Michael Wetter:
      First implementation.
      • -
    • - April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request - #1339. -
      • -
    • - May 2, 2021, by Ettore Zanetti:
      - Updated weather file as explained in #1478. -
      • -
    • - May 2, 2021, by Ettore Zanetti:
      - Added altitude to parameters.
      - This is for - IBPSA, #1477. -
    -------- Corrected Code -------- -

    - WD100: Base Case -

    - Weather data file : WD100.epw + This function computes the fan power consumption for given volume + flow rate, speed and performance data. The power consumption is +

    +

    + P = rN3   s(V̇/rN, d),

    - Table 1: Site Data for Weather file WD100.epw + where P is the power consumption, rN is the + normalized fan speed, V̇ is the volume flow rate and d + are performance data for fan or pump power consumption at + rN=1.

    - - - - - - - - - - - - - - - - - -
    -

    - Latitude -

    -     		-

    - 39.833° north -

    -
    -

    - Longitude -

    -     		-

    - 104.65° west -

    -
    -

    - Altitude -

    -     		-

    - 1650 m -

    -
    -

    - Time Zone -

    -     		-

    - -7 -

    -
    +

    + Implementation +

    - This model is a template for all the other test cases. It allows to - extrapolate all the weather data from the Reader TMY3 for a specific - location, incliation and azimuth. The model - AixLib.BoundaryConditions.Validation.IsotropicAndPerezDiffuseRadiation - outputs radiation data using the available Isotropic and Perez - methodlogies. The sky temperature is calculated using both the - Horizontal radiation model, from data reader weaBusHorRad and the dew - point temperature plus sky cover model from the datareader - weaBusSkyCovDewTem. + The function s(·, ·) is a cubic hermite spline. If the data + d define a monotone decreasing sequence, then s(·, d) + is a monotone decreasing function.

      -
    • September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the - weather data bus.
      - This is for IBPSA, - #1477. +
    • February 26, 2014, by Filip Jorissen:
      + Changed polynomial to be evaluated at V_flow/r_N + instead of V_flow to properly account for the scaling + law. See #202 + for a discussion and validation.
      • -
    • March 11, 2020, by Ettore Zanetti:
      +
    • September 28, 2011, by Michael Wetter:
      First implementation.
      • -
    • April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request #1339. -
      • -
    • May 2, 2021, by Ettore Zanetti:
      - Updated weather file as explained in #1478. -
      • -
    • May 2, 2021, by Ettore Zanetti:
      - Added altitude to parameters.
      - This is for IBPSA, - #1477. -
    -------- Errors -------- -line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Types.mo ---- +---- AixLib/Media/Specialized/Water/TemperatureDependentDensity.mo ---- -------- HTML Code -------- +

    + Base properties of the medium. +

    - Enumeration to define the choice of valve flow coefficient - (to be selected via choices menu): -

    - -
    - - - - - - - - - - - - - - - -
    EnumerationDescription
    OpPointflow coefficient defined by ratio m_flow_nominal/sqrt(dp_nominal)
    KvKv (metric) flow coefficient
    CvCv (US) flow coefficient
    AvAv (metric) flow coefficient
    - -

    - The details of the coefficients are explained in the - - Users Guide. + This function computes the density as a function of temperature.

    - - +

    Implementation

    - Enumeration that defines the heat exchanger construction. + The function is based on the IDA implementation in therpro.nmf, which + implements

    + 
    + d := 1000.12 + 1.43711e-2*T_degC -
+  5.83576e-3*T_degC^2 + 1.5009e-5*T_degC^3;
+

    - The following heat exchanger configurations are available in this enumeration: + This has been converted to Kelvin, which resulted in the above expression. + In addition, below 5 °C and above 100 °C, the density is replaced + by a linear function to avoid inflection points. + This linear extension is such that the density is once continuously differentiable.

    - - - - - - - - -
    EnumerationDescription
    ParallelFlowParallel flow
    CounterFlowCounter flow
    CrossFlowUnmixedCross flow, both streams unmixed
    CrossFlowStream1MixedStream2UnmixedCross flow, stream 1 mixed, stream 2 unmixed
    CrossFlowStream1UnmixedStream2MixedCross flow, stream 1 unmixed, stream 2 mixed
    ConstantTemperaturePhaseChangeConstant temperature phase change in one stream
    -

    - Note that for a given heat exchanger, the - HeatExchangerConfiguration is fixed. However, if the capacity - flow rates change, then the - - AixLib.Fluid.Types.HeatExchangerFlowRegime may change. For example, - a counter flow heat exchanger has HeatExchangerConfiguration=CounterFlow, - but the - AixLib.Fluid.Types.HeatExchangerFlowRegime can change to parallel flow if one of the two capacity flow rates reverts - its direction. -

    • - March 27, 2017, by Michael Wetter:
      - Added ConstantTemperaturePhaseChange.
      - This is for - - AixLib #694. + December 18, 2013, by Michael Wetter:
      + First implementation, based on the IDA implementation in therpro.nmf, + but converted from Celsius to Kelvin and linearly extended.
      • +
    + +

    + This function computes the dynamic viscosity. +

    + +
    • - February 18, 2009, by Michael Wetter:
      + December 2, 2013, by Michael Wetter:
      First implementation.

    - Enumeration to define the heat exchanger flow regime. + This function computes the specific enthalpy.

    + +
      +
    • + December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +
    +

    - This enumeration defines for the current capacity flow rate the kind of - heat transfer relation that will be used to compute the relation between - effectiveness and Number of Transfer Units. + This function computes the specific enthalpy of liquid water.

    + +
      +
    • + December 2, 2013, by Michael Wetter:
      + First implementation. +
      • +
    +

    - The following heat exchanger flow regimes are available in this enumeration: + This function computes the specific internal energy.

    - - - - - - - - -
    EnumerationDescription
    ParallelFlowParallel flow
    CounterFlowCounter flow
    CrossFlowUnmixedCross flow, both streams unmixed
    CrossFlowCMinMixedCMaxUnmixedCross flow, CMin mixed, CMax unmixed
    CrossFlowCMinUnmixedCMaxMixedCross flow, CMin unmixed, CMax mixed
    ConstantTemperaturePhaseChangeConstant temperature phase change in one stream
    • - March 27, 2017, by Michael Wetter:
      - Added ConstantTemperaturePhaseChange.
      + December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the specific entropy. +

    +

    + To obtain the state for a given pressure, entropy and mass fraction, use + + AixLib.Media.Air.setState_psX. +

    + +
      +
    • + December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the specific Gibbs energy. +

    + +
      +
    • + December 2, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the specific Helmholtz energy. +

    + +
      +
    • + December 2, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the specific enthalpy for + an isentropic state change from the temperature + that corresponds to the state refState + to reference_T. +

    + +
      +
    • + December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function returns the isobaric expansion coefficient, +

    +

    + βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p, +

    +

    + where + v is the specific volume, + T is the temperature and + p is the pressure. +

    + +
      +
    • + December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function returns the isothermal compressibility coefficient, + which is zero as this medium is incompressible. + The isothermal compressibility is defined as +

    +

    + κT = - 1 ⁄ v   (∂ v ⁄ ∂ p)T, +

    +

    + where + v is the specific volume, + T is the temperature and + p is the pressure. +

    + +
      +
    • + December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function returns the partial derivative of density + with respect to pressure at constant temperature, + which is zero as the medium is incompressible. +

    + +
      +
    • + December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the derivative of density with respect to temperature + at constant pressure. +

    + +
      +
    • + August 17, 2015, by Michael Wetter:
      + Removed dublicate entry of smooth and smoothOrder. This is for - - AixLib #694. + issue 303.
    • - February 18, 2009, by Michael Wetter:
      + December 18, 2013, by Michael Wetter:
      + First implementation, based on the IDA implementation in therpro.nmf, + but converted from Celsius to Kelvin. +
      • +
    + +

    + This function returns the partial derivative of density + with respect to mass fraction, + which is zero as the medium is a single substance. +

    + +
      +
    • + December 18, 2013, by Michael Wetter:
      First implementation.

    - This type allows defining which type of input should be used for movers. - This can either be + This function returns the specific heat capacity at constant pressure.

    -
      + +
      • - a constant set point declared by a parameter, + December 11, 2013, by Michael Wetter:
        + First implementation.
        • +
      + +

      + This function computes the specific heat capacity at constant volume. +

      + +
      • - a series of possible set points that can be switched using an integer input, or + December 11, 2013, by Michael Wetter:
        + First implementation.
        • +
      + +

      + This function returns the thermal conductivity. + The expression is obtained from Ramires et al. (1995). +

      +

      References

      +

      + Ramires, Maria L. V. and Nieto de Castro, Carlos A. and Nagasaka, Yuchi + and Nagashima, Akira and Assael, Marc J. and Wakeham, William A. + Standard Reference Data for the Thermal Conductivity of Water. + Journal of Physical and Chemical Reference Data, 24, p. 1377-1381, 1995. + DOI:10.1063/1.555963. +

      + +
      • - a continuously variable set point. + December 18, 2013, by Michael Wetter:
        + First implementation.
        • -
    + + +

    + This function returns the pressure. +

    • - April 2, 2015, by Filip Jorissen:
      + December 18, 2013, by Michael Wetter:
      First implementation.

    - This package contains type definitions. + This function returns the temperature.

    --------- Corrected Code -------- -

    - Enumeration to define the choice of valve flow coefficient (to be - selected via choices menu): -

    - - - - - - - - - - - - - - - - - - - - - -
    - Enumeration - - Description -
    - OpPoint - - flow coefficient defined by ratio m_flow_nominal/sqrt(dp_nominal) -
    - Kv - - Kv (metric) flow coefficient -
    - Cv - - Cv (US) flow coefficient -
    - Av - - Av (metric) flow coefficient -
    -

    - The details of the coefficients are explained in the - Users Guide. -

    -

    - Enumeration that defines the heat exchanger construction. -

    -

    - The following heat exchanger configurations are available in this - enumeration: -

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    - Enumeration - - Description -
    - ParallelFlow - - Parallel flow -
    - CounterFlow - - Counter flow -
    - CrossFlowUnmixed - - Cross flow, both streams unmixed -
    - CrossFlowStream1MixedStream2Unmixed - - Cross flow, stream 1 mixed, stream 2 unmixed -
    - CrossFlowStream1UnmixedStream2Mixed - - Cross flow, stream 1 unmixed, stream 2 mixed -
    - ConstantTemperaturePhaseChange - - Constant temperature phase change in one stream -
    -

    - Note that for a given heat exchanger, the - HeatExchangerConfiguration is fixed. However, if the - capacity flow rates change, then the AixLib.Fluid.Types.HeatExchangerFlowRegime - may change. For example, a counter flow heat exchanger has - HeatExchangerConfiguration=CounterFlow, but the AixLib.Fluid.Types.HeatExchangerFlowRegime - can change to parallel flow if one of the two capacity flow rates - reverts its direction. -

    -
      -
    • March 27, 2017, by Michael Wetter:
      - Added ConstantTemperaturePhaseChange.
      - This is for AixLib - #694. -
      • -
    • February 18, 2009, by Michael Wetter:
      - First implementation. -
      • -
    -

    - Enumeration to define the heat exchanger flow regime. -

    -

    - This enumeration defines for the current capacity flow rate the kind - of heat transfer relation that will be used to compute the relation - between effectiveness and Number of Transfer Units. -

    -

    - The following heat exchanger flow regimes are available in this - enumeration: -

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    - Enumeration - - Description -
    - ParallelFlow - - Parallel flow -
    - CounterFlow - - Counter flow -
    - CrossFlowUnmixed - - Cross flow, both streams unmixed -
    - CrossFlowCMinMixedCMaxUnmixed - - Cross flow, CMin mixed, CMax unmixed -
    - CrossFlowCMinUnmixedCMaxMixed - - Cross flow, CMin unmixed, CMax mixed -
    - ConstantTemperaturePhaseChange - - Constant temperature phase change in one stream -
    -
      -
    • March 27, 2017, by Michael Wetter:
      - Added ConstantTemperaturePhaseChange.
      - This is for AixLib - #694. -
      • -
    • February 18, 2009, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This type allows defining which type of input should be used for - movers. This can either be -

    -
      -
    1. a constant set point declared by a parameter, -
      2. -
    2. a series of possible set points that can be switched using an - integer input, or -
      3. -
    3. a continuously variable set point. -
      4. -
    -
      -
    • April 2, 2015, by Filip Jorissen:
      - First implementation. -
      • -
    -

    - This package contains type definitions. -

    - --------- Errors -------- -line 8 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 - - -line 8 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 - - -line 13 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 - - ----- AixLib/Fluid/FixedResistances/Validation/PlugFlowPipes/PlugFlowULg.mo ---- --------- HTML Code -------- - -

    - The example contains - experimental data from a real district heating network. -

    -

    - This model compares the results with the original Modelica Standard Library pipes. -

    -

    The pipes' temperatures are not initialized. Therefore, results of - outflow temperature before approximately the first 10000 seconds should not be - considered. -

    -

    Test bench schematic

    -

    \"Schematic

    -

    Calibration

    +
      +
    • + December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    +

    - There are some uncertainties about the heat loss coefficient between pipe and - surrounding air as well as regarding the heat conductivity of the insulation - material. - With the - given data, the length specific thermal resistance is R = 2.164 - ((m K)/W), calculated as follows: + This function returns the molar mass, + which is assumed to be constant.

    -

    - R=((1/(2*pipe.kIns)*log((0.0603+2*pipe.dIns)/(0.0603)))+1/(5*(0.0603+2*pipe.dIns)))/Modelica.Constants.pi

    -

    - U = 1/R = 0.462 W/(m K)

    • - March 7, 2020, by Michael Wetter:
      - Replaced measured data from specification in Modelica file to external table, - as this reduces the computing time.
      + December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function returns the thermodynamic state for a given pressure, + specific enthalpy and composition. +

    + +
      +
    • + December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function returns the thermodynamic state for a given pressure, + temperature and composition. +

    + +
      +
    • + December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function returns the thermodynamic state based on pressure, + specific entropy and mass fraction. +

    +

    + The state is computed by symbolically solving + + AixLib.Media.Specialized.Water.TemperatureDependentDensity.specificEntropy + for temperature. +

    + +
      +
    • + April 11, 2016 by Michael Wetter:
      + Corrected wrong hyperlink in documentation for + issue 450. +
      • +
    • + December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the derivative of the specific heat capacity + at constant pressure with respect to the state. +

    + +
      +
    • + December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the temperature derivative of the enthalpy of liquid water + per unit mass. +

    + +
      +
    • + December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + This function computes the kinematic viscosity as a function of temperature. +

    +

    Implementation

    +

    + The function is based on the IDA implementation in therpro.nmf. + The original equation is +

    + 
    + kinVis :=1E-6*Modelica.Math.exp(0.577449 - 3.253945e-2*T_degC + 2.17369e-4*
+       T_degC^2 - 7.22111e-7*T_degC^3);
+
    +

    + This has been converted to Kelvin, which resulted in the above expression. + In addition, at 5 °C the kinematic viscosity is linearly extrapolated + to avoid a large gradient at very low temperatures. + We selected the same point for the linearization as we used for the density, + as the density and the kinematic viscosity are combined in + + AixLib.Media.Specialized.Water.TemperatureDependentDensity.dynamicViscosity. +

    + +
      +
    • + April 11, 2016 by Michael Wetter:
      + Corrected wrong hyperlink in documentation for + issue 450. +
      • +
    • + December 18, 2013, by Michael Wetter:
      + First implementation, based on the IDA implementation in therpro.nmf, + but converted from Celsius to Kelvin. +
      • +
    + +

    + This medium package models liquid water. +

    +

    + The mass density is computed using a 3rd order polynomial, which yields the + density as a function of temperature as shown in the figure below. Note, however, + that computing density as a function of temperature can lead to considerably + slower computing time compared to using + + AixLib.Media.Water + in which the density is a constant. We therefore recommend to use + + AixLib.Media.Water + for typical building energy simulations. +

    +

    + \"Mass +

    +

    + For the specific heat capacities at constant pressure and at constant volume, + a constant value of 4184 J/(kg K), which corresponds to 20°C + is used. + The figure below shows the relative error of the specific heat capacity that + is introduced by this simplification. + Using a constant value for the specific heat capacity allows to compute + temperature from enthalpy without having to solve an implicit equation, + and therefore leads to faster simulation. +

    +

    + \"Relative +

    + + +

    + Thermal conductivity is calculated as a function of temperature as shown in the figure below. + The correlation used to calculate the thermal conductivity is +

    + +

    + λ(T) = λ(298.15 K) ⋅ (-1.48445+4.12292⋅(T/298.15)-1.63866⋅(T/298.15)2), +

    +

    + where λ(298.15 K) = 0.6065 W/(m ⋅ K) is the adopted standard value + of the thermal conductivity of water at 298.15 K and 0.1 MPa. +

    +

    + \"Thermal +

    + +

    + Dynamic viscosity is calculated as the product of density and kinematic viscosity, + both temperature dependent. However, the kinematic viscosity + has its own temperature dependent correlation, implemented at + + AixLib.Media.Specialized.Water.TemperatureDependentDensity.kinematicViscosity. + Results of the kinematic viscosity as a function of temperature are shown in the figure below. +

    +

    + \"Kinematic +

    + +

    + The enthalpy is computed using the convention that h=0 + if T=0 °C. +

    +

    Limitations

    +

    + Phase changes are not modeled. +

    + +
      +
    • + April 5, 2022, by Michael Wetter:
      + Corrected assignment of R_s in BaseProperties to avoid a unit error.
      This is for - #1289. + #1603.
    • - November 24, 2016 by Bram van der Heijde:
      Add pipe thickness for wall - capacity calculation and expand documentation section.
      • -
    • April 2, 2016 by Bram van der Heijde:
      Change thermal conductivity and - put boundary condition in K. + July 7, 2016, by Carles Ribas Tugores:
      + Correct Documentation. This is for + #487.
      • -
    • Januar 26, 2016 by Carles Ribas:
      First implementation. +
    • + June 6, 2015, by Michael Wetter:
      + Set AbsolutePressure(start=p_default) + and Temperature(start=T_default) + to have to have conistent start values. + See also revision notes of + + AixLib.Media.Water. + This is for + #266. +
      • +
    • + May 1, 2015, by Michael Wetter:
      + Added Inline=true for + + issue 227. +
      • +
    • + February 25, 2015, by Michael Wetter:
      + Removed stateSelect attribute on pressure as this caused + + AixLib.Examples.Tutorial.SpaceCooling.System3 + to fail with the error message + \"differentiated if-then-else was not continuous\". +
      • +
    • + February 3, 2015, by Michael Wetter:
      + Removed stateSelect.prefer for temperature. + This is for + #160. +
      • +
    • + October 15, 2014, by Michael Wetter:
      + Renamed from AixLib.Media.Water to + AixLib.Media.Water.Detailed to allow addition of + AixLib.Media.Water.Simple. +
      • +
    • + September 12, 2014, by Michael Wetter:
      + Set T(start=T_default) and p(start=p_default) in the + ThermodynamicState record. Setting the start value for + T is required to avoid an error due to conflicting start values + when checking + AixLib.Examples.VAVReheat.ClosedLoop in pedantic mode. +
      • +
    • + December 18, 2013, by Michael Wetter:
      + First implementation.
    -------- Corrected Code --------

    - The example contains experimental data from a real district heating - network. + Base properties of the medium.

    - This model compares the results with the original Modelica Standard - Library pipes. -

    -

    - The pipes' temperatures are not initialized. Therefore, results of - outflow temperature before approximately the first 10000 seconds - should not be considered. + This function computes the density as a function of temperature.

    - Test bench schematic + Implementation

    - \"Schematic + The function is based on the IDA implementation in + therpro.nmf, which implements

    -

    - Calibration -

    +
    + d := 1000.12 + 1.43711e-2*T_degC -
+  5.83576e-3*T_degC^2 + 1.5009e-5*T_degC^3;
+

    - There are some uncertainties about the heat loss coefficient between - pipe and surrounding air as well as regarding the heat conductivity - of the insulation material. With the - given data, the length specific thermal resistance is R = - 2.164 ((m K)/W), calculated as follows: -

    -

    - R=((1/(2*pipe.kIns)*log((0.0603+2*pipe.dIns)/(0.0603)))+1/(5*(0.0603+2*pipe.dIns)))/Modelica.Constants.pi -

    -

    - U = 1/R = 0.462 W/(m K) + This has been converted to Kelvin, which resulted in the above + expression. In addition, below 5 °C and above 100 °C, the density is + replaced by a linear function to avoid inflection points. This linear + extension is such that the density is once continuously + differentiable.

      -
    • March 7, 2020, by Michael Wetter:
      - Replaced measured data from specification in Modelica file to - external table, as this reduces the computing time.
      - This is for #1289. -
      • -
    • November 24, 2016 by Bram van der Heijde:
      - Add pipe thickness for wall capacity calculation and expand - documentation section. +
    • December 18, 2013, by Michael Wetter:
      + First implementation, based on the IDA implementation in + therpro.nmf, but converted from Celsius to Kelvin and + linearly extended.
      • -
    • April 2, 2016 by Bram van der Heijde:
      - Change thermal conductivity and put boundary condition in K. +
    +

    + This function computes the dynamic viscosity. +

    +
      +
    • December 2, 2013, by Michael Wetter:
      + First implementation.
      • -
    • Januar 26, 2016 by Carles Ribas:
      +
    +

    + This function computes the specific enthalpy. +

    +
      +
    • December 11, 2013, by Michael Wetter:
      First implementation.
    - --------- Errors -------- -line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 27 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/HeatExchangers/ActiveBeams/UsersGuide.mo ---- --------- HTML Code -------- -

    -This package contains models of active beams. -Active beams are devices used for heating, cooling and ventilation of spaces. -A schematic diagram of an active beam unit is given below. + This function computes the specific enthalpy of liquid water.

    -

    -\"image\" +

      +
    • December 2, 2013, by Michael Wetter:
      + First implementation. +
      • +
    +

    + This function computes the specific internal energy.

    +
      +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -The active beam unit consists of a primary air plenum, a mixing chamber, a heat exchanger (coil) and several nozzles. -Typically, an air-handling unit supplies primary air to the active beams. -The primary air is discharged to the mixing chamber through the nozzles. -This generates a low-pressure region which induces air from the room up through the heat exchanger, -where hot or cold water is circulating. -The conditioned induced air is then mixed with primary air, and the mixture descents back to the space. + This function computes the specific entropy.

    -This package contains two models. The model - -AixLib.Fluid.HeatExchangers.ActiveBeams.Cooling -is for cooling only, while the model - -AixLib.Fluid.HeatExchangers.ActiveBeams.CoolingAndHeating -has two water streams, one for heating and one for cooling. + To obtain the state for a given pressure, entropy and mass fraction, + use AixLib.Media.Air.setState_psX.

    - -

    Model equations for cooling

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -The performance of the model - -AixLib.Fluid.HeatExchangers.ActiveBeams.Cooling -is computed based on manufacturer data -specified in the package - -AixLib.Fluid.HeatExchangers.ActiveBeams.Data. + This function computes the specific Gibbs energy.

    +
      +
    • December 2, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -For off-design conditions, the performance is adjusted using modification factors -that account for changes in water flow rate, -primary air flow rate and temperature difference. -The total heat flow rate of the active beam unit is the sum of the heat flow rate provided by the primary air supply -Qsa and the cooling heat flow rate provided by the beam convector Qc,Beam -which injects room air and mixes it with the primary air. + This function computes the specific Helmholtz energy.

    +
      +
    • December 2, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -The heat flow rate -Qsa is delivered to a thermal zone -through the fluid ports, while the heat flow rate from the convector Qc,Beam -is coupled directly to the heat port. -See for example - -AixLib.Fluid.HeatExchangers.ActiveBeams.Examples.CoolingOnly -for how to connect these heat flow rates to a control volume. + This function computes the specific enthalpy for an isentropic state + change from the temperature that corresponds to the state + refState to reference_T.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -The primary air contribution is + This function returns the isobaric expansion coefficient,

    - Qsa = ṁsa cp,sa (Tsa-Tz) + βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p,

    -where ṁsa is the primary air mass flow rate, -cp,sa is the air specific heat capacity, -Tsa is the primary air temperature -and Tz is the zone air temperature. + where v is the specific volume, T is the temperature + and p is the pressure.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -The heat flow rate of the beam convector Qc,Beam is determined using -the rated capacity which is modified by three separate functions as + This function returns the isothermal compressibility coefficient, + which is zero as this medium is incompressible. The isothermal + compressibility is defined as

    - Qc,Beam = Qc,nominal -fΔT ( ΔTc ⁄ ΔTc,nominal ) -fsa( ṁsa ⁄ ṁsa,nominal ) -fw( ṁc,w ), + κT = - 1 ⁄ v   (∂ v ⁄ ∂ p)T,

    -the modification factors are as follows: -The modification factor fΔT(·) -describes how the capacity is adjusted to account for the temperature difference -between the zone air and the water entering the convector. -The independent variable is the ratio between the current temperature difference -ΔTc and the temperature difference used to rate beam performance ΔTc,nominal. -The temperature difference is -

    -

    - ΔTc = Tcw-Tz, + where v is the specific volume, T is the temperature + and p is the pressure.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -where Tcw is the chilled water temperature entering the convector. - -The modification factor fsa(·) adjusts the cooling capacity to account for varying primary air flow rate. -The independent variable is the ratio between the current primary air flow rate ṁsa -and the nominal air flow rate used to rate the beam performance. - -The modification factor fw(·) adjusts the cooling capacity for changes in water flow rate through the convector. -The independent variable is the ratio between the current water flow rate ṁw -and the nominal water flow rate used to rate the beam performance. + This function returns the partial derivative of density with respect + to pressure at constant temperature, which is zero as the medium is + incompressible.

    - -

    Model equations for heating

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -The performance of the model - -AixLib.Fluid.HeatExchangers.ActiveBeams.CoolingAndHeating -is computed identical to the above described model that only provides cooling, -with the exception that this model contains an additional water stream that -can be used to provide heating. + This function computes the derivative of density with respect to + temperature at constant pressure.

    +
      +
    • August 17, 2015, by Michael Wetter:
      + Removed dublicate entry of smooth and + smoothOrder. This is for issue 303. +
      • +
    • December 18, 2013, by Michael Wetter:
      + First implementation, based on the IDA implementation in + therpro.nmf, but converted from Celsius to Kelvin. +
      • +

    -For the heating water stream, the temperature difference ΔTh -used for the calculation of the modification factor fΔT(·) is -

    -

    -ΔTh = Thw-Tz, + This function returns the partial derivative of density with respect + to mass fraction, which is zero as the medium is a single substance.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -where Thw is the hot water temperature entering the convector in heating mode -and Tz is the zone air temperature. -

    - -

    Dynamics

    -

    -The model can be configured to be steady-state or dynamic. -If configured as dynamic, then a dynamic conservation equation is applied to the water streams -for heating and for cooling. -However, because the capacity of the beam depends on its inlet temperature, and is independent of the -outlet temperature, the heat transferred -to the room at the port heaPor.Q_flow, as well as the heat added to or removed from the -water streams, will instantaneously change. -The only dynamic responses are the water outlet temperatures, which change with a first -order response, parameterized with the time constant tau. -

    - -

    Energy balance

    -

    -All heat flow rate that is added to or extracted from the room is transmitted through the heat port -heaPor. Hence, this model does not cool the supply air between the ports -air_a and air_b. Rather, it adds this heat flow rate -to the heat port heaPor. -The rationale for this implementation is that the beam transfers heat by convection directly to the room, and -by induction of room air into the supply air. As this split of heat flow rate is generally not known, -and because the amount of inducted air is also unknown, -it was decided to transfer all heat through the heat port heaPor. -This also avoids having to add an extra air flow path for the air induced from the room. -

    - --------- Corrected Code -------- -

    - This package contains models of active beams. Active beams are - devices used for heating, cooling and ventilation of spaces. A - schematic diagram of an active beam unit is given below. -

    -

    - \"image\" + This function returns the specific heat capacity at constant + pressure.

    +
      +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - The active beam unit consists of a primary air plenum, a mixing - chamber, a heat exchanger (coil) and several nozzles. Typically, an - air-handling unit supplies primary air to the active beams. The - primary air is discharged to the mixing chamber through the nozzles. - This generates a low-pressure region which induces air from the room - up through the heat exchanger, where hot or cold water is - circulating. The conditioned induced air is then mixed with primary - air, and the mixture descents back to the space. + This function computes the specific heat capacity at constant volume.

    +
      +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - This package contains two models. The model AixLib.Fluid.HeatExchangers.ActiveBeams.Cooling - is for cooling only, while the model - AixLib.Fluid.HeatExchangers.ActiveBeams.CoolingAndHeating has two - water streams, one for heating and one for cooling. + This function returns the thermal conductivity. The expression is + obtained from Ramires et al. (1995).

    - Model equations for cooling + References

    - The performance of the model AixLib.Fluid.HeatExchangers.ActiveBeams.Cooling - is computed based on manufacturer data specified in the package - AixLib.Fluid.HeatExchangers.ActiveBeams.Data. + Ramires, Maria L. V. and Nieto de Castro, Carlos A. and Nagasaka, + Yuchi and Nagashima, Akira and Assael, Marc J. and Wakeham, William + A. Standard Reference Data for the Thermal Conductivity of Water. + Journal of Physical and Chemical Reference Data, 24, p. + 1377-1381, 1995. DOI:10.1063/1.555963.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - For off-design conditions, the performance is adjusted using - modification factors that account for changes in water flow rate, - primary air flow rate and temperature difference. The total heat flow - rate of the active beam unit is the sum of the heat flow rate - provided by the primary air supply Qsa and the - cooling heat flow rate provided by the beam convector - Qc,Beam which injects room air and mixes it with - the primary air. + This function returns the pressure.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - The heat flow rate Qsa is delivered to a thermal - zone through the fluid ports, while the heat flow rate from the - convector Qc,Beam is coupled directly to the heat - port. See for example - AixLib.Fluid.HeatExchangers.ActiveBeams.Examples.CoolingOnly for - how to connect these heat flow rates to a control volume. + This function returns the temperature.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - The primary air contribution is -

    -

    - Qsa = ṁsa cp,sa - (Tsa-Tz) + This function returns the molar mass, which is assumed to be + constant.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - where ṁsa is the primary air mass flow rate, - cp,sa is the air specific heat capacity, - Tsa is the primary air temperature and - Tz is the zone air temperature. + This function returns the thermodynamic state for a given pressure, + specific enthalpy and composition.

    +
      +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - The heat flow rate of the beam convector Qc,Beam is - determined using the rated capacity which is modified by three - separate functions as -

    -

    - Qc,Beam = Qc,nominal fΔT ( - ΔTc ⁄ ΔTc,nominal ) fsa( - ṁsa ⁄ ṁsa,nominal ) fw( - ṁc,w ), + This function returns the thermodynamic state for a given pressure, + temperature and composition.

    +
      +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - the modification factors are as follows: The modification factor - fΔT(·) describes how the capacity is adjusted to - account for the temperature difference between the zone air and the - water entering the convector. The independent variable is the ratio - between the current temperature difference ΔTc and - the temperature difference used to rate beam performance - ΔTc,nominal. The temperature difference is -

    -

    - ΔTc = Tcw-Tz, + This function returns the thermodynamic state based on pressure, + specific entropy and mass fraction.

    - where Tcw is the chilled water temperature entering - the convector. The modification factor fsa(·) - adjusts the cooling capacity to account for varying primary air flow - rate. The independent variable is the ratio between the current - primary air flow rate ṁsa and the nominal air flow - rate used to rate the beam performance. The modification factor - fw(·) adjusts the cooling capacity for changes in - water flow rate through the convector. The independent variable is - the ratio between the current water flow rate ṁw - and the nominal water flow rate used to rate the beam performance. + The state is computed by symbolically solving + AixLib.Media.Specialized.Water.TemperatureDependentDensity.specificEntropy + for temperature.

    -

    - Model equations for heating -

    +
      +
    • April 11, 2016 by Michael Wetter:
      + Corrected wrong hyperlink in documentation for issue 450. +
      • +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - The performance of the model - AixLib.Fluid.HeatExchangers.ActiveBeams.CoolingAndHeating is - computed identical to the above described model that only provides - cooling, with the exception that this model contains an additional - water stream that can be used to provide heating. + This function computes the derivative of the specific heat capacity + at constant pressure with respect to the state.

    +
      +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - For the heating water stream, the temperature difference - ΔTh used for the calculation of the - modification factor fΔT(·) is -

    -

    - ΔTh = Thw-Tz, + This function computes the temperature derivative of the enthalpy of + liquid water per unit mass.

    +
      +
    • December 11, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - where Thw is the hot water temperature entering the - convector in heating mode and Tz is the zone air + This function computes the kinematic viscosity as a function of temperature.

    - Dynamics + Implementation

    - The model can be configured to be steady-state or dynamic. If - configured as dynamic, then a dynamic conservation equation is - applied to the water streams for heating and for cooling. However, - because the capacity of the beam depends on its inlet temperature, - and is independent of the outlet temperature, the heat transferred to - the room at the port heaPor.Q_flow, as well as the heat - added to or removed from the water streams, will instantaneously - change. The only dynamic responses are the water outlet temperatures, - which change with a first order response, parameterized with the time - constant tau. + The function is based on the IDA implementation in + therpro.nmf. The original equation is

    -

    - Energy balance -

    +
    + kinVis :=1E-6*Modelica.Math.exp(0.577449 - 3.253945e-2*T_degC + 2.17369e-4*
+       T_degC^2 - 7.22111e-7*T_degC^3);
+

    - All heat flow rate that is added to or extracted from the room is - transmitted through the heat port heaPor. Hence, this - model does not cool the supply air between the ports - air_a and air_b. Rather, it adds this heat - flow rate to the heat port heaPor. The rationale for - this implementation is that the beam transfers heat by convection - directly to the room, and by induction of room air into the supply - air. As this split of heat flow rate is generally not known, and - because the amount of inducted air is also unknown, it was decided to - transfer all heat through the heat port heaPor. This - also avoids having to add an extra air flow path for the air induced - from the room. + This has been converted to Kelvin, which resulted in the above + expression. In addition, at 5 °C the kinematic viscosity is linearly + extrapolated to avoid a large gradient at very low temperatures. We + selected the same point for the linearization as we used for the + density, as the density and the kinematic viscosity are combined in + + AixLib.Media.Specialized.Water.TemperatureDependentDensity.dynamicViscosity.

    - --------- Errors -------- -line 7 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 59 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 72 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 87 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 115 column 1 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Chillers/BaseClasses/Carnot.mo ---- --------- HTML Code -------- - -

    - This is the base class for the Carnot chiller and the Carnot heat pump - whose coefficient of performance COP changes - with temperatures in the same way as the Carnot efficiency changes. -

    -

    - The model allows to either specify the Carnot effectivness - ηCarnot,0, or - a COP0 - at the nominal conditions, together with - the evaporator temperature Teva,0 and - the condenser temperature Tcon,0, in which - case the model computes the Carnot effectivness as -

    -

    - ηCarnot,0 = - COP0 - ⁄ (Tuse,0 ⁄ (Tcon,0-Teva,0)), -

    -

    - where - Tuse is the temperature of the the useful heat, - e.g., the evaporator temperature for a chiller or the condenser temperature - for a heat pump. -

    -

    - The COP is computed as the product -

    -

    - COP = ηCarnot,0 COPCarnot ηPL, -

    -

    - where COPCarnot is the Carnot efficiency and - ηPL is the part load efficiency, expressed using - a polynomial. - This polynomial has the form -

    -

    - ηPL = a1 + a2 y + a3 y2 + ... -

    -

    - where y ∈ [0, 1] is - either the part load for cooling in case of a chiller, or the part load of heating in - case of a heat pump, and the coefficients ai - are declared by the parameter a. -

    -

    Implementation

    -

    - To make this base class applicable to chiller or heat pumps, it uses - the boolean constant COP_is_for_cooling. - Depending on its value, the equations for the coefficient of performance - and the part load ratio are set up. -

    - -
      -
    • - April 14, 2020, by Michael Wetter:
      - Changed homotopyInitialization to a constant.
      - This is for - IBPSA, #1341. -
      • -
    • - September 12, 2019, by Michael Wetter:
      - Corrected value of evaluate_etaPL and how it is used. - This correction only affects protected variables and does not affect the results.
      - This is for - #1200. -
      • -
    • - June 16, 2017, by Michael Wetter:
      - Added temperature difference between fluids in condenser and evaporator - for computation of nominal COP and effectiveness.
      - This is for - #698. -
      • -
    • - March 28, 2017, by Felix Buenning:
      - Added temperature difference between fluids in condenser and evaporator. - The difference is based on discussions with Emerson Climate Technologies.
      - This is for - #698. -
      • -
    • - January 2, 2017, by Filip Jorissen:
      - Removed option for choosing what temperature - should be used to compute the Carnot efficiency. - This is for - - issue 497. -
      • -
    • - January 26, 2016, by Michael Wetter:
      - First implementation of this base class. -
      • -
    - --------- Corrected Code -------- +
      +
    • April 11, 2016 by Michael Wetter:
      + Corrected wrong hyperlink in documentation for issue 450. +
      • +
    • December 18, 2013, by Michael Wetter:
      + First implementation, based on the IDA implementation in + therpro.nmf, but converted from Celsius to Kelvin. +
      • +

    - This is the base class for the Carnot chiller and the Carnot heat - pump whose coefficient of performance COP changes with temperatures - in the same way as the Carnot efficiency changes. + This medium package models liquid water.

    - The model allows to either specify the Carnot effectivness - ηCarnot,0, or a COP0 at the - nominal conditions, together with the evaporator temperature - Teva,0 and the condenser temperature - Tcon,0, in which case the model computes the Carnot - effectivness as + The mass density is computed using a 3rd order polynomial, which + yields the density as a function of temperature as shown in the + figure below. Note, however, that computing density as a function of + temperature can lead to considerably slower computing time compared + to using AixLib.Media.Water in which the + density is a constant. We therefore recommend to use AixLib.Media.Water for typical + building energy simulations.

    -

    - ηCarnot,0 = COP0 ⁄ (Tuse,0 ⁄ - (Tcon,0-Teva,0)), +

    + \"Mass

    - where Tuse is the temperature of the the useful - heat, e.g., the evaporator temperature for a chiller or the condenser - temperature for a heat pump. + For the specific heat capacities at constant pressure and at constant + volume, a constant value of 4184 J/(kg K), which corresponds + to 20°C is used. The figure below shows the relative error of + the specific heat capacity that is introduced by this simplification. + Using a constant value for the specific heat capacity allows to + compute temperature from enthalpy without having to solve an implicit + equation, and therefore leads to faster simulation. +

    +

    + +

    - The COP is computed as the product + Thermal conductivity is calculated as a function of temperature as + shown in the figure below. The correlation used to calculate the + thermal conductivity is

    - COP = ηCarnot,0 COPCarnot ηPL, + λ(T) = λ(298.15 K) ⋅ + (-1.48445+4.12292⋅(T/298.15)-1.63866⋅(T/298.15)2),

    - where COPCarnot is the Carnot efficiency and - ηPL is the part load efficiency, expressed using a - polynomial. This polynomial has the form + where λ(298.15 K) = 0.6065 W/(m ⋅ K) is the adopted standard + value of the thermal conductivity of water at 298.15 K and + 0.1 MPa.

    -

    - ηPL = a1 + a2 y + a3 - y2 + ... +

    + \"Thermal

    - where y ∈ [0, 1] is either the part load for cooling in case - of a chiller, or the part load of heating in case of a heat pump, and - the coefficients ai are declared by the parameter - a. + Dynamic viscosity is calculated as the product of density and + kinematic viscosity, both temperature dependent. However, the + kinematic viscosity has its own temperature dependent correlation, + implemented at + AixLib.Media.Specialized.Water.TemperatureDependentDensity.kinematicViscosity. + Results of the kinematic viscosity as a function of temperature are + shown in the figure below. +

    +

    + \"Kinematic +

    +

    + The enthalpy is computed using the convention that h=0 if + T=0 °C.

    - Implementation + Limitations

    - To make this base class applicable to chiller or heat pumps, it uses - the boolean constant COP_is_for_cooling. Depending on - its value, the equations for the coefficient of performance and the - part load ratio are set up. + Phase changes are not modeled.

      -
    • April 14, 2020, by Michael Wetter:
      - Changed homotopyInitialization to a constant.
      - This is for IBPSA, - #1341. -
      • -
    • September 12, 2019, by Michael Wetter:
      - Corrected value of evaluate_etaPL and how it is used. - This correction only affects protected variables and does not - affect the results.
      +
    • April 5, 2022, by Michael Wetter:
      + Corrected assignment of R_s in + BaseProperties to avoid a unit error.
      This is for #1200. + \"https://github.com/ibpsa/modelica-ibpsa/issues/1603\">#1603.
      • -
    • June 16, 2017, by Michael Wetter:
      - Added temperature difference between fluids in condenser and - evaporator for computation of nominal COP and effectiveness.
      - This is for #698. +
    • July 7, 2016, by Carles Ribas Tugores:
      + Correct Documentation. This is for #487.
      • -
    • March 28, 2017, by Felix Buenning:
      - Added temperature difference between fluids in condenser and - evaporator. The difference is based on discussions with Emerson - Climate Technologies.
      - This is for #698. +
    • June 6, 2015, by Michael Wetter:
      + Set AbsolutePressure(start=p_default) and + Temperature(start=T_default) to have to have conistent + start values. See also revision notes of AixLib.Media.Water. This is for + #266.
      • -
    • January 2, 2017, by Filip Jorissen:
      - Removed option for choosing what temperature should be used to - compute the Carnot efficiency. This is for issue 497. +
    • May 1, 2015, by Michael Wetter:
      + Added Inline=true for issue 227.
      • -
    • January 26, 2016, by Michael Wetter:
      - First implementation of this base class. +
    • February 25, 2015, by Michael Wetter:
      + Removed stateSelect attribute on pressure as this + caused AixLib.Examples.Tutorial.SpaceCooling.System3 + to fail with the error message \"differentiated if-then-else was not + continuous\".
      • -
    +
  • February 3, 2015, by Michael Wetter:
    + Removed stateSelect.prefer for temperature. This is + for #160. +
    • +
  • October 15, 2014, by Michael Wetter:
    + Renamed from AixLib.Media.Water to + AixLib.Media.Water.Detailed to allow addition of + AixLib.Media.Water.Simple. +
    • +
  • September 12, 2014, by Michael Wetter:
    + Set T(start=T_default) and + p(start=p_default) in the + ThermodynamicState record. Setting the start value for + T is required to avoid an error due to conflicting + start values when checking AixLib.Examples.VAVReheat.ClosedLoop + in pedantic mode. +
    • +
  • December 18, 2013, by Michael Wetter:
    + First implementation. +
    • + -------- Errors -------- -line 16 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 30 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 39 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Movers/Validation/PowerSimplified.mo ---- +line 7 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +line 17 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 31 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 42 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 49 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 62 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/GroundTemperatureResponse.mo ---- -------- HTML Code --------

    - This example compares the power consumed by pumps that - take three different control signals. - Each pump has identical mass flow rate and pressure rise. + This model calculates the ground temperature response to obtain the temperature + at the borehole wall in a geothermal system where heat is being injected into or + extracted from the ground.

    - Note that for the instances - - AixLib.Fluid.Movers.FlowControlled_dp - and - - AixLib.Fluid.Movers.FlowControlled_m_flow, - we had to assign the efficiencies (otherwise the default constant - efficiency of 0.7 would have been used). - In these models, the power consumption is computed - using similarity laws, but using the mass flow rate as opposed - to the speed, because speed is not known in these two models. - This is an approximation at operating points in which - the speed is different from the nominal speed N_nominal - because similarity laws are valid for speed and not for - mass flow rate. + A load-aggregation scheme based on that developed by Claesson and Javed (2012) is + used to calculate the borehole wall temperature response with the temporal superposition + of ground thermal loads. In its base form, the + load-aggregation scheme uses fixed-length aggregation cells to agglomerate + thermal load history together, with more distant cells (denoted with a higher cell and vector index) + representing more distant thermal history. The more distant the thermal load, the + less impactful it is on the borehole wall temperature change at the current time step. + Each cell has an aggregation time associated to it denoted by nu, + which corresponds to the simulation time (since the beginning of heat injection or + extraction) at which the cell will begin shifting its thermal load to more distant + cells. To determine nu, cells have a temporal size rcel + (rcel in this model) + which follows the exponential growth +

    +

    + \"image\"

    - The figure below shows the approximation error for the - power calculation where the speed Nrpm differs from - the nominal speed Nnominal. + where nCel is the number of consecutive cells which can have the same size. + Decreasing rcel will generally decrease calculation times, at the cost of + precision in the temporal superposition. rcel is expressed in multiples + of the aggregation time resolution (via the parameter tLoaAgg). + Then, nu may be expressed as the sum of all rcel values + (multiplied by the aggregation time resolution) up to and including that cell in question. +

    +

    + To determine the weighting factors, the borefield's temperature + step response at the borefield wall is determined as

    - \"image\" + \"image\" +

    +

    + where g(·) is the borefield's thermal response factor known as the g-function, + H is the total length of all boreholes and ks is the thermal + conductivity of the soil. The weighting factors kappa (κ in the equation below) + for a given cell i are then expressed as follows. +

    +

    + \"image\" +

    +

    + where ν refers to the vector nu in this model and + Tstep(ν0)=0. +

    +

    + At every aggregation time step, a time event is generated to perform the load aggregation steps. + First, the thermal load is shifted. When shifting between cells of different size, total + energy is conserved. This operation is illustred in the figure below by Cimmino (2014). +

    +

    + \"image\" +

    +

    + After the cell-shifting operation is performed, the first aggregation cell has its + value set to the average thermal load since the last aggregation step. + Temporal superposition is then applied by means + of a scalar product between the aggregated thermal loads QAgg_flow and the + weighting factors κ. +

    +

    + Due to Modelica's variable time steps, the load aggregation scheme is modified by separating + the thermal response between the current aggregation time step and everything preceding it. + This is done according to +

    +

    + \"image\" +
    + \"image\" +

    +

    + where Tb is the borehole wall temperature, + Tg + is the undisturbed ground temperature, + Q is the ground thermal load per borehole length and h = g/(2 π ks) + is a temperature response factor based on the g-function. tk + is the last discrete aggregation time step, meaning that the current time t + satisfies tk≤t≤tk+1. + Δtagg(=tk+1-tk) is the + parameter tLoaAgg in the present model. +

    +

    + Thus, + ΔTb*(t) + is the borehole wall temperature change due to the thermal history prior to the current + aggregation step. At every aggregation time step, load aggregation and temporal superposition + are used to calculate its discrete value. Assuming no heat injection or extraction until + tk+1, this term is assumed to have a linear + time derivative, which is given by the difference between ΔTb*(tk+1) + (the temperature change from load history at the next discrete aggregation time step, which + is constant over the duration of the ongoing aggregation time step) and the total + temperature change at the last aggregation time step, ΔTb(t). +

    +

    + \"image\" +

    +

    + The second term ΔTb,q(t) concerns the ongoing aggregation time step. + To obtain the time derivative of this term, the thermal response factor h is assumed + to vary linearly over the course of an aggregation time step. Therefore, because + the ongoing aggregation time step always concerns the first aggregation cell, its derivative (denoted + by the parameter dTStepdt in this model) can be calculated as + kappa[1], the first value in the kappa vector, + divided by the aggregation time step Δt. + The derivative of the temperature change at the borehole wall is then expressed + as the multiplication of dTStepdt (which only needs to be + calculated once at the start of the simulation) and the heat flow Q at + the borehole wall. +

    +

    + \"image\" +

    +

    + \"image\" +

    +

    + With the two terms in the expression of ΔTb(t) expressed + as time derivatives, ΔTb(t) can itself also be + expressed as its time derivative and implemented as such directly in the Modelica + equations block with the der() operator. +

    +

    + \"image\" +
    + \"image\" +

    +

    + This load aggregation scheme is validated in + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.Validation.Analytic_20Years. +

    +

    References

    +

    + Cimmino, M. 2014. Développement et validation expérimentale de facteurs de réponse + thermique pour champs de puits géothermiques, + Ph.D. Thesis, École Polytechnique de Montréal. +

    +

    + Claesson, J. and Javed, S. 2012. A load-aggregation method to calculate extraction temperatures of borehole heat exchangers. ASHRAE Transactions 118(1): 530-539.

    • - October 15, 2021, by Hongxiang Fu:
      - Fixed the image in the documentation which was cut off - at the y-axis. This is for - IBPSA, #1533. -
      • -
    • - March 11, 2016, by Michael Wetter:
      - Revised implementation by assigning the data record directly in the - instances pump_dp and pump_m_flow, because - using a parameter and assigning this parameter leads - in OpenModelica to the error message - expected subtype of record AixLib.Fluid.Movers.Data.Generic. -
      • -
    • - March 2, 2016, by Filip Jorissen:
      - Revised implementation for - #417. -
      • -
    • - November 5, 2015, by Michael Wetter:
      - Changed parameters since the power is no longer a parameter for the movers - that take mass flow rate or head as an input. - This is for - issue 457. + August 30, 2018, by Michael Wetter:
      + Refactored model to compute the temperature difference relative to the initial temperature, + because the model is independent of the initial temperature.
    • - November 22, 2014, by Michael Wetter:
      - Revised implementation. + April 5, 2018, by Alex Laferrière:
      + First implementation.
    -------- Corrected Code --------

    - This example compares the power consumed by pumps that take three - different control signals. Each pump has identical mass flow rate and - pressure rise. -

    -

    - Note that for the instances AixLib.Fluid.Movers.FlowControlled_dp - and AixLib.Fluid.Movers.FlowControlled_m_flow, - we had to assign the efficiencies (otherwise the default constant - efficiency of 0.7 would have been used). In these models, the - power consumption is computed using similarity laws, but using the - mass flow rate as opposed to the speed, because speed is not known in - these two models. This is an approximation at operating points in - which the speed is different from the nominal speed - N_nominal because similarity laws are valid for speed - and not for mass flow rate. + This model calculates the ground temperature response to obtain the + temperature at the borehole wall in a geothermal system where heat is + being injected into or extracted from the ground.

    - The figure below shows the approximation error for the power - calculation where the speed Nrpm differs from the - nominal speed Nnominal. -

    -

    - \"image\" + A load-aggregation scheme based on that developed by Claesson and + Javed (2012) is used to calculate the borehole wall temperature + response with the temporal superposition of ground thermal loads. In + its base form, the load-aggregation scheme uses fixed-length + aggregation cells to agglomerate thermal load history together, with + more distant cells (denoted with a higher cell and vector index) + representing more distant thermal history. The more distant the + thermal load, the less impactful it is on the borehole wall + temperature change at the current time step. Each cell has an + aggregation time associated to it denoted by + nu, which corresponds to the simulation time (since the + beginning of heat injection or extraction) at which the cell will + begin shifting its thermal load to more distant cells. To determine + nu, cells have a temporal size rcel + (rcel in this model) which follows the exponential + growth +

    +

    + \"image\" +

    +

    + where nCel is the number of consecutive cells which + can have the same size. Decreasing rcel will + generally decrease calculation times, at the cost of precision in the + temporal superposition. rcel is expressed in multiples + of the aggregation time resolution (via the parameter + tLoaAgg). Then, nu may be expressed as the + sum of all rcel values (multiplied by the aggregation + time resolution) up to and including that cell in question. +

    +

    + To determine the weighting factors, the borefield's temperature step + response at the borefield wall is determined as +

    +

    + \"image\" +

    +

    + where g(·) is the borefield's thermal response factor known as + the g-function, H is the total length of all + boreholes and ks is the thermal conductivity of the + soil. The weighting factors kappa (κ in the + equation below) for a given cell i are then expressed as + follows. +

    +

    + \"image\" +

    +

    + where ν refers to the vector nu in this model and + Tstep(ν0)=0. +

    +

    + At every aggregation time step, a time event is generated to perform + the load aggregation steps. First, the thermal load is shifted. When + shifting between cells of different size, total energy is conserved. + This operation is illustred in the figure below by Cimmino (2014). +

    +

    + \"image\" +

    +

    + After the cell-shifting operation is performed, the first aggregation + cell has its value set to the average thermal load since the last + aggregation step. Temporal superposition is then applied by means of + a scalar product between the aggregated thermal loads + QAgg_flow and the weighting factors κ. +

    +

    + Due to Modelica's variable time steps, the load aggregation scheme is + modified by separating the thermal response between the current + aggregation time step and everything preceding it. This is done + according to +

    +

    + \"image\"
    + + \"image\" +

    +

    + where Tb is the borehole wall temperature, + Tg is the undisturbed ground temperature, Q + is the ground thermal load per borehole length and h = g/(2 π + ks) is a temperature response factor based on the + g-function. tk is the last discrete aggregation + time step, meaning that the current time t satisfies + tk≤t≤tk+1. + Δtagg(=tk+1-tk) is the + parameter tLoaAgg in the present model. +

    +

    + Thus, ΔTb*(t) is the borehole wall temperature + change due to the thermal history prior to the current aggregation + step. At every aggregation time step, load aggregation and temporal + superposition are used to calculate its discrete value. Assuming no + heat injection or extraction until tk+1, this term + is assumed to have a linear time derivative, which is given by the + difference between ΔTb*(tk+1) (the + temperature change from load history at the next discrete aggregation + time step, which is constant over the duration of the ongoing + aggregation time step) and the total temperature change at the last + aggregation time step, ΔTb(t). +

    +

    + \"image\" +

    +

    + The second term ΔTb,q(t) concerns the ongoing + aggregation time step. To obtain the time derivative of this term, + the thermal response factor h is assumed to vary linearly over + the course of an aggregation time step. Therefore, because the + ongoing aggregation time step always concerns the first aggregation + cell, its derivative (denoted by the parameter dTStepdt + in this model) can be calculated as kappa[1], the first + value in the kappa vector, divided by the aggregation + time step Δt. The derivative of the temperature change at the + borehole wall is then expressed as the multiplication of + dTStepdt (which only needs to be calculated once at the + start of the simulation) and the heat flow Q at the borehole + wall. +

    +

    + \"image\" +

    +

    + \"image\" +

    +

    + With the two terms in the expression of ΔTb(t) + expressed as time derivatives, ΔTb(t) can itself + also be expressed as its time derivative and implemented as such + directly in the Modelica equations block with the der() + operator. +

    +

    + \"image\"
    + + \"image\" +

    +

    + This load aggregation scheme is validated in + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.Validation.Analytic_20Years. +

    +

    + References +

    +

    + Cimmino, M. 2014. Développement et validation expérimentale de + facteurs de réponse thermique pour champs de puits géothermiques, + Ph.D. Thesis, École Polytechnique de Montréal. +

    +

    + Claesson, J. and Javed, S. 2012. A load-aggregation method to + calculate extraction temperatures of borehole heat exchangers. + ASHRAE Transactions 118(1): 530-539.

      -
    • October 15, 2021, by Hongxiang Fu:
      - Fixed the image in the documentation which was cut off at the - y-axis. This is for IBPSA, - #1533. -
      • -
    • March 11, 2016, by Michael Wetter:
      - Revised implementation by assigning the data record directly in the - instances pump_dp and pump_m_flow, - because using a parameter and assigning this - parameter leads in OpenModelica to the error message - expected subtype of record - AixLib.Fluid.Movers.Data.Generic. -
      • -
    • March 2, 2016, by Filip Jorissen:
      - Revised implementation for #417. -
      • -
    • November 5, 2015, by Michael Wetter:
      - Changed parameters since the power is no longer a parameter for the - movers that take mass flow rate or head as an input. This is for - issue - 457. +
    • August 30, 2018, by Michael Wetter:
      + Refactored model to compute the temperature difference relative to + the initial temperature, because the model is independent of the + initial temperature.
      • -
    • November 22, 2014, by Michael Wetter:
      - Revised implementation. +
    • April 5, 2018, by Alex Laferrière:
      + First implementation.
    -------- Errors -------- -line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 22 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 37 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 46 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 58 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 73 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 101 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 117 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 120 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 129 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Humidifiers/Humidifier_u.mo ---- +---- AixLib/Controls/Continuous/Examples/OffTimer.mo ---- -------- HTML Code --------

    - Model for an air humidifier or dehumidifier. -

    -

    - This model adds (or removes) moisture from the air stream. - The amount of exchanged moisture is equal to -

    -

    - ṁwat = u ṁwat,nom, -

    -

    - where u is the control input signal and - ṁwat,nom is equal to the parameter mWat_flow_nominal. - The parameter mWat_flow_nominal can be positive or negative. - If ṁwat is positive, then moisture is added - to the air stream, otherwise it is removed. + Example that demonstrates the use of the model + + AixLib.Controls.Continuous.OffTimer. + The input to the two timers are alternating boolean values. + Whenever the input becomes false(=0), the timer is reset. + The figures below show the input and output of the blocks.

    -

    - If the heat port heatPort is unconnected, then the enthalpy of the - air that flows through the device remains unchanged, e.g., the humidification - is adiabatic. To change the enthalpy of the air, add heat flow to the connector - heatPort. +

    + \"Input
    + \"Input

    • - March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for - #1542. -
      • -
    • - April 12, 2017, by Michael Wetter:
      - Removed parameters use_T_in and T. - This removes the optional specification of temperature through the parameter T - or the input connector T_in. - Exposed the heat port of the control volume to allow adding heat, - for example, to use the model as a steam humidifier.
      - This is for issue - - Buildings #704. -
      • -
    • - May 6, 2015, by Michael Wetter:
      - Set prescribedHeatFlowRate=true. - This is for issue - - #412. -
      • -
    • - May 29, 2014, by Michael Wetter:
      - Removed undesirable annotation Evaluate=true. -
      • -
    • - February 11, 2014 by Michael Wetter:
      - Corrected issue #197 - which led to twice the amount of latent heat being added to the fluid stream. -
      • -
    • - October 14, 2013 by Michael Wetter:
      - Constrained medium to be a subclass of - Modelica.Media.Interfaces.PartialCondensingGases, - as this base class declares the function - enthalpyOfCondensingGas. -
      • -
    • - July 30, 2013 by Michael Wetter:
      - Updated model to use new variable mWat_flow - in the base class. -
      • -
    • - May 24, 2011, by Michael Wetter:
      - Changed base class to allow using the model as a dynamic or a steady-state model. -
      • -
    • - April 14, 2010, by Michael Wetter:
      - Converted temperature input to a conditional connector. -
      • -
    • - April 17, 2008, by Michael Wetter:
      - First implementation. + November 21, 2011, by Michael Wetter:
      + Added documentation.
    -------- Corrected Code --------

    - Model for an air humidifier or dehumidifier. -

    -

    - This model adds (or removes) moisture from the air stream. The amount - of exchanged moisture is equal to -

    -

    - ṁwat = u ṁwat,nom, -

    -

    - where u is the control input signal and - ṁwat,nom is equal to the parameter - mWat_flow_nominal. The parameter - mWat_flow_nominal can be positive or negative. If - ṁwat is positive, then moisture is added to the - air stream, otherwise it is removed. + Example that demonstrates the use of the model AixLib.Controls.Continuous.OffTimer. + The input to the two timers are alternating boolean values. Whenever + the input becomes false(=0), the timer is reset. The + figures below show the input and output of the blocks.

    -

    - If the heat port heatPort is unconnected, then the - enthalpy of the air that flows through the device remains unchanged, - e.g., the humidification is adiabatic. To change the enthalpy of the - air, add heat flow to the connector heatPort. +

    + \"Input
    + \"Input

      -
    • March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for #1542. -
      • -
    • April 12, 2017, by Michael Wetter:
      - Removed parameters use_T_in and T. This - removes the optional specification of temperature through the - parameter T or the input connector T_in. - Exposed the heat port of the control volume to allow adding heat, - for example, to use the model as a steam humidifier.
      - This is for issue Buildings - #704. -
      • -
    • May 6, 2015, by Michael Wetter:
      - Set prescribedHeatFlowRate=true. This is for issue - #412. -
      • -
    • May 29, 2014, by Michael Wetter:
      - Removed undesirable annotation Evaluate=true. -
      • -
    • February 11, 2014 by Michael Wetter:
      - Corrected issue #197 - which led to twice the amount of latent heat being added to the - fluid stream. -
      • -
    • October 14, 2013 by Michael Wetter:
      - Constrained medium to be a subclass of - Modelica.Media.Interfaces.PartialCondensingGases, as - this base class declares the function - enthalpyOfCondensingGas. -
      • -
    • July 30, 2013 by Michael Wetter:
      - Updated model to use new variable mWat_flow in the - base class. -
      • -
    • May 24, 2011, by Michael Wetter:
      - Changed base class to allow using the model as a dynamic or a - steady-state model. -
      • -
    • April 14, 2010, by Michael Wetter:
      - Converted temperature input to a conditional connector. -
      • -
    • April 17, 2008, by Michael Wetter:
      - First implementation. +
    • November 21, 2011, by Michael Wetter:
      + Added documentation.
    -------- Errors -------- -line 9 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatExchangers/Heater_T.mo ---- +---- AixLib/Fluid/Types.mo ---- -------- HTML Code -------- +

    - Model for an ideal heater that controls its outlet temperature to - a prescribed outlet temperature. -

    -

    - This model forces the outlet temperature at port_b to be - no lower than the temperature of the input signal - TSet, subject to optional limits on the - capacity. - By default, the model has unlimited heating capacity. -

    -

    - The output signal Q_flow is the heat added - to the medium if the mass flow rate is from port_a to port_b. - If the flow is reversed, then Q_flow=0. -

    -

    - The outlet conditions at port_a are not affected by this model, - other than for a possible pressure difference due to flow friction. -

    -

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, - the component models the dynamic response using a first order differential equation. - The time constant of the component is equal to the parameter tau. - This time constant is adjusted based on the mass flow rate using -

    -

    - τeff = τ |ṁ| ⁄ ṁnom -

    -

    - where - τeff is the effective time constant for the given mass flow rate - ṁ and - τ is the time constant at the nominal mass flow rate - ṁnom. - This type of dynamics is equal to the dynamics that a completely mixed - control volume would have. + Enumeration to define the choice of valve flow coefficient + (to be selected via choices menu):

    + +
    + + + + + + + + + + + + + + + +
    EnumerationDescription
    OpPointflow coefficient defined by ratio m_flow_nominal/sqrt(dp_nominal)
    KvKv (metric) flow coefficient
    CvCv (US) flow coefficient
    AvAv (metric) flow coefficient
    +

    - Optionally, this model can have a flow resistance. - Set dp_nominal = 0 to disable the flow friction calculation. + The details of the coefficients are explained in the + + Users Guide.

    -

    - For a similar model that is a sensible cooling device, use - - AixLib.Fluid.HeatExchangers.SensibleCooler_T. - For a model that uses a control signal u ∈ [0, 1] and multiplies - this with the nominal heating or cooling power, use - - AixLib.Fluid.HeatExchangers.HeaterCooler_u -

    -

    Limitations

    +

    - If the flow is from port_b to port_a, - then the enthalpy of the medium is not affected by this model. + Enumeration that defines the heat exchanger construction.

    -

    Validation

    - The model has been validated against the analytical solution in - the examples - - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet - and - - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic. + The following heat exchanger configurations are available in this enumeration:

    + + + + + + + + +
    EnumerationDescription
    ParallelFlowParallel flow
    CounterFlowCounter flow
    CrossFlowUnmixedCross flow, both streams unmixed
    CrossFlowStream1MixedStream2UnmixedCross flow, stream 1 mixed, stream 2 unmixed
    CrossFlowStream1UnmixedStream2MixedCross flow, stream 1 unmixed, stream 2 mixed
    ConstantTemperaturePhaseChangeConstant temperature phase change in one stream
    +

    + Note that for a given heat exchanger, the + HeatExchangerConfiguration is fixed. However, if the capacity + flow rates change, then the + + AixLib.Fluid.Types.HeatExchangerFlowRegime may change. For example, + a counter flow heat exchanger has HeatExchangerConfiguration=CounterFlow, + but the + AixLib.Fluid.Types.HeatExchangerFlowRegime can change to parallel flow if one of the two capacity flow rates reverts + its direction. +

    • - September 10, 2018, by Michael Wetter:
      - Corrected missing propagation of initial conditions.
      + March 27, 2017, by Michael Wetter:
      + Added ConstantTemperaturePhaseChange.
      This is for - - AixLib, #1016. + + AixLib #694.
    • - May 3, 2017, by Michael Wetter:
      - First implementation.
      - This is for - - AixLib, #763. + February 18, 2009, by Michael Wetter:
      + First implementation.
    --------- Corrected Code -------- -

    - Model for an ideal heater that controls its outlet temperature to a - prescribed outlet temperature. -

    -

    - This model forces the outlet temperature at port_b to be - no lower than the temperature of the input signal TSet, - subject to optional limits on the capacity. By default, the model has - unlimited heating capacity. -

    -

    - The output signal Q_flow is the heat added to the medium - if the mass flow rate is from port_a to - port_b. If the flow is reversed, then - Q_flow=0. -

    -

    - The outlet conditions at port_a are not affected by this - model, other than for a possible pressure difference due to flow - friction. -

    -

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, the component - models the dynamic response using a first order differential - equation. The time constant of the component is equal to the - parameter tau. This time constant is adjusted based on - the mass flow rate using -

    -

    - τeff = τ |ṁ| ⁄ ṁnom -

    -

    - where τeff is the effective time constant for the - given mass flow rate ṁ and τ is the time constant at - the nominal mass flow rate ṁnom. This type of - dynamics is equal to the dynamics that a completely mixed control - volume would have. -

    -

    - Optionally, this model can have a flow resistance. Set - dp_nominal = 0 to disable the flow friction calculation. -

    -

    - For a similar model that is a sensible cooling device, use AixLib.Fluid.HeatExchangers.SensibleCooler_T. - For a model that uses a control signal u ∈ [0, 1] and - multiplies this with the nominal heating or cooling power, use - AixLib.Fluid.HeatExchangers.HeaterCooler_u -

    -

    - Limitations -

    -

    - If the flow is from port_b to port_a, then - the enthalpy of the medium is not affected by this model. -

    -

    - Validation -

    -

    - The model has been validated against the analytical solution in the - examples AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet - and - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic. -

    -
      -
    • September 10, 2018, by Michael Wetter:
      - Corrected missing propagation of initial conditions.
      - This is for AixLib, - #1016. -
      • -
    • May 3, 2017, by Michael Wetter:
      - First implementation.
      - This is for AixLib, - #763. -
      • -
    - --------- Errors -------- -line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/BoundaryConditions/Validation/BESTEST/WD600.mo ---- --------- HTML Code -------- - +

    + Enumeration to define the heat exchanger flow regime. +

    +

    + This enumeration defines for the current capacity flow rate the kind of + heat transfer relation that will be used to compute the relation between + effectiveness and Number of Transfer Units. +

    +

    + The following heat exchanger flow regimes are available in this enumeration: +

    + + + + + + + + +
    EnumerationDescription
    ParallelFlowParallel flow
    CounterFlowCounter flow
    CrossFlowUnmixedCross flow, both streams unmixed
    CrossFlowCMinMixedCMaxUnmixedCross flow, CMin mixed, CMax unmixed
    CrossFlowCMinUnmixedCMaxMixedCross flow, CMin unmixed, CMax mixed
    ConstantTemperaturePhaseChangeConstant temperature phase change in one stream
    +
    • - September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the weather data bus.
      + March 27, 2017, by Michael Wetter:
      + Added ConstantTemperaturePhaseChange.
      This is for - IBPSA, #1477. + + AixLib #694.
    • - March 11, 2020, by Ettore Zanetti:
      + February 18, 2009, by Michael Wetter:
      First implementation.
      • +
    + +

    + This type allows defining which type of input should be used for movers. + This can either be +

    +
    1. - April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request - #1339. + a constant set point declared by a parameter, +
      2. +
    2. + a series of possible set points that can be switched using an integer input, or +
      3. +
    3. + a continuously variable set point. +
      4. +
    + +
      +
    • + April 2, 2015, by Filip Jorissen:
      + First implementation.
    -

    WD600: Ground Reflactance

    -

    Weather data file : WD600.epw

    -

    Table 1: Site Data for Weather file WD600.epw

    - - - - - - - - - - - - - - - - -

    Latitude

    39.833° north

    Longitude

    104.65° west

    Altitude

    1650 m

    Time Zone

    -7

    +

    + This package contains type definitions. +

    -------- Corrected Code -------- -
      -
    • September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the - weather data bus.
      - This is for IBPSA, - #1477. -
      • -
    • March 11, 2020, by Ettore Zanetti:
      - First implementation. -
      • -
    • April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request #1339. -
      • -
    -

    - WD600: Ground Reflactance -

    -

    - Weather data file : WD600.epw -

    - Table 1: Site Data for Weather file WD600.epw + Enumeration to define the choice of valve flow coefficient (to be + selected via choices menu):

    - +
    + + + +
    + Enumeration + + Description +
    -

    - Latitude -

    + OpPoint     		-

    - 39.833° north -

    + flow coefficient defined by ratio m_flow_nominal/sqrt(dp_nominal)
    -

    - Longitude -

    + Kv     		-

    - 104.65° west -

    + Kv (metric) flow coefficient
    -

    - Altitude -

    + Cv     		-

    - 1650 m -

    + Cv (US) flow coefficient
    -

    - Time Zone -

    + Av     		-

    - -7 -

    + Av (metric) flow coefficient
    - --------- Errors -------- -line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 - - ----- AixLib/Controls/Continuous/Examples/SignalRanker.mo ---- --------- HTML Code -------- - -

    - Example that demonstrates the use of the signal ranker model. - The figure below shows the input and output signals of the block. - Note that - sigRan.y[1] ≥ sigRan.y[2] ≥ sigRan.y[3]. -

    -

    - \"Input
    - \"Output -

    - -
      -
    • - October 15, 2021, by Michael Wetter:
      - Moved start time of sine input signal to avoid simultaneous state event and time event.
      - This is for - IBPSA, #1534. -
      • -
    • - November 21, 2011, by Michael Wetter:
      - Added documentation. -
      • -
    - --------- Corrected Code --------

    - Example that demonstrates the use of the signal ranker model. The - figure below shows the input and output signals of the block. Note - that sigRan.y[1] ≥ sigRan.y[2] ≥ sigRan.y[3]. + The details of the coefficients are explained in the + Users Guide.

    -

    - \"Input
    - \"Output +

    + Enumeration that defines the heat exchanger construction. +

    +

    + The following heat exchanger configurations are available in this + enumeration: +

    +
    + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Enumeration + + Description +
    + ParallelFlow + + Parallel flow +
    + CounterFlow + + Counter flow +
    + CrossFlowUnmixed + + Cross flow, both streams unmixed +
    + CrossFlowStream1MixedStream2Unmixed + + Cross flow, stream 1 mixed, stream 2 unmixed +
    + CrossFlowStream1UnmixedStream2Mixed + + Cross flow, stream 1 unmixed, stream 2 mixed +
    + ConstantTemperaturePhaseChange + + Constant temperature phase change in one stream +
    +

    + Note that for a given heat exchanger, the + HeatExchangerConfiguration is fixed. However, if the + capacity flow rates change, then the AixLib.Fluid.Types.HeatExchangerFlowRegime + may change. For example, a counter flow heat exchanger has + HeatExchangerConfiguration=CounterFlow, but the AixLib.Fluid.Types.HeatExchangerFlowRegime + can change to parallel flow if one of the two capacity flow rates + reverts its direction.

      -
    • October 15, 2021, by Michael Wetter:
      - Moved start time of sine input signal to avoid simultaneous state - event and time event.
      +
    • March 27, 2017, by Michael Wetter:
      + Added ConstantTemperaturePhaseChange.
      This is for IBPSA, - #1534. + \"https://github.com/ibpsa/modelica-ibpsa/issues/694\">AixLib + #694.
      • -
    • November 21, 2011, by Michael Wetter:
      - Added documentation. +
    • February 18, 2009, by Michael Wetter:
      + First implementation.
    - --------- Errors -------- -line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/HeatExchangers/DryCoilEffectivenessNTU.mo ---- --------- HTML Code -------- - -

    - Model of a coil without humidity condensation. - This model transfers heat in the amount of -

    -

    - Q̇ = Q̇max ε
    - ε = f(NTU, Z, flowRegime), -

    -

    - where - Q̇max is the maximum heat that can be transferred, - ε is the heat transfer effectiveness, - NTU is the Number of Transfer Units, - Z is the ratio of minimum to maximum capacity flow rate and - flowRegime is the heat exchanger flow regime. - such as - parallel flow, cross flow or counter flow. -

    -

    - The flow regimes depend on the heat exchanger configuration. All configurations - defined in - - AixLib.Fluid.Types.HeatExchangerConfiguration - are supported. -

    -

    - The convective heat transfer coefficients scale proportional to - (ṁ/ṁ0)n, where - ṁ is the mass flow rate, - ṁ0 is the nominal mass flow rate, and - n=0.8 on the air-side and n=0.85 on the water side. -

    -

    - For a heat and moisture exchanger, use - - AixLib.Fluid.MassExchangers.ConstantEffectiveness. -

    - -
      -
    • - September 25, 2018, by Michael Wetter:
      - Refactored model to use a common base class. -
      • -
    - --------- Corrected Code -------- -

    - Model of a coil without humidity condensation. This model transfers - heat in the amount of -

    -

    - Q̇ = Q̇max ε
    - ε = f(NTU, Z, flowRegime), -

    -

    - where Q̇max is the maximum heat that can be - transferred, ε is the heat transfer effectiveness, NTU - is the Number of Transfer Units, Z is the ratio of minimum to - maximum capacity flow rate and flowRegime is the heat - exchanger flow regime. such as parallel flow, cross flow or counter - flow. -

    - The flow regimes depend on the heat exchanger configuration. All - configurations defined in AixLib.Fluid.Types.HeatExchangerConfiguration - are supported. + Enumeration to define the heat exchanger flow regime.

    - The convective heat transfer coefficients scale proportional to - (ṁ/ṁ0)n, where ṁ is the mass - flow rate, ṁ0 is the nominal mass flow rate, and - n=0.8 on the air-side and n=0.85 on the water side. + This enumeration defines for the current capacity flow rate the kind + of heat transfer relation that will be used to compute the relation + between effectiveness and Number of Transfer Units.

    - For a heat and moisture exchanger, use AixLib.Fluid.MassExchangers.ConstantEffectiveness. + The following heat exchanger flow regimes are available in this + enumeration:

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Enumeration + + Description +
    + ParallelFlow + + Parallel flow +
    + CounterFlow + + Counter flow +
    + CrossFlowUnmixed + + Cross flow, both streams unmixed +
    + CrossFlowCMinMixedCMaxUnmixed + + Cross flow, CMin mixed, CMax unmixed +
    + CrossFlowCMinUnmixedCMaxMixed + + Cross flow, CMin unmixed, CMax mixed +
    + ConstantTemperaturePhaseChange + + Constant temperature phase change in one stream +
      -
    • September 25, 2018, by Michael Wetter:
      - Refactored model to use a common base class. +
    • March 27, 2017, by Michael Wetter:
      + Added ConstantTemperaturePhaseChange.
      + This is for AixLib + #694. +
      • +
    • February 18, 2009, by Michael Wetter:
      + First implementation. +
      • +
    +

    + This type allows defining which type of input should be used for + movers. This can either be +

    +
      +
    1. a constant set point declared by a parameter, +
      2. +
    2. a series of possible set points that can be switched using an + integer input, or +
      3. +
    3. a continuously variable set point. +
      4. +
    +
      +
    • April 2, 2015, by Filip Jorissen:
      + First implementation.
    +

    + This package contains type definitions. +

    -------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 8 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 ----- AixLib/Fluid/Actuators/Valves/ThreeWayTable.mo ---- +line 8 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 + + +line 13 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 + + +---- AixLib/ThermalZones/ReducedOrder/RC/BaseClasses/splitFacVal.mo ---- -------- HTML Code -------- -

    - Three way valve with table-specified opening characteristics. - A separate characteristic for each flow path is used. -

    -

    - Each flow path uses an instance of the model - - AixLib.Fluid.Actuators.Valves.TwoWayTable. - Therefore, this model needs to be parameterized the same way as - - AixLib.Fluid.Actuators.Valves.TwoWayTable. - Specifically, - the mass flow rate for the fully open valve is determined based - on the value of the parameter CvData. - For the different valve positions y ∈ [0, 1], this nominal flow rate is - scaled by the values of the parameter - flowCharacteristics1 and flowCharacteristics3, respectively. - These parameters declare a table of the form -

    -
    - - - - - - -
    y 0 ... 1
    φ l ... 1
    -

    - where l = Kv(y=0)/Kv(y=1) > 0 is the valve leakage. - The first row is the valve opening, and the second row is the - mass flow rate, relative to the mass flow rate of the fully open - valve, under the assumption of a constant pressure difference across the - valve. - A suggested value for the valve leakage is l=0.0001. - If l = 0, then this model will replace it with - l = 10-8 for numerical reasons. - For example, if a valve has Kv=0.5 [m3/h/bar1/2] and - a linear opening characteristics and - a valve leakage of l=0.0001, then one would set -

    - 
    -  CvData=AixLib.Fluid.Types.CvTypes.Kv
-  Kv = 0.5
-  flowCharacteristics1(y={0,1}, phi={0.0001,1})
-  flowCharacteristics3(y={0,1}, phi={0.0001,1})
-
    -

    - Note, however, that - - AixLib.Fluid.Actuators.Valves.ThreeWayLinear provides a more - efficient implementation for this simple case. -

    -

    - The parameters flowCharacteristics1 and flowCharacteristics3 must meet the following - requirements, otherwise the model stops with an error: -

    -
      -
    • - Their arrays - y and phi - must be strictly monotonic increasing. -
      • -
    • - The first value must satisfy - y[1]=0, and - phi[1] must be equal to the - leakage flow rate, which must be bigger than zero. - Otherwise, a default value of 1E-8 is used. -
      • -
    • - The last values must satisfy - y[end]=1 and - phi[end]=1. -
      • -
    -

    - This model is based on the partial valve model - - AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. - Check this model for more information, such - as the regularization near the origin. -

    -

    - For an example that specifies an opening characteristics, see - - AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable. +

    Calculates the ratio of the surface areas of a wall to the total wall area, + unless the area is zero. It subtracts the wall area AExt + for first entry in AArray and AWin for + second entry in AArray unless AArray[1] and/or + AArray[2] are not zero. This is done separately for each + orientation. Consequently, the function gives an nRow x nCol + array back as output. Each row stands for one area in + AArray and each column for one orientation in + AExt and AWin. The function is used to + calculate the split factors for + + AixLib.ThermalZones.ReducedOrder.RC.BaseClasses.ThermSplitter.

    + For internal gains, the calculation is: +

    + SplitFaci = AArray[i] + /ATot +

    + whereby ATot is the sum of AArray. To + perform this, + AExt and AWin can just be set to vectors of + zeros with length 1. + For solar radiation through windows, the window and wall area with the same + orientation as the incoming radiation should be subtracted as these areas + cannot be hit by the radiation. This needs to be done separately for each + orientation and for exterior walls and windows only, according to: +

    + SplitFaci,k = (AArray[i] + - AExt[k]) + /(ATot + - AExt[k] + -AWin[k]) +

    + and +

    + SplitFaci,k = (AArray[i] + - AWin[k]) + /(ATot + - AExt[k] + - AWin[k]) +

    + respectively. For all other walls, the equation is: +

    + SplitFaci,k = AArray[i] + /(ATot + - AExt[k] + - AWin[k]) +

    + +
      +
    • December 15, 2015 by Moritz Lauster:
      + First Implementation. +
      • +
    + +-------- Corrected Code -------- +

    + Calculates the ratio of the surface areas of a wall to the total wall + area, unless the area is zero. It subtracts the wall area + AExt for first entry in AArray and + AWin for second entry in AArray unless + AArray[1] and/or AArray[2] are not zero. + This is done separately for each orientation. Consequently, the + function gives an nRow x nCol array back as output. Each + row stands for one area in AArray and each column for + one orientation in AExt and AWin. The + function is used to calculate the split factors for AixLib.ThermalZones.ReducedOrder.RC.BaseClasses.ThermSplitter. +

    For internal gains, the calculation is: +

    + SplitFaci = AArray[i] /ATot +

    whereby ATot is the sum of AArray. To +perform this, AExt and AWin can just be set +to vectors of zeros with length 1. For solar radiation through windows, +the window and wall area with the same orientation as the incoming +radiation should be subtracted as these areas cannot be hit by the +radiation. This needs to be done separately for each orientation and +for exterior walls and windows only, according to: +

    + SplitFaci,k = (AArray[i] - AExt[k]) /(ATot - AExt[k] + -AWin[k]) +

    and +

    + SplitFaci,k = (AArray[i] - AWin[k]) /(ATot - AExt[k] - + AWin[k]) +

    respectively. For all other walls, the equation is: +

    + SplitFaci,k = AArray[i] /(ATot - AExt[k] - AWin[k]) +

    +
      +
    • December 15, 2015 by Moritz Lauster:
      + First Implementation. +
      • +
    + +-------- Errors -------- +line 15 column 4 - Warning:

    attribute "align" not allowed for HTML5 +line 27 column 4 - Warning:

    attribute "align" not allowed for HTML5 +line 35 column 4 - Warning:

    attribute "align" not allowed for HTML5 +line 43 column 4 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Utilities/Math/Functions/polynomial.mo ---- +-------- HTML Code -------- + + This function computes a polynomial of arbitrary order. + The polynomial has the form +

    + y = a1 + a2 x + a3 x2 + ...

    -
    • - March 7, 2022, by Michael Wetter:
      - Set final massDynamics=energyDynamics.
      + December 14, 2016, by Michael Wetter:
      + Removed derivative annotation.
      This is for - #1542. + issue 602.
    • - June 10, 2021, by Michael Wetter:
      - Changed implementation of the filter and changed the parameter order to a constant - as most users need not change this value.
      - This is for - #1498. + March 30, 2011, by Michael Wetter:
      + Added zeroDerivative keyword.
    • - November 28, 2019, by Michael Wetter:
      - Revised implementation. + March 2, by Michael Wetter:
      + Removed redundant smoothOrder annotation.
    • - November 15, 2019, by Alexander Kümpel:
      + February 29, 2009 by Michael Wetter:
      First implementation.
    -------- Corrected Code -------- -

    - Three way valve with table-specified opening characteristics. A - separate characteristic for each flow path is used. +This function computes a polynomial of arbitrary order. The polynomial +has the form +

    + y = a1 + a2 x + a3 x2 + + ... +

    +
      +
    • December 14, 2016, by Michael Wetter:
      + Removed derivative annotation.
      + This is for issue 602. +
      • +
    • March 30, 2011, by Michael Wetter:
      + Added zeroDerivative keyword. +
      • +
    • March 2, by Michael Wetter:
      + Removed redundant smoothOrder annotation. +
      • +
    • February 29, 2009 by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 4 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/BoundaryConditions/Validation/BESTEST/WD300.mo ---- +-------- HTML Code -------- + +

      +
    • + September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the weather data bus.
      + This is for + IBPSA, #1477. +
      • +
    • + March 11, 2020, by Ettore Zanetti:
      + First implementation. +
      • +
    • + April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request + #1339. +
      • +
    • + May 2, 2021, by Ettore Zanetti:
      + Updated weather file as explained in #1478. +
      • +
    + +

    WD300: Southern Hemisphere Case

    +

    Weather data file : WD300.epw

    +

    Table 1: Site Data for Weather file WD300.epw

    + + + + + + + + + + + + + + + + +

    Latitude

    33.393° south

    Longitude

    70.786° west

    Altitude

    474 m

    Time Zone

    -4

    + +-------- Corrected Code -------- +
      +
    • September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the + weather data bus.
      + This is for IBPSA, + #1477. +
      • +
    • March 11, 2020, by Ettore Zanetti:
      + First implementation. +
      • +
    • April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request #1339. +
      • +
    • May 2, 2021, by Ettore Zanetti:
      + Updated weather file as explained in #1478. +
      • +
    +

    + WD300: Southern Hemisphere Case +

    +

    + Weather data file : WD300.epw

    - Each flow path uses an instance of the model AixLib.Fluid.Actuators.Valves.TwoWayTable. - Therefore, this model needs to be parameterized the same way as - AixLib.Fluid.Actuators.Valves.TwoWayTable. - Specifically, the mass flow rate for the fully open valve is - determined based on the value of the parameter CvData. - For the different valve positions y ∈ [0, 1], this nominal - flow rate is scaled by the values of the parameter - flowCharacteristics1 and - flowCharacteristics3, respectively. These parameters - declare a table of the form + Table 1: Site Data for Weather file WD300.epw

    - +
    + + + +
    - y +

    + Latitude +

    		- 0 +

    + 33.393° south +

    - ... +

    + Longitude +

    		- 1 +

    + 70.786° west +

    - φ +

    + Altitude +

    		- l +

    + 474 m +

    - ... +

    + Time Zone +

    		- 1 +

    + -4 +

    + +-------- Errors -------- +line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +---- AixLib/BoundaryConditions/UsersGuide.mo ---- +-------- HTML Code -------- + +

    This package contains models to read or compute boundary conditions, such as weather data, solar irradition and sky temperatures. +The calculations follow the description in Wetter (2004), Appendix A.4.2.

    +

    Accessing weather data

    - where l = Kv(y=0)/Kv(y=1) > 0 is the - valve leakage. The first row is the valve opening, and the second row - is the mass flow rate, relative to the mass flow rate of the fully - open valve, under the assumption of a constant pressure difference - across the valve. A suggested value for the valve leakage is - l=0.0001. If l = 0, then this model will replace it - with l = 10-8 for numerical reasons. For example, - if a valve has Kv=0.5 - [m3/h/bar1/2] and a linear opening - characteristics and a valve leakage of l=0.0001, then one - would set +The model + +AixLib.BoundaryConditions.WeatherData.ReaderTMY3 +can read TMY3 weather data for different locations. +The documentation of that model explains how to add +weather data for locations that are not distributed with the +AixLib library.

    -
    -  CvData=AixLib.Fluid.Types.CvTypes.Kv
-  Kv = 0.5
-  flowCharacteristics1(y={0,1}, phi={0.0001,1})
-  flowCharacteristics3(y={0,1}, phi={0.0001,1})
-

    - Note, however, that AixLib.Fluid.Actuators.Valves.ThreeWayLinear - provides a more efficient implementation for this simple case. +To access these weather data from the graphical model editor, +proceed as follows:

    +
      +

    1. - The parameters flowCharacteristics1 and - flowCharacteristics3 must meet the following - requirements, otherwise the model stops with an error: +Create an instance of + +AixLib.BoundaryConditions.WeatherData.ReaderTMY3.

      -
        -
      • Their arrays y and phi must be strictly - monotonic increasing. -
        • -
      • The first value must satisfy y[1]=0, and - phi[1] must be equal to the leakage flow rate, which - must be bigger than zero. Otherwise, a default value of - 1E-8 is used. -
        • -
      • The last values must satisfy y[end]=1 and - phi[end]=1. -
        • -
      +
      2. +

    2. - This model is based on the partial valve model AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. - Check this model for more information, such as the regularization - near the origin. +Create an instance of + +AixLib.BoundaryConditions.WeatherData.Bus.

      +
      3. +

    3. - For an example that specifies an opening characteristics, see - - AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable. +Draw a connection between these two instances.

      -
        -
      • March 7, 2022, by Michael Wetter:
        - Set final massDynamics=energyDynamics.
        - This is for #1542. -
        • -
      • June 10, 2021, by Michael Wetter:
        - Changed implementation of the filter and changed the parameter - order to a constant as most users need not change this - value.
        - This is for #1498. -
        • -
      • November 28, 2019, by Michael Wetter:
        - Revised implementation. -
        • -
      • November 15, 2019, by Alexander Kümpel:
        - First implementation. -
        • -
      - --------- Errors -------- -line 21 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 - - ----- AixLib/Controls/Continuous/LimPID.mo ---- --------- HTML Code -------- - -

    - PID controller in the standard form -

    -

    - y = k   ( e(t) + 1 ⁄ Ti   ∫ e(s) ds + Td de(t)⁄dt ), -

    -

    - where - y is the control signal, - e(t) = us - um is the control error, - with us being the set point and um being - the measured quantity, - k is the gain, - Ti is the time constant of the integral term and - Td is the time constant of the derivative term. -

    -

    - Note that the units of k are the inverse of the units of the control error, - while the units of Ti and Td are seconds. -

    -

    - For detailed treatment of integrator anti-windup, set-point weights and output limitation, see - Modelica.Blocks.Continuous.LimPID. -

    -

    Options

    - This controller can be configured as follows. -
    P, PI, PD, or PID action
    -

    - Through the parameter controllerType, the controller can be configured - as P, PI, PD or PID controller. The default configuration is PI. -

    -
    Direct or reverse acting
    -

    - Through the parameter reverseActing, the controller can be configured to - be reverse or direct acting. - The above standard form is reverse acting, which is the default configuration. - For a reverse acting controller, for a constant set point, - an increase in measurement signal u_m decreases the control output signal y - (Montgomery and McDowall, 2008). - Thus, -

    -
      -
    • - for a heating coil with a two-way valve, leave reverseActing = true, but -
      • -
    • - for a cooling coil with a two-way valve, set reverseActing = false. -
      • -
    -
    Reset of the controller output
    -

    - The controller can be configured to enable an input port that allows resetting the controller - output. The controller output can be reset as follows: -

    -
      -
    • - If reset = AixLib.Types.Reset.Disabled, which is the default, - then the controller output is never reset. -
      • -
    • - If reset = AixLib.Types.Reset.Parameter, then a boolean - input signal trigger is enabled. Whenever the value of - this input changes from false to true, - the controller output is reset by setting y - to the value of the parameter y_reset. -
      • -
    • - If reset = AixLib.Types.Reset.Input, then a boolean - input signal trigger and a real input signal y_reset_in - are enabled. Whenever the value of - trigger changes from false to true, - the controller output is reset by setting the value of y - to y_reset_in. -
      • -
    -

    - Note that this controller implements an integrator anti-windup. Therefore, - for most applications, keeping the default setting of - reset = AixLib.Types.Reset.Disabled is sufficient. - However, if the controller is used in conjuction with equipment that is being - switched on, better control performance may be achieved by resetting the controller - output when the equipment is switched on. - This is in particular the case in situations - where the equipment control input should continuously increase as the equipment is - switched on, such as a light dimmer that may slowly increase the luminance, or - a variable speed drive of a motor that should continuously increase the speed. -

    -

    References

    -

    - R. Montgomery and R. McDowall (2008). - \"Fundamentals of HVAC Control Systems.\" - American Society of Heating Refrigerating and Air-Conditioning Engineers Inc. Atlanta, GA. -

    - - -
      -
    • - June 1, 2020, by Michael Wetter:
      - Corrected wrong convention of reverse and direct action.
      - Changed default configuration from PID to PI.
      - This is for issue 1365. -
      • -
    • - March 9, 2020, by Michael Wetter:
      - Corrected wrong unit declaration for parameter k.
      - This is for issue 1316. -
      • -
    • - October 19, 2019, by Filip Jorissen:
      - Disabled homotopy to ensure bounded outputs - by copying the implementation from MSL 3.2.3 and by - hardcoding the implementation for homotopyType=NoHomotopy. - See issue 1221. -
      • -
    • - September 29, 2016, by Michael Wetter:
      - Refactored model. -
      • -
    • - August 25, 2016, by Michael Wetter:
      - Removed parameter limitsAtInit because it was only propagated to - the instance limiter, but this block no longer makes use of this parameter. - This is a non-backward compatible change.
      - Revised implemenentation, added comments, made some parameter in the instances final. -
      • -
    • July 18, 2016, by Philipp Mehrfeld:
      - Added integrator reset. - This is for issue 494. -
      • -
    • - March 15, 2016, by Michael Wetter:
      - Changed the default value to strict=true in order to avoid events - when the controller saturates. - This is for issue 433. -
      • -
    • - February 24, 2010, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code -------- + +

  • - PID controller in the standard form -

    -

    - y = k   ( e(t) + 1 ⁄ Ti   ∫ e(s) ds + - Td de(t)⁄dt ), +Finally, to send weather data to an input connector of a model, +connect the input connector of that model with the instance of + +AixLib.BoundaryConditions.WeatherData.Bus. +Some models connect to the whole weather data bus, such as + +AixLib.BoundaryConditions.SolarGeometry.Examples.IncidenceAngle, +in which case the connection will directly be drawn. +Other models require only an individual signal from the weather data bus, +such as + +AixLib.BoundaryConditions.SkyTemperature.Examples.BlackBody. +In this situation, Modelica modeling environments typically show a window that allows you to +select what data from this weather data bus you want to connect +with your model.

    +
    • + +

    Conventions for surface azimuth and tilt

    +

    To compute the solar irradiation, parameters such as the surface azimuth and the surface tilt are defined as shown in the following three figures.

    +

    \"image\"

    +

    \"image\"

    +

    \"image\"

    - where y is the control signal, e(t) = us - - um is the control error, with us - being the set point and um being the measured - quantity, k is the gain, Ti is the time - constant of the integral term and Td is the time - constant of the derivative term. +For the surface azimuth and tilt, the enumerations + +AixLib.Types.Azimuth +and + +AixLib.Types.Tilt +can be used.

    - Note that the units of k are the inverse of the units of the - control error, while the units of Ti and - Td are seconds. +Note that a ceiling has a tilt of 0 + +if they are facing straight upwards. +This is correct because +the solar irradiation on a ceiling construction is on the other-side surface, +which faces upwards toward the sky. Hence, a construction is considered +a ceiling from the view point of a person standing inside a room.

    + +

    References

    + + +-------- Corrected Code --------

    - For detailed treatment of integrator anti-windup, set-point weights - and output limitation, see Modelica.Blocks.Continuous.LimPID. + This package contains models to read or compute boundary conditions, + such as weather data, solar irradition and sky temperatures. The + calculations follow the description in Wetter (2004), Appendix A.4.2.

    - Options -

    This controller can be configured as follows. -
    - P, PI, PD, or PID action -
    + Accessing weather data +

    - Through the parameter controllerType, the controller can - be configured as P, PI, PD or PID controller. The default - configuration is PI. + The model AixLib.BoundaryConditions.WeatherData.ReaderTMY3 + can read TMY3 weather data for different locations. The documentation + of that model explains how to add weather data for locations that are + not distributed with the AixLib library.

    -
    - Direct or reverse acting -

    - Through the parameter reverseActing, the controller can - be configured to be reverse or direct acting. The above standard form - is reverse acting, which is the default configuration. For a reverse - acting controller, for a constant set point, an increase in - measurement signal u_m decreases the control output - signal y (Montgomery and McDowall, 2008). Thus, + To access these weather data from the graphical model editor, proceed + as follows:

    - -
    - Reset of the controller output -
    -

    - The controller can be configured to enable an input port that allows - resetting the controller output. The controller output can be reset - as follows: -

    -
      -
    • If reset = AixLib.Types.Reset.Disabled, which is the - default, then the controller output is never reset. +
    • +

      + Create an instance of AixLib.BoundaryConditions.WeatherData.Bus. +

      • -
    • If reset = AixLib.Types.Reset.Parameter, then a - boolean input signal trigger is enabled. Whenever the - value of this input changes from false to - true, the controller output is reset by setting - y to the value of the parameter y_reset. +
    • +

      + Draw a connection between these two instances. +

      • -
    • If reset = AixLib.Types.Reset.Input, then a boolean - input signal trigger and a real input signal - y_reset_in are enabled. Whenever the value of - trigger changes from false to - true, the controller output is reset by setting the - value of y to y_reset_in. +
    • +

      + Finally, to send weather data to an input connector of a model, + connect the input connector of that model with the instance of + AixLib.BoundaryConditions.WeatherData.Bus. + Some models connect to the whole weather data bus, such as + + AixLib.BoundaryConditions.SolarGeometry.Examples.IncidenceAngle, + in which case the connection will directly be drawn. Other models + require only an individual signal from the weather data bus, such + as + AixLib.BoundaryConditions.SkyTemperature.Examples.BlackBody. + In this situation, Modelica modeling environments typically show + a window that allows you to select what data from this weather + data bus you want to connect with your model. +

      • -
    + +

    + Conventions for surface azimuth and tilt +

    - Note that this controller implements an integrator anti-windup. - Therefore, for most applications, keeping the default setting of - reset = AixLib.Types.Reset.Disabled is sufficient. - However, if the controller is used in conjuction with equipment that - is being switched on, better control performance may be achieved by - resetting the controller output when the equipment is switched on. - This is in particular the case in situations where the equipment - control input should continuously increase as the equipment is - switched on, such as a light dimmer that may slowly increase the - luminance, or a variable speed drive of a motor that should - continuously increase the speed. + To compute the solar irradiation, parameters such as the surface + azimuth and the surface tilt are defined as shown in the following + three figures. +

    +

    + \"image\" +

    +

    + \"image\" +

    +

    + \"image\" +

    +

    + For the surface azimuth and tilt, the enumerations AixLib.Types.Azimuth and + AixLib.Types.Tilt can be + used. +

    +

    + Note that a ceiling has a tilt of 0 + if they are facing straight upwards. This is correct because the + solar irradiation on a ceiling construction is on the other-side + surface, which faces upwards toward the sky. Hence, a construction is + considered a ceiling from the view point of a person standing inside + a room.

    References

    -

    - R. Montgomery and R. McDowall (2008). \"Fundamentals of HVAC Control - Systems.\" American Society of Heating Refrigerating and - Air-Conditioning Engineers Inc. Atlanta, GA. -

      -
    • June 1, 2020, by Michael Wetter:
      - Corrected wrong convention of reverse and direct action.
      - Changed default configuration from PID to PI.
      - This is for issue - 1365. +
    • Michael Wetter.
      + Simulation-based + Building Energy Optimization.
      + Dissertation. University of California at Berkeley. 2004.
      • -
    • March 9, 2020, by Michael Wetter:
      - Corrected wrong unit declaration for parameter k.
      +
    + +-------- Errors -------- +line 60 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 61 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 62 column 1 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/ThermalZones/ReducedOrder/RC/FourElements.mo ---- +-------- HTML Code -------- + +

      +
    • + March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      + This is for + #1542. +
      • +
    • + December 9, 2019, by Moritz Lauster:
      + Changes nExt to nRoof for + RRoof and CRoof +
      • +
    • + July 11, 2019, by Katharina Brinkmann:
      + Renamed alphaRoof to hConRoof, + alphaRoofConst to hConRoof_const +
      • +
    • + August 31, 2018 by Moritz Lauster:
      + Updated schema in documentation and fixes + orientation and connections of roofRC for + + issue 997. +
      • +
    • + September 11, 2015 by Moritz Lauster:
      + First Implementation. +
      • +
    + +

    + This model adds another element for the roof. Roofs commonly + exhibit the same excitations as exterior walls but have different coefficients + of heat transfer due to their orientation. Adding an extra element for the roof + might lead to a finer resolution of the dynamic behaviour but increases + calculation times. The roof is parameterized via the length of the RC-chain + nRoof, + the vector of capacities CRoof[nRoof], the vector of resistances + RRoof[nRoof] and remaining resistances RRoofRem. +

    +

    + The image below shows the RC-network of this model. +

    +

    + \"image\"/ +

    + +-------- Corrected Code -------- +
      +
    • March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      This is for issue - 1316. -
      • -
    • October 19, 2019, by Filip Jorissen:
      - Disabled homotopy to ensure bounded outputs by copying the - implementation from MSL 3.2.3 and by hardcoding the implementation - for homotopyType=NoHomotopy. See issue - 1221. -
      • -
    • September 29, 2016, by Michael Wetter:
      - Refactored model. + \"https://github.com/ibpsa/modelica-ibpsa/issues/1542\">#1542.
      • -
    • August 25, 2016, by Michael Wetter:
      - Removed parameter limitsAtInit because it was only - propagated to the instance limiter, but this block no - longer makes use of this parameter. This is a non-backward - compatible change.
      - Revised implemenentation, added comments, made some parameter in - the instances final. +
    • December 9, 2019, by Moritz Lauster:
      + Changes nExt to nRoof for + RRoof and CRoof
      • -
    • July 18, 2016, by Philipp Mehrfeld:
      - Added integrator reset. This is for issue 494. +
    • July 11, 2019, by Katharina Brinkmann:
      + Renamed alphaRoof to hConRoof, + alphaRoofConst to hConRoof_const
      • -
    • March 15, 2016, by Michael Wetter:
      - Changed the default value to strict=true in order to - avoid events when the controller saturates. This is for issue 433. +
    • August 31, 2018 by Moritz Lauster:
      + Updated schema in documentation and fixes orientation and + connections of roofRC for issue 997.
      • -
    • February 24, 2010, by Michael Wetter:
      - First implementation. +
    • September 11, 2015 by Moritz Lauster:
      + First Implementation.
    +

    + This model adds another element for the roof. Roofs commonly exhibit + the same excitations as exterior walls but have different + coefficients of heat transfer due to their orientation. Adding an + extra element for the roof might lead to a finer resolution of the + dynamic behaviour but increases calculation times. The roof is + parameterized via the length of the RC-chain nRoof, the + vector of capacities CRoof[nRoof], the vector of + resistances RRoof[nRoof] and remaining resistances + RRoofRem. +

    +

    + The image below shows the RC-network of this model. +

    +

    + \"image\" +

    -------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 15 column 4 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/ThermalZones/ReducedOrder/RC/BaseClasses/splitFacVal.mo ---- +---- AixLib/Utilities/Math/Polynomial.mo ---- -------- HTML Code -------- -

    Calculates the ratio of the surface areas of a wall to the total wall area, - unless the area is zero. It subtracts the wall area AExt - for first entry in AArray and AWin for - second entry in AArray unless AArray[1] and/or - AArray[2] are not zero. This is done separately for each - orientation. Consequently, the function gives an nRow x nCol - array back as output. Each row stands for one area in - AArray and each column for one orientation in - AExt and AWin. The function is used to - calculate the split factors for - - AixLib.ThermalZones.ReducedOrder.RC.BaseClasses.ThermSplitter.

    - For internal gains, the calculation is: -

    - SplitFaci = AArray[i] - /ATot -

    - whereby ATot is the sum of AArray. To - perform this, - AExt and AWin can just be set to vectors of - zeros with length 1. - For solar radiation through windows, the window and wall area with the same - orientation as the incoming radiation should be subtracted as these areas - cannot be hit by the radiation. This needs to be done separately for each - orientation and for exterior walls and windows only, according to: -

    - SplitFaci,k = (AArray[i] - - AExt[k]) - /(ATot - - AExt[k] - -AWin[k]) -

    - and -

    - SplitFaci,k = (AArray[i] - - AWin[k]) - /(ATot - - AExt[k] - - AWin[k]) -

    - respectively. For all other walls, the equation is: -

    - SplitFaci,k = AArray[i] - /(ATot - - AExt[k] - - AWin[k]) -

    - -
      -
    • December 15, 2015 by Moritz Lauster:
      - First Implementation. -
      • -
    - --------- Corrected Code -------- -

    - Calculates the ratio of the surface areas of a wall to the total wall - area, unless the area is zero. It subtracts the wall area - AExt for first entry in AArray and - AWin for second entry in AArray unless - AArray[1] and/or AArray[2] are not zero. - This is done separately for each orientation. Consequently, the - function gives an nRow x nCol array back as output. Each - row stands for one area in AArray and each column for - one orientation in AExt and AWin. The - function is used to calculate the split factors for AixLib.ThermalZones.ReducedOrder.RC.BaseClasses.ThermSplitter. -

    For internal gains, the calculation is: -

    - SplitFaci = AArray[i] /ATot -

    whereby ATot is the sum of AArray. To -perform this, AExt and AWin can just be set -to vectors of zeros with length 1. For solar radiation through windows, -the window and wall area with the same orientation as the incoming -radiation should be subtracted as these areas cannot be hit by the -radiation. This needs to be done separately for each orientation and -for exterior walls and windows only, according to: -

    - SplitFaci,k = (AArray[i] - AExt[k]) /(ATot - AExt[k] - -AWin[k]) -

    and -

    - SplitFaci,k = (AArray[i] - AWin[k]) /(ATot - AExt[k] - - AWin[k]) -

    respectively. For all other walls, the equation is: -

    - SplitFaci,k = AArray[i] /(ATot - AExt[k] - AWin[k]) -

    -
      -
    • December 15, 2015 by Moritz Lauster:
      - First Implementation. -
      • -
    - --------- Errors -------- -line 15 column 4 - Warning:

    attribute "align" not allowed for HTML5 -line 27 column 4 - Warning:

    attribute "align" not allowed for HTML5 -line 35 column 4 - Warning:

    attribute "align" not allowed for HTML5 -line 43 column 4 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/HeatPumps/Compressors/ScrollCompressor.mo ---- --------- HTML Code -------- - -

    - Model for a scroll processor, as detailed in Jin (2002). The rate of heat transferred to the evaporator is given by: -

    -

    - Q̇Eva = ṁref ( hVap(TEva) - hLiq(TCon) ). -

    -

    - The power consumed by the compressor is given by a linear efficiency relation: -

    -

    - P = PTheoretical / η + PLoss,constant. -

    -

    - Variable speed is achieved by multiplying the full load suction volume flow rate - by the normalized compressor speed. The power and heat transfer rates are forced - to zero if the resulting heat pump state has higher evaporating pressure than - condensing pressure. -

    -

    Assumptions and limitations

    -

    - The compression process is assumed isentropic. The thermal energy - of superheating is ignored in the evaluation of the heat transferred to the refrigerant - in the evaporator. There is no supercooling. -

    -

    References

    -

    - H. Jin. - - Parameter estimation based models of water source heat pumps. - - PhD Thesis. Oklahoma State University. Stillwater, Oklahoma, USA. 2002. -

    +

    This block computes a polynomial of arbitrary order. The polynomial has the form

    +

    y = a1 + a2 x + a3 x2 + ...

    • - January 25, 2019, by Michael Wetter:
      - Added start value to avoid warning in JModelica. -
      • -
    • - May 30, 2017, by Filip Jorissen:
      - Removed pressure_error as - this is replaced by - - AixLib.Fluid.HeatPumps.Compressors.BaseClasses.TemperatureProtection. - See #769. + September 21, 2021, by Michael Wetter:
      + Renamed class to correct typo in class name.
      + This is for + IBPSA, #1524.
    • - November 11, 2016, by Massimo Cimmino:
      + November 28, 2013, by Marcus Fuchs:
      First implementation.
    -------- Corrected Code --------

    - Model for a scroll processor, as detailed in Jin (2002). The rate of - heat transferred to the evaporator is given by: -

    -

    - Q̇Eva = ṁref ( - hVap(TEva) - hLiq(TCon) - ). -

    -

    - The power consumed by the compressor is given by a linear efficiency - relation: -

    -

    - P = PTheoretical / η + PLoss,constant. -

    -

    - Variable speed is achieved by multiplying the full load suction - volume flow rate by the normalized compressor speed. The power and - heat transfer rates are forced to zero if the resulting heat pump - state has higher evaporating pressure than condensing pressure. -

    -

    - Assumptions and limitations -

    -

    - The compression process is assumed isentropic. The thermal energy of - superheating is ignored in the evaluation of the heat transferred to - the refrigerant in the evaporator. There is no supercooling. + This block computes a polynomial of arbitrary order. The polynomial + has the form

    -

    - References -

    -

    - H. Jin. Parameter estimation based models of water source heat - pumps. PhD Thesis. Oklahoma State University. Stillwater, - Oklahoma, USA. 2002. +

    + y = a1 + a2 x + a3 x2 + ...

      -
    • January 25, 2019, by Michael Wetter:
      - Added start value to avoid warning in JModelica. -
      • -
    • May 30, 2017, by Filip Jorissen:
      - Removed pressure_error as this is replaced by - AixLib.Fluid.HeatPumps.Compressors.BaseClasses.TemperatureProtection. - See #769. +
    • September 21, 2021, by Michael Wetter:
      + Renamed class to correct typo in class name.
      + This is for IBPSA, + #1524.
      • -
    • November 11, 2016, by Massimo Cimmino:
      +
    • November 28, 2013, by Marcus Fuchs:
      First implementation.
    -------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/FMI/ExportContainers/ThermalZone.mo ---- +---- AixLib/BoundaryConditions/Validation/BESTEST/WD600.mo ---- -------- HTML Code -------- -

    - Model that is used as a container for a single thermal zone - that is to be exported as an FMU. -

    -

    Typical use and important parameters

    -

    - To use this model as a container for an FMU, extend - from this model, rather than instantiate it, - add your thermal zone and a vector of mass flow rate sensors. - By extending from this model, the top-level - signal connectors on the left stay at the top-level, and hence - will be visible at the FMI interface. -

    - - Note that
    • - The vector of mass flow rate sensors is used to connect - the thermal zone adapter and your thermal zone. -
      • -
    • - The vector of mass flow rate sensors must have the size nPorts. + September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the weather data bus.
      + This is for + IBPSA, #1477.
    • - All fluid ports of the mass flow rate sensor must be connected. + March 11, 2020, by Ettore Zanetti:
      + First implementation.
    • - If the vector of mass flow rate sensors is not used, and your themal zone - has fluid ports which are autosized, then a direct connection between - the thermal zone adpater theZonAda and your thermal - zone will be rejected. The reason is because autosized fluid ports - can only be connected to vector of ports whose sizes are literal. + April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request + #1339.
    -

    - The example - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone - shows how a simple thermal zone can be implemented and exported as - an FMU. - -

    - -

    - The conversion between the fluid ports and signal ports is done - in the thermal zone adapter theZonAda. - This adapter has a vector of fluid ports called ports[nPorts] - which needs to be connected to the air volume of the thermal zone. - At this port, air exchanged between the thermal zone, the HVAC system - and any infiltration flow paths. -

    -

    - This model has input signals fluPor[nPorts], which carry - the mass flow rate for each flow that is connected to ports, together with its - temperature, water vapor mass fraction per total mass of the air (not per kg dry - air), and trace substances. These quantities are always as if the flow - enters the room, even if the flow is zero or negative. - If a medium has no moisture, e.g., if Medium.nXi=0, or - if it has no trace substances, e.g., if Medium.nC=0, then - the output signal for these properties are removed. - Thus, a thermal zone model that uses these signals to compute the - heat added by the HVAC system need to implement an equation such as -

    -

    - Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), -

    -

    - where - Qsen is the sensible heat flow rate added to the thermal zone, - ṁsup is the supply air mass flow rate from - the port fluPor (which is negative if it is an exhaust), - cp is the specific heat capacity at constant pressure, - Tsup is the supply air temperature and - Tair,zon is the zone air temperature. - Note that without the max(·, ·), the energy - balance would be wrong. - For example, - - the control volumes in - - AixLib.Fluid.MixingVolumes - implement such a max(·, ·) function. -

    -

    - The zone air temperature, - the water vapor mass fraction per total mass of the air (unless Medium.nXi=0) - and trace substances (unless Medium.nC=0) - can be obtained from the outupt connector - fluPor.backward. - These signals are the same as the inflowing fluid stream(s) - at the port theAdaZon.ports[1:nPorts]. - The fluid connector ports[nPorts] has a prescribed mass flow rate, but - it does not set any pressure. -

    -

    - This model has a user-defined parameter nPorts - which sets the number of fluid ports, which in turn is used - for the ports fluPor and ports. - All nPorts - ports[1:nPorts] need to be connected as demonstrated in the example - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. -

    -

    - -

    - -
      -
    • - January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air. - See #1050. -
      • -
    • - September 20, 2016, by Thierry S. Nouidui:
      - Revised documentation to explain the rationale - of needing mass flow rate sensors. -
      • -
    • - June 29, 2016, by Michael Wetter:
      - Revised implementation and documentation. -
      • -
    • - April 27, 2016, by Thierry S. Nouidui:
      - First implementation. -
      • -
    +

    WD600: Ground Reflactance

    +

    Weather data file : WD600.epw

    +

    Table 1: Site Data for Weather file WD600.epw

    +
    + + + + + + + + + + + + + + + +

    Latitude

    39.833° north

    Longitude

    104.65° west

    Altitude

    1650 m

    Time Zone

    -7

    -------- Corrected Code -------- -

    - Model that is used as a container for a single thermal zone that is - to be exported as an FMU. -

    -

    - Typical use and important parameters -

    -

    - To use this model as a container for an FMU, extend from this model, - rather than instantiate it, add your thermal zone and a vector of - mass flow rate sensors. By extending from this model, the top-level - signal connectors on the left stay at the top-level, and hence will - be visible at the FMI interface. -

    Note that
      -
    • The vector of mass flow rate sensors is used to connect the - thermal zone adapter and your thermal zone. -
      • -
    • The vector of mass flow rate sensors must have the size - nPorts. +
    • September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the + weather data bus.
      + This is for IBPSA, + #1477.
      • -
    • All fluid ports of the mass flow rate sensor must be connected. +
    • March 11, 2020, by Ettore Zanetti:
      + First implementation.
      • -
    • If the vector of mass flow rate sensors is not used, and your - themal zone has fluid ports which are autosized, then a direct - connection between the thermal zone adpater theZonAda - and your thermal zone will be rejected. The reason is because - autosized fluid ports can only be connected to vector of ports whose - sizes are literal. +
    • April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request #1339.
    +

    + WD600: Ground Reflactance +

    - The example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone shows - how a simple thermal zone can be implemented and exported as an FMU. - + Weather data file : WD600.epw

    - The conversion between the fluid ports and signal ports is done in - the thermal zone adapter theZonAda. This adapter has a - vector of fluid ports called ports[nPorts] which needs - to be connected to the air volume of the thermal zone. At this port, - air exchanged between the thermal zone, the HVAC system and any - infiltration flow paths. + Table 1: Site Data for Weather file WD600.epw

    + + + + + + + + + + + + + + + + + +
    +

    + Latitude +

    +     		+

    + 39.833° north +

    +
    +

    + Longitude +

    +     		+

    + 104.65° west +

    +
    +

    + Altitude +

    +     		+

    + 1650 m +

    +
    +

    + Time Zone +

    +     		+

    + -7 +

    +
    + +-------- Errors -------- +line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +---- AixLib/ThermalZones/ReducedOrder/RC/BaseClasses/InteriorWall.mo ---- +-------- HTML Code -------- + +

    InteriorWall represents heat storage within walls. It links a + variable number n of thermal resistances and capacities to a + series connection. n thus defines the spatial discretization of + thermal effects within the wall. All effects are considered as one-dimensional + normal to the wall's surface. This model is thought for interior wall + elements that only serve as heat storage elements. The RC-chain is defined via + a vector of capacities CInt[n] and a vector of resistances + RInt[n]. + Resistances and capacities are connected alternately, starting with the first + resistance RInt[1], from heat port_a into the wall. +

    +

    \"image\"/

    + +
      +
    • + April 27, 2016, by Michael Wetter:
      + Added graphical connections. +
      • +
    • + April 17, 2015, by Moritz Lauster:
      + Implemented. +
      • +
    + +-------- Corrected Code --------

    - This model has input signals fluPor[nPorts], which carry - the mass flow rate for each flow that is connected to - ports, together with its temperature, water vapor mass - fraction per total mass of the air (not per kg dry air), and trace - substances. These quantities are always as if the flow enters the - room, even if the flow is zero or negative. If a medium has no - moisture, e.g., if Medium.nXi=0, or if it has no trace - substances, e.g., if Medium.nC=0, then the output signal - for these properties are removed. Thus, a thermal zone model that - uses these signals to compute the heat added by the HVAC system need - to implement an equation such as -

    -

    - Qsen = max(0, ṁsup)   cp   - (Tsup - Tair,zon), -

    -

    - where Qsen is the sensible heat flow rate added to - the thermal zone, ṁsup is the supply air mass flow - rate from the port fluPor (which is negative if it is an - exhaust), cp is the specific heat capacity at - constant pressure, Tsup is the supply air - temperature and Tair,zon is the zone air - temperature. Note that without the max(·, ·), the energy - balance would be wrong. For example, - the control volumes in AixLib.Fluid.MixingVolumes - implement such a max(·, ·) function. + InteriorWall represents heat storage within walls. It + links a variable number n of thermal resistances and + capacities to a series connection. n thus defines the + spatial discretization of thermal effects within the wall. All + effects are considered as one-dimensional normal to the wall's + surface. This model is thought for interior wall elements that only + serve as heat storage elements. The RC-chain is defined via a vector + of capacities CInt[n] and a vector of resistances + RInt[n]. Resistances and capacities are connected + alternately, starting with the first resistance RInt[1], + from heat port_a into the wall.

    -

    - The zone air temperature, the water vapor mass fraction per total - mass of the air (unless Medium.nXi=0) and trace - substances (unless Medium.nC=0) can be obtained from the - outupt connector fluPor.backward. These signals are the - same as the inflowing fluid stream(s) at the port - theAdaZon.ports[1:nPorts]. The fluid connector - ports[nPorts] has a prescribed mass flow rate, but it - does not set any pressure. +

    + \"image\"

    +
      +
    • April 27, 2016, by Michael Wetter:
      + Added graphical connections. +
      • +
    • April 17, 2015, by Moritz Lauster:
      + Implemented. +
      • +
    + +-------- Errors -------- +line 13 column 4 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Controls/Continuous/NumberOfRequests.mo ---- +-------- HTML Code -------- + +

    + Block that outputs the number of inputs that exceed a threshold. + The parameter kind is used to determine the kind of the + inequality. The table below shows the allowed settings. +

    +
    + + + + + + + + + + + + + + + + + + + + +
    Value of parameter kindOutput signal incremented by 1 for each i ∈ {1, ..., nin} if
    0u[i] > threShold
    1u[i] ≥ threShold
    2u[i] ≤ threShold
    3u[i] < threShold
    +

    + This model may be used to check how many rooms + exceed a temperature threshold. +

    + +
      +
    • + November 21, 2011, by Michael Wetter:
      + Improved documentation. +
      • +
    • + November 25, 2008, by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Corrected Code --------

    - This model has a user-defined parameter nPorts which - sets the number of fluid ports, which in turn is used for the ports - fluPor and ports. All nPorts - ports[1:nPorts] need to be connected as demonstrated in - the example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. + Block that outputs the number of inputs that exceed a threshold. The + parameter kind is used to determine the kind of the + inequality. The table below shows the allowed settings.

    + + + + + + + + + + + + + + + + + + + + + +
    + Value of parameter kind + + Output signal incremented by 1 for each i ∈ {1, ..., nin} + if +
    + 0 + + u[i] > threShold +
    + 1 + + u[i] ≥ threShold +
    + 2 + + u[i] ≤ threShold +
    + 3 + + u[i] < threShold +

    - + This model may be used to check how many rooms exceed a temperature + threshold.

      -
    • January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air. See #1050. -
      • -
    • September 20, 2016, by Thierry S. Nouidui:
      - Revised documentation to explain the rationale of needing mass flow - rate sensors. -
      • -
    • June 29, 2016, by Michael Wetter:
      - Revised implementation and documentation. +
    • November 21, 2011, by Michael Wetter:
      + Improved documentation.
      • -
    • April 27, 2016, by Thierry S. Nouidui:
      +
    • November 25, 2008, by Michael Wetter:
      First implementation.
    -------- Errors -------- -line 72 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 7 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 ----- AixLib/Fluid/HeatExchangers/Radiators/RadiatorEN442_2.mo ---- +---- AixLib/Controls/Continuous/LimPID.mo ---- -------- HTML Code --------

    - This is a model of a radiator that can be used as a dynamic or steady-state model. - The required parameters are data that are typically available from - manufacturers that follow the European Norm EN 442-2. -

    -

    - However, to allow for varying mass flow rates, the transferred heat is computed - using a discretization along the water flow path, and heat is exchanged between - each compartment and a uniform room air and radiation temperature. - This discretization is different from the computation in EN 442-2, which - may yield water outlet temperatures that are below - the room temperature at low mass flow rates. - Furthermore, rather than using only one room temperature, this model uses - a room air and room radiation temperature. -

    -

    - The transferred heat is modeled as follows: - Let N denote the number of elements used to discretize the radiator model. - For each element i ∈ {1, … , N}, - the convective and radiative heat transfer - Qic and - Qir - from the radiator to the room is + PID controller in the standard form

    - Qic = sign(Ti-Ta) - (1-fr) UA ⁄ N |Ti-Ta|n -

    - Qir = sign(Ti-Tr) - fr UA ⁄ N |Ti-Tr|n + y = k   ( e(t) + 1 ⁄ Ti   ∫ e(s) ds + Td de(t)⁄dt ),

    where - Ti is the water temperature of the element, - Ta is the temperature of the room air, - Tr is the radiative temperature, - 0 < fr < 1 is the fraction of radiant to total heat transfer, - UA is the UA-value of the radiator, - and - n is an exponent for the heat transfer. - The model computes the UA-value by numerically solving the above equations - for given - nominal heating power, nominal temperatures, fraction radiant to total heat transfer - and exponent for heat transfer. + y is the control signal, + e(t) = us - um is the control error, + with us being the set point and um being + the measured quantity, + k is the gain, + Ti is the time constant of the integral term and + Td is the time constant of the derivative term.

    - The parameter energyDynamics (in the Assumptions tab), - determines whether the model computes the dynamic or the steady-state response. - For the transient response, heat storage is computed using a - finite volume approach for the - water and the metal mass, which are both assumed to be at the same - temperature. + Note that the units of k are the inverse of the units of the control error, + while the units of Ti and Td are seconds.

    - The default parameters for the heat capacities are valid for a flat plate radiator without fins, - with one plate of water carying fluid, and a height of 0.42 meters. + For detailed treatment of integrator anti-windup, set-point weights and output limitation, see + Modelica.Blocks.Continuous.LimPID.

    - -
      -
    • - March 7, 2022, by Michael Wetter:
      - Set final massDynamics=energyDynamics.
      - This is for - #1542. -
      • -
    • - April 14, 2020, by Michael Wetter:
      - Changed homotopyInitialization to a constant.
      - This is for - IBPSA, #1341. -
      • -
    • - February 21, 2020, by Michael Wetter:
      - Changed icon to display its operating state.
      - This is for - #1294. -
      • -
    • - November 17, 2016, by Filip Jorissen:
      - Added pressure drop equations and parameters.
      - This is for - #586. -
      • -
    • - November 3, 2016, by Michael Wetter:
      - Set preHea(final alpha=0) as this allows to simplify the - system of equations.
      - This is for - #570. -
      • -
    • - March 17, 2016, by Michael Wetter:
      - Reformulated model to reduce the dimension of the nonlinear system of equations. - This is for - #435. -
      • -
    • - November 19, 2015, by Michael Wetter:
      - Removed assignment of parameter - showDesignFlowDirection in extends statement. - This is for - #349. -
      • -
    • - April 11, 2015, by Filip Jorissen:
      - Propagated vol.massDynamics to - top level parameter massDynamics instead of energyDynamics. -
      • -
    • - November 25, 2014, by Carles Ribas Tugores:
      - Interchange position of fraRad parameter and the complementary (1-fraRad) - in the equation used to calculate the nominal heating power of each element, QEle_flow_nominal[i]. -
      • -
    • - October 29, 2014, by Michael Wetter:
      - Made assignment of mFactor final, and changed computation of - density to use default medium states as are also used to compute the - specific heat capacity. -
      • -
    • - October 21, 2014, by Filip Jorissen:
      - Added parameter mFactor and removed thermal capacity - which can lead to an index reduction. -
      • +

      Options

      + This controller can be configured as follows. +
      P, PI, PD, or PID action
      +

      + Through the parameter controllerType, the controller can be configured + as P, PI, PD or PID controller. The default configuration is PI. +

      +
      Direct or reverse acting
      +

      + Through the parameter reverseActing, the controller can be configured to + be reverse or direct acting. + The above standard form is reverse acting, which is the default configuration. + For a reverse acting controller, for a constant set point, + an increase in measurement signal u_m decreases the control output signal y + (Montgomery and McDowall, 2008). + Thus, +

      +
        +
      • + for a heating coil with a two-way valve, leave reverseActing = true, but +
        • +
      • + for a cooling coil with a two-way valve, set reverseActing = false. +
        • +
      +
      Reset of the controller output
      +

      + The controller can be configured to enable an input port that allows resetting the controller + output. The controller output can be reset as follows: +

      +
        +
      • + If reset = AixLib.Types.Reset.Disabled, which is the default, + then the controller output is never reset. +
        • +
      • + If reset = AixLib.Types.Reset.Parameter, then a boolean + input signal trigger is enabled. Whenever the value of + this input changes from false to true, + the controller output is reset by setting y + to the value of the parameter y_reset. +
        • +
      • + If reset = AixLib.Types.Reset.Input, then a boolean + input signal trigger and a real input signal y_reset_in + are enabled. Whenever the value of + trigger changes from false to true, + the controller output is reset by setting the value of y + to y_reset_in. +
        • +
      +

      + Note that this controller implements an integrator anti-windup. Therefore, + for most applications, keeping the default setting of + reset = AixLib.Types.Reset.Disabled is sufficient. + However, if the controller is used in conjuction with equipment that is being + switched on, better control performance may be achieved by resetting the controller + output when the equipment is switched on. + This is in particular the case in situations + where the equipment control input should continuously increase as the equipment is + switched on, such as a light dimmer that may slowly increase the luminance, or + a variable speed drive of a motor that should continuously increase the speed. +

      +

      References

      +

      + R. Montgomery and R. McDowall (2008). + \"Fundamentals of HVAC Control Systems.\" + American Society of Heating Refrigerating and Air-Conditioning Engineers Inc. Atlanta, GA. +

      + + +
      • - May 29, 2014, by Michael Wetter:
        - Removed undesirable annotation Evaluate=true. + June 1, 2020, by Michael Wetter:
        + Corrected wrong convention of reverse and direct action.
        + Changed default configuration from PID to PI.
        + This is for issue 1365.
      • - October 8, 2013 by Michael Wetter:
        - Removed conditional statement in the declaration of the parameter - mDry, as this is incorrect syntax. + March 9, 2020, by Michael Wetter:
        + Corrected wrong unit declaration for parameter k.
        + This is for issue 1316.
      • - September 26, 2013 by Michael Wetter:
        - Reformulated implementation to avoid mixing textual and graphical - declarations in the equation section. + October 19, 2019, by Filip Jorissen:
        + Disabled homotopy to ensure bounded outputs + by copying the implementation from MSL 3.2.3 and by + hardcoding the implementation for homotopyType=NoHomotopy. + See issue 1221.
      • - April 4, 2011 by Michael Wetter:
        - Changed the implementation to use - - AixLib.Utilities.Math.Functions.regNonZeroPower. - This allows formulating the model without any non-differentiable function - inside the equation section. + September 29, 2016, by Michael Wetter:
        + Refactored model.
      • - April 2, 2011 by Michael Wetter:
        - Added homotopy operator. + August 25, 2016, by Michael Wetter:
        + Removed parameter limitsAtInit because it was only propagated to + the instance limiter, but this block no longer makes use of this parameter. + This is a non-backward compatible change.
        + Revised implemenentation, added comments, made some parameter in the instances final.
        • -
      • - February 11, 2011 by Michael Wetter:
        - Revised the initialization to ensure that at the nominal conditions, the - amount of transferred heat is excatly the same as the specified nominal power. - In the previous implementation, the UA-value was computed using a simplified - expression for the temperature difference, leading to a slightly different amount - of heat transfer. +
      • July 18, 2016, by Philipp Mehrfeld:
        + Added integrator reset. + This is for issue 494.
      • - February 4, 2011 by Michael Wetter:
        - Simplified implementation. + March 15, 2016, by Michael Wetter:
        + Changed the default value to strict=true in order to avoid events + when the controller saturates. + This is for issue 433.
      • - January 30, 2009 by Michael Wetter:
        + February 24, 2010, by Michael Wetter:
        First implementation.
      -------- Corrected Code --------

      - This is a model of a radiator that can be used as a dynamic or - steady-state model. The required parameters are data that are - typically available from manufacturers that follow the European Norm - EN 442-2. -

      -

      - However, to allow for varying mass flow rates, the transferred heat - is computed using a discretization along the water flow path, and - heat is exchanged between each compartment and a uniform room air and - radiation temperature. This discretization is different from the - computation in EN 442-2, which may yield water outlet temperatures - that are below the room temperature at low mass flow rates. - Furthermore, rather than using only one room temperature, this model - uses a room air and room radiation temperature. -

      -

      - The transferred heat is modeled as follows: Let N denote the - number of elements used to discretize the radiator model. For each - element i ∈ {1, … , N}, the convective and radiative heat - transfer Qic and - Qir from the radiator to the room is + PID controller in the standard form

      - Qic = sign(Ti-Ta) - (1-fr) UA ⁄ N - |Ti-Ta|n
      -
      - Qir = sign(Ti-Tr) - fr UA ⁄ N |Ti-Tr|n + y = k   ( e(t) + 1 ⁄ Ti   ∫ e(s) ds + + Td de(t)⁄dt ),

      - where Ti is the water temperature of the element, - Ta is the temperature of the room air, - Tr is the radiative temperature, 0 < - fr < 1 is the fraction of radiant to total heat - transfer, UA is the UA-value of the radiator, and n is - an exponent for the heat transfer. The model computes the UA-value by - numerically solving the above equations for given nominal heating - power, nominal temperatures, fraction radiant to total heat transfer - and exponent for heat transfer. + where y is the control signal, e(t) = us - + um is the control error, with us + being the set point and um being the measured + quantity, k is the gain, Ti is the time + constant of the integral term and Td is the time + constant of the derivative term.

      - The parameter energyDynamics (in the Assumptions tab), - determines whether the model computes the dynamic or the steady-state - response. For the transient response, heat storage is computed using - a finite volume approach for the water and the metal mass, which are - both assumed to be at the same temperature. + Note that the units of k are the inverse of the units of the + control error, while the units of Ti and + Td are seconds.

      - The default parameters for the heat capacities are valid for a flat - plate radiator without fins, with one plate of water carying fluid, - and a height of 0.42 meters. + For detailed treatment of integrator anti-windup, set-point weights + and output limitation, see Modelica.Blocks.Continuous.LimPID.

      -
        -
      • March 7, 2022, by Michael Wetter:
        - Set final massDynamics=energyDynamics.
        - This is for #1542. -
        • -
      • April 14, 2020, by Michael Wetter:
        - Changed homotopyInitialization to a constant.
        - This is for IBPSA, - #1341. -
        • -
      • February 21, 2020, by Michael Wetter:
        - Changed icon to display its operating state.
        - This is for #1294. -
        • -
      • November 17, 2016, by Filip Jorissen:
        - Added pressure drop equations and parameters.
        - This is for #586. -
        • -
      • November 3, 2016, by Michael Wetter:
        - Set preHea(final alpha=0) as this allows to simplify - the system of equations.
        - This is for #570. -
        • -
      • March 17, 2016, by Michael Wetter:
        - Reformulated model to reduce the dimension of the nonlinear system - of equations. This is for #435. -
        • -
      • November 19, 2015, by Michael Wetter:
        - Removed assignment of parameter - showDesignFlowDirection in extends - statement. This is for #349. +

        + Options +

        This controller can be configured as follows. +
        + P, PI, PD, or PID action +
        +

        + Through the parameter controllerType, the controller can + be configured as P, PI, PD or PID controller. The default + configuration is PI. +

        +
        + Direct or reverse acting +
        +

        + Through the parameter reverseActing, the controller can + be configured to be reverse or direct acting. The above standard form + is reverse acting, which is the default configuration. For a reverse + acting controller, for a constant set point, an increase in + measurement signal u_m decreases the control output + signal y (Montgomery and McDowall, 2008). Thus, +

        +
          +
        • for a heating coil with a two-way valve, leave + reverseActing = true, but
          • -
        • April 11, 2015, by Filip Jorissen:
          - Propagated vol.massDynamics to top level parameter - massDynamics instead of energyDynamics. +
        • for a cooling coil with a two-way valve, set reverseActing + = false.
          • -
        • November 25, 2014, by Carles Ribas Tugores:
          - Interchange position of fraRad parameter and the - complementary (1-fraRad) in the equation used to - calculate the nominal heating power of each element, - QEle_flow_nominal[i]. +
        +
        + Reset of the controller output +
        +

        + The controller can be configured to enable an input port that allows + resetting the controller output. The controller output can be reset + as follows: +

        +
          +
        • If reset = AixLib.Types.Reset.Disabled, which is the + default, then the controller output is never reset.
          • -
        • October 29, 2014, by Michael Wetter:
          - Made assignment of mFactor final, and changed - computation of density to use default medium states as are also - used to compute the specific heat capacity. +
        • If reset = AixLib.Types.Reset.Parameter, then a + boolean input signal trigger is enabled. Whenever the + value of this input changes from false to + true, the controller output is reset by setting + y to the value of the parameter y_reset.
          • -
        • October 21, 2014, by Filip Jorissen:
          - Added parameter mFactor and removed thermal capacity - which can lead to an index reduction. +
        • If reset = AixLib.Types.Reset.Input, then a boolean + input signal trigger and a real input signal + y_reset_in are enabled. Whenever the value of + trigger changes from false to + true, the controller output is reset by setting the + value of y to y_reset_in.
          • -
        • May 29, 2014, by Michael Wetter:
          - Removed undesirable annotation Evaluate=true. +
        +

        + Note that this controller implements an integrator anti-windup. + Therefore, for most applications, keeping the default setting of + reset = AixLib.Types.Reset.Disabled is sufficient. + However, if the controller is used in conjuction with equipment that + is being switched on, better control performance may be achieved by + resetting the controller output when the equipment is switched on. + This is in particular the case in situations where the equipment + control input should continuously increase as the equipment is + switched on, such as a light dimmer that may slowly increase the + luminance, or a variable speed drive of a motor that should + continuously increase the speed. +

        +

        + References +

        +

        + R. Montgomery and R. McDowall (2008). \"Fundamentals of HVAC Control + Systems.\" American Society of Heating Refrigerating and + Air-Conditioning Engineers Inc. Atlanta, GA. +

        +
          +
        • June 1, 2020, by Michael Wetter:
          + Corrected wrong convention of reverse and direct action.
          + Changed default configuration from PID to PI.
          + This is for issue + 1365.
          • -
        • October 8, 2013 by Michael Wetter:
          - Removed conditional statement in the declaration of the parameter - mDry, as this is incorrect syntax. +
        • March 9, 2020, by Michael Wetter:
          + Corrected wrong unit declaration for parameter k.
          + This is for issue + 1316.
          • -
        • September 26, 2013 by Michael Wetter:
          - Reformulated implementation to avoid mixing textual and graphical - declarations in the equation section. +
        • October 19, 2019, by Filip Jorissen:
          + Disabled homotopy to ensure bounded outputs by copying the + implementation from MSL 3.2.3 and by hardcoding the implementation + for homotopyType=NoHomotopy. See issue + 1221.
          • -
        • April 4, 2011 by Michael Wetter:
          - Changed the implementation to use AixLib.Utilities.Math.Functions.regNonZeroPower. - This allows formulating the model without any non-differentiable - function inside the equation section. +
        • September 29, 2016, by Michael Wetter:
          + Refactored model.
          • -
        • April 2, 2011 by Michael Wetter:
          - Added homotopy operator. +
        • August 25, 2016, by Michael Wetter:
          + Removed parameter limitsAtInit because it was only + propagated to the instance limiter, but this block no + longer makes use of this parameter. This is a non-backward + compatible change.
          + Revised implemenentation, added comments, made some parameter in + the instances final.
          • -
        • February 11, 2011 by Michael Wetter:
          - Revised the initialization to ensure that at the nominal - conditions, the amount of transferred heat is excatly the same as - the specified nominal power. In the previous implementation, the - UA-value was computed using a simplified expression for the - temperature difference, leading to a slightly different amount of - heat transfer. +
        • July 18, 2016, by Philipp Mehrfeld:
          + Added integrator reset. This is for issue 494.
          • -
        • February 4, 2011 by Michael Wetter:
          - Simplified implementation. +
        • March 15, 2016, by Michael Wetter:
          + Changed the default value to strict=true in order to + avoid events when the controller saturates. This is for issue 433.
          • -
        • January 30, 2009 by Michael Wetter:
          +
        • February 24, 2010, by Michael Wetter:
          First implementation.
        -------- Errors -------- -line 26 column 2 - Warning:

        attribute "align" not allowed for HTML5 +line 5 column 2 - Warning:

        attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Geothermal/Borefields/Types.mo ---- +---- AixLib/Fluid/HeatPumps/Carnot_y.mo ---- -------- HTML Code --------

        - Enumeration that defines the pipe configuration in the borehole. + This is model of a heat pump whose coefficient of performance COP changes + with temperatures in the same way as the Carnot efficiency changes. + The input signal y is the control signal for the compressor.

        - The following pipe configurations are available in this enumeration: + The model allows to either specify the Carnot effectivness + ηCarnot,0, or + a COP0 + at the nominal conditions, together with + the evaporator temperature Teva,0 and + the condenser temperature Tcon,0, in which + case the model computes the Carnot effectivness as +

        +

        + ηCarnot,0 = + COP0 + ⁄ (Tcon,0 ⁄ (Tcon,0-Teva,0)). +

        +

        + The heat pump COP is computed as the product +

        +

        + COP = ηCarnot,0 COPCarnot ηPL, +

        +

        + where COPCarnot is the Carnot efficiency and + ηPL is a polynomial in the heating part load ratio yPL + that can be used to take into account a change in COP at part load + conditions. + This polynomial has the form +

        +

        + ηPL = a1 + a2 yPL + a3 yPL2 + ... +

        +

        + where the coefficients ai are declared by the parameter a. +

        +

        + On the Dynamics tag, the model can be parametrized to compute a transient + or steady-state response. + The transient response of the model is computed using a first + order differential equation for the evaporator and condenser fluid volumes. + The heat pump outlet temperatures are equal to the temperatures of these lumped volumes. +

        +

        Typical use and important parameters

        +

        + When using this component, make sure that the evaporator and the condenser have sufficient mass flow rate. + Based on the mass flow rates, the compressor power, temperature difference and the efficiencies, + the model computes how much heat will be added to the condenser and removed at the evaporator. + If the mass flow rates are too small, very high temperature differences can result. +

        +

        + The condenser heat flow rate QCon_flow_nominal is used to assign + the default value for the mass flow rates, which are used for the pressure drop + calculations. + It is also used to compute the part load efficiency. + Hence, make sure that QCon_flow_nominal is set to a reasonable value. +

        +

        + The maximum heating capacity is set by the parameter QCon_flow_max, + which is by default set to infinity. +

        +

        + The coefficient of performance depends on the + evaporator and condenser leaving temperature + since otherwise the second law of thermodynamics may be violated. +

        +

        Notes

        +

        + For a similar model that can be used as a chiller, see + AixLib.Fluid.Chillers.Carnot_y.

        -
    - - - - - -
    EnumerationDescription
    SingleUTubeSingle U-tube configuration
    DoubleUTubeParallelDouble U-tube configuration with pipes connected in parallel
    DoubleUTubeSeriesDouble U-tube configuration with pipes connected in series

    • - July 15, 2018, by Michael Wetter:
      - First implementation. + January 3, 2017, by Michael Wetter:
      + Removed parameters + effInpEva and effInpCon + and updated documentation. + This is for + + issue 497.
      • -
    - -

    - This package contains type definitions. -

    - --------- Corrected Code -------- -

    - Enumeration that defines the pipe configuration in the borehole. -

    -

    - The following pipe configurations are available in this enumeration: -

    - - - - - - - - - - - - - - - - - -
    - Enumeration - - Description -
    - SingleUTube - - Single U-tube configuration -
    - DoubleUTubeParallel - - Double U-tube configuration with pipes connected in parallel -
    - DoubleUTubeSeries - - Double U-tube configuration with pipes connected in series -
    -
      -
    • July 15, 2018, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This package contains type definitions. -

    - --------- Errors -------- -line 8 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 - - ----- AixLib/ThermalZones/ReducedOrder/RC/ThreeElements.mo ---- --------- HTML Code -------- - -
    • - March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      + August 8, 2016, by Michael Wetter:
      + Changed default temperature to compute COP to be the leaving temperature as + use of the entering temperature can violate the 2nd law if the temperature + lift is small.
      This is for - #1542. + + Annex 60, issue 497.
    • - December 9, 2019, by Moritz Lauster:
      - Changes nExt to nFloor for - RFloor and CFloor + January 26, 2016, by Michael Wetter:
      + Refactored model to use the same base class as + AixLib.Fluid.Chillers.Carnot_y.
      + Changed part load efficiency to depend on heating part load ratio rather than on the compressor + part load ratio.
    • - July 11, 2019, by Katharina Brinkmann:
      - Renamed alphaFloor to hConFloor, - alphaFloorConst to hConFloor_const + January 20, 2015, by Damien Picard:
      + Add Carnot model to Annex 60 from the Buildings library.
      + Removed the flow direction dependency of + staA1, staB1, staA2 and staB2 as the + efficiency of the Carnot machine should only be computed in the design flow direction.
    • - August 31, 2018 by Moritz Lauster:
      - Updated schema in documentation to fix - - issue 997. + December 18, 2015, by Michael Wetter:
      + Corrected wrong computation of staB1 and staB2 + which mistakenly used the inStream operator + for the configuration without flow reversal. + This is for + + issue 476.
    • - July 15, 2015 by Moritz Lauster:
      - First Implementation. + November 25, 2015 by Michael Wetter:
      + Changed sign convention for dTEva_nominal to be consistent with + other models. + The model will still work with the old values for dTEva_nominal, + but it will write a warning so that users can transition their models. +
      + Corrected assert statement for the efficiency curve. + This is for + + issue 468. +
      • +
    • + September 3, 2015 by Michael Wetter:
      + Expanded documentation. +
      • +
    • + May 6, 2015 by Michael Wetter:
      + Added prescribedHeatFlowRate=true for vol2. +
      • +
    • + October 9, 2013 by Michael Wetter:
      + Reimplemented the computation of the port states to avoid using + the conditionally removed variables sta_a1, + sta_a2, sta_b1 and sta_b2. +
      • +
    • + May 10, 2013 by Michael Wetter:
      + Added electric power P as an output signal. +
      • +
    • + October 11, 2010 by Michael Wetter:
      + Fixed bug in energy balance. +
      • +
    • + March 3, 2009 by Michael Wetter:
      + First implementation.
    -

    This model adds one further element for - the floor plate. Long-term effects dominate the excitation of the floor plate - and thus the excitation fundamentally differs from excitation of outer walls. - Adding an extra element for the floor plate leads to a finer resolution of the - dynamic behaviour but increases calculation times. The floor plate is - parameterized via the length of the RC-chain nFloor, - the vector of the capacities - CFloor[nFloor], the vector of the resistances - RFloor[nFloor] - and the remaining resistance RFloorRem. -

    -

    - The image below shows the RC-network of this model. -

    -

    - \"image\"/ -

    - -------- Corrected Code -------- -
      -
    • March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for #1542. -
      • -
    • December 9, 2019, by Moritz Lauster:
      - Changes nExt to nFloor for - RFloor and CFloor -
      • -
    • July 11, 2019, by Katharina Brinkmann:
      - Renamed alphaFloor to hConFloor, - alphaFloorConst to hConFloor_const -
      • -
    • August 31, 2018 by Moritz Lauster:
      - Updated schema in documentation to fix issue 997. -
      • -
    • July 15, 2015 by Moritz Lauster:
      - First Implementation. -
      • -

    - This model adds one further element for the floor plate. Long-term - effects dominate the excitation of the floor plate and thus the - excitation fundamentally differs from excitation of outer walls. - Adding an extra element for the floor plate leads to a finer - resolution of the dynamic behaviour but increases calculation times. - The floor plate is parameterized via the length of the RC-chain - nFloor, the vector of the capacities - CFloor[nFloor], the vector of the resistances - RFloor[nFloor] and the remaining resistance - RFloorRem. + This is model of a heat pump whose coefficient of performance COP + changes with temperatures in the same way as the Carnot efficiency + changes. The input signal y is the control signal for the + compressor.

    - The image below shows the RC-network of this model. + The model allows to either specify the Carnot effectivness + ηCarnot,0, or a COP0 at the + nominal conditions, together with the evaporator temperature + Teva,0 and the condenser temperature + Tcon,0, in which case the model computes the Carnot + effectivness as

    -

    - \"image\" +

    + ηCarnot,0 = COP0 ⁄ (Tcon,0 ⁄ + (Tcon,0-Teva,0)).

    - --------- Errors -------- -line 16 column 4 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Sensors/UsersGuide.mo ---- --------- HTML Code -------- -

    -This package contains models of sensors. -There are models with one and with two fluid ports. + The heat pump COP is computed as the product +

    +

    + COP = ηCarnot,0 COPCarnot ηPL,

    - -

    Selection and parameterization of sensor models

    -When selecting a sensor model, a distinction needs to be made -whether the measured quantity depends on the direction of the flow or -not, and whether the sensor output signal is the product of the mass flow rate -and a medium property. + where COPCarnot is the Carnot efficiency and + ηPL is a polynomial in the heating part load ratio + yPL that can be used to take into account a change + in COP at part load conditions. This polynomial has the form +

    +

    + ηPL = a1 + a2 yPL + + a3 yPL2 + ...

    -

    -Output signals that depend on the flow direction and are not multiplied by -the mass flow rate are temperature, relative humidity, -water vapor concentration X, trace substances C and density. -For such quantities, sensors with two fluid ports need to be used. -An exception is if the quantity is measured directly in a fluid volume, which is the case -for models from the package - -AixLib.Fluid.MixingVolumes. -Therefore, to measure for example the outlet temperature of a heat exchanger, the -configuration labelled correct use in the figure below should be used, and not the configuration -labelled not recommended. -For an explanation, see - -Modelica.Fluid.Examples.Explanatory.MeasuringTemperature. -

    - -
    - - - - - - -
    Correct use - \"image\" -
    Not recommended - \"image\" -
    - -

    -Except for the mass flow rate sensor, -all sensors with two ports can be -configured as dynamic sensors or as steady-state sensor. -The list below advices on how to configure sensors. -

    -
      -
    • -

      - -Sensors for quantities that depend on the direction of the mass flow rate but -not of its magnitude: - -Such quantities include density, mass fraction, PPM, relative humidity, specific enthalpy, specific entropy and trace substances. -Not that these are all quantities that are carried by the fluid that flows through the sensor. -For these sensors, if the parameter allowFlowReversal=true is set (which is the default setting), -then it is strongly recommended to configure them -as a dynamic sensor. This is the default setting.
      -Configuring a sensor as a dynamic sensor is done by setting the time constant to a non-zero -value. Typically, setting tau=10 seconds yields good results. -For tau=0, numerical problems may occur if the mass flow rate is close to zero -and allowFlowReversal=true.
      -If allowFlowReversal=false, then the measurement of these sensors only depends on properties -at port_a. -If the mass flow rate at port_a is ṁa ≤ 0, -i.e., fluid flows from port_b to port_a, -the model still assumes ṁa > 0. Hence there are no numerical problems; -but use of the sensor output may yield wrong results. -Therefore, only set allowFlowReversal=false if you can guarantee ṁa ≥ 0. -

      -
      • -
    • -

      - -Sensors for quantities that are the product of mass flow rate times a measured fluid property: - -Such quantities include volumentric flow rate or enthalpy flow rate. -For these quantities, sensors are by default configured as steady-state sensor. -These sensors may be configured by the user -as a dynamic sensor by setting tau > 0, but there is typically no benefit as these sensors typically -do not cause numerical problems. -The reason is that these sensors multiply the quantity that is carried by the flow, -such as specific enthalpy h by the mass flow rate ṁ -to compute the measured signal Ḣ=ṁ h. -Hence, as the mass flow rate goes to zero, the sensor output -signal also goes to zero, which avoids numerical problems. -

      -
      • -
    • -

      -Static pressure measurements: - -For static pressure measurements, sensors always output the instantaneous measurement. -These sensors cannot be configured to be dynamic. -

      -
      • -
    -

    -The table below summarizes the recommendations for the use of sensors. -

    - - - - - - - - - - - - - - - - - - - - - - - -
    Measured quantityOne port sensorTwo port sensor
    steady-state (tau=0)dynamic (tau > 0)
    temperature
    - relative humidity
    - mass fraction
    - trace substances
    - specific enthalpy
    - specific entropy    		use only if connected to a volumeavoidrecommended
    volume flow rate
    - enthalpy flow rate
    - entropy flow rate    		-recommendedrecommended
    pressurerecommendedrecommendedrecommended
    - -

    Sensor Dynamics

    -
    Dynamic response to fluid flowing through the sensor
    -

    -If a sensor is configured as a dynamic sensor by setting tau > 0, -then the measured quantity, say the temperature T, is -computed as -

    -

    - τ   dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T), -

    -

    -where τ is a user-defined time constant of the sensor (a suggested value is around 10 seconds, -which is the default setting for the components), -dT ⁄ dt is the time derivative of the sensor output signal, -|ṁ| is the absolute value of the mass flow rate, -ṁ0 is the user-specified nominal value of the mass flow rate and -θ is the temperature of the medium inside the sensor. -An equivalent physical model of such a sensor would be a perfectly mixed volume -with a sensor that outputs the temperature of this volume. In this situation, the size of the volume would -be V=τ   ṁ0 ⁄ ρ, where -ρ is the density of the fluid. -

    -
    Dynamic response to ambient temperature
    -

    -For the sensor - -AixLib.Fluid.Sensors.TemperatureTwoPort, -by setting transferHeat = true, heat transfer to a -fixed ambient can be approximated. The heat transfer is computed as -

    -

    - τHeaTra   dT ⁄ dt = (TAmb-T), -

    -

    -where τHeaTra is a fixed time constant and -TAmb is a fixed ambient temperature. -Setting transferHeat = true is useful if the sensor output T -is used to switch the mass flow rate on again. If transferHeat = false, -then the sensor output T remains constant if the mass flow rate is zero -and hence a fan or pump controller that uses this signal may never switch the device -on again. -If the sensor output T is not used to switch on the mass flow rate, then -in general one can use transferHeat=false. + where the coefficients ai are declared by the + parameter a.

    -Note that since in practice the heat transfer is due to a combination of ambient -temperature and upstream or downstream fluid temperature, for example by two-way -buoyancy-driven flow inside the duct or pipe, the model uses as an approximation -a fixed ambient temperature. -Since the sensor is not affecting the temperature of the medium, this approximation -of the heat transfer does not add or remove heat from the fluid. + On the Dynamics tag, the model can be parametrized to + compute a transient or steady-state response. The transient response + of the model is computed using a first order differential equation + for the evaporator and condenser fluid volumes. The heat pump outlet + temperatures are equal to the temperatures of these lumped volumes.

    -
    Combined dynamic response
    +

    + Typical use and important parameters +

    -For the sensor - -AixLib.Fluid.Sensors.TemperatureTwoPort, -if both dynamic effects are enabled, then -the output T is computed as -

    -

    -dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T) ⁄ τ + -(TAmb-T) ⁄ τHeaTra. + When using this component, make sure that the evaporator and the + condenser have sufficient mass flow rate. Based on the mass flow + rates, the compressor power, temperature difference and the + efficiencies, the model computes how much heat will be added to the + condenser and removed at the evaporator. If the mass flow rates are + too small, very high temperature differences can result.

    -

    Implementation

    -The above equation is implemented in such a way that it is differentiable in the mass flow rate. + The condenser heat flow rate QCon_flow_nominal is used + to assign the default value for the mass flow rates, which are used + for the pressure drop calculations. It is also used to compute the + part load efficiency. Hence, make sure that + QCon_flow_nominal is set to a reasonable value.

    -Note that the implementation of the dynamic sensors does not use the model - -AixLib.Fluid.MixingVolumes. -The reason is that depending on the selected medium model, the -mixing volume may introduce states for the pressure, species concentration, -trace substance, specific enthalpy and specific entropy. Not all states are typically needed to -model the dynamics of a sensor. Moreover, in many building system applications, -the sensor dynamics is not of concern, but is rather used here to avoid numerical -problems that steady-state models of sensors cause when flow rates are -very close to zero. + The maximum heating capacity is set by the parameter + QCon_flow_max, which is by default set to infinity.

    - --------- Corrected Code --------

    - This package contains models of sensors. There are models with one - and with two fluid ports. + The coefficient of performance depends on the evaporator and + condenser leaving temperature since otherwise the second law of + thermodynamics may be violated.

    - Selection and parameterization of sensor models + Notes

    - When selecting a sensor model, a distinction needs to be made whether - the measured quantity depends on the direction of the flow or not, - and whether the sensor output signal is the product of the mass flow - rate and a medium property. -

    -

    - Output signals that depend on the flow direction and are not - multiplied by the mass flow rate are temperature, relative humidity, - water vapor concentration X, trace substances C and - density. For such quantities, sensors with two fluid ports need to be - used. An exception is if the quantity is measured directly in a fluid - volume, which is the case for models from the package AixLib.Fluid.MixingVolumes. - Therefore, to measure for example the outlet temperature of a heat - exchanger, the configuration labelled correct use in the - figure below should be used, and not the configuration labelled - not recommended. For an explanation, see - Modelica.Fluid.Examples.Explanatory.MeasuringTemperature. -

    - - - - - - - - - -
    - Correct use - - \"image\" -
    - Not recommended - - \"image\" -
    -

    - Except for the mass flow rate sensor, all sensors with two ports can - be configured as dynamic sensors or as steady-state sensor. The list - below advices on how to configure sensors. + For a similar model that can be used as a chiller, see AixLib.Fluid.Chillers.Carnot_y.

      -
    • -

      - Sensors for quantities that depend on the direction of the - mass flow rate but not of its magnitude: Such quantities - include density, mass fraction, PPM, relative humidity, specific - enthalpy, specific entropy and trace substances. Not that these - are all quantities that are carried by the fluid that flows - through the sensor. For these sensors, if the parameter - allowFlowReversal=true is set (which is the default - setting), then it is strongly recommended to configure them as a - dynamic sensor. This is the default setting.
      - Configuring a sensor as a dynamic sensor is done by setting the - time constant to a non-zero value. Typically, setting - tau=10 seconds yields good results. For - tau=0, numerical problems may occur if the mass flow - rate is close to zero and - allowFlowReversal=true.
      - If allowFlowReversal=false, then the measurement of - these sensors only depends on properties at port_a. - If the mass flow rate at port_a is ṁa - ≤ 0, i.e., fluid flows from port_b to - port_a, the model still assumes ṁa - > 0. Hence there are no numerical problems; but use of the - sensor output may yield wrong results. Therefore, only set - allowFlowReversal=false if you can guarantee - ṁa ≥ 0. -

      +
    • January 3, 2017, by Michael Wetter:
      + Removed parameters effInpEva and + effInpCon and updated documentation. This is for + issue + 497.
      • -
    • -

      - Sensors for quantities that are the product of mass flow rate - times a measured fluid property: Such quantities include - volumentric flow rate or enthalpy flow rate. For these - quantities, sensors are by default configured as steady-state - sensor. These sensors may be configured by the user as a dynamic - sensor by setting tau > 0, but there is typically - no benefit as these sensors typically do not cause numerical - problems. The reason is that these sensors multiply the quantity - that is carried by the flow, such as specific enthalpy h - by the mass flow rate ṁ to compute the measured signal - Ḣ=ṁ h. Hence, as the mass flow rate goes to zero, the - sensor output signal also goes to zero, which avoids numerical - problems. -

      +
    • August 8, 2016, by Michael Wetter:
      + Changed default temperature to compute COP to be the leaving + temperature as use of the entering temperature can violate the 2nd + law if the temperature lift is small.
      + This is for Annex 60, + issue 497.
      • -
    • -

      - Static pressure measurements: For static pressure - measurements, sensors always output the instantaneous - measurement. These sensors cannot be configured to be dynamic. -

      +
    • January 26, 2016, by Michael Wetter:
      + Refactored model to use the same base class as AixLib.Fluid.Chillers.Carnot_y.
      + + Changed part load efficiency to depend on heating part load ratio + rather than on the compressor part load ratio. +
      • +
    • January 20, 2015, by Damien Picard:
      + Add Carnot model to Annex 60 from the Buildings library.
      + Removed the flow direction dependency of staA1, + staB1, staA2 and staB2 as + the efficiency of the Carnot machine should only be computed in the + design flow direction.
      +
      • +
    • December 18, 2015, by Michael Wetter:
      + Corrected wrong computation of staB1 and + staB2 which mistakenly used the inStream + operator for the configuration without flow reversal. This is for + issue + 476. +
      • +
    • November 25, 2015 by Michael Wetter:
      + Changed sign convention for dTEva_nominal to be + consistent with other models. The model will still work with the + old values for dTEva_nominal, but it will write a + warning so that users can transition their models.
      + Corrected assert statement for the efficiency curve. + This is for issue + 468. +
      • +
    • September 3, 2015 by Michael Wetter:
      + Expanded documentation. +
      • +
    • May 6, 2015 by Michael Wetter:
      + Added prescribedHeatFlowRate=true for + vol2. +
      • +
    • October 9, 2013 by Michael Wetter:
      + Reimplemented the computation of the port states to avoid using the + conditionally removed variables sta_a1, + sta_a2, sta_b1 and sta_b2. +
      • +
    • May 10, 2013 by Michael Wetter:
      + Added electric power P as an output signal. +
      • +
    • October 11, 2010 by Michael Wetter:
      + Fixed bug in energy balance. +
      • +
    • March 3, 2009 by Michael Wetter:
      + First implementation.
    + +-------- Errors -------- +line 16 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 24 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 34 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/HeatExchangers/BaseClasses/PartialEffectivenessNTU.mo ---- +-------- HTML Code -------- + +

    + Partial model of a heat exchanger without humidity condensation. + This model transfers heat in the amount of +

    +

    + Q = Qmax ε
    + ε = f(NTU, Z, flowRegime), +

    +

    + where + Qmax is the maximum heat that can be transferred, + ε is the heat transfer effectiveness, + NTU is the Number of Transfer Units, + Z is the ratio of minimum to maximum capacity flow rate and + flowRegime is the heat exchanger flow regime. + such as + parallel flow, cross flow or counter flow. +

    +

    + The flow regimes depend on the heat exchanger configuration. All configurations + defined in + + AixLib.Fluid.Types.HeatExchangerConfiguration + are supported. +

    +

    + Models that extend from this partial model need to provide an assignment + for UA. +

    + +
      +
    • + February 25, 2021 by Baptiste Ravache:
      + Added a warning for when Q_flow_nominal is specified with the wrong sign. +
      • +
    • + January 10, 2018 by Michael Wetter:
      + Removed variable Z that is not used. + This is for + issue 1328. +
      • +
    • + January 10, 2018 by Filip Jorissen:
      + Corrected an error where the value of NTU was assigned to Z. + This is for + issue 1328. +
      • +
    • + February 27, 2016 by Michael Wetter:
      + Introduced sta1_default and sta2_default + to enable translation under OpenModelica. + Removed max=1 attribute for Z. This is needed as near + zero flow, Z can be larger than one due to the regularization. + As Z is not used in this model other than for reporting, this bound + need not be enforced (and the calculation of eps is fine at these small flow rates). + This is for + issue 490. +
      • +
    • + April 29, 2014 by Michael Wetter:
      + Changed assert statement to avoid comparing + enumeration with an integer, which triggers a warning + in Dymola 2015. +
      • +
    • + July 30, 2013 by Michael Wetter:
      + Updated model to use new variable mWat_flow + in the base class. +
      • +
    • + February 12, 2010, by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Corrected Code --------

    - The table below summarizes the recommendations for the use of - sensors. -

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    - Measured quantity - - One port sensor - - Two port sensor -
    - steady-state (tau=0) - - dynamic (tau > 0) -
    - temperature
    - relative humidity
    - mass fraction
    - trace substances
    - specific enthalpy
    - specific entropy -     		- use only if connected to a volume - - avoid - - recommended -
    - volume flow rate
    - enthalpy flow rate
    - entropy flow rate -     		- - - - recommended - - recommended -
    - pressure - - recommended - - recommended - - recommended -
    -

    - Sensor Dynamics -

    -
    - Dynamic response to fluid flowing through the sensor -
    -

    - If a sensor is configured as a dynamic sensor by setting tau - > 0, then the measured quantity, say the temperature - T, is computed as -

    -

    - τ   dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T), -

    -

    - where τ is a user-defined time constant of the sensor (a - suggested value is around 10 seconds, which is the default setting - for the components), dT ⁄ dt is the time derivative of the - sensor output signal, |ṁ| is the absolute value of the mass - flow rate, ṁ0 is the user-specified nominal value - of the mass flow rate and θ is the temperature of the medium - inside the sensor. An equivalent physical model of such a sensor - would be a perfectly mixed volume with a sensor that outputs the - temperature of this volume. In this situation, the size of the volume - would be V=τ   ṁ0 ⁄ ρ, where ρ is the - density of the fluid. -

    -
    - Dynamic response to ambient temperature -
    -

    - For the sensor AixLib.Fluid.Sensors.TemperatureTwoPort, - by setting transferHeat = true, heat transfer to a fixed - ambient can be approximated. The heat transfer is computed as + Partial model of a heat exchanger without humidity condensation. This + model transfers heat in the amount of

    - τHeaTra   dT ⁄ dt = (TAmb-T), -

    -

    - where τHeaTra is a fixed time constant and - TAmb is a fixed ambient temperature. Setting - transferHeat = true is useful if the sensor output - T is used to switch the mass flow rate on again. If - transferHeat = false, then the sensor output T - remains constant if the mass flow rate is zero and hence a fan or - pump controller that uses this signal may never switch the device on - again. If the sensor output T is not used to switch on the - mass flow rate, then in general one can use - transferHeat=false. -

    -

    - Note that since in practice the heat transfer is due to a combination - of ambient temperature and upstream or downstream fluid temperature, - for example by two-way buoyancy-driven flow inside the duct or pipe, - the model uses as an approximation a fixed ambient temperature. Since - the sensor is not affecting the temperature of the medium, this - approximation of the heat transfer does not add or remove heat from - the fluid. + Q = Qmax ε
    + ε = f(NTU, Z, flowRegime),

    -
    - Combined dynamic response -

    - For the sensor AixLib.Fluid.Sensors.TemperatureTwoPort, - if both dynamic effects are enabled, then the output T is - computed as -

    -

    - dT ⁄ dt = |ṁ| ⁄ ṁ0   (θ-T) ⁄ τ + - (TAmb-T) ⁄ τHeaTra. + where Qmax is the maximum heat that can be + transferred, ε is the heat transfer effectiveness, NTU + is the Number of Transfer Units, Z is the ratio of minimum to + maximum capacity flow rate and flowRegime is the heat + exchanger flow regime. such as parallel flow, cross flow or counter + flow.

    -

    - Implementation -

    - The above equation is implemented in such a way that it is - differentiable in the mass flow rate. + The flow regimes depend on the heat exchanger configuration. All + configurations defined in AixLib.Fluid.Types.HeatExchangerConfiguration + are supported.

    - Note that the implementation of the dynamic sensors does not use the - model AixLib.Fluid.MixingVolumes. - The reason is that depending on the selected medium model, the mixing - volume may introduce states for the pressure, species concentration, - trace substance, specific enthalpy and specific entropy. Not all - states are typically needed to model the dynamics of a sensor. - Moreover, in many building system applications, the sensor dynamics - is not of concern, but is rather used here to avoid numerical - problems that steady-state models of sensors cause when flow rates - are very close to zero. + Models that extend from this partial model need to provide an + assignment for UA.

    +
      +
    • February 25, 2021 by Baptiste Ravache:
      + Added a warning for when Q_flow_nominal is specified with the wrong + sign. +
      • +
    • January 10, 2018 by Michael Wetter:
      + Removed variable Z that is not used. This is for + issue + 1328. +
      • +
    • January 10, 2018 by Filip Jorissen:
      + Corrected an error where the value of NTU was assigned to Z. This + is for issue + 1328. +
      • +
    • February 27, 2016 by Michael Wetter:
      + Introduced sta1_default and sta2_default + to enable translation under OpenModelica. Removed + max=1 attribute for Z. This is needed as + near zero flow, Z can be larger than one due to the + regularization. As Z is not used in this model other + than for reporting, this bound need not be enforced (and the + calculation of eps is fine at these small flow rates). + This is for issue + 490. +
      • +
    • April 29, 2014 by Michael Wetter:
      + Changed assert statement to avoid comparing + enumeration with an integer, which triggers a warning in Dymola + 2015. +
      • +
    • July 30, 2013 by Michael Wetter:
      + Updated model to use new variable mWat_flow in the + base class. +
      • +
    • February 12, 2010, by Michael Wetter:
      + First implementation. +
      • +
    -------- Errors -------- -line 32 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 -line 105 column 1 - Warning: The summary attribute on the
    element is obsolete in HTML5 -line 33 column 5 - Warning:
    attribute "align" not allowed for HTML5 -line 38 column 5 - Warning: attribute "align" not allowed for HTML5 -line 144 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 167 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 197 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatPumps/ScrollWaterToWater.mo ---- +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/timeGeometric.mo ---- -------- HTML Code --------

    - Model for a water to water heat pump with a scroll compressor, as described - in Jin (2002). The thermodynamic heat pump cycle is represented below. -

    -

    - \"image\" -

    -

    - The rate of heat transferred to the evaporator is given by: -

    -

    - Q̇Eva = ṁref ( hVap(TEva) - hLiq(TCon) ). -

    -

    - The power consumed by the compressor is given by a linear efficiency relation: -

    -

    - P = PTheoretical / η + PLoss,constant. -

    -

    - Heat transfer in the evaporator and condenser is calculated using an - ε-NTU method, assuming constant refrigerant temperature and constant heat - transfer coefficient between fluid and refrigerant. + This function attemps to build a vector of length nTim with a geometric + expansion of the time variable between dt and t_max.

    - Variable speed is achieved by multiplying the full load suction volume flow rate - by the normalized compressor speed. The power and heat transfer rates are forced - to zero if the resulting heat pump state has higher evaporating pressure than - condensing pressure. + If t_max > nTim*dt, then a geometrically expanding vector is built as

    -

    - The model parameters are obtained by calibration of the heat pump model to - manufacturer performance data. Calibrated model parameters for various heat - pumps from different manufacturers are found in - - AixLib.Fluid.HeatPumps.Data.ScrollWaterToWater. The calibrated model is - located in - - AixLib.Fluid.HeatPumps.Calibration.ScrollWaterToWater. +

    + t = [dt, dt*(1-r2)/(1-r), ... , dt*(1-rn)/(1-r), ... , tmax],

    -

    Options

    - Parameters TConMax and TEvaMin - may be used to set an upper or lower bound for the - condenser and evaporator. - The compressor is disabled when these conditions - are not satisfied, or when the - evaporator temperature is larger - than the condenser temperature. - This mimics the temperature protection - of heat pumps and moreover it avoids - non-converging algebraic loops of equations, - or freezing of evaporator medium. - This option can be disabled by setting - enable_temperature_protection = false. + where r is the geometric expansion factor.

    -

    Assumptions and limitations

    - The compression process is assumed isentropic. The thermal energy - of superheating is ignored in the evaluation of the heat transferred to the refrigerant - in the evaporator. There is no supercooling. + If t_max < nTim*dt, then a linearly expanding vector is built as

    -

    References

    -

    - H. Jin. - - Parameter estimation based models of water source heat pumps. - - PhD Thesis. Oklahoma State University. Stillwater, Oklahoma, USA. 2002. +

    + t = [dt, 2*dt, ... , n*dt, ... , nTim*dt]

    • - May 30, 2017, by Filip Jorissen:
      - Revised documentation for temperature protection. - See #769. -
      • -
    • - November 11, 2016, by Massimo Cimmino:
      + June 28, 2018 by Massimo Cimmino:
      First implementation.
    -------- Corrected Code --------

    - Model for a water to water heat pump with a scroll compressor, as - described in Jin (2002). The thermodynamic heat pump cycle is - represented below. -

    -

    - \"image\" -

    -

    - The rate of heat transferred to the evaporator is given by: -

    -

    - Q̇Eva = ṁref ( - hVap(TEva) - hLiq(TCon) - ). -

    -

    - The power consumed by the compressor is given by a linear efficiency - relation: -

    -

    - P = PTheoretical / η + PLoss,constant. -

    -

    - Heat transfer in the evaporator and condenser is calculated using an - ε-NTU method, assuming constant refrigerant temperature and constant - heat transfer coefficient between fluid and refrigerant. + This function attemps to build a vector of length nTim + with a geometric expansion of the time variable between + dt and t_max.

    - Variable speed is achieved by multiplying the full load suction - volume flow rate by the normalized compressor speed. The power and - heat transfer rates are forced to zero if the resulting heat pump - state has higher evaporating pressure than condensing pressure. + If t_max > nTim*dt, then a geometrically expanding + vector is built as

    -

    - The model parameters are obtained by calibration of the heat pump - model to manufacturer performance data. Calibrated model parameters - for various heat pumps from different manufacturers are found in - AixLib.Fluid.HeatPumps.Data.ScrollWaterToWater. - The calibrated model is located in AixLib.Fluid.HeatPumps.Calibration.ScrollWaterToWater. +

    + t = [dt, dt*(1-r2)/(1-r), ... , + dt*(1-rn)/(1-r), ... , tmax],

    -

    - Options -

    - Parameters TConMax and TEvaMin may be used - to set an upper or lower bound for the condenser and evaporator. The - compressor is disabled when these conditions are not satisfied, or - when the evaporator temperature is larger than the condenser - temperature. This mimics the temperature protection of heat pumps and - moreover it avoids non-converging algebraic loops of equations, or - freezing of evaporator medium. This option can be disabled by setting - enable_temperature_protection = false. + where r is the geometric expansion factor.

    -

    - Assumptions and limitations -

    - The compression process is assumed isentropic. The thermal energy of - superheating is ignored in the evaluation of the heat transferred to - the refrigerant in the evaporator. There is no supercooling. + If t_max < nTim*dt, then a linearly expanding vector + is built as

    -

    - References -

    -

    - H. Jin. Parameter estimation based models of water source heat - pumps. PhD Thesis. Oklahoma State University. Stillwater, - Oklahoma, USA. 2002. +

    + t = [dt, 2*dt, ... , n*dt, ... , nTim*dt]

      -
    • May 30, 2017, by Filip Jorissen:
      - Revised documentation for temperature protection. See #769. -
      • -
    • November 11, 2016, by Massimo Cimmino:
      +
    • June 28, 2018 by Massimo Cimmino:
      First implementation.
    -------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 9 column 2 - Warning:

    attribute "align" not allowed for HTML5 line 18 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatExchangers/BaseClasses/WetCoilDryWetRegime.mo ---- +---- AixLib/ThermalZones/ReducedOrder/RC/TwoElements.mo ---- -------- HTML Code --------

    • - Jan 21, 2021, by Donghun Kim:
      First implementation. + March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      + This is for + #1542. +
      • +
    • + July 11, 2019, by Katharina Brinkmann:
      + Renamed alphaInt to hConInt, + alphaIntWall to hConIntWall +
      • +
    • + January 25, 2019, by Michael Wetter:
      + Added start value to avoid warning in JModelica. +
      • +
    • + April 18, 2015, by Moritz Lauster:
      + First implementation.
    -

    - This model implements the switching algorithm for the dry and wet regime. -

    -

    - The switching criteria for (counter-flow) cooling coil modes are as follows.

    -

    - R1: If the coil surface temperature at the air inlet is lower than the dew-point - temperature at the inlet to the coil, then the cooling coil surface is fully-wet.

    -

    - R2: If the surface temperature at the air outlet section is higher than - the dew-point temperature of the air at the inlet, then the cooling coil surface is fully-dry.

    -

    - At each point of a simulation time step, the fuzzy-modeling approach determines - the weights for R1 and R2 respectively (namely μFW and μFD) - from the dew-point and coil surface temperatures.

    -

    - It calculates total and sensible heat transfer rates according to the weights as follows. -

    -

    - Q̇tot=μFD Q̇tot,FD+μFW Qtot,FW -

    -

    - Q̇sen=μFD Q̇sen,FD+μFW Qsen,FW -

    -

    - The fuzzy-modeling ensures μFW + μFD = 1, - μFW >=0 and μFD >=0, which means the fuzzy - model outcomes of Q̇sen and Q̇tot are always convex combinations of heat transfer - rates for fully-dry and fully-wet modes and therefore are always bounded by them. -

    -

    - The modeling approach also results in n-th order differentiable model - depending on the selection of the underlying membership functions. This cooling - coil model is once continuously differentiable at the mode switches. -

    - +

    This model distinguishes between internal + thermal masses and exterior walls. While exterior walls contribute to heat + transfer to the ambient, adiabatic conditions apply to internal masses. + Parameters for the internal wall element are the length of the RC-chain + nInt, the vector of the capacities + CInt[nInt] and the vector of the resistances RInt[nInt]. + This approach allows considering the dynamic behaviour induced by internal + heat storage. +

    +

    + The image below shows the RC-network of this model. +

    +

    + \"image\"/ +

    + -------- Corrected Code --------
      -
    • Jan 21, 2021, by Donghun Kim:
      +
    • March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      + This is for #1542. +
      • +
    • July 11, 2019, by Katharina Brinkmann:
      + Renamed alphaInt to hConInt, + alphaIntWall to hConIntWall +
      • +
    • January 25, 2019, by Michael Wetter:
      + Added start value to avoid warning in JModelica. +
      • +
    • April 18, 2015, by Moritz Lauster:
      First implementation.

    - This model implements the switching algorithm for the dry and wet - regime. + This model distinguishes between internal thermal masses and exterior + walls. While exterior walls contribute to heat transfer to the + ambient, adiabatic conditions apply to internal masses. Parameters + for the internal wall element are the length of the RC-chain + nInt, the vector of the capacities + CInt[nInt] and the vector of the resistances + RInt[nInt]. This approach allows considering the dynamic + behaviour induced by internal heat storage.

    - The switching criteria for (counter-flow) cooling coil modes are as - follows. + The image below shows the RC-network of this model.

    -

    - R1: If the coil surface temperature at the air inlet is lower than - the dew-point temperature at the inlet to the coil, then the cooling - coil surface is fully-wet. +

    + \"image\"

    + +-------- Errors -------- +line 14 column 4 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Storage/UsersGuide.mo ---- +-------- HTML Code -------- +

    - R2: If the surface temperature at the air outlet section is higher - than the dew-point temperature of the air at the inlet, then the - cooling coil surface is fully-dry. +This user's guide describes the storage tank models. +There are three storage tank models in the this package.

    + + + + + + + + + + + + + + +
    Model name Description
    + +AixLib.Fluid.Storage.Stratified +

    - At each point of a simulation time step, the fuzzy-modeling approach - determines the weights for R1 and R2 respectively (namely - μFW and μFD) from the dew-point - and coil surface temperatures. +This is a model of a stratified storage tank as shown in the figure below.

    -

    - It calculates total and sensible heat transfer rates according to the - weights as follows. +

    +\"Image

    -

    - Q̇tot=μFD Q̇tot,FD+μFW - Qtot,FW +

    +The tank uses several volumes to model the stratification. +Heat conduction is modeled between the volumes through the fluid, +and between the volumes and the ambient.

    -

    - Q̇sen=μFD Q̇sen,FD+μFW - Qsen,FW +

    +The heat port heaPorVol may be used to connect a temperature sensor +that measures the fluid temperature of an individual volume. It may also +be used to add heat to individual volumes, for example if the tank contains +an electrical resistance heater.

    - The fuzzy-modeling ensures μFW + μFD = - 1, μFW >=0 and μFD >=0, - which means the fuzzy model outcomes of Q̇sen and - Q̇tot are always convex combinations of heat - transfer rates for fully-dry and fully-wet modes and therefore are - always bounded by them. +Similarly, the fluid port fluPorVol may be used to connect a fluid pipe +to an individual volume. This allows for example to draw water from that volume whose temperature +is close to the temperature required by the consumer. +Conversely, water could be added to that tank volume whose temperature is close to the +inlet water temperature. +If you don't use such a pipe, simply leave the ports unconnected.

    - The modeling approach also results in n-th order - differentiable model depending on the selection of the underlying - membership functions. This cooling coil model is once continuously - differentiable at the mode switches. +The tank has nSeg fluid volumes. The top segment has the index 1. +Thus, to add a heating element to the bottom element, connect a heat input to +heaPorVol[nSeg].

    - --------- Errors -------- -line 20 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 23 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Movers/Validation/PowerExact.mo ---- --------- HTML Code -------- - -

    - This example is identical to - - AixLib.Fluid.Movers.Validation.PowerSimplified, except that the - performance data for the flow controlled pumps - pump_dp and pump_m_flow contain - the pressure curves and efficiency curves. - The plot below shows that this leads to a computation of the power consumption - that is identical to the one from the speed controlled pump pump_Nrpm. -

    -

    - \"image\" -

    - -
      -
    • - October 15, 2021, by Hongxiang Fu:
      - Fixed the image in the documentation which was cut off - at the y-axis. This is for - IBPSA, #1533. -
      • -
    • - March 2, 2016, by Filip Jorissen:
      - First implementation for - #417. -
      • -
    - --------- Corrected Code --------

    - This example is identical to AixLib.Fluid.Movers.Validation.PowerSimplified, - except that the performance data for the flow controlled pumps - pump_dp and pump_m_flow contain the - pressure curves and efficiency curves. The plot below shows that this - leads to a computation of the power consumption that is identical to - the one from the speed controlled pump pump_Nrpm. +The heat ports outside the tank insulation can be +used to specify an ambient temperature. +Leave these ports unconnected to force adiabatic boundary conditions. +Note, however, that all heat conduction elements through the tank wall (but not the top and bottom) are connected to the +heat port heaPorSid. Thus, not connecting +heaPorSid means an adiabatic boundary condition in the sense +that heaPorSid.Q_flow = 0. This, however, still allows heat to flow +through the tank walls, modeled by conWal, from one fluid volume +to another one.

    -

    - \"image\" +

    + +AixLib.Fluid.Storage.StratifiedEnhanced + +

    +The model is identical to + +AixLib.Fluid.Storage.Stratified, +except for the following:

      -
    • October 15, 2021, by Hongxiang Fu:
      - Fixed the image in the documentation which was cut off at the - y-axis. This is for IBPSA, - #1533. -
      • -
    • March 2, 2016, by Filip Jorissen:
      - First implementation for #417. -
      • +
    • +It adds a correction that reduces the numerical dissipation. +
      • +
    • +It does not contain the fluid ports fluPorVol that +connect from the outside to the individual volumes. +
    - --------- Errors -------- -line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/Boreholes/BaseClasses/Functions/convectionResistanceCircularPipe.mo ---- --------- HTML Code -------- - -

    - This model computes the convection resistance in the pipes of a borehole segment - with heigth hSeg using correlations suggested by Bergman et al. (2011). -

    -

    - If the flow is laminar (Re ≤ 2300, with Re being the Reynolds number of the flow), - the Nusselt number of the flow is assumed to be constant at 3.66. If the flow is turbulent (Re > 2300), - the correlation of Dittus-Boelter is used to find the convection heat transfer coefficient as -

    -

    - Nu = 0.023   Re0.8   Prn, -

    -

    - where Nu is the Nusselt number and - Pr is the Prandlt number. - A value of n=0.35 is used, as the reference uses n=0.4 for heating and - n=0.3 for cooling. To ensure that the function is continuously differentiable, - a smooth transition between the laminar and turbulent values is created for the - range 2300 < Re < 2400. -

    -

    References

    -

    - Bergman, T. L., Incropera, F. P., DeWitt, D. P., & Lavine, A. S. (2011). Fundamentals of heat and mass - transfer (7th ed.). New York: John Wiley & Sons. -

    - -
      -
    • - July 10, 2018, by Alex Laferrière:
      - Added laminar flow and smooth laminar-turbulent transition. - Revised documentation. -
      • -
    • - February 14, 2014, by Michael Wetter:
      - Removed unused input rBor. - Revised documentation. -
      • -
    • - January 24, 2014, by Michael Wetter:
      - Revised implementation. - Changed cpFluid to cpMed to use consistent notation. - Added regularization for computation of convective heat transfer coefficient to - avoid an event and a non-differentiability. -
      • -
    • - January 23, 2014, by Damien Picard:
      - First implementation. -
      • -
    - --------- Corrected Code --------

    - This model computes the convection resistance in the pipes of a - borehole segment with heigth hSeg using - correlations suggested by Bergman et al. (2011). +The correction uses a third order upwind scheme to compute the +outlet temperatures of the segments in the tank. This model +is implemented in + +AixLib.Fluid.Storage.BaseClasses.ThirdOrderStratifier.

    +
    + +AixLib.Fluid.Storage.StratifiedEnhancedInternalHex +

    - If the flow is laminar (Re ≤ 2300, with Re being the - Reynolds number of the flow), the Nusselt number of the flow is - assumed to be constant at 3.66. If the flow is turbulent (Re > - 2300), the correlation of Dittus-Boelter is used to find the - convection heat transfer coefficient as -

    -

    - Nu = 0.023   Re0.8   Prn, +This model is identical to + +AixLib.Fluid.Storage.StratifiedEnhanced +except that it adds a heat exchanger to the tank.

    - where Nu is the Nusselt number and Pr is the Prandlt - number. A value of n=0.35 is used, as the reference uses - n=0.4 for heating and n=0.3 for cooling. To ensure that - the function is continuously differentiable, a smooth transition - between the laminar and turbulent values is created for the range - 2300 < Re < 2400. +The modifications consist of adding a heat exchanger +and fluid ports to connect to the heat exchanger. +The modifications allow to run a fluid through the tank causing heat transfer to the stored fluid. +A typical example is a storage tank in a solar hot water system.

    -

    - References -

    - Bergman, T. L., Incropera, F. P., DeWitt, D. P., & Lavine, A. S. - (2011). Fundamentals of heat and mass transfer (7th ed.). New - York: John Wiley & Sons. +The heat exchanger model assumes flow through the inside of a helical coil heat exchanger, +and stagnant fluid on the outside. Parameters are used to describe the +heat transfer on the inside of the heat exchanger at nominal conditions, and +geometry of the outside of the heat exchanger. This information is used to compute +an hA-value for each side of the coil. +Convection calculations are then performed to identify heat transfer +between the heat transfer fluid and the fluid in the tank.

    -
      -
    • July 10, 2018, by Alex Laferrière:
      - Added laminar flow and smooth laminar-turbulent transition. Revised - documentation. -
      • -
    • February 14, 2014, by Michael Wetter:
      - Removed unused input rBor. Revised documentation. -
      • -
    • January 24, 2014, by Michael Wetter:
      - Revised implementation. Changed cpFluid to - cpMed to use consistent notation. Added regularization - for computation of convective heat transfer coefficient to avoid an - event and a non-differentiability. -
      • -
    • January 23, 2014, by Damien Picard:
      - First implementation. -
      • -
    - --------- Errors -------- -line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Controls/SetPoints/Examples/OccupancySchedule.mo ---- --------- HTML Code -------- - -

    - Example that demonstrates the use of the occupancy schedule. - The figure below shows how the time until the next occupancy starts or ends - is decreased. The red line hits zero when the schedule indicates an occupied time, - and the blue line hits zero when the schedule indicates a non-occupied time. -

    -

    - \"Time -

    - -
      -
    • - November 21, 2011, by Michael Wetter:
      - Added documentation. -
      • -
    - --------- Corrected Code --------

    - Example that demonstrates the use of the occupancy schedule. The - figure below shows how the time until the next occupancy starts or - ends is decreased. The red line hits zero when the schedule indicates - an occupied time, and the blue line hits zero when the schedule - indicates a non-occupied time. +The location of the heat exchanger can be parameterized as follows: +The parameters hHex_a and hHex_b are the heights +of the heat exchanger ports portHex_a and portHex_b, +measured from the bottom of the tank. +For example, to place the port portHex_b at the bottom of the tank, +set hHexB_b=0. +The parameters hHex_a and hHex_b are then used to provide +a default value for the parameters +segHex_a and segHex_b, which are the numbers of the tank +segments to which the heat exchanger ports portHex_a and portHex_b +are connected.

    - \"Time +\"Image

    -
      -
    • November 21, 2011, by Michael Wetter:
      - Added documentation. -
      • -
    - --------- Errors -------- -line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/ThermalZones/ReducedOrder/RC/FourElements.mo ---- --------- HTML Code -------- - -

      -
    • - March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for - #1542. -
      • -
    • - December 9, 2019, by Moritz Lauster:
      - Changes nExt to nRoof for - RRoof and CRoof -
      • -
    • - July 11, 2019, by Katharina Brinkmann:
      - Renamed alphaRoof to hConRoof, - alphaRoofConst to hConRoof_const -
      • -
    • - August 31, 2018 by Moritz Lauster:
      - Updated schema in documentation and fixes - orientation and connections of roofRC for - - issue 997. -
      • -
    • - September 11, 2015 by Moritz Lauster:
      - First Implementation. -
      • -
    - -

    - This model adds another element for the roof. Roofs commonly - exhibit the same excitations as exterior walls but have different coefficients - of heat transfer due to their orientation. Adding an extra element for the roof - might lead to a finer resolution of the dynamic behaviour but increases - calculation times. The roof is parameterized via the length of the RC-chain - nRoof, - the vector of capacities CRoof[nRoof], the vector of resistances - RRoof[nRoof] and remaining resistances RRoofRem. -

    -

    - The image below shows the RC-network of this model. -

    -

    - \"image\"/ -

    - --------- Corrected Code -------- -
      -
    • March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for #1542. -
      • -
    • December 9, 2019, by Moritz Lauster:
      - Changes nExt to nRoof for - RRoof and CRoof -
      • -
    • July 11, 2019, by Katharina Brinkmann:
      - Renamed alphaRoof to hConRoof, - alphaRoofConst to hConRoof_const -
      • -
    • August 31, 2018 by Moritz Lauster:
      - Updated schema in documentation and fixes orientation and - connections of roofRC for issue 997. -
      • -
    • September 11, 2015 by Moritz Lauster:
      - First Implementation. -
      • -

    - This model adds another element for the roof. Roofs commonly exhibit - the same excitations as exterior walls but have different - coefficients of heat transfer due to their orientation. Adding an - extra element for the roof might lead to a finer resolution of the - dynamic behaviour but increases calculation times. The roof is - parameterized via the length of the RC-chain nRoof, the - vector of capacities CRoof[nRoof], the vector of - resistances RRoof[nRoof] and remaining resistances - RRoofRem. +Optionally, this model computes a dynamic response of the heat exchanger. +This can be configured using the parameters +energyDynamicsHexSolid, +energyDynamicsHex and +massDynamicsHex. +For this computation, the fluid volume inside the heat exchanger +and the heat capacity of the heat +exchanger wall CHex are approximated. +Both depend on the length lHex +of the heat exchanger. +The model provides default values for these +parameters, as well as for the heat exchanger material which is +assumed to be steel. These default values can be overwritten by the user. +The default values for the heat exchanger geometry are computed assuming +that there is a cylindrical heat exchanger +made of steel whose diameter is half the diameter of the tank, e.g., +rHex=rTan/2. +Hence, the length of the heat exchanger is approximated as +lHex = 2 rHex π h = 2 rTan/2 π h, +where h is the distance between the heat exchanger inlet and outlet. +The wall thickness is assumed to be 10% of the heat exchanger +outer diameter. +For typical applications, users do not need to change these values.

    - The image below shows the RC-network of this model. +Setting energyDynamicsHexSolid to a dynamic balance and +energyDynamicsHex to a steady-state balance may be of interest +to remove very fast dynamics of the fluid, while still modeling slower +dynamics that arises from the metal of the heat exchanger. +By default, energyDynamicsHexSolid is set +to the same value as energyDynamicsHex +as this seems to be the typical configuration.

    -

    - \"image\" +

    +The heat exchanger is implemented in + +AixLib.Fluid.Storage.BaseClasses.IndirectTankHeatExchanger.

    +
    --------- Errors -------- -line 15 column 4 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Chillers/Carnot_TEva.mo ---- --------- HTML Code -------- - -

    - This is a model of a chiller whose coefficient of performance COP changes - with temperatures in the same way as the Carnot efficiency changes. - The control input is the setpoint of the evaporator leaving temperature, which - is met exactly at steady state if the chiller has sufficient capacity. -

    -

    - The model allows to either specify the Carnot effectivness - ηCarnot,0, or - a COP0 - at the nominal conditions, together with - the evaporator temperature Teva,0 and - the condenser temperature Tcon,0, in which - case the model computes the Carnot effectivness as -

    -

    - ηCarnot,0 = - COP0 - ⁄ (Teva,0 ⁄ (Tcon,0-Teva,0)). -

    -

    - On the Advanced tab, a user can specify the temperatures that - will be used as the evaporator and condenser temperature. -

    -

    - During the simulation, the chiller COP is computed as the product -

    -

    - COP = ηCarnot,0 COPCarnot ηPL, -

    -

    - where COPCarnot is the Carnot efficiency and - ηPL is a polynomial in the cooling part load ratio yPL - that can be used to take into account a change in COP at part load - conditions. - This polynomial has the form -

    -

    - ηPL = a1 + a2 yPL + a3 yPL2 + ... -

    -

    - where the coefficients ai - are declared by the parameter a. -

    -

    - On the Dynamics tag, the model can be parametrized to compute a transient - or steady-state response. - The transient response of the model is computed using a first - order differential equation for the evaporator and condenser fluid volumes. - The chiller outlet temperatures are equal to the temperatures of these lumped volumes. -

    -

    Typical use and important parameters

    -

    - When using this component, make sure that the condenser has sufficient mass flow rate. - Based on the evaporator mass flow rate, temperature difference and the efficiencies, - the model computes how much heat will be added to the condenser. - If the mass flow rate is too small, very high outlet temperatures can result. -

    -

    - The evaporator heat flow rate QEva_flow_nominal is used to assign - the default value for the mass flow rates, which are used for the pressure drop - calculations. - It is also used to compute the part load efficiency. - Hence, make sure that QEva_flow_nominal is set to a reasonable value. -

    -

    - The maximum cooling capacity is set by the parameter QEva_flow_min, - which is by default set to negative infinity. -

    -

    - The coefficient of performance depends on the - evaporator and condenser leaving temperature - since otherwise the second law of thermodynamics may be violated. -

    -

    Notes

    -

    - For a similar model that can be used as a heat pump, see - - AixLib.Fluid.HeatPumps.Examples.Carnot_TCon. -

    - -
      -
    • - May 8, 2017, by Michael Wetter:
      - Replaced model that interfaces with fluid stream.
      - This is for - - AixLib, #763. -
      • -
    • - January 2, 2017, by Filip Jorissen:
      - Removed parameters - effInpEva and effInpCon - and updated documentation. - This is for - - issue 497. -
      • -
    • - August 8, 2016, by Michael Wetter:
      - Changed default temperature to compute COP to be the leaving temperature as - use of the entering temperature can violate the 2nd law if the temperature - lift is small.
      - This is for - - Annex 60, issue 497. -
      • -
    • - November 25, 2015 by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code -------- -

    - This is a model of a chiller whose coefficient of performance COP - changes with temperatures in the same way as the Carnot efficiency - changes. The control input is the setpoint of the evaporator leaving - temperature, which is met exactly at steady state if the chiller has - sufficient capacity. -

    -

    - The model allows to either specify the Carnot effectivness - ηCarnot,0, or a COP0 at the - nominal conditions, together with the evaporator temperature - Teva,0 and the condenser temperature - Tcon,0, in which case the model computes the Carnot - effectivness as -

    -

    - ηCarnot,0 = COP0 ⁄ (Teva,0 ⁄ - (Tcon,0-Teva,0)). -

    -

    - On the Advanced tab, a user can specify the temperatures - that will be used as the evaporator and condenser temperature. -

    -

    - During the simulation, the chiller COP is computed as the product -

    -

    - COP = ηCarnot,0 COPCarnot ηPL, -

    -

    - where COPCarnot is the Carnot efficiency and - ηPL is a polynomial in the cooling part load ratio - yPL that can be used to take into account a change - in COP at part load conditions. This polynomial has the form -

    -

    - ηPL = a1 + a2 yPL + - a3 yPL2 + ... -

    -

    - where the coefficients ai are declared by the - parameter a. -

    -

    - On the Dynamics tag, the model can be parametrized to - compute a transient or steady-state response. The transient response - of the model is computed using a first order differential equation - for the evaporator and condenser fluid volumes. The chiller outlet - temperatures are equal to the temperatures of these lumped volumes. -

    -

    - Typical use and important parameters -

    -

    - When using this component, make sure that the condenser has - sufficient mass flow rate. Based on the evaporator mass flow rate, - temperature difference and the efficiencies, the model computes how - much heat will be added to the condenser. If the mass flow rate is - too small, very high outlet temperatures can result. -

    -

    - The evaporator heat flow rate QEva_flow_nominal is used - to assign the default value for the mass flow rates, which are used - for the pressure drop calculations. It is also used to compute the - part load efficiency. Hence, make sure that - QEva_flow_nominal is set to a reasonable value. -

    -

    - The maximum cooling capacity is set by the parameter - QEva_flow_min, which is by default set to negative - infinity. -

    -

    - The coefficient of performance depends on the evaporator and - condenser leaving temperature since otherwise the second law of - thermodynamics may be violated. -

    -

    - Notes -

    -

    - For a similar model that can be used as a heat pump, see AixLib.Fluid.HeatPumps.Examples.Carnot_TCon. -

    -
      -
    • May 8, 2017, by Michael Wetter:
      - Replaced model that interfaces with fluid stream.
      - This is for AixLib, - #763. -
      • -
    • January 2, 2017, by Filip Jorissen:
      - Removed parameters effInpEva and - effInpCon and updated documentation. This is for - issue - 497. -
      • -
    • August 8, 2016, by Michael Wetter:
      - Changed default temperature to compute COP to be the leaving - temperature as use of the entering temperature can violate the 2nd - law if the temperature lift is small.
      - This is for Annex 60, - issue 497. -
      • -
    • November 25, 2015 by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 17 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 39 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Utilities/Math/Functions/polynomial.mo ---- --------- HTML Code -------- - - This function computes a polynomial of arbitrary order. - The polynomial has the form -

    - y = a1 + a2 x + a3 x2 + ... -

    - -
      -
    • - December 14, 2016, by Michael Wetter:
      - Removed derivative annotation.
      - This is for - issue 602. -
      • -
    • - March 30, 2011, by Michael Wetter:
      - Added zeroDerivative keyword. -
      • -
    • - March 2, by Michael Wetter:
      - Removed redundant smoothOrder annotation. -
      • -
    • - February 29, 2009 by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code -------- -This function computes a polynomial of arbitrary order. The polynomial -has the form -

    - y = a1 + a2 x + a3 x2 + - ... -

    -
      -
    • December 14, 2016, by Michael Wetter:
      - Removed derivative annotation.
      - This is for issue 602. -
      • -
    • March 30, 2011, by Michael Wetter:
      - Added zeroDerivative keyword. -
      • -
    • March 2, by Michael Wetter:
      - Removed redundant smoothOrder annotation. -
      • -
    • February 29, 2009 by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 4 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/ThermalZones/ReducedOrder/RC/BaseClasses/InteriorWall.mo ---- --------- HTML Code -------- - -

    InteriorWall represents heat storage within walls. It links a - variable number n of thermal resistances and capacities to a - series connection. n thus defines the spatial discretization of - thermal effects within the wall. All effects are considered as one-dimensional - normal to the wall's surface. This model is thought for interior wall - elements that only serve as heat storage elements. The RC-chain is defined via - a vector of capacities CInt[n] and a vector of resistances - RInt[n]. - Resistances and capacities are connected alternately, starting with the first - resistance RInt[1], from heat port_a into the wall. -

    -

    \"image\"/

    - -
      -
    • - April 27, 2016, by Michael Wetter:
      - Added graphical connections. -
      • -
    • - April 17, 2015, by Moritz Lauster:
      - Implemented. -
      • -
    - --------- Corrected Code -------- -

    - InteriorWall represents heat storage within walls. It - links a variable number n of thermal resistances and - capacities to a series connection. n thus defines the - spatial discretization of thermal effects within the wall. All - effects are considered as one-dimensional normal to the wall's - surface. This model is thought for interior wall elements that only - serve as heat storage elements. The RC-chain is defined via a vector - of capacities CInt[n] and a vector of resistances - RInt[n]. Resistances and capacities are connected - alternately, starting with the first resistance RInt[1], - from heat port_a into the wall. -

    -

    - \"image\" -

    -
      -
    • April 27, 2016, by Michael Wetter:
      - Added graphical connections. -
      • -
    • April 17, 2015, by Moritz Lauster:
      - Implemented. -
      • -
    - --------- Errors -------- -line 13 column 4 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Utilities/Math/QuadraticLinear.mo ---- --------- HTML Code -------- - -

    Block for function quadraticLinear, which computes

    -

    y = a1 + a2 x1 + a3 x12 + (a4 + a5 x1 + a6 x12) x2

    - -
      -
    • - November 29, 2013 by Marcus Fuchs:
      - Implementation based on Functions.quadraticLinear. -
      • -
    - -------- Corrected Code --------

    - Block for function quadraticLinear, which computes -

    -

    - y = a1 + a2 x1 + a3 x12 + (a4 + a5 x1 + a6 x12) x2 + This user's guide describes the storage tank models. There are three + storage tank models in the this package.

    -
      -
    • November 29, 2013 by Marcus Fuchs:
      - Implementation based on Functions.quadraticLinear. -
      • -
    + + + + + + + + + + + + + + + + + +
    + Model name + + Description +
    + AixLib.Fluid.Storage.Stratified + +

    + This is a model of a stratified storage tank as shown in the + figure below. +

    +

    + \"Image +

    +

    + The tank uses several volumes to model the stratification. Heat + conduction is modeled between the volumes through the fluid, + and between the volumes and the ambient. +

    +

    + The heat port heaPorVol may be used to connect a + temperature sensor that measures the fluid temperature of an + individual volume. It may also be used to add heat to + individual volumes, for example if the tank contains an + electrical resistance heater. +

    +

    + Similarly, the fluid port fluPorVol may be used to + connect a fluid pipe to an individual volume. This allows for + example to draw water from that volume whose temperature is + close to the temperature required by the consumer. Conversely, + water could be added to that tank volume whose temperature is + close to the inlet water temperature. If you don't use such a + pipe, simply leave the ports unconnected. +

    +

    + The tank has nSeg fluid volumes. The top segment + has the index 1. Thus, to add a heating element to + the bottom element, connect a heat input to + heaPorVol[nSeg]. +

    +

    + The heat ports outside the tank insulation can be used to + specify an ambient temperature. Leave these ports unconnected + to force adiabatic boundary conditions. Note, however, that all + heat conduction elements through the tank wall (but not the top + and bottom) are connected to the heat port + heaPorSid. Thus, not connecting + heaPorSid means an adiabatic boundary condition in + the sense that heaPorSid.Q_flow = 0. This, + however, still allows heat to flow through the tank walls, + modeled by conWal, from one fluid volume to + another one. +

    +
    + AixLib.Fluid.Storage.StratifiedEnhanced + +

    + The model is identical to AixLib.Fluid.Storage.Stratified, + except for the following: +

    +
      +
    • It adds a correction that reduces the numerical + dissipation. +
      • +
    • It does not contain the fluid ports fluPorVol + that connect from the outside to the individual volumes. +
      • +
    +

    + The correction uses a third order upwind scheme to compute the + outlet temperatures of the segments in the tank. This model is + implemented in + AixLib.Fluid.Storage.BaseClasses.ThirdOrderStratifier. +

    +
    + AixLib.Fluid.Storage.StratifiedEnhancedInternalHex + +

    + This model is identical to AixLib.Fluid.Storage.StratifiedEnhanced + except that it adds a heat exchanger to the tank. +

    +

    + The modifications consist of adding a heat exchanger and fluid + ports to connect to the heat exchanger. The modifications allow + to run a fluid through the tank causing heat transfer to the + stored fluid. A typical example is a storage tank in a solar + hot water system. +

    +

    + The heat exchanger model assumes flow through the inside of a + helical coil heat exchanger, and stagnant fluid on the outside. + Parameters are used to describe the heat transfer on the inside + of the heat exchanger at nominal conditions, and geometry of + the outside of the heat exchanger. This information is used to + compute an hA-value for each side of the coil. + Convection calculations are then performed to identify heat + transfer between the heat transfer fluid and the fluid in the + tank. +

    +

    + The location of the heat exchanger can be parameterized as + follows: The parameters hHex_a and + hHex_b are the heights of the heat exchanger ports + portHex_a and portHex_b, measured + from the bottom of the tank. For example, to place the port + portHex_b at the bottom of the tank, set + hHexB_b=0. The parameters hHex_a and + hHex_b are then used to provide a default value + for the parameters segHex_a and + segHex_b, which are the numbers of the tank + segments to which the heat exchanger ports + portHex_a and portHex_b are + connected. +

    +

    + \"Image +

    +

    + Optionally, this model computes a dynamic response of the heat + exchanger. This can be configured using the parameters + energyDynamicsHexSolid, + energyDynamicsHex and + massDynamicsHex. For this computation, the fluid + volume inside the heat exchanger and the heat capacity of the + heat exchanger wall CHex are approximated. Both + depend on the length lHex of the heat exchanger. + The model provides default values for these parameters, as well + as for the heat exchanger material which is assumed to be + steel. These default values can be overwritten by the user. The + default values for the heat exchanger geometry are computed + assuming that there is a cylindrical heat exchanger made of + steel whose diameter is half the diameter of the tank, e.g., + rHex=rTan/2. Hence, the length of + the heat exchanger is approximated as lHex = 2 + rHex π h = 2 rTan/2 π h, where + h is the distance between the heat exchanger inlet and + outlet. The wall thickness is assumed to be 10% of the + heat exchanger outer diameter. For typical applications, users + do not need to change these values. +

    +

    + Setting energyDynamicsHexSolid to a dynamic + balance and energyDynamicsHex to a steady-state + balance may be of interest to remove very fast dynamics of the + fluid, while still modeling slower dynamics that arises from + the metal of the heat exchanger. By default, + energyDynamicsHexSolid is set to the same value as + energyDynamicsHex as this seems to be the typical + configuration. +

    +

    + The heat exchanger is implemented in AixLib.Fluid.Storage.BaseClasses.IndirectTankHeatExchanger. +

    +
    -------- Errors -------- -line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 6 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 +line 17 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 129 column 1 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/ThermalZones/ReducedOrder/RC/BaseClasses/ExteriorWall.mo ---- --------- HTML Code -------- - -

    ExteriorWall represents heat conduction and heat storage - within walls. It links a variable number n of thermal resistances - and capacities to a series connection. n thus defines the spatial - discretization of thermal effects within the wall. All effects are considered - as one-dimensional normal to the wall's surface. This model is thought - for exterior wall elements that contribute to heat transfer to the outdoor. - The RC-chain is defined via a vector of capacities CExt[n] and a - vector of resistances RExt[n]. Resistances and capacities are - connected alternately, starting with the first resistance RExt[1], - from heat port_a to heat port_b. RExtRem - is the resistance between the last capacity CExt[end] and the - heat port_b.

    -

    \"image\"/

    - -
      -
    • - April 27, 2016, by Michael Wetter:
      - Added graphical connections. -
      • -
    • - April 17, 2015, by Moritz Lauster:
      - Implemented. -
      • -
    - --------- Corrected Code -------- -

    - ExteriorWall represents heat conduction and heat storage - within walls. It links a variable number n of thermal - resistances and capacities to a series connection. n - thus defines the spatial discretization of thermal effects within the - wall. All effects are considered as one-dimensional normal to the - wall's surface. This model is thought for exterior wall elements that - contribute to heat transfer to the outdoor. The RC-chain is defined - via a vector of capacities CExt[n] and a vector of - resistances RExt[n]. Resistances and capacities are - connected alternately, starting with the first resistance - RExt[1], from heat port_a to heat - port_b. RExtRem is the resistance between - the last capacity CExt[end] and the heat - port_b. -

    -

    - \"image\" -

    -
      -
    • April 27, 2016, by Michael Wetter:
      - Added graphical connections. -
      • -
    • April 17, 2015, by Moritz Lauster:
      - Implemented. -
      • -
    - --------- Errors -------- -line 14 column 4 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/BoundaryConditions/Validation/UsersGuide.mo ---- +---- AixLib/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow.mo ---- -------- HTML Code -------- +

    + Function that computes the pressure drop of flow elements as +

    +

    + Δp = sign(m) (m ⁄ k)2 +

    +

    + with regularization near the origin. + Therefore, the flow coefficient is +

    +

    + k = m ⁄ √ Δp   +

    +

    + The input m_flow_turbulent determines the location of the regularization. +

    + +
      +
    • + December 9, 2019, by Michael Wetter:
      + Added smooth(2, . ), similar to + + AixLib.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp.
      + See #1240. +
      • +
    • + January 4, 2019, by Michael Wetter:
      + Set `Inline=false`.
      + See #1070. +
      • +
    • + May 1, 2017, by Filip Jorissen:
      + Revised implementation such that + + AixLib.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow + is C2 continuous. + See #725. +
      • +
    • + January 22, 2016, by Michael Wetter:
      + Corrected type declaration of pressure difference. + This is + for #404. +
      • +
    • + July 28, 2015, by Michael Wetter:
      + Removed double declaration of smooth(..) and smoothOrder + and changed Inline=true to LateInline=true. + This is for + issue 301. +
      • +
    • + July 15, 2015, by Filip Jorissen:
      + New, more efficient implementation based on regularisation using simple polynomial. + Expanded common subexpressions for function inlining to be possible. + Set Inline=true for inlining to occur. + This is for + #279. +
      • +
    • + August 10, 2011, by Michael Wetter:
      + Removed if-then optimization that set dp=0 if m_flow=0, + as this causes the derivative to be discontinuous at m_flow=0. +
      • +
    • + August 4, 2011, by Michael Wetter:
      + Removed option to use a linear function. The linear implementation is now done + in models that call this function. With the previous implementation, + the symbolic processor may not rearrange the equations, which can lead + to coupled equations instead of an explicit solution. +
      • +
    • + April 13, 2009, by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Corrected Code --------

    -The package AixLib.BoundaryConditions.Validation.BESTEST -contains the models that are used for the BESTEST validation ASHRAE 2020 for weather data acquisition and postprocessing. + Function that computes the pressure drop of flow elements as

    -

    -Each model represents a different climate with different days as shown in the tables below. -All examples have a script that runs the simulation according to the specifications and derive the required Json file as reported below. +

    + Δp = sign(m) (m ⁄ k)2

    -The weather radiation data has to be provided at different orientations and inclinations. + with regularization near the origin. Therefore, the flow coefficient + is

    -

    Table 2: Azimuth and Slope for Surfaces

    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    Azimuth

    Slope

    Horizontal

    0° from horizontal

    South

    90° from horizontal

    East

    90° from horizontal

    North

    90° from horizontal

    West

    90° from horizontal

    45° East of South

    90° from horizontal

    45° West of South

    90° from horizontal

    East

    30° from horizontal

    South

    30° from horizontal

    West

    30° from horizontal

    - -

    Additional parameters and correlations

    -
      -
    • Ground reflectance ρ is set to 0 for cases from WD100 to WD500 and 0.2 for WD600
      • -
    • -Sky black body temperature -calculated using Horizontal radiation or dew point temperature and sky cover. -
      • -
    • Diffused radiation calculated using Perez and -Isotropic sky models
      • -
    -

    Outputs required

    -

    Annual Outputs

    -

     The following outputs are provided for an annual simulation:

    -
      -
    • Average dry bulb temperature (°C)
      • -
    • Average relative humidity (%)
      • -
    • Average dewpoint temperature (°C)
      • -
    • Average humidity ratio (kg moisture/kg dry air)
      • -
    • Average wet bulb temperature (°C)
      • -
    • Sum of total, beam, and diffuse solar radiation incident on each surface (Wh/m2)
      • -
    -

    Hourly Outputs

    -

    The following outputs are provided for each hour of the days specified for each test case in Table 3:

    -
      -
    • Dry bulb temperature (°C)
      • -
    • Relative humidity (%)
      • -
    • Dewpoint temperature (°C)
      • -
    • Humidity ratio (kg moisture/kg dry air)
      • -
    • Wet bulb temperature (°C)
      • -
    • Windspeed (m/s)
      • -
    • Wind direction (degrees from north)
      • -
    • Station pressure (mbar)
      • -
    • Total cloud cover (tenths of sky)
      • -
    • Opaque cloud cover (tenths of sky)
      • -
    • Sky temperature (°C)
      • -
    • Sum of total, beam, and diffuse solar radiation incident on each surface (Wh/m2) 
      • -
    -

    Table 3: Specific Days for Output

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    Case

    Days

    WD100

    May 4th, July 14th, September 6th

    WD200

    May 24th, August 26th

    WD300

    February 7th, August 13th

    WD400

    January 24th, July 1st

    WD500

    March 1st, September 14th

    WD600

    May 4th, July 14th, September 6th

    -

    Sub-hourly Outputs

    -

    The following outputs are provided at each timestep of the days specified for each test case in Table 3:

    -
      -
    • Dry bulb temperature (C)
      • -
    • Relative humidity (%)
      • -
    • Sum of total, beam, and diffuse solar radiation incident on each surface (Wh/m2)
      • -
    -

    The following outputs are provided integrated hourly for the days specified for each test case in Table 3:

    -
      -
    • Total incident horizontal solar radiation (Wh/m2)
      • -
    • Total incident horizontal beam solar radiation (Wh/m2)
      • -
    • Total incident horizontal diffuse solar radiation (Wh/m2)
      • -
    -

    Validation results

    -

    (Not available yet)

    -

    Implementation

    -

    To generate the data shown in this user guide, run

    -
    -cd AixLib/Resources/Data/BoundaryConditions/Validation/BESTEST
-python3 generateResults.py -p
-
    -

    At the beginning of the Python script there are several options that the user can choose, by default the script will: +

    + k = m ⁄ √ Δp +  

    -
      -
    • Clone the last master branch of the AixLib repository into a temporary directory
      • -
    • Execute all the simulations and create the folders with the .mat and .json files inside the BESTEST/Simulations folder
      • -
    -

    References

    -

    (Not available yet)

    - -
      -
    • -March 11, 2020, by Ettore Zanetti:
      -first implementation of BESTEST weather validation -
      • -
    - --------- Corrected Code --------

    - The package AixLib.BoundaryConditions.Validation.BESTEST - contains the models that are used for the BESTEST validation ASHRAE - 2020 for weather data acquisition and postprocessing. -

    -

    - Each model represents a different climate with different days as - shown in the tables below. All examples have a script that runs the - simulation according to the specifications and derive the required - Json file as reported below. -

    -

    - The weather radiation data has to be provided at different - orientations and inclinations. -

    -

    - Table 2: Azimuth and Slope for Surfaces -

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    -

    - Azimuth -

    -     		-

    - Slope -

    -
    -

    - Horizontal -

    -     		-

    - 0° from horizontal -

    -
    -

    - South -

    -     		-

    - 90° from horizontal -

    -
    -

    - East -

    -     		-

    - 90° from horizontal -

    -
    -

    - North -

    -     		-

    - 90° from horizontal -

    -
    -

    - West -

    -     		-

    - 90° from horizontal -

    -
    -

    - 45° East of South -

    -     		-

    - 90° from horizontal -

    -
    -

    - 45° West of South -

    -     		-

    - 90° from horizontal -

    -
    -

    - East -

    -     		-

    - 30° from horizontal -

    -
    -

    - South -

    -     		-

    - 30° from horizontal -

    -
    -

    - West -

    -     		-

    - 30° from horizontal -

    -

    -

    - Additional parameters and correlations -

    -
      -
    • Ground reflectance ρ is set to 0 for cases from WD100 to WD500 - and 0.2 for WD600 -
      • -
    • - Sky - black body temperature calculated using Horizontal radiation or - dew point temperature and sky cover. -
      • -
    • Diffused radiation calculated using - Perez and - Isotropic sky models -
      • -
    -

    - Outputs required -

    -

    - Annual Outputs -

    -

    -  The following outputs are provided for an annual - simulation: -

    -
      -
    • Average dry bulb temperature (°C) -
      • -
    • Average relative humidity (%) -
      • -
    • Average dewpoint temperature (°C) -
      • -
    • Average humidity ratio (kg moisture/kg dry air) -
      • -
    • Average wet bulb temperature (°C) -
      • -
    • Sum of total, beam, and diffuse solar radiation incident on each - surface (Wh/m2) -
      • -

    -

    - Hourly Outputs -

    -

    - The following outputs are provided for each hour of the days - specified for each test case in Table 3: + The input m_flow_turbulent determines the location of + the regularization.

      -
    • Dry bulb temperature (°C) -
      • -
    • Relative humidity (%) -
      • -
    • Dewpoint temperature (°C) -
      • -
    • Humidity ratio (kg moisture/kg dry air) +
    • December 9, 2019, by Michael Wetter:
      + Added smooth(2, . ), similar to + AixLib.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp.
      + See #1240.
      • -
    • Wet bulb temperature (°C) +
    • January 4, 2019, by Michael Wetter:
      + Set `Inline=false`.
      + See #1070.
      • -
    • Windspeed (m/s) +
    • May 1, 2017, by Filip Jorissen:
      + Revised implementation such that + AixLib.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow is + C2 continuous. See #725.
      • -
    • Wind direction (degrees from north) +
    • January 22, 2016, by Michael Wetter:
      + Corrected type declaration of pressure difference. This is for + #404.
      • -
    • Station pressure (mbar) +
    • July 28, 2015, by Michael Wetter:
      + Removed double declaration of smooth(..) and + smoothOrder and changed Inline=true to + LateInline=true. This is for issue 301.
      • -
    • Total cloud cover (tenths of sky) +
    • July 15, 2015, by Filip Jorissen:
      + New, more efficient implementation based on regularisation using + simple polynomial. Expanded common subexpressions for function + inlining to be possible. Set Inline=true for inlining + to occur. This is for #279.
      • -
    • Opaque cloud cover (tenths of sky) +
    • August 10, 2011, by Michael Wetter:
      + Removed if-then optimization that set + dp=0 if m_flow=0, as this causes the + derivative to be discontinuous at m_flow=0.
      • -
    • Sky temperature (°C) +
    • August 4, 2011, by Michael Wetter:
      + Removed option to use a linear function. The linear implementation + is now done in models that call this function. With the previous + implementation, the symbolic processor may not rearrange the + equations, which can lead to coupled equations instead of an + explicit solution.
      • -
    • Sum of total, beam, and diffuse solar radiation incident on each - surface (Wh/m2)  -
      • -

    -

    - Table 3: Specific Days for Output -

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    -

    - Case -

    -     		-

    - Days -

    -
    -

    - WD100 -

    -     		-

    - May 4th, July 14th, September 6th -

    -
    -

    - WD200 -

    -     		-

    - May 24th, August 26th -

    -
    -

    - WD300 -

    -     		-

    - February 7th, August 13th -

    -
    -

    - WD400 -

    -     		-

    - January 24th, July 1st -

    -
    -

    - WD500 -

    -     		-

    - March 1st, September 14th -

    -
    -

    - WD600 -

    -     		-

    - May 4th, July 14th, September 6th -

    -

    -

    - Sub-hourly Outputs -

    -

    - The following outputs are provided at each timestep of the days - specified for each test case in Table 3: -

    -
      -
    • Dry bulb temperature (C) -
      • -
    • Relative humidity (%) -
      • -
    • Sum of total, beam, and diffuse solar radiation incident on each - surface (Wh/m2) -
      • -
    -

    - The following outputs are provided integrated hourly for the days - specified for each test case in Table 3: -

    -
      -
    • Total incident horizontal solar radiation (Wh/m2) -
      • -
    • Total incident horizontal beam solar radiation (Wh/m2) -
      • -
    • Total incident horizontal diffuse solar radiation (Wh/m2) -
      • -
    -

    - Validation results -

    -

    - (Not available yet) -

    -

    - Implementation -

    -

    - To generate the data shown in this user guide, run -

    -
    -cd AixLib/Resources/Data/BoundaryConditions/Validation/BESTEST
-python3 generateResults.py -p
-
    -

    - At the beginning of the Python script there are several options that - the user can choose, by default the script will: -

    -
      -
    • Clone the last master branch of the AixLib repository into a - temporary directory -
      • -
    • Execute all the simulations and create the folders with the .mat - and .json files inside the BESTEST/Simulations folder -
      • -
    -

    - References -

    -

    - (Not available yet) -

    -
      -
    • March 11, 2020, by Ettore Zanetti:
      - first implementation of BESTEST weather validation +
    • April 13, 2009, by Michael Wetter:
      + First implementation.
    -------- Errors -------- -line 14 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 -line 98 column 1 - Warning: The summary attribute on the
    element is obsolete in HTML5 +line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/LoadAggregation/Validation/ShiftAggregationCells.mo ---- +---- AixLib/Fluid/Sensors/LatentEnthalpyFlowRate.mo ---- -------- HTML Code --------

    - This validation case replicates the load-shifting procedure illustred in the figure below by Cimmino (2014). + This model outputs the latent enthalphy flow rate of the medium in the flow + between its fluid ports. In particular, if the total enthalpy flow rate is

    -

    - \"image\" +

    + Ḣtot = Ḣsen + Ḣlat,

    -

    References

    - Cimmino, M. 2014. Développement et validation expérimentale de facteurs de réponse - thermique pour champs de puits géothermiques, - Ph.D. Thesis, École Polytechnique de Montréal. + where + Ḣsen = ṁ (1-Xw) cp,air, + then this sensor outputs Ḣ = Ḣlat.

    - -
      -
    • - July 18, 2018, by Alex Laferrière:
      - First implementation. -
      • -
    - --------- Corrected Code -------- -

    - This validation case replicates the load-shifting procedure illustred - in the figure below by Cimmino (2014). -

    -

    - \"image\" -

    -

    - References -

    -

    - Cimmino, M. 2014. Développement et validation expérimentale de - facteurs de réponse thermique pour champs de puits géothermiques, - Ph.D. Thesis, École Polytechnique de Montréal. -

    -
      -
    • July 18, 2018, by Alex Laferrière:
      - First implementation. -
      • -
    - --------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Controls/Continuous/Examples/OffTimer.mo ---- --------- HTML Code -------- -

    - Example that demonstrates the use of the model - - AixLib.Controls.Continuous.OffTimer. - The input to the two timers are alternating boolean values. - Whenever the input becomes false(=0), the timer is reset. - The figures below show the input and output of the blocks. + If the parameter tau is non-zero, then the measured + specific latent enthalpy hout that is used to + compute the latent enthalpy flow rate + Ḣlat = ṁ hout + is computed using a first order differential equation. + See + AixLib.Fluid.Sensors.UsersGuide for an explanation.

    -

    - \"Input
    - \"Input +

    + For a sensor that measures + Ḣtot, use + + AixLib.Fluid.Sensors.EnthalpyFlowRate.
    + For a sensor that measures + Ḣsen, use + + AixLib.Fluid.Sensors.SensibleEnthalpyFlowRate. +

    +

    + The sensor is ideal, i.e., it does not influence the fluid. + The sensor can only be used with medium models that implement the function + enthalpyOfNonCondensingGas(T).

    • - November 21, 2011, by Michael Wetter:
      - Added documentation. + October 19, 2020, by Antoine Gautier:
      + Changed default value for tau from 1 to 0.
      + This is for + #1406.
      • -
    - --------- Corrected Code -------- -

    - Example that demonstrates the use of the model AixLib.Controls.Continuous.OffTimer. - The input to the two timers are alternating boolean values. Whenever - the input becomes false(=0), the timer is reset. The - figures below show the input and output of the blocks. -

    -

    - \"Input
    - \"Input -

    -
      -
    • November 21, 2011, by Michael Wetter:
      - Added documentation. -
      • -
    - --------- Errors -------- -line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Sources/Outside_CpLowRise.mo ---- --------- HTML Code -------- - -

    - This model describes boundary conditions for - pressure, enthalpy, and species concentration that can be obtained - from weather data. The model is identical to - - AixLib.Fluid.Sources.Outside, - except that it adds the wind pressure to the - pressure at the fluid port ports. - The correlation that is used to compute the wind pressure is based - on Swami and Chandra (1987) and valid for low-rise buildings - with rectangular shape. - The same correlation is also implemented in CONTAM (Persily and Ivy, 2001). - -

    -

    - The wind pressure coefficient is computed based on the - side ratio of the walls, which is defined as -

    -

    - s = x ⁄ y -

    -

    - where x is the length of the wall that will be connected to - this model, and y is the length of the adjacent wall. - The wind direction is computed relative to the azimuth of this surface, - which is equal to the parameter azi. - The surface azimuth is defined in - - AixLib.Types.Azimuth. - For example, if an exterior wall is South oriented, i.e., its outside-facing - surface is towards South, use - AixLib.Types.Azimuth.S. -

    -

    - Based on the surface azimuth, the wind direction and the side ratio - of the walls, the model computes how much the wind pressure - is attenuated compared to the reference wind pressure Cp0. - The reference wind pressure Cp0 is a user-defined parameter, - and must be equal to the wind pressure at zero wind incidence angle. - Swami and Chandra (1987) recommend Cp0 = 0.6 for - all low-rise buildings as this represents the average of - various values reported in the literature. - The computation of the actual wind pressure coefficient Cp - is explained in the function - - Buildings.Airflow.Multizone.BaseClasses.windPressureLowRise - that is called by this model. -

    -

    - The pressure p at the port ports is computed as -

    -

    - p = pw + Cp 1 ⁄ 2 v2 ρ, -

    -

    - where - pw is the atmospheric pressure from the weather bus, - v is the wind speed from the weather bus, and - ρ is the fluid density. -

    - -

    - This model differs from - AixLib.Fluid.Sources.Outside_CpData by the calculation of the wind pressure coefficient Cp,act. - The wind pressure coefficient is defined by an equation in stead of a user-defined table. - This model is only suited for low-rise rectangular buildings. -

    - -

    References

    - - -
    • - February 2, 2022, by Michael Wetter:
      - Revised implementation.
      - This is for - IBPSA, #1436. + September 10, 2013, by Michael Wetter:
      + Changed medium declaration in the extends statement + to replaceable to avoid a translation error in + OpenModelica.
    • - Jun 28, 2021, by Klaas De Jonge:
      - Documentation changes to explain the difference with - AixLib.Fluid.Sources.Outside_CpData. + August 31, 2013, by Michael Wetter:
      + Removed default value tau=0 as the base class + already sets tau=1. + This change was made so that all sensors use the same default value.
    • - January 26, 2016, by Michael Wetter:
      - Added unit and quantity attributes. + December 18, 2012, by Michael Wetter:
      + Moved computation of i_w to new base class + + AixLib.Fluid.BaseClasses.IndexWater. + The value of this parameter is now assigned dynamically and does not require to be specified + by the user.
    • - October 26, 2011 by Michael Wetter:
      + November 3, 2011, by Michael Wetter:
      + Moved der(h_out) := 0; from the initial algorithm section to + the initial equation section + as this assignment does not conform to the Modelica specification. +
      • +
    • + August 10, 2011 by Michael Wetter:
      + Added parameter i_w and an assert statement to + make sure it is set correctly. Without this change, Dymola + cannot differentiate the model when reducing the index of the DAE. +
      • +
    • + June 3, 2011 by Michael Wetter:
      + Revised implementation to add dynamics in such a way that + the time constant increases as the mass flow rate tends to zero. + This can improve the numerics. +
      • +
    • + February 22, by Michael Wetter:
      + Improved code that searches for index of 'water' in medium model. +
      • +
    • + September 9, 2009 by Michael Wetter:
      First implementation. + Implementation is based on enthalpy sensor of Modelica.Fluid.
    -------- Corrected Code --------

    - This model describes boundary conditions for pressure, enthalpy, and - species concentration that can be obtained from weather data. The - model is identical to AixLib.Fluid.Sources.Outside, - except that it adds the wind pressure to the pressure at the fluid - port ports. The correlation that is used to compute the - wind pressure is based on Swami and Chandra (1987) and valid for - low-rise buildings with rectangular shape. The same correlation is - also implemented in CONTAM (Persily and Ivy, 2001). - -

    -

    - The wind pressure coefficient is computed based on the side ratio of - the walls, which is defined as + This model outputs the latent enthalphy flow rate of the + medium in the flow between its fluid ports. In particular, if the + total enthalpy flow rate is

    - s = x ⁄ y + Ḣtot = Ḣsen + Ḣlat,

    - where x is the length of the wall that will be connected to - this model, and y is the length of the adjacent wall. The wind - direction is computed relative to the azimuth of this surface, which - is equal to the parameter azi. The surface azimuth is - defined in AixLib.Types.Azimuth. For - example, if an exterior wall is South oriented, i.e., its - outside-facing surface is towards South, use - AixLib.Types.Azimuth.S. + where Ḣsen = ṁ (1-Xw) + cp,air, then this sensor outputs Ḣ = + Ḣlat.

    - Based on the surface azimuth, the wind direction and the side ratio - of the walls, the model computes how much the wind pressure is - attenuated compared to the reference wind pressure Cp0. - The reference wind pressure Cp0 is a user-defined - parameter, and must be equal to the wind pressure at zero wind - incidence angle. Swami and Chandra (1987) recommend Cp0 - = 0.6 for all low-rise buildings as this represents the average - of various values reported in the literature. The computation of the - actual wind pressure coefficient Cp is explained in - the function - Buildings.Airflow.Multizone.BaseClasses.windPressureLowRise that - is called by this model. + If the parameter tau is non-zero, then the measured + specific latent enthalpy hout that is used to + compute the latent enthalpy flow rate Ḣlat = ṁ + hout is computed using a first order differential + equation. See AixLib.Fluid.Sensors.UsersGuide + for an explanation.

    - The pressure p at the port ports is computed as -

    -

    - p = pw + Cp 1 ⁄ 2 v2 ρ, + For a sensor that measures Ḣtot, use AixLib.Fluid.Sensors.EnthalpyFlowRate.
    + + For a sensor that measures Ḣsen, use AixLib.Fluid.Sensors.SensibleEnthalpyFlowRate.

    - where pw is the atmospheric pressure from the - weather bus, v is the wind speed from the weather bus, and - ρ is the fluid density. + The sensor is ideal, i.e., it does not influence the fluid. The + sensor can only be used with medium models that implement the + function enthalpyOfNonCondensingGas(T).

    -

    - This model differs from AixLib.Fluid.Sources.Outside_CpData - by the calculation of the wind pressure coefficient - Cp,act. The wind pressure coefficient is defined by an - equation in stead of a user-defined table. This model is only suited - for low-rise rectangular buildings. -

    -

    - References -

    -
      -
    • February 2, 2022, by Michael Wetter:
      - Revised implementation.
      +
    • February 25, 2020, by Michael Wetter:
      + Changed icon to display its operating state.
      This is for IBPSA, - #1436. + \"https://github.com/ibpsa/modelica-ibpsa/issues/1294\">#1294.
      • -
    • Jun 28, 2021, by Klaas De Jonge:
      - Documentation changes to explain the difference with AixLib.Fluid.Sources.Outside_CpData. +
    • January 18, 2016 by Filip Jorissen:
      + Using parameter tauInv since this now exists in + + AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. This + is for #372.
      • -
    • January 26, 2016, by Michael Wetter:
      - Added unit and quantity attributes. +
    • September 10, 2013, by Michael Wetter:
      + Changed medium declaration in the extends statement to + replaceable to avoid a translation error in + OpenModelica.
      • -
    • October 26, 2011 by Michael Wetter:
      - First implementation. +
    • August 31, 2013, by Michael Wetter:
      + Removed default value tau=0 as the base class already + sets tau=1. This change was made so that all sensors + use the same default value. +
      • +
    • December 18, 2012, by Michael Wetter:
      + Moved computation of i_w to new base class AixLib.Fluid.BaseClasses.IndexWater. + The value of this parameter is now assigned dynamically and does + not require to be specified by the user. +
      • +
    • November 3, 2011, by Michael Wetter:
      + Moved der(h_out) := 0; from the initial algorithm + section to the initial equation section as this assignment does not + conform to the Modelica specification. +
      • +
    • August 10, 2011 by Michael Wetter:
      + Added parameter i_w and an assert statement to make + sure it is set correctly. Without this change, Dymola cannot + differentiate the model when reducing the index of the DAE. +
      • +
    • June 3, 2011 by Michael Wetter:
      + Revised implementation to add dynamics in such a way that the time + constant increases as the mass flow rate tends to zero. This can + improve the numerics. +
      • +
    • February 22, by Michael Wetter:
      + Improved code that searches for index of 'water' in medium model. +
      • +
    • September 9, 2009 by Michael Wetter:
      + First implementation. Implementation is based on enthalpy sensor of + Modelica.Fluid.
    -------- Errors -------- -line 28 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 61 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/FMI/Adaptors/HVAC.mo ---- +---- AixLib/Controls/Discrete/BooleanDelay.mo ---- -------- HTML Code --------

    - The (time varying) vector Real output signal of this block can be defined in its - parameter menu via variable y. The purpose is to support the - easy definition of vector-valued Real expressions in a block diagram. -

    - -

    - Adaptor that can be used to connect an HVAC system (with acausal ports) - to input/output signals, which then can be exposed in an FMI interface. -

    -

    - The adaptor has a vector of fluid ports called ports. - The supply and return air ducts need to be connected to these ports. - Also, if a thermal zone has interzonal air exchange or air infiltration, - these flow paths also need be connected to ports. -

    -

    - This model outputs at the port fluPor the mass flow rate for - each flow that is connected to ports, together with its - temperature, water vapor mass fraction per total mass of the air (not per kg dry - air), and trace substances. These quantities are always as if the flow - enters the room, even if the flow is zero or negative. - If a medium has no moisture, e.g., if Medium.nXi=0, or - if it has no trace substances, e.g., if Medium.nC=0, then - the output signal for these properties are removed. - These quantities are always as if the flow - enters the room, even if the flow is zero or negative. - Thus, a thermal zone model that uses these signals to compute the - heat added by the HVAC system need to implement an equation such as + Block that delays the boolean input signal by + one sampling interval. + For example, + if u denotes the input, + y denotes the output, and + ti and ti+1 + denote subsequent sampling + instants, then the model outputs

    - Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), -

    -

    - where - Qsen is the sensible heat flow rate added to the thermal zone, - ṁsup is the supply air mass flow rate from - the port fluPor (which is negative if it is an exhaust), - cp is the specific heat capacity at constant pressure, - Tsup is the supply air temperature and - Tair,zon is the zone air temperature. - Note that without the max(·, ·) function, the energy - balance would be wrong. -

    -

    - The output signals of this model are the zone air temperature, - the water vapor mass fraction per total mass of the air (unless Medium.nXi=0) - and trace substances (unless Medium.nC=0). - These output connectors can be used to connect to a controller. - These values are obtained from the fluid stream(s) that flow into this component - at the port fluPor, e.g., from the connector - fluPor.backward. - Note that there are nPorts of these signals. - For a completely mixed room, they will all have the same value, but - for a room with non-uniform temperatures, they can have different values. -

    -

    Assumption and limitations

    -

    - The mass flow rates at ports sum to zero, hence this - model conserves mass. -

    -

    - This model does not impose any pressure, other than setting the pressure - of all fluid connections to ports to be equal. - The reason is that setting a pressure can lead to non-physical system models, - for example if a mass flow rate is imposed and the HVAC system is connected - to a model that sets a pressure boundary condition such as - - AixLib.Fluid.Sources.Outside. - Also, setting a pressure would make it impossible to use multiple instances - of this model (one for each thermal zone) and build in Modelica an airflow network - model with pressure driven mass flow rates. -

    -

    - The model has no pressure drop. Hence, the pressure drop - of an air diffuser or of an exhaust grill need to be modelled - in models that are connected to ports. -

    -

    Typical use and important parameters

    -

    - See - - AixLib.Fluid.FMI.ExportContainers.HVACZone - for a model that uses this model. + y(ti+1) = u(ti).

    • - January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air only. - See #1050. -
      • -
    • - September 13, 2017, by Michael Wetter:
      - Removed erroneous each. -
      • -
    • - October 4, 2016, by Michael Wetter:
      - Corrected assignment of quantity in CZon. + June 6, 2015, by Michael Wetter:
      + Set start value and fixed attribute + for firstTrigger + to avoid a translation warning in pedantic mode + in Dymola 2016. + This is for + #266.
    • - June 29, 2016, by Michael Wetter:
      - Revised implementation. + November 21, 2011, by Michael Wetter:
      + Improved documentation.
    • - April 14, 2016, by Michael Wetter:
      + November 26, 2008, by Michael Wetter:
      First implementation.
    -------- Corrected Code --------

    - The (time varying) vector Real output signal of this - block can be defined in its parameter menu via variable - y. The purpose is to support the easy definition of - vector-valued Real expressions in a block diagram. -

    -

    - Adaptor that can be used to connect an HVAC system (with acausal - ports) to input/output signals, which then can be exposed in an FMI - interface. -

    -

    - The adaptor has a vector of fluid ports called ports. - The supply and return air ducts need to be connected to these ports. - Also, if a thermal zone has interzonal air exchange or air - infiltration, these flow paths also need be connected to - ports. -

    -

    - This model outputs at the port fluPor the mass flow rate - for each flow that is connected to ports, together with - its temperature, water vapor mass fraction per total mass of the air - (not per kg dry air), and trace substances. These quantities are - always as if the flow enters the room, even if the flow is zero or - negative. If a medium has no moisture, e.g., if - Medium.nXi=0, or if it has no trace substances, e.g., if - Medium.nC=0, then the output signal for these properties - are removed. These quantities are always as if the flow enters the - room, even if the flow is zero or negative. Thus, a thermal zone - model that uses these signals to compute the heat added by the HVAC - system need to implement an equation such as + Block that delays the boolean input signal by one sampling interval. + For example, if u denotes the input, y denotes the + output, and ti and ti+1 denote + subsequent sampling instants, then the model outputs

    - Qsen = max(0, ṁsup)   cp   - (Tsup - Tair,zon), -

    -

    - where Qsen is the sensible heat flow rate added to - the thermal zone, ṁsup is the supply air mass flow - rate from the port fluPor (which is negative if it is an - exhaust), cp is the specific heat capacity at - constant pressure, Tsup is the supply air - temperature and Tair,zon is the zone air - temperature. Note that without the max(·, ·) function, the - energy balance would be wrong. -

    -

    - The output signals of this model are the zone air temperature, the - water vapor mass fraction per total mass of the air (unless - Medium.nXi=0) and trace substances (unless - Medium.nC=0). These output connectors can be used to - connect to a controller. These values are obtained from the fluid - stream(s) that flow into this component at the port - fluPor, e.g., from the connector - fluPor.backward. Note that there are nPorts - of these signals. For a completely mixed room, they will all have the - same value, but for a room with non-uniform temperatures, they can - have different values. -

    -

    - Assumption and limitations -

    -

    - The mass flow rates at ports sum to zero, hence this - model conserves mass. -

    -

    - This model does not impose any pressure, other than setting the - pressure of all fluid connections to ports to be equal. - The reason is that setting a pressure can lead to non-physical system - models, for example if a mass flow rate is imposed and the HVAC - system is connected to a model that sets a pressure boundary - condition such as AixLib.Fluid.Sources.Outside. - Also, setting a pressure would make it impossible to use multiple - instances of this model (one for each thermal zone) and build in - Modelica an airflow network model with pressure driven mass flow - rates. -

    -

    - The model has no pressure drop. Hence, the pressure drop of an air - diffuser or of an exhaust grill need to be modelled in models that - are connected to ports. -

    -

    - Typical use and important parameters -

    -

    - See AixLib.Fluid.FMI.ExportContainers.HVACZone - for a model that uses this model. + y(ti+1) = u(ti).

      -
    • January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air only. See #1050. -
      • -
    • September 13, 2017, by Michael Wetter:
      - Removed erroneous each. -
      • -
    • October 4, 2016, by Michael Wetter:
      - Corrected assignment of quantity in CZon. +
    • June 6, 2015, by Michael Wetter:
      + Set start value and fixed attribute for + firstTrigger to avoid a translation warning in + pedantic mode in Dymola 2016. This is for #266.
      • -
    • June 29, 2016, by Michael Wetter:
      - Revised implementation. +
    • November 21, 2011, by Michael Wetter:
      + Improved documentation.
      • -
    • April 14, 2016, by Michael Wetter:
      +
    • November 26, 2008, by Michael Wetter:
      First implementation.
    -------- Errors -------- -line 26 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Actuators/Valves/Examples/TwoWayValveTable.mo ---- +---- AixLib/Media/Antifreeze/EthyleneGlycolWater.mo ---- -------- HTML Code -------- +

    + This base properties model is identical to + + Modelica.Media.Water.ConstantPropertyLiquidWater, + except that the equation + u = cv_const*(T - reference_T) + has been replaced by u=h because + cp_const=cv_const. + Also, the model checks if the mass fraction of the mixture is within the + allowed limits. +

    + +

    + Density of propylene antifreeze-water mixture at specified mass fraction + and temperature, based on Melinder (2010). +

    +

    References

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF. +

    + + +

    - Test model for a two way valve in which a table is used to specify the - opening characteristics. - The valve has the following opening characteristics, which is taken from a test case - of the IEA EBC Annex 60 project. + Dynamic viscosity of antifreeze-water mixture at specified mass fraction and + temperature, based on Melinder (2010).

    -
    - - - - - -
    y0 0.1667 0.3333 0.5 0.6667 1
    Kv0 0.19 0.35 0.45 0.5 0.65
    +

    References

    - The Kv value is the volume flow rate in m3/h at a pressure difference - of 1 bar. - Hence, the Kv value of the fully open valve is Kv=0.65. + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    + + +

    - Plotting the variables kv.y versus y.y shows that the valve - reproduces the Kv values shown in the above table. + Fusion temperature of antifreeze-water mixture at specified mass fraction and + temperature, based on Melinder (2010).

    -

    - \"image\" +

    References

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF. +

    + + + +

    + Evaluates a thermophysical property of a mixture, based on correlations proposed + by Melinder (2010).

    - The parameter filterOpening is set to false, - as this model is used to plot the flow at different opening signals - without taking into account the travel time of the actuator. + The polynomial has the form +

    +

    + f = a1 (x-xm)0(y-ym)0 + + a2 (x-xm)0(y-ym)1 + + ... + + any[1] (x-xm)0(y-ym)ny[1]-1 + + ... + + any[1])+1 (x-xm)1(y-ym)0 + + ... + + any[1]+ny[2] (x-xm)1(y-ym)ny[2]-1 + + ... +

    +

    References

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    • - August 12, 2014 by Michael Wetter:
      - Added parameter keyword to datVal, - as this is needed to asssign datVal to a parameter - in the instance valTab. - This also avoids an error in OpenModelica. + March 16, 2018 by Massimo Cimmino:
      + First implementation. + This function is used models in + + AixLib.Media.Antifreeze.
      • +
    + +

    + Specific heat capacity of antifreeze-water mixture at specified mass fraction + and temperature, based on Melinder (2010). +

    +

    References

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF. +

    + + --------- Corrected Code -------- -

    - Test model for a two way valve in which a table is used to specify - the opening characteristics. The valve has the following opening - characteristics, which is taken from a test case of the IEA EBC Annex - 60 project. -

    - - - - - - - - - - - - - - - - - - - -
    - y - - 0 - - 0.1667 - - 0.3333 - - 0.5 - - 0.6667 - - 1 -
    - Kv - - 0 - - 0.19 - - 0.35 - - 0.45 - - 0.5 - - 0.65 -
    -

    - The Kv value is the volume flow rate in - m3/h at a pressure difference of 1 bar. Hence, the - Kv value of the fully open valve is - Kv=0.65. -

    -

    - Plotting the variables kv.y versus y.y - shows that the valve reproduces the Kv values shown - in the above table. -

    -

    - \"image\" -

    -

    - The parameter filterOpening is set to - false, as this model is used to plot the flow at - different opening signals without taking into account the travel time - of the actuator. -

    -
      -
    • August 12, 2014 by Michael Wetter:
      - Added parameter keyword to datVal, as - this is needed to asssign datVal to a parameter in the - instance valTab. This also avoids an error in - OpenModelica. -
      • -
    • April 2, 2014 by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 8 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 -line 24 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/FixedResistances/Validation/PlugFlowPipes/MSLAIT2Nodes.mo ---- --------- HTML Code -------- - -

    The example contains - - experimental data from a real district heating network. - This data is used to validate this library's - plug flow pipe model - in - AixLib.Fluid.FixedResistances.Validation.PlugFlowPipes.PlugFlowAIT. +

    + Thermal conductivity of antifreeze-water mixture at specified mass fraction and + temperature, based on Melinder (2010).

    +

    References

    - Note that these three models are identical, except for the pipe model that is used: + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    + +

    - This comparison between different discretization levels and pipe models is made - to check the influence of the discretization and pipe model on computation time - and simulation accuracy. + This medium package models ethylene glycol - water mixtures.

    -

    The pipes' temperatures are not initialized, thus results of outflow temperature - before approximately the first 10000 seconds should not be considered. +

    + The mass density, specific heat capacity, thermal conductivity and viscosity + are assumed constant and evaluated at a set temperature and mass fraction of + ethylene glycol within the mixture. The dependence of the four properties + are shown on the figure below. +

    +

    + \"Relative

    -

    Test bench schematic

    -

    \"Schematic

    -

    Calibration

    - To calculate the length specific thermal resistance R of the pipe, - the thermal resistance of the surrounding ground is added. + The accuracy of the thermophysical properties is dependent on the temperature + variations encountered during simulations. + The figure below shows the relative error of the the four properties over a + 10 °C range around the temperature used to evaluate the constant + properties. The maximum errors are 0.8 % for mass density, 2.7 % + for specific heat capacity, 3.2 % for thermal conductivity and 160 + % for dynamic viscosity.

    -

    - R=1/(0.208)+1/(2   lambdag Modelica.Constants.pi)   log(1/0.18) +

    + \"Relative

    - Where the thermal conductivity of the ground lambda_g = 2.4 W/(m K). + The figure below shows the relative error of the the four properties over a + 20 °C range around the temperature used to evaluate the constant + proepties. The maximum errors are 1.5 % for mass density, 5.3 % + for specific heat capacity, 5.9 % for thermal conductivity and 500 + % for dynamic viscosity. +

    +

    + \"Relative +

    +

    + The enthalpy is computed using the convention that h=0 + if T=0 °C. +

    +

    Limitations

    +

    + Density, specific heat capacity, thermal conductivity and viscosity are constant. + The ethylene glycol/water mixture is modeled as an incompressible liquid. + There are no phase changes. The medium is limited to temperatures below + 100 °C and mass fractions below 0.60. + As is the case for AixLib.Media.Water, + this medium package should not be used if + the simulation relies on the dynamic viscosity. +

    +

    Typical use and important parameters

    +

    + The temperature and mass fraction must be specified for the evaluation of the + constant thermophysical properties. A typical use of the package is (e.g. for + a temperature of 20 °C and a mass fraction of 0.40): +

    +

    + Medium = AixLib.Media.Antifreeze.EthyleneGlycolWater(property_T=293.15, X_a=0.40)

    • - March 7, 2020, by Michael Wetter:
      - Replaced measured data from specification in Modelica file to external table, - as this reduces the computing time.
      - This is for - #1289. -
      • -
    • - May 15, 2019, by Jianjun Hu:
      - Replaced fluid source. This is for - #1072. -
      • -
    • November 28, 2016 by Bram van der Heijde:
      Remove pipVol. -
      • -
    • - August 24, 2016 by Bram van der Heijde:
      - Implement validation with MSL pipes for comparison, based on AIT validation. -
      • -
    • - July 4, 2016 by Bram van der Heijde:
      Added parameters to test the - influence of allowFlowReversal and the presence of explicit volumes in the pipe. + August 05, 2020, by Wen HU:
      + First implementation.
      • -
    • January 26, 2016 by Carles Ribas:
      First implementation.
    -------- Corrected Code --------

    - The example contains - experimental data from a real district heating network. This data - is used to validate this library's plug flow - pipe model in - AixLib.Fluid.FixedResistances.Validation.PlugFlowPipes.PlugFlowAIT. + This base properties model is identical to Modelica.Media.Water.ConstantPropertyLiquidWater, + except that the equation u = cv_const*(T - reference_T) + has been replaced by u=h because + cp_const=cv_const. Also, the model checks if the mass + fraction of the mixture is within the allowed limits.

    - Note that these three models are identical, except for the pipe model - that is used: + Density of propylene antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010). +

    +

    + References +

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

    - This comparison between different discretization levels and pipe - models is made to check the influence of the discretization and pipe - model on computation time and simulation accuracy. -

    -

    - The pipes' temperatures are not initialized, thus results of outflow - temperature before approximately the first 10000 seconds should not - be considered. + Dynamic viscosity of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010).

    - Test bench schematic + References

    - \"Schematic + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF. +

    + +

    + Fusion temperature of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010).

    - Calibration + References

    - To calculate the length specific thermal resistance R of - the pipe, the thermal resistance of the surrounding ground is added. -

    -

    - R=1/(0.208)+1/(2   lambdag Modelica.Constants.pi) -   log(1/0.18) + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

    +

    - Where the thermal conductivity of the ground lambda_g = - 2.4 W/(m K). + Evaluates a thermophysical property of a mixture, based on + correlations proposed by Melinder (2010). +

    +

    + The polynomial has the form +

    +

    + f = a1 (x-xm)0(y-ym)0 + + a2 (x-xm)0(y-ym)1 + ... + + any[1] (x-xm)0(y-ym)ny[1]-1 + ... + + any[1])+1 (x-xm)1(y-ym)0 + ... + + any[1]+ny[2] (x-xm)1(y-ym)ny[2]-1 + + ... +

    +

    + References +

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

      -
    • March 7, 2020, by Michael Wetter:
      - Replaced measured data from specification in Modelica file to - external table, as this reduces the computing time.
      - This is for #1289. -
      • -
    • May 15, 2019, by Jianjun Hu:
      - Replaced fluid source. This is for #1072. -
      • -
    • November 28, 2016 by Bram van der Heijde:
      - Remove pipVol. +
    • March 16, 2018 by Massimo Cimmino:
      + First implementation. This function is used models in AixLib.Media.Antifreeze.
      • -
    • August 24, 2016 by Bram van der Heijde:
      - Implement validation with MSL pipes for comparison, based on AIT - validation. +
    +

    + Specific heat capacity of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010). +

    +

    + References +

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF. +

    +
      +
    • March 16, 2018 by Massimo Cimmino:
      + First implementation. This function is used by AixLib.Media.Antifreeze.EthyleneGlycolWater.
      • -
    • July 4, 2016 by Bram van der Heijde:
      - Added parameters to test the influence of allowFlowReversal and the - presence of explicit volumes in the pipe. +
    +

    + Thermal conductivity of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010). +

    +

    + References +

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF. +

    + +

    + This medium package models ethylene glycol - water mixtures. +

    +

    + The mass density, specific heat capacity, thermal conductivity and + viscosity are assumed constant and evaluated at a set temperature and + mass fraction of ethylene glycol within the mixture. The dependence + of the four properties are shown on the figure below. +

    +

    + + +

    +

    + The accuracy of the thermophysical properties is dependent on the + temperature variations encountered during simulations. The figure + below shows the relative error of the the four properties over a + 10 °C range around the temperature used to evaluate the + constant properties. The maximum errors are 0.8 % for mass + density, 2.7 % for specific heat capacity, 3.2 % for + thermal conductivity and 160 % for dynamic viscosity. +

    +

    + + +

    +

    + The figure below shows the relative error of the the four properties + over a 20 °C range around the temperature used to evaluate the + constant proepties. The maximum errors are 1.5 % for mass + density, 5.3 % for specific heat capacity, 5.9 % for + thermal conductivity and 500 % for dynamic viscosity. +

    +

    + + +

    +

    + The enthalpy is computed using the convention that h=0 if + T=0 °C. +

    +

    + Limitations +

    +

    + Density, specific heat capacity, thermal conductivity and viscosity + are constant. The ethylene glycol/water mixture is modeled as an + incompressible liquid. There are no phase changes. The medium is + limited to temperatures below 100 °C and mass fractions below + 0.60. As is the case for AixLib.Media.Water, this medium + package should not be used if the simulation relies on the dynamic + viscosity. +

    +

    + Typical use and important parameters +

    +

    + The temperature and mass fraction must be specified for the + evaluation of the constant thermophysical properties. A typical use + of the package is (e.g. for a temperature of 20 °C and a mass + fraction of 0.40): +

    +

    + Medium = + AixLib.Media.Antifreeze.EthyleneGlycolWater(property_T=293.15, + X_a=0.40) +

    +
      +
    • August 05, 2020, by Wen HU:
      First implementation.
    -------- Errors -------- -line 51 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 9 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Media/Specialized/Water/TemperatureDependentDensity.mo ---- +line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 24 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 35 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/HeatPumps/ScrollWaterToWater.mo ---- -------- HTML Code -------- -

    - Base properties of the medium. -

    -

    - This function computes the density as a function of temperature. + Model for a water to water heat pump with a scroll compressor, as described + in Jin (2002). The thermodynamic heat pump cycle is represented below.

    -

    Implementation

    -

    - The function is based on the IDA implementation in therpro.nmf, which - implements +

    + \"image\"

    - 
    - d := 1000.12 + 1.43711e-2*T_degC -
-  5.83576e-3*T_degC^2 + 1.5009e-5*T_degC^3;
-

    - This has been converted to Kelvin, which resulted in the above expression. - In addition, below 5 °C and above 100 °C, the density is replaced - by a linear function to avoid inflection points. - This linear extension is such that the density is once continuously differentiable. + The rate of heat transferred to the evaporator is given by:

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation, based on the IDA implementation in therpro.nmf, - but converted from Celsius to Kelvin and linearly extended. -
      • -
    - -

    - This function computes the dynamic viscosity. +

    + Q̇Eva = ṁref ( hVap(TEva) - hLiq(TCon) ).

    - -
      -
    • - December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the specific enthalpy. + The power consumed by the compressor is given by a linear efficiency relation:

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function computes the specific enthalpy of liquid water. +

    + P = PTheoretical / η + PLoss,constant.

    - -
      -
    • - December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the specific internal energy. + Heat transfer in the evaporator and condenser is calculated using an + ε-NTU method, assuming constant refrigerant temperature and constant heat + transfer coefficient between fluid and refrigerant.

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the specific entropy. + Variable speed is achieved by multiplying the full load suction volume flow rate + by the normalized compressor speed. The power and heat transfer rates are forced + to zero if the resulting heat pump state has higher evaporating pressure than + condensing pressure.

    - To obtain the state for a given pressure, entropy and mass fraction, use - - AixLib.Media.Air.setState_psX. + The model parameters are obtained by calibration of the heat pump model to + manufacturer performance data. Calibrated model parameters for various heat + pumps from different manufacturers are found in + + AixLib.Fluid.HeatPumps.Data.ScrollWaterToWater. The calibrated model is + located in + + AixLib.Fluid.HeatPumps.Calibration.ScrollWaterToWater.

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - +

    Options

    - This function computes the specific Gibbs energy. + Parameters TConMax and TEvaMin + may be used to set an upper or lower bound for the + condenser and evaporator. + The compressor is disabled when these conditions + are not satisfied, or when the + evaporator temperature is larger + than the condenser temperature. + This mimics the temperature protection + of heat pumps and moreover it avoids + non-converging algebraic loops of equations, + or freezing of evaporator medium. + This option can be disabled by setting + enable_temperature_protection = false.

    - -
      -
    • - December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - +

    Assumptions and limitations

    - This function computes the specific Helmholtz energy. + The compression process is assumed isentropic. The thermal energy + of superheating is ignored in the evaluation of the heat transferred to the refrigerant + in the evaporator. There is no supercooling.

    - -
      -
    • - December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - +

    References

    - This function computes the specific enthalpy for - an isentropic state change from the temperature - that corresponds to the state refState - to reference_T. + H. Jin. + + Parameter estimation based models of water source heat pumps. + + PhD Thesis. Oklahoma State University. Stillwater, Oklahoma, USA. 2002.

    • - December 18, 2013, by Michael Wetter:
      + May 30, 2017, by Filip Jorissen:
      + Revised documentation for temperature protection. + See #769. +
      • +
    • + November 11, 2016, by Massimo Cimmino:
      First implementation.
    +-------- Corrected Code -------- +

    + Model for a water to water heat pump with a scroll compressor, as + described in Jin (2002). The thermodynamic heat pump cycle is + represented below. +

    +

    + \"image\" +

    +

    + The rate of heat transferred to the evaporator is given by: +

    +

    + Q̇Eva = ṁref ( + hVap(TEva) - hLiq(TCon) + ). +

    +

    + The power consumed by the compressor is given by a linear efficiency + relation: +

    +

    + P = PTheoretical / η + PLoss,constant. +

    +

    + Heat transfer in the evaporator and condenser is calculated using an + ε-NTU method, assuming constant refrigerant temperature and constant + heat transfer coefficient between fluid and refrigerant. +

    +

    + Variable speed is achieved by multiplying the full load suction + volume flow rate by the normalized compressor speed. The power and + heat transfer rates are forced to zero if the resulting heat pump + state has higher evaporating pressure than condensing pressure. +

    +

    + The model parameters are obtained by calibration of the heat pump + model to manufacturer performance data. Calibrated model parameters + for various heat pumps from different manufacturers are found in + AixLib.Fluid.HeatPumps.Data.ScrollWaterToWater. + The calibrated model is located in AixLib.Fluid.HeatPumps.Calibration.ScrollWaterToWater. +

    +

    + Options +

    +

    + Parameters TConMax and TEvaMin may be used + to set an upper or lower bound for the condenser and evaporator. The + compressor is disabled when these conditions are not satisfied, or + when the evaporator temperature is larger than the condenser + temperature. This mimics the temperature protection of heat pumps and + moreover it avoids non-converging algebraic loops of equations, or + freezing of evaporator medium. This option can be disabled by setting + enable_temperature_protection = false. +

    +

    + Assumptions and limitations +

    +

    + The compression process is assumed isentropic. The thermal energy of + superheating is ignored in the evaluation of the heat transferred to + the refrigerant in the evaporator. There is no supercooling. +

    +

    + References +

    +

    + H. Jin. Parameter estimation based models of water source heat + pumps. PhD Thesis. Oklahoma State University. Stillwater, + Oklahoma, USA. 2002. +

    +
      +
    • May 30, 2017, by Filip Jorissen:
      + Revised documentation for temperature protection. See #769. +
      • +
    • November 11, 2016, by Massimo Cimmino:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 18 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/FixedResistances/HydraulicDiameter.mo ---- +-------- HTML Code -------- +

    - This function returns the isobaric expansion coefficient, + This is a model of a flow resistance with a fixed flow coefficient. + The mass flow rate is computed as

    - βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p, + ṁ = k + √ΔP,

    where - v is the specific volume, - T is the temperature and - p is the pressure. + k is a constant and + ΔP is the pressure drop. + The constant k is equal to + k=m_flow_nominal/sqrt(dp_nominal), + where m_flow_nominal is a parameter.

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - +

    Assumptions

    - This function returns the isothermal compressibility coefficient, - which is zero as this medium is incompressible. - The isothermal compressibility is defined as + In the region + abs(m_flow) < m_flow_turbulent, + the square root is replaced by a differentiable function + with finite slope. + The value of m_flow_turbulent is + computed as + m_flow_turbulent = eta_nominal*dh/4*π*ReC, + where + eta_nominal is the dynamic viscosity, obtained from + the medium model. The parameter + dh is the hydraulic diameter and + ReC=4000 is the critical Reynolds number, which both + can be set by the user.

    -

    - κT = - 1 ⁄ v   (∂ v ⁄ ∂ p)T, +

    Important parameters

    +

    + By default, the pressure drop at nominal flow rate is computed as

    + 
    + dp_nominal = fac * dpStraightPipe_nominal,
+

    - where - v is the specific volume, - T is the temperature and - p is the pressure. + where dpStraightPipe_nominal is a parameter that is automatically computed + based on the + nominal mass flow rate, hydraulic diameter, pipe roughness and medium properties. + The hydraulic diameter dh is by default + computed based on the flow velocity v_nominal and the nominal + mass flow rate m_flow_nominal. Hence, users should change the + default values of dh or v_nominal + if they are not applicable for their model.

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the partial derivative of density - with respect to pressure at constant temperature, - which is zero as the medium is incompressible. + The factor fac takes into account additional resistances such as + for bends. The default value of 2 can be changed by the user.

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the derivative of density with respect to temperature - at constant pressure. + The parameter from_dp is used to determine + whether the mass flow rate is computed as a function of the + pressure drop (if from_dp=true), or vice versa. + This setting can affect the size of the nonlinear system of equations.

    - -
      -
    • - August 17, 2015, by Michael Wetter:
      - Removed dublicate entry of smooth and smoothOrder. - This is for - issue 303. -
      • -
    • - December 18, 2013, by Michael Wetter:
      - First implementation, based on the IDA implementation in therpro.nmf, - but converted from Celsius to Kelvin. -
      • -
    - -

    - This function returns the partial derivative of density - with respect to mass fraction, - which is zero as the medium is a single substance. -

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function returns the specific heat capacity at constant pressure. -

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function computes the specific heat capacity at constant volume. -

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function returns the thermal conductivity. - The expression is obtained from Ramires et al. (1995). -

    -

    References

    -

    - Ramires, Maria L. V. and Nieto de Castro, Carlos A. and Nagasaka, Yuchi - and Nagashima, Akira and Assael, Marc J. and Wakeham, William A. - Standard Reference Data for the Thermal Conductivity of Water. - Journal of Physical and Chemical Reference Data, 24, p. 1377-1381, 1995. - DOI:10.1063/1.555963. -

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function returns the pressure. -

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function returns the temperature. -

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the molar mass, - which is assumed to be constant. + If the parameter linearized is set to true, + then the pressure drop is computed as a linear function of the + mass flow rate.

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the thermodynamic state for a given pressure, - specific enthalpy and composition. + Setting allowFlowReversal=false can lead to simpler + equations. However, this should only be set to false + if one can guarantee that the flow never reverses its direction. + This can be difficult to guarantee, as pressure imbalance after + the initialization, or due to medium expansion and contraction, + can lead to reverse flow.

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the thermodynamic state for a given pressure, - temperature and composition. + If the parameter + show_T is set to true, + then the model will compute the + temperature at its ports. Note that this can lead to state events + when the mass flow rate approaches zero, + which can increase computing time.

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - +

    Notes

    - This function returns the thermodynamic state based on pressure, - specific entropy and mass fraction. + For more detailed models that compute the actual flow friction, + models from the package + + Modelica.Fluid + can be used and combined with models from the + AixLib library.

    - The state is computed by symbolically solving - - AixLib.Media.Specialized.Water.TemperatureDependentDensity.specificEntropy - for temperature. -

    - -
      -
    • - April 11, 2016 by Michael Wetter:
      - Corrected wrong hyperlink in documentation for - issue 450. -
      • -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function computes the derivative of the specific heat capacity - at constant pressure with respect to the state. + For a model that uses dp_nominal as a parameter rather than + geoemetric data, use + + AixLib.Fluid.FixedResistances.PressureDrop.

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - +

    Implementation

    - This function computes the temperature derivative of the enthalpy of liquid water - per unit mass. + The pressure drop is computed by calling a function in the package + + AixLib.Fluid.BaseClasses.FlowModels, + This package contains regularized implementations of the equation

    - -
      -
    • - December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This function computes the kinematic viscosity as a function of temperature. +

    + m = sign(Δp) k √ Δp  

    -

    Implementation

    - The function is based on the IDA implementation in therpro.nmf. - The original equation is + and its inverse function.

    - 
    - kinVis :=1E-6*Modelica.Math.exp(0.577449 - 3.253945e-2*T_degC + 2.17369e-4*
-       T_degC^2 - 7.22111e-7*T_degC^3);
-

    - This has been converted to Kelvin, which resulted in the above expression. - In addition, at 5 °C the kinematic viscosity is linearly extrapolated - to avoid a large gradient at very low temperatures. - We selected the same point for the linearization as we used for the density, - as the density and the kinematic viscosity are combined in - - AixLib.Media.Specialized.Water.TemperatureDependentDensity.dynamicViscosity. + To decouple the energy equation from the mass equations, + the pressure drop is a function of the mass flow rate, + and not the volume flow rate. + This leads to simpler equations.

    • - April 11, 2016 by Michael Wetter:
      - Corrected wrong hyperlink in documentation for - issue 450. + September 21, 2021, by Michael Wetter:
      + Corrected typo in comments.
      + This is for + #1525.
    • - December 18, 2013, by Michael Wetter:
      - First implementation, based on the IDA implementation in therpro.nmf, - but converted from Celsius to Kelvin. -
      • -
    - -

    - This medium package models liquid water. -

    -

    - The mass density is computed using a 3rd order polynomial, which yields the - density as a function of temperature as shown in the figure below. Note, however, - that computing density as a function of temperature can lead to considerably - slower computing time compared to using - - AixLib.Media.Water - in which the density is a constant. We therefore recommend to use - - AixLib.Media.Water - for typical building energy simulations. -

    -

    - \"Mass -

    -

    - For the specific heat capacities at constant pressure and at constant volume, - a constant value of 4184 J/(kg K), which corresponds to 20°C - is used. - The figure below shows the relative error of the specific heat capacity that - is introduced by this simplification. - Using a constant value for the specific heat capacity allows to compute - temperature from enthalpy without having to solve an implicit equation, - and therefore leads to faster simulation. -

    -

    - \"Relative -

    - - -

    - Thermal conductivity is calculated as a function of temperature as shown in the figure below. - The correlation used to calculate the thermal conductivity is -

    - -

    - λ(T) = λ(298.15 K) ⋅ (-1.48445+4.12292⋅(T/298.15)-1.63866⋅(T/298.15)2), -

    -

    - where λ(298.15 K) = 0.6065 W/(m ⋅ K) is the adopted standard value - of the thermal conductivity of water at 298.15 K and 0.1 MPa. -

    -

    - \"Thermal -

    - -

    - Dynamic viscosity is calculated as the product of density and kinematic viscosity, - both temperature dependent. However, the kinematic viscosity - has its own temperature dependent correlation, implemented at - - AixLib.Media.Specialized.Water.TemperatureDependentDensity.kinematicViscosity. - Results of the kinematic viscosity as a function of temperature are shown in the figure below. -

    -

    - \"Kinematic -

    - -

    - The enthalpy is computed using the convention that h=0 - if T=0 °C. -

    -

    Limitations

    -

    - Phase changes are not modeled. -

    - -
      -
    • - April 5, 2022, by Michael Wetter:
      - Corrected assignment of R_s in BaseProperties to avoid a unit error.
      - This is for - #1603. -
      • -
    • - July 7, 2016, by Carles Ribas Tugores:
      - Correct Documentation. This is for - #487. -
      • -
    • - June 6, 2015, by Michael Wetter:
      - Set AbsolutePressure(start=p_default) - and Temperature(start=T_default) - to have to have conistent start values. - See also revision notes of - - AixLib.Media.Water. - This is for - #266. -
      • -
    • - May 1, 2015, by Michael Wetter:
      - Added Inline=true for - - issue 227. -
      • -
    • - February 25, 2015, by Michael Wetter:
      - Removed stateSelect attribute on pressure as this caused - - AixLib.Examples.Tutorial.SpaceCooling.System3 - to fail with the error message - \"differentiated if-then-else was not continuous\". -
      • -
    • - February 3, 2015, by Michael Wetter:
      - Removed stateSelect.prefer for temperature. - This is for - #160. -
      • -
    • - October 15, 2014, by Michael Wetter:
      - Renamed from AixLib.Media.Water to - AixLib.Media.Water.Detailed to allow addition of - AixLib.Media.Water.Simple. -
      • -
    • - September 12, 2014, by Michael Wetter:
      - Set T(start=T_default) and p(start=p_default) in the - ThermodynamicState record. Setting the start value for - T is required to avoid an error due to conflicting start values - when checking - AixLib.Examples.VAVReheat.ClosedLoop in pedantic mode. -
      • -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. + December 1, 2016, by Michael Wetter:
      + First implementation for + #480.
    -------- Corrected Code --------

    - Base properties of the medium. + This is a model of a flow resistance with a fixed flow coefficient. + The mass flow rate is computed as +

    +

    + ṁ = k √ΔP,

    - This function computes the density as a function of temperature. + where k is a constant and ΔP is the pressure drop. The + constant k is equal to + k=m_flow_nominal/sqrt(dp_nominal), where + m_flow_nominal is a parameter.

    - Implementation + Assumptions

    - The function is based on the IDA implementation in - therpro.nmf, which implements -

    -
    - d := 1000.12 + 1.43711e-2*T_degC -
-  5.83576e-3*T_degC^2 + 1.5009e-5*T_degC^3;
-
    -

    - This has been converted to Kelvin, which resulted in the above - expression. In addition, below 5 °C and above 100 °C, the density is - replaced by a linear function to avoid inflection points. This linear - extension is such that the density is once continuously - differentiable. + In the region abs(m_flow) < m_flow_turbulent, the + square root is replaced by a differentiable function with finite + slope. The value of m_flow_turbulent is computed as + m_flow_turbulent = eta_nominal*dh/4*π*ReC, where + eta_nominal is the dynamic viscosity, obtained from the + medium model. The parameter dh is the hydraulic diameter + and ReC=4000 is the critical Reynolds number, which both + can be set by the user.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation, based on the IDA implementation in - therpro.nmf, but converted from Celsius to Kelvin and - linearly extended. -
      • -
    +

    + Important parameters +

    - This function computes the dynamic viscosity. + By default, the pressure drop at nominal flow rate is computed as

    -
      -
    • December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -
    +
    + dp_nominal = fac * dpStraightPipe_nominal,
+

    - This function computes the specific enthalpy. + where dpStraightPipe_nominal is a parameter that is + automatically computed based on the nominal mass flow rate, hydraulic + diameter, pipe roughness and medium properties. The hydraulic + diameter dh is by default computed based on the flow + velocity v_nominal and the nominal mass flow rate + m_flow_nominal. Hence, users should change the default + values of dh or v_nominal if they are not + applicable for their model.

    -
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function computes the specific enthalpy of liquid water. + The factor fac takes into account additional resistances + such as for bends. The default value of 2 can be changed + by the user.

    -
      -
    • December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function computes the specific internal energy. + The parameter from_dp is used to determine whether the + mass flow rate is computed as a function of the pressure drop (if + from_dp=true), or vice versa. This setting can affect + the size of the nonlinear system of equations.

    -
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function computes the specific entropy. + If the parameter linearized is set to true, + then the pressure drop is computed as a linear function of the mass + flow rate.

    - To obtain the state for a given pressure, entropy and mass fraction, - use AixLib.Media.Air.setState_psX. + Setting allowFlowReversal=false can lead to simpler + equations. However, this should only be set to false if + one can guarantee that the flow never reverses its direction. This + can be difficult to guarantee, as pressure imbalance after the + initialization, or due to medium expansion and contraction, can lead + to reverse flow.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function computes the specific Gibbs energy. + If the parameter show_T is set to true, + then the model will compute the temperature at its ports. Note that + this can lead to state events when the mass flow rate approaches + zero, which can increase computing time.

    -
      -
    • December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -
    +

    + Notes +

    - This function computes the specific Helmholtz energy. + For more detailed models that compute the actual flow friction, + models from the package Modelica.Fluid can be used and + combined with models from the AixLib library.

    -
      -
    • December 2, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function computes the specific enthalpy for an isentropic state - change from the temperature that corresponds to the state - refState to reference_T. + For a model that uses dp_nominal as a parameter rather + than geoemetric data, use AixLib.Fluid.FixedResistances.PressureDrop.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    +

    + Implementation +

    - This function returns the isobaric expansion coefficient, + The pressure drop is computed by calling a function in the package + AixLib.Fluid.BaseClasses.FlowModels, + This package contains regularized implementations of the equation

    - βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p, + m = sign(Δp) k √ Δp +  

    - where v is the specific volume, T is the temperature - and p is the pressure. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the isothermal compressibility coefficient, - which is zero as this medium is incompressible. The isothermal - compressibility is defined as -

    -

    - κT = - 1 ⁄ v   (∂ v ⁄ ∂ p)T, -

    -

    - where v is the specific volume, T is the temperature - and p is the pressure. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the partial derivative of density with respect - to pressure at constant temperature, which is zero as the medium is - incompressible. + and its inverse function.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function computes the derivative of density with respect to - temperature at constant pressure. + To decouple the energy equation from the mass equations, the pressure + drop is a function of the mass flow rate, and not the volume flow + rate. This leads to simpler equations.

      -
    • August 17, 2015, by Michael Wetter:
      - Removed dublicate entry of smooth and - smoothOrder. This is for issue 303. +
    • September 21, 2021, by Michael Wetter:
      + Corrected typo in comments.
      + This is for #1525.
      • -
    • December 18, 2013, by Michael Wetter:
      - First implementation, based on the IDA implementation in - therpro.nmf, but converted from Celsius to Kelvin. +
    • December 1, 2016, by Michael Wetter:
      + First implementation for #480.
    + +-------- Errors -------- +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 104 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Geothermal/Borefields/UsersGuide.mo ---- +-------- HTML Code -------- +

    - This function returns the partial derivative of density with respect - to mass fraction, which is zero as the medium is a single substance. +This package contains borefield models. These models can simulate any arbitrary +configuration of vertical boreholes with equal lengths with both short and +long-term accuracy with an aggregation method to speed up the calculations of the ground heat transfer. Examples +of how to use the borefield models and validation cases can be found in + +AixLib.Fluid.Geothermal.Borefields.Examples +and + +AixLib.Fluid.Geothermal.Borefields.Validation, +respectively.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function returns the specific heat capacity at constant - pressure. -

    +The major features and configurations currently supported are:
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • +
    • User-defined borefield characteristics and geometry (borehole radius, pipe radius, shank spacing, etc.), +including single U-tube, double U-tube in parallel and double U-tube in series configurations. +
      • +
    • The resistances Rb and Ra are +either automatically calculated using the multipole method, +or the resistance Rb can be directly provided by the user. +In this case, the resistances Rb and Ra are +still evaluated internally, but their values are weighted so that the borehole +resistance matches the specified value. +
      • +
    • +User-defined vertical discretization of boreholes are supported. +However, the borehole wall temperature +is identical for each borehole, as the ground temperature response model only computes the average borehole wall temperature +for all boreholes combined. +
      • +
    • +Borefields can consist of one or many boreholes. Each borehole can be positioned +at an arbitrary position in the field using cartesian coordinates. +
      • +
    • +The resolution and precision of the load aggregation method for the ground heat transfer can be adapted. +
      • +
    • +The thermal response of the ground heat transfer is stored locally to avoid +having to recalculate it for future simulations with the same borefield configuration. +
      • +
    • +Pressure losses are calculated if the dp_nominal parameter is set to a non-zero value. +
    +

    - This function computes the specific heat capacity at constant volume. +The model is limited to the simulation of borefields with boreholes connected in +parallel, as shown on the figure below for a single U-tube configuration. All +boreholes have the same length hBor, the same radius +rBor, and are buried at the same depth dBor below the +ground surface (also known as the inactive borehole length).

    -
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the thermal conductivity. The expression is - obtained from Ramires et al. (1995). +

    +\"image\"

    -

    - References -

    + +

    How to use the borefield models

    +
    Borefield data record

    - Ramires, Maria L. V. and Nieto de Castro, Carlos A. and Nagasaka, - Yuchi and Nagashima, Akira and Assael, Marc J. and Wakeham, William - A. Standard Reference Data for the Thermal Conductivity of Water. - Journal of Physical and Chemical Reference Data, 24, p. - 1377-1381, 1995. DOI:10.1063/1.555963. +Most of the parameter values of the model are contained in the record called borFieDat. +This record is composed of three subrecords: +filDat (containing the thermal characteristics of the borehole filling material), +soiDat (containing the thermal characteristics of the surrounding soil), +and conDat (containing all others parameters, namely parameters +defining the configuration of the borefield). +The structure and default values of the record are in the package: +AixLib.Fluid.Geothermal.Borefields.Data. +The borFieDat record +can be found in the +AixLib.Fluid.Geothermal.Borefields.Data.Borefield subpackage therein. +Examples of the subrecords conDat, filDat and soiDat +can be found in + +AixLib.Fluid.Geothermal.Borefields.Data.Configuration, + +AixLib.Fluid.Geothermal.Borefields.Data.Filling and + +AixLib.Fluid.Geothermal.Borefields.Data.Soil, respectively.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function returns the pressure. +It is important to make sure that the borCon parameter within +the conDat subrecord is compatible with the chosen borefield model. +For example, if a double U-tube +borefield model is chosen, the borCon parameter could be set +to both a parallel double U-tube configuration and a double U-tube configuration in series, +but could not be set to a single U-tube configuration. An incompatible borehole +configuration will stop the simulation.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    +
    Ground heat transfer parameters

    - This function returns the temperature. +Other than the parameters contained in the borFieDat record, +the borefield models have other parameters which can be modified by the user. +The tLoaAgg parameter is the time resolution of the load aggregation +for the calculation of the ground heat transfer. It represents the +frequency at which the load aggregation procedure is performed in the simulation. +Therefore, smaller values of tLoaAgg will improve +the accuracy of the model, at the cost of increased simulation times +due to a higher number of events occuring in the simulation. While a default value +is provided for this parameter, it is advisable to ensure that it is lower +than a fraction (e.g. half) of the time required for the fluid to completely circulate +through the borefield, +as increasing the value of tLoaAgg beyond this +will result in non-physical borehole wall temperatures.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function returns the molar mass, which is assumed to be - constant. +The nCel parameter also affects the accuracy and simulation time +of the ground heat transfer calculations. As this parameter sets the number +of consecutive equal-size aggregation cells before increasing the size of cells, +increasing its value will result in less load aggregation, which will increase +accuracy at the cost of computation time. On the other hand, +decreasing the value of nCel (down to a minimum of 1) +will decrease accuracy but improve +computation time. The default value is chosen as a compromise between the two.

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -

    - This function returns the thermodynamic state for a given pressure, - specific enthalpy and composition. +Further information on the tLoaAgg and nCel parameters can +be found in the documentation of + +AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse.

    -
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    +
    Other parameters

    - This function returns the thermodynamic state for a given pressure, - temperature and composition. +Other parameters which can be modified include the dynamics, initial conditions, +and further information regarding the fluid flow, for example whether the flow is reversible. +It is worth noting that regardless of the energyDynamics chosen, +the dynFil parameter can be set to false +to remove the effect of the thermal capacitance +of the filling material in the borehole(s). +The nSeg parameter specifies the number of segments for the vertical discretization of the borehole(s). +Further information on this discretization can be found in the "Model description" section below.

    -
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    +
    Running simulations

    - This function returns the thermodynamic state based on pressure, - specific entropy and mass fraction. +When running simulations using the borefield models, +the tmp/temperatureResponseMatrix directory within the current directory +will be checked to see if any of the +borefield configurations used in the simulation have already +had their ground temperature response calculated previously +If the data doesn't exist in the tmp/temperatureResponseMatrix folder, +it will be calculated during the initialization of the model +and will be saved there for future use.

    +

    Model description

    - The state is computed by symbolically solving - AixLib.Media.Specialized.Water.TemperatureDependentDensity.specificEntropy - for temperature. -

    -
      -
    • April 11, 2016 by Michael Wetter:
      - Corrected wrong hyperlink in documentation for issue 450. -
      • -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the derivative of the specific heat capacity - at constant pressure with respect to the state. -

    -
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the temperature derivative of the enthalpy of - liquid water per unit mass. -

    -
      -
    • December 11, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the kinematic viscosity as a function of - temperature. -

    -

    - Implementation -

    -

    - The function is based on the IDA implementation in - therpro.nmf. The original equation is -

    -
    - kinVis :=1E-6*Modelica.Math.exp(0.577449 - 3.253945e-2*T_degC + 2.17369e-4*
-       T_degC^2 - 7.22111e-7*T_degC^3);
-
    -

    - This has been converted to Kelvin, which resulted in the above - expression. In addition, at 5 °C the kinematic viscosity is linearly - extrapolated to avoid a large gradient at very low temperatures. We - selected the same point for the linearization as we used for the - density, as the density and the kinematic viscosity are combined in - - AixLib.Media.Specialized.Water.TemperatureDependentDensity.dynamicViscosity. -

    +The borefield models rely on the following key assumptions:
      -
    • April 11, 2016 by Michael Wetter:
      - Corrected wrong hyperlink in documentation for issue 450. -
      • -
    • December 18, 2013, by Michael Wetter:
      - First implementation, based on the IDA implementation in - therpro.nmf, but converted from Celsius to Kelvin. -
      • +
    • The thermal properties of the soil (conductivity and diffusivity) are constant, +homogenous and isotropic. +
      • +
    • +The conductivity, capacitance and density of the grout and pipe material are constant, homogenous and isotropic. +
      • +
    • +There is no heat extraction or injection prior to the simulation start. +
      • +
    • +All of the boreholes in the borefield have uniform dimensions (including the pipe dimensions). +
      • +
    • +Inside the boreholes, the non-advective heat transfer is only in the radial direction. +

    - This medium package models liquid water. -

    -

    - The mass density is computed using a 3rd order polynomial, which - yields the density as a function of temperature as shown in the - figure below. Note, however, that computing density as a function of - temperature can lead to considerably slower computing time compared - to using AixLib.Media.Water in which the - density is a constant. We therefore recommend to use AixLib.Media.Water for typical - building energy simulations. +The borefield models are constructed in two main parts: the borehole(s) and the ground heat transfer. +The former is modeled as a vertical discretization of borehole segments, where a uniform temperature increase or decrease +(due to heat injection or extraction) is superimposed to the far-field ground temperature to obtain the borehole wall +temperature. The thermal effects of the circulating fluid (including the convection resistance), +of the pipes and of the filling material are all taken into consideration, which allows modeling +short-term thermal effects in the borehole. The borehole segments do not take into account axial effects, +thus only radial (horizontal) effects are considered within the borehole(s). The thermal +behavior between the pipes and borehole wall are modeled as a resistance-capacitance network, with +the grout capacitance being split in the number of pipes present in a borehole section. +The capacitance is only present if the dynFil parameter is set to true. +The figure below shows an example for a borehole section within a single U-tube configuration.

    - \"Mass +\"image\"

    - For the specific heat capacities at constant pressure and at constant - volume, a constant value of 4184 J/(kg K), which corresponds - to 20°C is used. The figure below shows the relative error of - the specific heat capacity that is introduced by this simplification. - Using a constant value for the specific heat capacity allows to - compute temperature from enthalpy without having to solve an implicit - equation, and therefore leads to faster simulation. +The second main part of the borefield models is the ground heat transfer, which shares a thermal boundary +condition at the uniform borehole wall with all of the borehole segments. The heat transfer in the ground +is modeled analytically as a convolution integral between the heat flux at the borehole wall +and the borefield's thermal response factor.

    - - +\"image\"

    - Thermal conductivity is calculated as a function of temperature as - shown in the figure below. The correlation used to calculate the - thermal conductivity is -

    -

    - λ(T) = λ(298.15 K) ⋅ - (-1.48445+4.12292⋅(T/298.15)-1.63866⋅(T/298.15)2), +The model uses a load aggregation technique to reduce the time required to calculate +the borehole wall temperature changes resulting from heat injection or extraction.

    - where λ(298.15 K) = 0.6065 W/(m ⋅ K) is the adopted standard - value of the thermal conductivity of water at 298.15 K and - 0.1 MPa. -

    -

    - \"Thermal +The ground heat transfer takes into account both the borehole axial effects and +the borehole radial effects which are a result of its cylindrical geometry. The borefield's +thermal response to a constant load, also known as its g-function, is used +to calculate the thermal response in the simulation. This g-function +is stored in the tmp/temperatureResponseMatrix subdirectory, +as discussed previously in the +"How to use the borefield models" section. Further information on the +ground heat transfer model and the thermal temperature response calculations can +be found in + +AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse +and + +AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.gFunction.

    +

    References

    - Dynamic viscosity is calculated as the product of density and - kinematic viscosity, both temperature dependent. However, the - kinematic viscosity has its own temperature dependent correlation, - implemented at - AixLib.Media.Specialized.Water.TemperatureDependentDensity.kinematicViscosity. - Results of the kinematic viscosity as a function of temperature are - shown in the figure below. -

    -

    - \"Kinematic +D. Picard, L. Helsen. +Advanced Hybrid Model for Borefield Heat +Exchanger Performance Evaluation; an Implementation in Modelica +Proc. of the 10th Intertional ModelicaConference, p. 857-866. Lund, Sweden. March 2014. +https://lirias.kuleuven.be/retrieve/270880.

    + +-------- Corrected Code --------

    - The enthalpy is computed using the convention that h=0 if - T=0 °C. + This package contains borefield models. These models can simulate any + arbitrary configuration of vertical boreholes with equal lengths with + both short and long-term accuracy with an aggregation method to speed + up the calculations of the ground heat transfer. Examples of how to + use the borefield models and validation cases can be found in + AixLib.Fluid.Geothermal.Borefields.Examples + and AixLib.Fluid.Geothermal.Borefields.Validation, + respectively.

    -

    - Limitations -

    - Phase changes are not modeled. + The major features and configurations currently supported are:

      -
    • April 5, 2022, by Michael Wetter:
      - Corrected assignment of R_s in - BaseProperties to avoid a unit error.
      - This is for #1603. -
      • -
    • July 7, 2016, by Carles Ribas Tugores:
      - Correct Documentation. This is for #487. +
    • User-defined borefield characteristics and geometry (borehole + radius, pipe radius, shank spacing, etc.), including single U-tube, + double U-tube in parallel and double U-tube in series configurations.
      • -
    • June 6, 2015, by Michael Wetter:
      - Set AbsolutePressure(start=p_default) and - Temperature(start=T_default) to have to have conistent - start values. See also revision notes of AixLib.Media.Water. This is for - #266. +
    • The resistances Rb and Ra are + either automatically calculated using the multipole method, or the + resistance Rb can be directly provided by the user. + In this case, the resistances Rb and + Ra are still evaluated internally, but their values + are weighted so that the borehole resistance matches the specified + value.
      • -
    • May 1, 2015, by Michael Wetter:
      - Added Inline=true for issue 227. +
    • User-defined vertical discretization of boreholes are supported. + However, the borehole wall temperature is identical for each + borehole, as the ground temperature response model only computes the + average borehole wall temperature for all boreholes combined.
      • -
    • February 25, 2015, by Michael Wetter:
      - Removed stateSelect attribute on pressure as this - caused AixLib.Examples.Tutorial.SpaceCooling.System3 - to fail with the error message \"differentiated if-then-else was not - continuous\". +
    • Borefields can consist of one or many boreholes. Each borehole + can be positioned at an arbitrary position in the field using + cartesian coordinates.
      • -
    • February 3, 2015, by Michael Wetter:
      - Removed stateSelect.prefer for temperature. This is - for #160. +
    • The resolution and precision of the load aggregation method for + the ground heat transfer can be adapted.
      • -
    • October 15, 2014, by Michael Wetter:
      - Renamed from AixLib.Media.Water to - AixLib.Media.Water.Detailed to allow addition of - AixLib.Media.Water.Simple. +
    • The thermal response of the ground heat transfer is stored + locally to avoid having to recalculate it for future simulations with + the same borefield configuration.
      • -
    • September 12, 2014, by Michael Wetter:
      - Set T(start=T_default) and - p(start=p_default) in the - ThermodynamicState record. Setting the start value for - T is required to avoid an error due to conflicting - start values when checking AixLib.Examples.VAVReheat.ClosedLoop - in pedantic mode. +
    • Pressure losses are calculated if the dp_nominal + parameter is set to a non-zero value.
      • -
    • December 18, 2013, by Michael Wetter:
      - First implementation. +
    +

    + The model is limited to the simulation of borefields with boreholes + connected in parallel, as shown on the figure below for a single + U-tube configuration. All boreholes have the same length + hBor, the same radius rBor, and are buried + at the same depth dBor below the ground surface (also + known as the inactive borehole length). +

    +

    + \"image\" +

    +

    + How to use the borefield models +

    +
    + Borefield data record +
    +

    + Most of the parameter values of the model are contained in the record + called borFieDat. This record is composed of three + subrecords: filDat (containing the thermal + characteristics of the borehole filling material), + soiDat (containing the thermal characteristics of the + surrounding soil), and conDat (containing all others + parameters, namely parameters defining the configuration of the + borefield). The structure and default values of the record are in the + package: AixLib.Fluid.Geothermal.Borefields.Data. + The borFieDat record can be found in the AixLib.Fluid.Geothermal.Borefields.Data.Borefield + subpackage therein. Examples of the subrecords conDat, + filDat and soiDat can be found in AixLib.Fluid.Geothermal.Borefields.Data.Configuration, + AixLib.Fluid.Geothermal.Borefields.Data.Filling + and AixLib.Fluid.Geothermal.Borefields.Data.Soil, + respectively. +

    +

    + It is important to make sure that the borCon parameter + within the conDat subrecord is compatible with the + chosen borefield model. For example, if a double U-tube borefield + model is chosen, the borCon parameter could be set to + both a parallel double U-tube configuration and a double U-tube + configuration in series, but could not be set to a single U-tube + configuration. An incompatible borehole configuration will stop the + simulation. +

    +
    + Ground heat transfer parameters +
    +

    + Other than the parameters contained in the borFieDat + record, the borefield models have other parameters which can be + modified by the user. The tLoaAgg parameter is the time + resolution of the load aggregation for the calculation of the ground + heat transfer. It represents the frequency at which the load + aggregation procedure is performed in the simulation. Therefore, + smaller values of tLoaAgg will improve the accuracy of + the model, at the cost of increased simulation times due to a higher + number of events occuring in the simulation. While a default value is + provided for this parameter, it is advisable to ensure that it is + lower than a fraction (e.g. half) of the time required for the fluid + to completely circulate through the borefield, as increasing the + value of tLoaAgg beyond this will result in non-physical + borehole wall temperatures. +

    +

    + The nCel parameter also affects the accuracy and + simulation time of the ground heat transfer calculations. As this + parameter sets the number of consecutive equal-size aggregation cells + before increasing the size of cells, increasing its value will result + in less load aggregation, which will increase accuracy at the cost of + computation time. On the other hand, decreasing the value of + nCel (down to a minimum of 1) will decrease accuracy but + improve computation time. The default value is chosen as a compromise + between the two. +

    +

    + Further information on the tLoaAgg and nCel + parameters can be found in the documentation of + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse. +

    +
    + Other parameters +
    +

    + Other parameters which can be modified include the dynamics, initial + conditions, and further information regarding the fluid flow, for + example whether the flow is reversible. It is worth noting that + regardless of the energyDynamics chosen, the + dynFil parameter can be set to false to + remove the effect of the thermal capacitance of the filling material + in the borehole(s). The nSeg parameter specifies the + number of segments for the vertical discretization of the + borehole(s). Further information on this discretization can be found + in the \"Model description\" section below. +

    +
    + Running simulations +
    +

    + When running simulations using the borefield models, the + tmp/temperatureResponseMatrix directory within the + current directory will be checked to see if any of the borefield + configurations used in the simulation have already had their ground + temperature response calculated previously If the data doesn't exist + in the tmp/temperatureResponseMatrix folder, it will be + calculated during the initialization of the model and will be saved + there for future use. +

    +

    + Model description +

    +

    + The borefield models rely on the following key assumptions: +

    +
      +
    • The thermal properties of the soil (conductivity and diffusivity) + are constant, homogenous and isotropic. +
      • +
    • The conductivity, capacitance and density of the grout and pipe + material are constant, homogenous and isotropic. +
      • +
    • There is no heat extraction or injection prior to the simulation + start. +
      • +
    • All of the boreholes in the borefield have uniform dimensions + (including the pipe dimensions). +
      • +
    • Inside the boreholes, the non-advective heat transfer is only in + the radial direction.
    +

    + The borefield models are constructed in two main parts: the + borehole(s) and the ground heat transfer. The former is modeled as a + vertical discretization of borehole segments, where a uniform + temperature increase or decrease (due to heat injection or + extraction) is superimposed to the far-field ground temperature to + obtain the borehole wall temperature. The thermal effects of the + circulating fluid (including the convection resistance), of the pipes + and of the filling material are all taken into consideration, which + allows modeling short-term thermal effects in the borehole. The + borehole segments do not take into account axial effects, thus only + radial (horizontal) effects are considered within the borehole(s). + The thermal behavior between the pipes and borehole wall are modeled + as a resistance-capacitance network, with the grout capacitance being + split in the number of pipes present in a borehole section. The + capacitance is only present if the dynFil parameter is + set to true. The figure below shows an example for a + borehole section within a single U-tube configuration. +

    +

    + \"image\" +

    +

    + The second main part of the borefield models is the ground heat + transfer, which shares a thermal boundary condition at the uniform + borehole wall with all of the borehole segments. The heat transfer in + the ground is modeled analytically as a convolution integral between + the heat flux at the borehole wall and the borefield's thermal + response factor. +

    +

    + \"image\" +

    +

    + The model uses a load aggregation technique to reduce the time + required to calculate the borehole wall temperature changes resulting + from heat injection or extraction. +

    +

    + The ground heat transfer takes into account both the borehole axial + effects and the borehole radial effects which are a result of its + cylindrical geometry. The borefield's thermal response to a constant + load, also known as its g-function, is used to calculate the + thermal response in the simulation. This g-function is stored in the + tmp/temperatureResponseMatrix subdirectory, as discussed + previously in the \"How to use the borefield models\" section. Further + information on the ground heat transfer model and the thermal + temperature response calculations can be found in + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse + and + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.gFunction. +

    +

    + References +

    +

    + D. Picard, L. Helsen. Advanced Hybrid Model for Borefield Heat + Exchanger Performance Evaluation; an Implementation in Modelica + Proc. of the 10th Intertional ModelicaConference, p. 857-866. Lund, + Sweden. March 2014. https://lirias.kuleuven.be/retrieve/270880. +

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    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/FixedResistances/PressureDrop.mo ---- +---- AixLib/Media/Antifreeze/PropyleneGlycolWater.mo ---- -------- HTML Code -------- +

    + This base properties model is identical to + + Modelica.Media.Water.ConstantPropertyLiquidWater, + except that the equation + u = cv_const*(T - reference_T) + has been replaced by u=h because + cp_const=cv_const. + Also, the model checks if the mass fraction of the mixture is within the + allowed limits. +

    + +

    + Density of propylene antifreeze-water mixture at specified mass fraction + and temperature, based on Melinder (2010). +

    +

    References

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF. +

    + + +

    - Model of a flow resistance with a fixed flow coefficient. - The mass flow rate is + Dynamic viscosity of antifreeze-water mixture at specified mass fraction and + temperature, based on Melinder (2010).

    -

    - ṁ = k - √ΔP, +

    References

    +

    + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    + + +

    - where - k is a constant and - ΔP is the pressure drop. - The constant k is equal to - k=m_flow_nominal/sqrt(dp_nominal), - where m_flow_nominal and dp_nominal - are parameters. + Fusion temperature of antifreeze-water mixture at specified mass fraction and + temperature, based on Melinder (2010).

    -

    Assumptions

    +

    References

    - In the region - abs(m_flow) < m_flow_turbulent, - the square root is replaced by a differentiable function - with finite slope. - The value of m_flow_turbulent is - computed as - m_flow_turbulent = deltaM * abs(m_flow_nominal), - where deltaM=0.3 and - m_flow_nominal are parameters that can be set by the user. + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    + + +

    - The figure below shows the pressure drop for the parameters - m_flow_nominal=5 kg/s, - dp_nominal=10 Pa and - deltaM=0.3. + Evaluates a thermophysical property of a mixture, based on correlations proposed + by Melinder (2010).

    -

    - \"image\" +

    + The polynomial has the form

    -

    Important parameters

    +

    + f = a1 (x-xm)0(y-ym)0 + + a2 (x-xm)0(y-ym)1 + + ... + + any[1] (x-xm)0(y-ym)ny[1]-1 + + ... + + any[1])+1 (x-xm)1(y-ym)0 + + ... + + any[1]+ny[2] (x-xm)1(y-ym)ny[2]-1 + + ... +

    +

    References

    - The parameter from_dp is used to determine - whether the mass flow rate is computed as a function of the - pressure drop (if from_dp=true), or vice versa. - This setting can affect the size of the nonlinear system of equations. + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    + +
      +
    • + March 16, 2018 by Massimo Cimmino:
      + First implementation. + This function is used models in + + AixLib.Media.Antifreeze. +
      • +
    +

    - If the parameter linearized is set to true, - then the pressure drop is computed as a linear function of the - mass flow rate. + Specific heat capacity of antifreeze-water mixture at specified mass fraction + and temperature, based on Melinder (2010).

    +

    References

    - Setting allowFlowReversal=false can lead to simpler - equations. However, this should only be set to false - if one can guarantee that the flow never reverses its direction. - This can be difficult to guarantee, as pressure imbalance after - the initialization, or due to medium expansion and contraction, - can lead to reverse flow. + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    + + +

    - If the parameter - show_T is set to true, - then the model will compute the - temperature at its ports. Note that this can lead to state events - when the mass flow rate approaches zero, - which can increase computing time. + Thermal conductivity of antifreeze-water mixture at specified mass fraction and + temperature, based on Melinder (2010).

    -

    Notes

    +

    References

    - For more detailed models that compute the actual flow friction, - models from the package - - Modelica.Fluid - can be used and combined with models from the - AixLib library. + Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary + Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: + IIR/IIF.

    + + +

    - For a model that uses the hydraulic parameter and flow velocity at nominal conditions - as a parameter, use - - AixLib.Fluid.FixedResistances.HydraulicDiameter. + This medium package models propylene glycol - water mixtures.

    -

    Implementation

    - The pressure drop is computed by calling a function in the package - - AixLib.Fluid.BaseClasses.FlowModels, - This package contains regularized implementations of the equation + The mass density, specific heat capacity, thermal conductivity and viscosity + are assumed constant and evaluated at a set temperature and mass fraction of + propylene glycol within the mixture. The dependence of the four properties + are shown on the figure below.

    -

    - m = sign(Δp) k √ Δp   +

    + \"Relative

    - and its inverse function. + The accuracy of the thermophysical properties is dependent on the temperature + variations encountered during simulations. + The figure below shows the relative error of the the four properties over a + 10 °C range around the temperature used to evaluate the constant + properties. The maximum errors are 0.8 % for mass density, 1.5 % + for specific heat capacity, 3.2 % for thermal conductivity and 250 + % for dynamic viscosity. +

    +

    + \"Relative

    - To decouple the energy equation from the mass equations, - the pressure drop is a function of the mass flow rate, - and not the volume flow rate. - This leads to simpler equations. + The figure below shows the relative error of the the four properties over a + 20 °C range around the temperature used to evaluate the constant + proepties. The maximum errors are 1.6 % for mass density, 3.0 % + for specific heat capacity, 6.2 % for thermal conductivity and 950 + % for dynamic viscosity. +

    +

    + \"Relative +

    +

    + The enthalpy is computed using the convention that h=0 + if T=0 °C. +

    +

    Limitations

    +

    + Density, specific heat capacity, thermal conductivity and viscosity are constant. + The propylene glycol/water mixture is modeled as an incompressible liquid. + There are no phase changes. The medium is limited to temperatures below + 100 °C and mass fractions below 0.60. + As is the case for AixLib.Media.Water, + this medium package should not be used if + the simulation relies on the dynamic viscosity. +

    +

    Typical use and important parameters

    +

    + The temperature and mass fraction must be specified for the evaluation of the + constant thermophysical properties. A typical use of the package is (e.g. for + a temperature of 20 °C and a mass fraction of 0.40): +

    +

    + Medium = AixLib.Media.Antifreeze.PropyleneGlycolWater(property_T=293.15, X_a=0.40)

    • - September 21, 2018, by Michael Wetter:
      - Decrease value of deltaM(min=...) attribute. - See #1026. -
      • -
    • - February 3, 2018, by Filip Jorissen:
      - Revised implementation of pressure drop equation - such that it depends on from_dp - when linearized=true. - See #884. -
      • -
    • - December 1, 2016, by Michael Wetter:
      - Simplified model by removing the geometry dependent parameters into the new - model - - AixLib.Fluid.FixedResistances.HydraulicDiameter. -
      • -
    • - November 23, 2016, by Filip Jorissen:
      - Removed dp_nominal and - m_flow_nominal labels from icon. -
      • -
    • - October 14, 2016, by Michael Wetter:
      - Updated comment for parameter use_dh. + October 26, 2018, by Filip Jorissen and Michael Wetter:
      + Now printing different messages if temperature or mass fraction is above or below its limit, + and adding instance name as JModelica does not print the full instance name in the assertion. + This is for + #1045.
    • - November 26, 2014, by Michael Wetter:
      - Added the required annotation(Evaluate=true) so - that the system of nonlinear equations in - - AixLib.Fluid.FixedResistances.Validation.PressureDropsExplicit - remains the same. -
      • -
    • - November 20, 2014, by Michael Wetter:
      - Rewrote the warning message using an assert with - AssertionLevel.warning - as this is the proper way to write warnings in Modelica. -
      • -
    • - August 5, 2014, by Michael Wetter:
      - Corrected error in documentation of computation of k. -
      • -
    • - May 29, 2014, by Michael Wetter:
      - Removed undesirable annotation Evaluate=true. -
      • -
    • - October 8, 2013, by Michael Wetter:
      - Removed parameter show_V_flow. -
      • -
    • - December 14, 2012 by Michael Wetter:
      - Renamed protected parameters for consistency with the naming conventions. -
      • -
    • - January 16, 2012 by Michael Wetter:
      - To simplify object inheritance tree, revised base classes - AixLib.Fluid.BaseClasses.PartialResistance, - AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve, - AixLib.Fluid.Actuators.BaseClasses.PartialDamperExponential, - AixLib.Fluid.Actuators.BaseClasses.PartialActuator - and model - AixLib.Fluid.FixedResistances.PressureDrop. -
      • -
    • - May 30, 2008 by Michael Wetter:
      - Added parameters use_dh and deltaM for easier parameterization. -
      • -
    • - July 20, 2007 by Michael Wetter:
      - First implementation. + March 16, 2018, by Massimo Cimmino:
      + First implementation.
    -------- Corrected Code --------

    - Model of a flow resistance with a fixed flow coefficient. The mass - flow rate is -

    -

    - ṁ = k √ΔP, + This base properties model is identical to Modelica.Media.Water.ConstantPropertyLiquidWater, + except that the equation u = cv_const*(T - reference_T) + has been replaced by u=h because + cp_const=cv_const. Also, the model checks if the mass + fraction of the mixture is within the allowed limits.

    - where k is a constant and ΔP is the pressure drop. The - constant k is equal to - k=m_flow_nominal/sqrt(dp_nominal), where - m_flow_nominal and dp_nominal are - parameters. + Density of propylene antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010).

    - Assumptions + References

    - In the region abs(m_flow) < m_flow_turbulent, the - square root is replaced by a differentiable function with finite - slope. The value of m_flow_turbulent is computed as - m_flow_turbulent = deltaM * abs(m_flow_nominal), where - deltaM=0.3 and m_flow_nominal are - parameters that can be set by the user. + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

    +

    - The figure below shows the pressure drop for the parameters - m_flow_nominal=5 kg/s, dp_nominal=10 Pa and - deltaM=0.3. -

    -

    - \"image\" + Dynamic viscosity of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010).

    - Important parameters + References

    - The parameter from_dp is used to determine whether the - mass flow rate is computed as a function of the pressure drop (if - from_dp=true), or vice versa. This setting can affect - the size of the nonlinear system of equations. + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

    +

    - If the parameter linearized is set to true, - then the pressure drop is computed as a linear function of the mass - flow rate. + Fusion temperature of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010).

    +

    + References +

    - Setting allowFlowReversal=false can lead to simpler - equations. However, this should only be set to false if - one can guarantee that the flow never reverses its direction. This - can be difficult to guarantee, as pressure imbalance after the - initialization, or due to medium expansion and contraction, can lead - to reverse flow. + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

    +

    - If the parameter show_T is set to true, - then the model will compute the temperature at its ports. Note that - this can lead to state events when the mass flow rate approaches - zero, which can increase computing time. + Evaluates a thermophysical property of a mixture, based on + correlations proposed by Melinder (2010). +

    +

    + The polynomial has the form +

    +

    + f = a1 (x-xm)0(y-ym)0 + + a2 (x-xm)0(y-ym)1 + ... + + any[1] (x-xm)0(y-ym)ny[1]-1 + ... + + any[1])+1 (x-xm)1(y-ym)0 + ... + + any[1]+ny[2] (x-xm)1(y-ym)ny[2]-1 + + ...

    - Notes + References

    - For more detailed models that compute the actual flow friction, - models from the package Modelica.Fluid can be used and - combined with models from the AixLib library. + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

    +
      +
    • March 16, 2018 by Massimo Cimmino:
      + First implementation. This function is used models in AixLib.Media.Antifreeze. +
      • +

    - For a model that uses the hydraulic parameter and flow velocity at - nominal conditions as a parameter, use AixLib.Fluid.FixedResistances.HydraulicDiameter. + Specific heat capacity of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010).

    - Implementation + References

    - The pressure drop is computed by calling a function in the package - AixLib.Fluid.BaseClasses.FlowModels, - This package contains regularized implementations of the equation -

    -

    - m = sign(Δp) k √ Δp -   + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

    +

    - and its inverse function. + Thermal conductivity of antifreeze-water mixture at specified mass + fraction and temperature, based on Melinder (2010).

    +

    + References +

    - To decouple the energy equation from the mass equations, the pressure - drop is a function of the mass flow rate, and not the volume flow - rate. This leads to simpler equations. + Melinder, Åke. 2010. Properties of Secondary Working Fluids + (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for + Indirect Systems. Paris: IIR/IIF.

      -
    • September 21, 2018, by Michael Wetter:
      - Decrease value of deltaM(min=...) attribute. See - #1026. -
      • -
    • February 3, 2018, by Filip Jorissen:
      - Revised implementation of pressure drop equation such that it - depends on from_dp when linearized=true. - See #884. -
      • -
    • December 1, 2016, by Michael Wetter:
      - Simplified model by removing the geometry dependent parameters into - the new model AixLib.Fluid.FixedResistances.HydraulicDiameter. -
      • -
    • November 23, 2016, by Filip Jorissen:
      - Removed dp_nominal and m_flow_nominal - labels from icon. -
      • -
    • October 14, 2016, by Michael Wetter:
      - Updated comment for parameter use_dh. -
      • -
    • November 26, 2014, by Michael Wetter:
      - Added the required annotation(Evaluate=true) so that - the system of nonlinear equations in - AixLib.Fluid.FixedResistances.Validation.PressureDropsExplicit - remains the same. -
      • -
    • November 20, 2014, by Michael Wetter:
      - Rewrote the warning message using an assert with - AssertionLevel.warning as this is the proper way to - write warnings in Modelica. -
      • -
    • August 5, 2014, by Michael Wetter:
      - Corrected error in documentation of computation of k. -
      • -
    • May 29, 2014, by Michael Wetter:
      - Removed undesirable annotation Evaluate=true. -
      • -
    • October 8, 2013, by Michael Wetter:
      - Removed parameter show_V_flow. -
      • -
    • December 14, 2012 by Michael Wetter:
      - Renamed protected parameters for consistency with the naming - conventions. -
      • -
    • January 16, 2012 by Michael Wetter:
      - To simplify object inheritance tree, revised base classes - AixLib.Fluid.BaseClasses.PartialResistance, - AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve, - AixLib.Fluid.Actuators.BaseClasses.PartialDamperExponential, - AixLib.Fluid.Actuators.BaseClasses.PartialActuator and - model AixLib.Fluid.FixedResistances.PressureDrop. -
      • -
    • May 30, 2008 by Michael Wetter:
      - Added parameters use_dh and deltaM for - easier parameterization. -
      • -
    • July 20, 2007 by Michael Wetter:
      - First implementation. +
    • March 16, 2018 by Massimo Cimmino:
      + First implementation. This function is used by AixLib.Media.Antifreeze.PropyleneGlycolWater.
    - --------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 37 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 90 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/cylindricalHeatSource.mo ---- --------- HTML Code -------- - -

    - This function evaluates the cylindrical heat source solution. This solution - gives the relation between the constant heat transfer rate (per unit length) - injected by a cylindrical heat source of infinite length and the temperature - raise in the medium. The cylindrical heat source solution is defined by -

    -

    - \"image\" -

    -

    - where ΔT(t,r) is the temperature raise after a time t of - constant heat injection and at a distance r from the cylindrical source, - Q' is the heat injection rate per unit length, ks is - the soil thermal conductivity, Fo is the Fourier number, - aSois is the ground thermal diffusivity, - rb is the radius of the cylindrical source and G - is the cylindrical heat source solution. -

    -

    - The cylindrical heat source solution is given by: -

    -

    - \"image\" -

    -

    - The integral is solved numerically, with the integrand defined in - - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource_Integrand. -

    - -
      -
    • - March 22, 2018 by Massimo Cimmino:
      - First implementation. -
      • -
    - --------- Corrected Code --------

    - This function evaluates the cylindrical heat source solution. This - solution gives the relation between the constant heat transfer rate - (per unit length) injected by a cylindrical heat source of infinite - length and the temperature raise in the medium. The cylindrical heat - source solution is defined by + This medium package models propylene glycol - water mixtures. +

    +

    + The mass density, specific heat capacity, thermal conductivity and + viscosity are assumed constant and evaluated at a set temperature and + mass fraction of propylene glycol within the mixture. The dependence + of the four properties are shown on the figure below.

    - \"image\" + +

    - where ΔT(t,r) is the temperature raise after a time t - of constant heat injection and at a distance r from the - cylindrical source, Q' is the heat injection rate per unit - length, ks is the soil thermal conductivity, - Fo is the Fourier number, aSois is the - ground thermal diffusivity, rb is the radius of the - cylindrical source and G is the cylindrical heat source - solution. + The accuracy of the thermophysical properties is dependent on the + temperature variations encountered during simulations. The figure + below shows the relative error of the the four properties over a + 10 °C range around the temperature used to evaluate the + constant properties. The maximum errors are 0.8 % for mass + density, 1.5 % for specific heat capacity, 3.2 % for + thermal conductivity and 250 % for dynamic viscosity. +

    +

    + +

    - The cylindrical heat source solution is given by: + The figure below shows the relative error of the the four properties + over a 20 °C range around the temperature used to evaluate the + constant proepties. The maximum errors are 1.6 % for mass + density, 3.0 % for specific heat capacity, 6.2 % for + thermal conductivity and 950 % for dynamic viscosity.

    - \"image\" + +

    - The integral is solved numerically, with the integrand defined in - - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource_Integrand. + The enthalpy is computed using the convention that h=0 if + T=0 °C. +

    +

    + Limitations +

    +

    + Density, specific heat capacity, thermal conductivity and viscosity + are constant. The propylene glycol/water mixture is modeled as an + incompressible liquid. There are no phase changes. The medium is + limited to temperatures below 100 °C and mass fractions below + 0.60. As is the case for AixLib.Media.Water, this medium + package should not be used if the simulation relies on the dynamic + viscosity. +

    +

    + Typical use and important parameters +

    +

    + The temperature and mass fraction must be specified for the + evaluation of the constant thermophysical properties. A typical use + of the package is (e.g. for a temperature of 20 °C and a mass + fraction of 0.40): +

    +

    + Medium = + AixLib.Media.Antifreeze.PropyleneGlycolWater(property_T=293.15, + X_a=0.40)

      -
    • March 22, 2018 by Massimo Cimmino:
      +
    • October 26, 2018, by Filip Jorissen and Michael Wetter:
      + Now printing different messages if temperature or mass fraction is + above or below its limit, and adding instance name as JModelica + does not print the full instance name in the assertion. This is for + #1045. +
      • +
    • March 16, 2018, by Massimo Cimmino:
      First implementation.
    -------- Errors -------- -line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 23 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 9 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Media/Air.mo ---- +line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 24 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 35 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Media/Water.mo ---- -------- HTML Code --------

    Model with basic thermodynamic properties.

    + This base properties model is identical to + + Modelica.Media.Water.ConstantPropertyLiquidWater, + except that the equation + u = cv_const*(T - reference_T) + has been replaced by u=h because + cp_const=cv_const. +

    +

    This model provides equation for the following thermodynamic properties:

    @@ -13683,501 +11588,137 @@ line 23 column 2 - Warning:

    attribute "align" not allowed for HTML5

    molar mass
    -
      -
    • - September 22, 2020, by Michael Wetter:
      - First implementation based on Modelica Standard Library, - but with noEvent added to check of bounds. -
      • -
    - - Density is computed from pressure, temperature and composition in the thermodynamic state record applying the ideal gas law. - -

    - This function returns the dynamic viscosity. -

    -

    Implementation

    - The function is based on the 5th order polynomial - of - - Modelica.Media.Air.MoistAir.dynamicViscosity. - However, for the typical range of temperatures encountered - in building applications, a linear function sufficies. - This implementation is therefore the above 5th order polynomial, - linearized around 20°C. - The relative error of this linearization is - 0.4% at -20°C, - and less then - 0.2% between -5°C and +50°C. + Enthalpy of the water.

    - The ideal gas constant for moist air is computed from thermodynamic state assuming that all water is in the gas phase. - - Pressure is returned from the thermodynamic state record input as a simple assignment. -

    - This function returns the isobaric expansion coefficient at constant pressure, - which is zero for this medium. - The isobaric expansion coefficient at constant pressure is -

    -

    - βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p = 0, + This medium package models liquid water.

    - where - v is the specific volume, - T is the temperature and - p is the pressure. + The mass density is computed using a constant value of 995.586 kg/s. + For a medium model in which the density is a function of temperature, use + + AixLib.Media.Specialized.Water.TemperatureDependentDensity which may have considerably higher computing time.

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the isothermal compressibility coefficient. - The isothermal compressibility is + For the specific heat capacities at constant pressure and at constant volume, + a constant value of 4184 J/(kg K), which corresponds to 20°C + is used. + The figure below shows the relative error of the specific heat capacity that + is introduced by this simplification.

    -

    - κT = -1 ⁄ v   (∂ v ⁄ ∂ p)T - = -1 ⁄ p, +

    + \"Relative

    - where - v is the specific volume, - T is the temperature and - p is the pressure. + The enthalpy is computed using the convention that h=0 + if T=0 °C. +

    +

    Limitations

    +

    + Density, specific heat capacity, thermal conductivity and viscosity are constant. + Water is modeled as an incompressible liquid. + There are no phase changes.

    • - December 18, 2013, by Michael Wetter:
      - First implementation. + September 28, 2020, by Michael Wetter:
      + Reformulated BaseProperties to avoid event-triggering assertions.
      + This is for + #1401.
      • -
    - -

    - This function computes the specific entropy. -

    -

    - The specific entropy of the mixture is obtained from -

    -

    - s = ss + sm, -

    -

    - where - ss is the entropy change due to the state change - (relative to the reference temperature) and - sm is the entropy change due to mixing - of the dry air and water vapor. -

    -

    - The entropy change due to change in state is obtained from -

    -

    - ss = cv ln(T/T0) + R ln(v/v0)
    - = cv ln(T/T0) + R ln(ρ0/ρ) -

    -

    If we assume ρ = p0/(R T), - and because cp = cv + R, - we can write -

    -

    - ss = cv ln(T/T0) + R ln(T/T0)
    - =cp ln(T/T0). -

    -

    - Next, the entropy of mixing is obtained from a reversible isothermal - expansion process. Hence, -

    -

    - sm = -R ∑i( Xi ⁄ Mi - ln(Yi p/p0)), -

    -

    - where R is the gas constant, - X is the mass fraction, - M is the molar mass, and - Y is the mole fraction. -

    -

    - To obtain the state for a given pressure, entropy and mass fraction, use - - AixLib.Media.Air.setState_psX. -

    -

    Limitations

    -

    - This function is only valid for a relative humidity below 100%. -

    - -
    • - November 27, 2013, by Michael Wetter:
      - First implementation. + October 26, 2018, by Filip Jorissen and Michael Wetter:
      + Now printing different messages if temperature is above or below its limit, + and adding instance name as JModelica does not print the full instance name in the assertion. + This is for + #1045.
      • -
    - -

    - This function returns the partial derivative of density - with respect to pressure at constant temperature. -

    - -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. + June 6, 2015, by Michael Wetter:
      + Set AbsolutePressure(start=p_default) to avoid + a translation error if + + AixLib.Fluid.Sources.Examples.TraceSubstancesFlowSource + (if used with water instead of air) + is translated in pedantic mode in Dymola 2016. + The reason is that pressures use Medium.p_default as start values, + but + + Modelica.Media.Interfaces.Types + sets a default value of 1E-5. + A similar change has been done for pressure and density. + This fixes + #266.
      • -
    - -

    - This function computes the derivative of density with respect to temperature - at constant pressure. -

    - -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. + June 6, 2015, by Michael Wetter:
      + Changed type of BaseProperties.T from + Modelica.Units.SI.Temperature to Temperature. + Otherwise, it has a different start value than Medium.T, which + causes an error if + + AixLib.Media.Examples.WaterProperties + is translated in pedantic mode. + This fixes + #266.
      • -
    - -

    - This function returns the partial derivative of density - with respect to mass fraction. - This value is zero because in this medium, density is proportional - to pressure, but independent of the species concentration. -

    - -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. + June 5, 2015, by Michael Wetter:
      + Added stateSelect attribute in BaseProperties.T + to allow correct use of preferredMediumState as + described in + + Modelica.Media.Interfaces.PartialMedium, + and set preferredMediumState=false + to keep the same states as were used before. + This is for + #260.
      • -
    - -

    - The thermodynamic state record - is computed from density d, temperature T and composition X. -

    - - The - thermodynamic state record is computed from pressure p, specific enthalpy h and composition X. - - The - thermodynamic state record is computed from pressure p, temperature T and composition X. - -

    - This function returns the thermodynamic state based on pressure, - specific entropy and mass fraction. -

    -

    - The state is computed by symbolically solving - - AixLib.Media.Air.specificEntropy - for temperature. -

    - -
    • - November 27, 2013, by Michael Wetter:
      - First implementation. + June 5, 2015, by Michael Wetter:
      + Removed ThermodynamicState declaration as this lead to + the error + \"Attempting to redeclare record ThermodynamicState when the original was not replaceable.\" + in Dymola 2016 using the pedantic model check.
      • -
    - - Specific enthalpy as a function of temperature and species concentration. - The pressure is input for compatibility with the medium models, but the specific enthalpy - is independent of the pressure. - -
    • - April 30, 2015, by Filip Jorissen and Michael Wetter:
      + May 1, 2015, by Michael Wetter:
      Added Inline=true for issue 227.
      • -
    - -

    - This function computes the specific enthalpy for - an isentropic state change from the temperature - that corresponds to the state refState - to reference_T. -

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - - Temperature is returned from the thermodynamic state record input as a simple assignment. - -

    - This function returns the molar mass. -

    - -
      -
    • - December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - - Temperature as a function of specific enthalpy and species concentration. - The pressure is input for compatibility with the medium models, but the temperature - is independent of the pressure. - -
    • - April 30, 2015, by Filip Jorissen and Michael Wetter:
      - Added Inline=true for - - issue 227. + February 25, 2015, by Michael Wetter:
      + Removed stateSelect attribute on pressure as this caused + + AixLib.Examples.Tutorial.SpaceCooling.System3 + to fail with the error message + \"differentiated if-then-else was not continuous\".
      • -
    - -

    - This data record contains the coefficients for perfect gases. -

    - -
    • - September 12, 2014, by Michael Wetter:
      - Corrected the wrong location of the preferredView - and the revisions annotation. + October 15, 2014, by Michael Wetter:
      + Reimplemented media based on + 446aa83.
    • - November 21, 2013, by Michael Wetter:
      - First implementation. -
      • -
    - -

    - This medium package models moist air using a gas law in which pressure and temperature - are independent, which often leads to significantly faster and more robust computations. - The specific heat capacities at constant pressure and at constant volume are constant. - The air is assumed to be not saturated. -

    -

    - This medium uses the gas law -

    -

    - ρ/ρstp = p/pstp, -

    -

    - where - pstd and ρstp are constant reference - temperature and density, rathern than the ideal gas law -

    -

    - ρ = p ⁄(R T), -

    -

    - where R is the gas constant and T is the temperature. -

    -

    - This formulation often leads to smaller systems of nonlinear equations - because equations for pressure and temperature are decoupled. - Therefore, if air inside a control volume such as room air is heated, it - does not increase its specific volume. Consequently, merely heating or cooling - a control volume does not affect the air flow calculations in a duct network - that may be connected to that volume. - Note that multizone air exchange simulation in which buoyancy drives the - air flow is still possible as the models in - - AixLib.Airflow.Multizone compute the mass density using the function - - AixLib.Utilities.Psychrometrics.Functions.density_pTX in which density - is a function of temperature. -

    -

    - Note that models in this package implement the equation for the internal energy as -

    -

    - u = h - pstp ⁄ ρstp, -

    -

    - where - u is the internal energy per unit mass, - h is the enthalpy per unit mass, - pstp is the static pressure and - ρstp is the mass density at standard pressure and temperature. - The reason for this implementation is that in general, -

    -

    - h = u + p v, -

    -

    - from which follows that -

    -

    - u = h - p v = h - p ⁄ ρ = h - pstp ⁄ ρstd, -

    -

    - because p ⁄ ρ = pstp ⁄ ρstp in this medium model. -

    -

    - The enthalpy is computed using the convention that h=0 - if T=0 °C and no water vapor is present. -

    - -
      -
    • - September 28, 2020, by Michael Wetter:
      - Reformulated BaseProperties to avoid event-triggering assertions.
      - This is for - #1401. -
      • -
    • - January 11, 2019 by Michael Wetter:
      - Reforulated assignment of X_int in setState_psX.
      - This is for - #1079. -
      • -
    • - October 26, 2018, by Filip Jorissen and Michael Wetter:
      - Now printing different messages if temperature is above or below its limit, - and adding instance name as JModelica does not print the full instance name in the assertion. - This is for - #1045. -
      • -
    • - November 4, 2016, by Michael Wetter:
      - Set default value for dT.start in base properties.
      - This is for - #575. -
      • -
    • - June 6, 2015, by Michael Wetter:
      - Set AbsolutePressure(start=p_default) to avoid - a translation error if - - AixLib.Fluid.Sources.Examples.TraceSubstancesFlowSource - is translated in pedantic mode in Dymola 2016. - The reason is that pressures use Medium.p_default as start values, - but - - Modelica.Media.Interfaces.Types - sets a default value of 1E-5. - A similar change has been done for pressure. - This fixes - #266. -
      • -
    • - June 5, 2015, by Michael Wetter:
      - Added stateSelect attribute in BaseProperties.T - to allow correct use of preferredMediumState as - described in - - Modelica.Media.Interfaces.PartialMedium. - Note that the default is preferredMediumState=false - and hence the same states are used as were used before. - This is for - #260. -
      • -
    • - May 11, 2015, by Michael Wetter:
      - Removed - p(stateSelect=if preferredMediumStates then StateSelect.prefer else StateSelect.default) - in declaration of BaseProperties. - Otherwise, when models that contain a fluid volume - are exported as an FMU, their pressure would be - differentiated with respect to time. This would require - the time derivative of the inlet pressure, which is not available, - causing the translation to stop with an error. -
      • -
    • - May 1, 2015, by Michael Wetter:
      - Added Inline=true for - - issue 227. -
      • -
    • - March 20, 2015, by Michael Wetter:
      - Added missing term state.p/reference_p in function - specificEntropy. - #193. -
      • -
    • - February 3, 2015, by Michael Wetter:
      - Removed stateSelect.prefer for temperature. - This is for - #160. -
      • -
    • - July 24, 2014, by Michael Wetter:
      - Changed implementation to use - - AixLib.Utilities.Psychrometrics.Constants. - This was done to use consistent values throughout the library. -
      • -
    • - November 16, 2013, by Michael Wetter:
      - Revised and simplified the implementation. -
      • -
    • - November 14, 2013, by Michael Wetter:
      - Removed function - HeatCapacityOfWater - which is neither needed nor implemented in the - Modelica Standard Library. -
      • -
    • - November 13, 2013, by Michael Wetter:
      - Removed non-used computations in specificEnthalpy_pTX and - in temperature_phX. -
      • -
    • - March 29, 2013, by Michael Wetter:
      - Added final standardOrderComponents=true in the - BaseProperties declaration. This avoids an error - when models are checked in Dymola 2014 in the pedenatic mode. -
      • -
    • - April 12, 2012, by Michael Wetter:
      - Added keyword each to Xi(stateSelect=...). -
      • -
    • - April 4, 2012, by Michael Wetter:
      - Added redeclaration of ThermodynamicState to avoid a warning - during model check and translation. -
      • -
    • - August 3, 2011, by Michael Wetter:
      - Fixed bug in u=h-R*T, which is only valid for ideal gases. - For this medium, the function is u=h-pStd/dStp. -
      • -
    • - January 27, 2010, by Michael Wetter:
      - Fixed bug in else branch of function setState_phX - that lead to a run-time error when the constructor of this function was called. -
      • -
    • - January 22, 2010, by Michael Wetter:
      - Added implementation of function - - enthalpyOfNonCondensingGas and its derivative. -
      • -
    • - January 13, 2010, by Michael Wetter:
      - Fixed implementation of derivative functions. -
      • -
    • - August 28, 2008, by Michael Wetter:
      - First implementation. + November 15, 2013, by Michael Wetter:
      + Complete new reimplementation because the previous version + had the option to add a compressibility to the medium, which + has never been used.
    @@ -14185,6 +11726,13 @@ line 23 column 2 - Warning:

    attribute "align" not allowed for HTML5

    Model with basic thermodynamic properties.

    +

    + This base properties model is identical to Modelica.Media.Water.ConstantPropertyLiquidWater, + except that the equation u = cv_const*(T - reference_T) + has been replaced by u=h because + cp_const=cv_const. +

    This model provides equation for the following thermodynamic properties: @@ -14291,5264 +11839,6551 @@ line 23 column 2 - Warning:

    attribute "align" not allowed for HTML5

    +

    + Enthalpy of the water. +

      -
    • September 22, 2020, by Michael Wetter:
      - First implementation based on Modelica Standard Library, but with - noEvent added to check of bounds. +
    • October 16, 2014 by Michael Wetter:
      + First implementation. This function is used by AixLib.Fluid.MixingVolumes.MixingVolumeMoistAir.
    -Density is computed from pressure, temperature and composition in the -thermodynamic state record applying the ideal gas law.

    - This function returns the dynamic viscosity. + This medium package models liquid water.

    -

    - Implementation -

    - The function is based on the 5th order polynomial of Modelica.Media.Air.MoistAir.dynamicViscosity. - However, for the typical range of temperatures encountered in - building applications, a linear function sufficies. This - implementation is therefore the above 5th order polynomial, - linearized around 20°C. The relative error of this - linearization is 0.4% at -20°C, and less then - 0.2% between -5°C and +50°C. + The mass density is computed using a constant value of 995.586 + kg/s. For a medium model in which the density is a function of + temperature, use + AixLib.Media.Specialized.Water.TemperatureDependentDensity which + may have considerably higher computing time.

    -
      -
    • December 19, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -The ideal gas constant for moist air is computed from thermodynamic -state assuming that all water is in the gas phase. -Pressure is returned from the thermodynamic state record input as a -simple assignment.

    - This function returns the isobaric expansion coefficient at constant - pressure, which is zero for this medium. The isobaric expansion - coefficient at constant pressure is + For the specific heat capacities at constant pressure and at constant + volume, a constant value of 4184 J/(kg K), which corresponds + to 20°C is used. The figure below shows the relative error of + the specific heat capacity that is introduced by this simplification.

    -

    - βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p = 0, +

    + +

    - where v is the specific volume, T is the temperature - and p is the pressure. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the isothermal compressibility coefficient. The - isothermal compressibility is -

    -

    - κT = -1 ⁄ v   (∂ v ⁄ ∂ p)T = -1 ⁄ p, -

    -

    - where v is the specific volume, T is the temperature - and p is the pressure. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the specific entropy. -

    -

    - The specific entropy of the mixture is obtained from -

    -

    - s = ss + sm, -

    -

    - where ss is the entropy change due to the state - change (relative to the reference temperature) and - sm is the entropy change due to mixing of the dry - air and water vapor. -

    -

    - The entropy change due to change in state is obtained from -

    -

    - ss = cv ln(T/T0) + R - ln(v/v0)
    - = cv ln(T/T0) + R ln(ρ0/ρ) -

    -

    - If we assume ρ = p0/(R T), and because - cp = cv + R, we can write -

    -

    - ss = cv ln(T/T0) + R - ln(T/T0)
    - =cp ln(T/T0). -

    -

    - Next, the entropy of mixing is obtained from a reversible isothermal - expansion process. Hence, -

    -

    - sm = -R ∑i( Xi ⁄ Mi - ln(Yi p/p0)), -

    -

    - where R is the gas constant, X is the mass fraction, - M is the molar mass, and Y is the mole fraction. -

    -

    - To obtain the state for a given pressure, entropy and mass fraction, - use AixLib.Media.Air.setState_psX. + The enthalpy is computed using the convention that h=0 if + T=0 °C.

    Limitations

    - This function is only valid for a relative humidity below 100%. -

    -
      -
    • November 27, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function returns the partial derivative of density with respect - to pressure at constant temperature. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. -
      • -
    -

    - This function computes the derivative of density with respect to - temperature at constant pressure. + Density, specific heat capacity, thermal conductivity and viscosity + are constant. Water is modeled as an incompressible liquid. There are + no phase changes.

      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. +
    • September 28, 2020, by Michael Wetter:
      + Reformulated BaseProperties to avoid event-triggering + assertions.
      + This is for #1401.
      • -
    -

    - This function returns the partial derivative of density with respect - to mass fraction. This value is zero because in this medium, density - is proportional to pressure, but independent of the species - concentration. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. +
    • October 26, 2018, by Filip Jorissen and Michael Wetter:
      + Now printing different messages if temperature is above or below + its limit, and adding instance name as JModelica does not print the + full instance name in the assertion. This is for #1045.
      • -
    -

    - The - thermodynamic state record is computed from density - d, temperature T and composition - X. -

    -The -thermodynamic state record is computed from pressure p, specific -enthalpy h and composition X. -The -thermodynamic state record is computed from pressure p, temperature -T and composition X. -

    - This function returns the thermodynamic state based on pressure, - specific entropy and mass fraction. -

    -

    - The state is computed by symbolically solving AixLib.Media.Air.specificEntropy - for temperature. -

    -
      -
    • November 27, 2013, by Michael Wetter:
      - First implementation. +
    • June 6, 2015, by Michael Wetter:
      + Set AbsolutePressure(start=p_default) to avoid a + translation error if + AixLib.Fluid.Sources.Examples.TraceSubstancesFlowSource (if + used with water instead of air) is translated in pedantic mode in + Dymola 2016. The reason is that pressures use + Medium.p_default as start values, but Modelica.Media.Interfaces.Types + sets a default value of 1E-5. A similar change has been done + for pressure and density. This fixes #266.
      • -
    -Specific enthalpy as a function of temperature and species -concentration. The pressure is input for compatibility with the medium -models, but the specific enthalpy is independent of the pressure. -
      -
    • April 30, 2015, by Filip Jorissen and Michael Wetter:
      - Added Inline=true for issue 227. +
    • June 6, 2015, by Michael Wetter:
      + Changed type of BaseProperties.T from + Modelica.Units.SI.Temperature to + Temperature. Otherwise, it has a different start value + than Medium.T, which causes an error if AixLib.Media.Examples.WaterProperties + is translated in pedantic mode. This fixes #266.
      • -
    -

    - This function computes the specific enthalpy for an isentropic state - change from the temperature that corresponds to the state - refState to reference_T. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. +
    • June 5, 2015, by Michael Wetter:
      + Added stateSelect attribute in + BaseProperties.T to allow correct use of + preferredMediumState as described in Modelica.Media.Interfaces.PartialMedium, + and set preferredMediumState=false to keep the same + states as were used before. This is for #260.
      • -
    -Temperature is returned from the thermodynamic state record input as a -simple assignment. -

    - This function returns the molar mass. -

    -
      -
    • December 18, 2013, by Michael Wetter:
      - First implementation. +
    • June 5, 2015, by Michael Wetter:
      + Removed ThermodynamicState declaration as this lead to + the error \"Attempting to redeclare record ThermodynamicState when + the original was not replaceable.\" in Dymola 2016 using the + pedantic model check.
      • -
    -Temperature as a function of specific enthalpy and species -concentration. The pressure is input for compatibility with the medium -models, but the temperature is independent of the pressure. -
      -
    • April 30, 2015, by Filip Jorissen and Michael Wetter:
      +
    • May 1, 2015, by Michael Wetter:
      Added Inline=true for issue 227.
      • -
    -

    - This data record contains the coefficients for perfect gases. -

    -
      -
    • September 12, 2014, by Michael Wetter:
      - Corrected the wrong location of the preferredView and - the revisions annotation. +
    • February 25, 2015, by Michael Wetter:
      + Removed stateSelect attribute on pressure as this + caused AixLib.Examples.Tutorial.SpaceCooling.System3 + to fail with the error message \"differentiated if-then-else was not + continuous\".
      • -
    • November 21, 2013, by Michael Wetter:
      - First implementation. +
    • October 15, 2014, by Michael Wetter:
      + Reimplemented media based on + 446aa83. +
      • +
    • November 15, 2013, by Michael Wetter:
      + Complete new reimplementation because the previous version had the + option to add a compressibility to the medium, which has never been + used.
    + +-------- Errors -------- +line 17 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +line 18 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Sensors/SensibleEnthalpyFlowRate.mo ---- +-------- HTML Code -------- + +

    + This model outputs the sensible enthalphy flow rate of the medium in the flow + between its fluid ports. In particular, if the total enthalpy flow rate is +

    +

    + Ḣtot = Ḣsen + Ḣlat, +

    +

    + where + Ḣsen = ṁ (1-Xw) cp,air, + then this sensor outputs Ḣ = Ḣsen. +

    + +

    + If the parameter tau is non-zero, then the measured + specific sensible enthalpy hout that is used to + compute the sensible enthalpy flow rate + Ḣsen = ṁ hout + is computed using a first order differential equation. + See + AixLib.Fluid.Sensors.UsersGuide for an explanation. +

    + +

    + For a sensor that measures + Ḣtot, use + + AixLib.Fluid.Sensors.EnthalpyFlowRate.
    + For a sensor that measures + Ḣlat, use + + AixLib.Fluid.Sensors.LatentEnthalpyFlowRate. +

    + +

    + The sensor is ideal, i.e., it does not influence the fluid. + The sensor can only be used with medium models that implement the function + enthalpyOfNonCondensingGas(T).

    + + +
      +
    • + October 19, 2020, by Antoine Gautier:
      + Changed default value for tau from 1 to 0.
      + This is for + #1406. +
      • +
    • + February 25, 2020, by Michael Wetter:
      + Changed icon to display its operating state.
      + This is for + #1294. +
      • +
    • + January 18, 2016 by Filip Jorissen:
      + Using parameter tauInv + since this now exists in + AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. + This is for + #372. +
      • +
    • + September 10, 2013, by Michael Wetter:
      + Changed medium declaration in the extends statement + to replaceable to avoid a translation error in + OpenModelica. +
      • +
    • + August 31, 2013, by Michael Wetter:
      + Removed default value tau=0 as the base class + already sets tau=1. + This change was made so that all sensors use the same default value. +
      • +
    • + December 18, 2012, by Michael Wetter:
      + Moved computation of i_w to new base class + + AixLib.Fluid.BaseClasses.IndexWater. + The value of this parameter is now assigned dynamically and does not require to be specified + by the user. +
      • +
    • + November 3, 2011, by Michael Wetter:
      + Moved der(h_out) := 0; from the initial algorithm section to + the initial equation section + as this assignment does not conform to the Modelica specification. +
      • +
    • + August 10, 2011 by Michael Wetter:
      + Added parameter i_w and an assert statement to + make sure it is set correctly. Without this change, Dymola + cannot differentiate the model when reducing the index of the DAE. +
      • +
    • + June 3, 2011 by Michael Wetter:
      + Revised implementation to add dynamics in such a way that + the time constant increases as the mass flow rate tends to zero. + This can improve the numerics. +
      • +
    • + February 22, by Michael Wetter:
      + Improved code that searches for index of 'water' in the medium model. +
      • +
    • + September 9, 2009 by Michael Wetter:
      + First implementation. + Implementation is based on enthalpy sensor of Modelica.Fluid. +
      • +
    + +-------- Corrected Code --------

    - This medium package models moist air using a gas law in which - pressure and temperature are independent, which often leads to - significantly faster and more robust computations. The specific heat - capacities at constant pressure and at constant volume are constant. - The air is assumed to be not saturated. -

    -

    - This medium uses the gas law -

    -

    - ρ/ρstp = p/pstp, -

    -

    - where pstd and ρstp are constant - reference temperature and density, rathern than the ideal gas law -

    -

    - ρ = p ⁄(R T), -

    -

    - where R is the gas constant and T is the temperature. -

    -

    - This formulation often leads to smaller systems of nonlinear - equations because equations for pressure and temperature are - decoupled. Therefore, if air inside a control volume such as room air - is heated, it does not increase its specific volume. Consequently, - merely heating or cooling a control volume does not affect the air - flow calculations in a duct network that may be connected to that - volume. Note that multizone air exchange simulation in which buoyancy - drives the air flow is still possible as the models in AixLib.Airflow.Multizone - compute the mass density using the function AixLib.Utilities.Psychrometrics.Functions.density_pTX - in which density is a function of temperature. -

    -

    - Note that models in this package implement the equation for the - internal energy as + This model outputs the sensible enthalphy flow rate of the + medium in the flow between its fluid ports. In particular, if the + total enthalpy flow rate is

    - u = h - pstp ⁄ ρstp, + Ḣtot = Ḣsen + Ḣlat,

    - where u is the internal energy per unit mass, h is the - enthalpy per unit mass, pstp is the static pressure - and ρstp is the mass density at standard pressure - and temperature. The reason for this implementation is that in - general, -

    -

    - h = u + p v, + where Ḣsen = ṁ (1-Xw) + cp,air, then this sensor outputs Ḣ = + Ḣsen.

    - from which follows that -

    -

    - u = h - p v = h - p ⁄ ρ = h - pstp ⁄ ρstd, + If the parameter tau is non-zero, then the measured + specific sensible enthalpy hout that is used to + compute the sensible enthalpy flow rate Ḣsen = ṁ + hout is computed using a first order differential + equation. See AixLib.Fluid.Sensors.UsersGuide + for an explanation.

    - because p ⁄ ρ = pstp ⁄ ρstp in this - medium model. + For a sensor that measures Ḣtot, use AixLib.Fluid.Sensors.EnthalpyFlowRate.
    + + For a sensor that measures Ḣlat, use AixLib.Fluid.Sensors.LatentEnthalpyFlowRate.

    - The enthalpy is computed using the convention that h=0 if - T=0 °C and no water vapor is present. + The sensor is ideal, i.e., it does not influence the fluid. The + sensor can only be used with medium models that implement the + function enthalpyOfNonCondensingGas(T).

      -
    • September 28, 2020, by Michael Wetter:
      - Reformulated BaseProperties to avoid event-triggering - assertions.
      - This is for #1401. -
      • -
    • January 11, 2019 by Michael Wetter:
      - Reforulated assignment of X_int in - setState_psX.
      +
    • October 19, 2020, by Antoine Gautier:
      + Changed default value for tau from 1 to + 0.
      This is for #1079. -
      • -
    • October 26, 2018, by Filip Jorissen and Michael Wetter:
      - Now printing different messages if temperature is above or below - its limit, and adding instance name as JModelica does not print the - full instance name in the assertion. This is for #1045. + \"https://github.com/ibpsa/modelica-ibpsa/issues/1406\">#1406.
      • -
    • November 4, 2016, by Michael Wetter:
      - Set default value for dT.start in base properties.
      +
    • February 25, 2020, by Michael Wetter:
      + Changed icon to display its operating state.
      This is for #575. -
      • -
    • June 6, 2015, by Michael Wetter:
      - Set AbsolutePressure(start=p_default) to avoid a - translation error if - AixLib.Fluid.Sources.Examples.TraceSubstancesFlowSource is - translated in pedantic mode in Dymola 2016. The reason is that - pressures use Medium.p_default as start values, but - Modelica.Media.Interfaces.Types - sets a default value of 1E-5. A similar change has been done - for pressure. This fixes #266. + \"https://github.com/ibpsa/modelica-ibpsa/issues/1294\">#1294.
      • -
    • June 5, 2015, by Michael Wetter:
      - Added stateSelect attribute in - BaseProperties.T to allow correct use of - preferredMediumState as described in Modelica.Media.Interfaces.PartialMedium. - Note that the default is preferredMediumState=false - and hence the same states are used as were used before. This is for +
    • January 18, 2016 by Filip Jorissen:
      + Using parameter tauInv since this now exists in #260. + \"modelica://AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor\"> + AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. This + is for #372.
      • -
    • May 11, 2015, by Michael Wetter:
      - Removed p(stateSelect=if preferredMediumStates then - StateSelect.prefer else StateSelect.default) in declaration - of BaseProperties. Otherwise, when models that contain - a fluid volume are exported as an FMU, their pressure would be - differentiated with respect to time. This would require the time - derivative of the inlet pressure, which is not available, causing - the translation to stop with an error. +
    • September 10, 2013, by Michael Wetter:
      + Changed medium declaration in the extends statement to + replaceable to avoid a translation error in + OpenModelica.
      • -
    • May 1, 2015, by Michael Wetter:
      - Added Inline=true for issue 227. +
    • August 31, 2013, by Michael Wetter:
      + Removed default value tau=0 as the base class already + sets tau=1. This change was made so that all sensors + use the same default value.
      • -
    • March 20, 2015, by Michael Wetter:
      - Added missing term state.p/reference_p in function - specificEntropy. #193. +
    • December 18, 2012, by Michael Wetter:
      + Moved computation of i_w to new base class AixLib.Fluid.BaseClasses.IndexWater. + The value of this parameter is now assigned dynamically and does + not require to be specified by the user.
      • -
    • February 3, 2015, by Michael Wetter:
      - Removed stateSelect.prefer for temperature. This is - for #160. -
      • -
    • July 24, 2014, by Michael Wetter:
      - Changed implementation to use AixLib.Utilities.Psychrometrics.Constants. - This was done to use consistent values throughout the library. -
      • -
    • November 16, 2013, by Michael Wetter:
      - Revised and simplified the implementation. -
      • -
    • November 14, 2013, by Michael Wetter:
      - Removed function HeatCapacityOfWater which is neither - needed nor implemented in the Modelica Standard Library. -
      • -
    • November 13, 2013, by Michael Wetter:
      - Removed non-used computations in specificEnthalpy_pTX - and in temperature_phX. -
      • -
    • March 29, 2013, by Michael Wetter:
      - Added final standardOrderComponents=true in the - BaseProperties declaration. This avoids an error when - models are checked in Dymola 2014 in the pedenatic mode. -
      • -
    • April 12, 2012, by Michael Wetter:
      - Added keyword each to - Xi(stateSelect=...). -
      • -
    • April 4, 2012, by Michael Wetter:
      - Added redeclaration of ThermodynamicState to avoid a - warning during model check and translation. -
      • -
    • August 3, 2011, by Michael Wetter:
      - Fixed bug in u=h-R*T, which is only valid for ideal - gases. For this medium, the function is u=h-pStd/dStp. +
    • November 3, 2011, by Michael Wetter:
      + Moved der(h_out) := 0; from the initial algorithm + section to the initial equation section as this assignment does not + conform to the Modelica specification.
      • -
    • January 27, 2010, by Michael Wetter:
      - Fixed bug in else branch of function - setState_phX that lead to a run-time error when the - constructor of this function was called. +
    • August 10, 2011 by Michael Wetter:
      + Added parameter i_w and an assert statement to make + sure it is set correctly. Without this change, Dymola cannot + differentiate the model when reducing the index of the DAE.
      • -
    • January 22, 2010, by Michael Wetter:
      - Added implementation of function - enthalpyOfNonCondensingGas and its derivative. +
    • June 3, 2011 by Michael Wetter:
      + Revised implementation to add dynamics in such a way that the time + constant increases as the mass flow rate tends to zero. This can + improve the numerics.
      • -
    • January 13, 2010, by Michael Wetter:
      - Fixed implementation of derivative functions. +
    • February 22, by Michael Wetter:
      + Improved code that searches for index of 'water' in the medium + model.
      • -
    • August 28, 2008, by Michael Wetter:
      - First implementation. +
    • September 9, 2009 by Michael Wetter:
      + First implementation. Implementation is based on enthalpy sensor of + Modelica.Fluid.
    -------- Errors -------- -line 8 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 - - -line 7 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 21 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 37 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - -line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 19 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 43 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 54 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 60 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/BoundaryConditions/Validation/BESTEST/WD400.mo ---- +---- AixLib/Fluid/Humidifiers/Humidifier_u.mo ---- -------- HTML Code -------- +

    + Model for an air humidifier or dehumidifier. +

    +

    + This model adds (or removes) moisture from the air stream. + The amount of exchanged moisture is equal to +

    +

    + ṁwat = u ṁwat,nom, +

    +

    + where u is the control input signal and + ṁwat,nom is equal to the parameter mWat_flow_nominal. + The parameter mWat_flow_nominal can be positive or negative. + If ṁwat is positive, then moisture is added + to the air stream, otherwise it is removed. +

    +

    + If the heat port heatPort is unconnected, then the enthalpy of the + air that flows through the device remains unchanged, e.g., the humidification + is adiabatic. To change the enthalpy of the air, add heat flow to the connector + heatPort. +

    +
    • - September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the weather data bus.
      + March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      This is for - IBPSA, #1477. + #1542.
    • - March 11, 2020, by Ettore Zanetti:
      - First implementation. + April 12, 2017, by Michael Wetter:
      + Removed parameters use_T_in and T. + This removes the optional specification of temperature through the parameter T + or the input connector T_in. + Exposed the heat port of the control volume to allow adding heat, + for example, to use the model as a steam humidifier.
      + This is for issue + + Buildings #704.
    • - April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request - #1339. + May 6, 2015, by Michael Wetter:
      + Set prescribedHeatFlowRate=true. + This is for issue + + #412.
    • - May 2, 2021, by Ettore Zanetti:
      - Updated weather file as explained in #1478. + May 29, 2014, by Michael Wetter:
      + Removed undesirable annotation Evaluate=true. +
      • +
    • + February 11, 2014 by Michael Wetter:
      + Corrected issue #197 + which led to twice the amount of latent heat being added to the fluid stream. +
      • +
    • + October 14, 2013 by Michael Wetter:
      + Constrained medium to be a subclass of + Modelica.Media.Interfaces.PartialCondensingGases, + as this base class declares the function + enthalpyOfCondensingGas. +
      • +
    • + July 30, 2013 by Michael Wetter:
      + Updated model to use new variable mWat_flow + in the base class. +
      • +
    • + May 24, 2011, by Michael Wetter:
      + Changed base class to allow using the model as a dynamic or a steady-state model. +
      • +
    • + April 14, 2010, by Michael Wetter:
      + Converted temperature input to a conditional connector. +
      • +
    • + April 17, 2008, by Michael Wetter:
      + First implementation.
    -

    WD400: High Latitude Case

    -

    Weather data file : WD400.epw

    -

    Table 1: Site Data for Weather file WD400.epw

    -
    - - - - - - - - - - - - - - - -

    Latitude

    71.286° north

    Longitude

    156.767° west

    Altitude

    10 m

    Time Zone

    -9

    - -------- Corrected Code -------- +

    + Model for an air humidifier or dehumidifier. +

    +

    + This model adds (or removes) moisture from the air stream. The amount + of exchanged moisture is equal to +

    +

    + ṁwat = u ṁwat,nom, +

    +

    + where u is the control input signal and + ṁwat,nom is equal to the parameter + mWat_flow_nominal. The parameter + mWat_flow_nominal can be positive or negative. If + ṁwat is positive, then moisture is added to the + air stream, otherwise it is removed. +

    +

    + If the heat port heatPort is unconnected, then the + enthalpy of the air that flows through the device remains unchanged, + e.g., the humidification is adiabatic. To change the enthalpy of the + air, add heat flow to the connector heatPort. +

      -
    • September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the - weather data bus.
      +
    • March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      This is for IBPSA, - #1477. + \"https://github.com/ibpsa/modelica-ibpsa/issues/1542\">#1542.
      • -
    • March 11, 2020, by Ettore Zanetti:
      - First implementation. +
    • April 12, 2017, by Michael Wetter:
      + Removed parameters use_T_in and T. This + removes the optional specification of temperature through the + parameter T or the input connector T_in. + Exposed the heat port of the control volume to allow adding heat, + for example, to use the model as a steam humidifier.
      + This is for issue Buildings + #704.
      • -
    • April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request #1339. +
    • May 6, 2015, by Michael Wetter:
      + Set prescribedHeatFlowRate=true. This is for issue + #412.
      • -
    • May 2, 2021, by Ettore Zanetti:
      - Updated weather file as explained in #1478. +
    • May 29, 2014, by Michael Wetter:
      + Removed undesirable annotation Evaluate=true.
      • -
    -

    - WD400: High Latitude Case -

    -

    - Weather data file : WD400.epw -

    -

    - Table 1: Site Data for Weather file WD400.epw -

    - - - - - - - - - - - - - - - - - -
    -

    - Latitude -

    -     		-

    - 71.286° north -

    -
    -

    - Longitude -

    -     		-

    - 156.767° west -

    -
    -

    - Altitude -

    -     		-

    - 10 m -

    -
    -

    - Time Zone -

    -     		-

    - -9 -

    -
    +
  • February 11, 2014 by Michael Wetter:
    + Corrected issue #197 + which led to twice the amount of latent heat being added to the + fluid stream. +
    • +
  • October 14, 2013 by Michael Wetter:
    + Constrained medium to be a subclass of + Modelica.Media.Interfaces.PartialCondensingGases, as + this base class declares the function + enthalpyOfCondensingGas. +
    • +
  • July 30, 2013 by Michael Wetter:
    + Updated model to use new variable mWat_flow in the + base class. +
    • +
  • May 24, 2011, by Michael Wetter:
    + Changed base class to allow using the model as a dynamic or a + steady-state model. +
    • +
  • April 14, 2010, by Michael Wetter:
    + Converted temperature input to a conditional connector. +
    • +
  • April 17, 2008, by Michael Wetter:
    + First implementation. +
    • + -------- Errors -------- -line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 +line 9 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Actuators/Valves/TwoWayTable.mo ---- +---- AixLib/Controls/Continuous/Examples/NumberOfRequests.mo ---- -------- HTML Code -------- +

      +
    • + January 12, 2017, by Thierry S. Nouidui:
      + Modified example to prevent simultaneous events + This is for + #646. +
      • +
    • + November 21, 2011, by Michael Wetter:
      + Added documentation. +
      • +
    +

    - Two way valve with opening characteristic that is configured through - a table. -

    -

    - The mass flow rate for the fully open valve is determined based - on the value of the parameter CvData. - For the different valve positions y ∈ [0, 1], this nominal flow rate is - scaled by the values of the parameter - flowCharacteristics. - The parameter flowCharacteristics declares a table of the form + Example that demonstrates the use of the block + + AixLib.Controls.Continuous.NumberOfRequests. + The parameters of the block are such that the output is incremented + for each input signal that is strictly larger than 0. + The figure below shows the inputs and the output of the block.

    -
    - - - - - - -
    y 0 ... 1
    φ l ... 1
    -

    - where l = Kv(y=0)/Kv(y=1) > 0 is the valve leakage. - The first row is the valve opening, and the second row is the - mass flow rate, relative to the mass flow rate of the fully open - valve, under the assumption of a constant pressure difference across the - valve. - A suggested value for the valve leakage is l=0.0001. - If l = 0, then this model will replace it with - l = 10-8 for numerical reasons. - For example, if a valve has Kv=0.5 [m3/h/bar1/2] and - a linear opening characteristics and - a valve leakage of l=0.0001, then one would set +

    + \"Simulation

    - 
    -  CvData=AixLib.Fluid.Types.CvTypes.Kv
-  Kv = 0.5
-  flowCharacteristics(y={0,1}, phi={0.0001,1})
-
    + +-------- Corrected Code -------- +
      +
    • January 12, 2017, by Thierry S. Nouidui:
      + Modified example to prevent simultaneous events This is for + #646. +
      • +
    • November 21, 2011, by Michael Wetter:
      + Added documentation. +
      • +
    +

    + Example that demonstrates the use of the block AixLib.Controls.Continuous.NumberOfRequests. + The parameters of the block are such that the output is incremented + for each input signal that is strictly larger than 0. The + figure below shows the inputs and the output of the block. +

    +

    + \"Simulation +

    + +-------- Errors -------- +line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Media/Air.mo ---- +-------- HTML Code -------- +

    - Note, however, that - - AixLib.Fluid.Actuators.Valves.TwoWayLinear provides a more - efficient implementation for this simple case. + Model with basic thermodynamic properties.

    - The parameter flowCharacteristics must meet the following - requirements, otherwise the model stops with an error: + This model provides equation for the following thermodynamic properties:

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    VariableUnitDescription
    TKtemperature
    pPaabsolute pressure
    dkg/m3density
    hJ/kgspecific enthalpy
    uJ/kgspecific internal energy
    Xi[nXi]kg/kgindependent mass fractions m_i/m
    RJ/kg.Kgas constant
    Mkg/molmolar mass
    +
    • - Their arrays - y and phi - must be strictly monotonic increasing. -
      • -
    • - The first value must satisfy - y[1]=0, and - phi[1] must be equal to the - leakage flow rate, which must be bigger than zero. - Otherwise, a default value of 1E-8 is used. -
      • -
    • - The last values must satisfy - y[end]=1 and - phi[end]=1. + September 22, 2020, by Michael Wetter:
      + First implementation based on Modelica Standard Library, + but with noEvent added to check of bounds.
    + + Density is computed from pressure, temperature and composition in the thermodynamic state record applying the ideal gas law. +

    - This model is based on the partial valve model - - AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. - Check this model for more information, such - as the regularization near the origin. + This function returns the dynamic viscosity.

    +

    Implementation

    - For an example that specifies an opening characteristics, see - - AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable. + The function is based on the 5th order polynomial + of + + Modelica.Media.Air.MoistAir.dynamicViscosity. + However, for the typical range of temperatures encountered + in building applications, a linear function sufficies. + This implementation is therefore the above 5th order polynomial, + linearized around 20°C. + The relative error of this linearization is + 0.4% at -20°C, + and less then + 0.2% between -5°C and +50°C.

    • - June 10, 2021, by Michael Wetter:
      - Changed implementation of the filter and changed the parameter order to a constant - as most users need not change this value.
      - This is for - #1498. + December 19, 2013, by Michael Wetter:
      + First implementation.
      • +
    + + The ideal gas constant for moist air is computed from thermodynamic state assuming that all water is in the gas phase. + + Pressure is returned from the thermodynamic state record input as a simple assignment. + +

    + This function returns the isobaric expansion coefficient at constant pressure, + which is zero for this medium. + The isobaric expansion coefficient at constant pressure is +

    +

    + βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p = 0, +

    +

    + where + v is the specific volume, + T is the temperature and + p is the pressure. +

    + +
    • - August 7, 2020, by Ettore Zanetti:
      - changed the computation of phi using - max(0.1*l, . ) to avoid - phi=0. - See - issue 1376. + December 18, 2013, by Michael Wetter:
      + First implementation.
      • +
    + +

    + This function returns the isothermal compressibility coefficient. + The isothermal compressibility is +

    +

    + κT = -1 ⁄ v   (∂ v ⁄ ∂ p)T + = -1 ⁄ p, +

    +

    + where + v is the specific volume, + T is the temperature and + p is the pressure. +

    + +
    • - November 9, 2019, by Filip Jorissen:
      - Guarded the computation of phi using - max(0, . ) to avoid - negative phi. - See - issue 1223. + December 18, 2013, by Michael Wetter:
      + First implementation.
      • +
    + +

    + This function computes the specific entropy. +

    +

    + The specific entropy of the mixture is obtained from +

    +

    + s = ss + sm, +

    +

    + where + ss is the entropy change due to the state change + (relative to the reference temperature) and + sm is the entropy change due to mixing + of the dry air and water vapor. +

    +

    + The entropy change due to change in state is obtained from +

    +

    + ss = cv ln(T/T0) + R ln(v/v0)
    + = cv ln(T/T0) + R ln(ρ0/ρ) +

    +

    If we assume ρ = p0/(R T), + and because cp = cv + R, + we can write +

    +

    + ss = cv ln(T/T0) + R ln(T/T0)
    + =cp ln(T/T0). +

    +

    + Next, the entropy of mixing is obtained from a reversible isothermal + expansion process. Hence, +

    +

    + sm = -R ∑i( Xi ⁄ Mi + ln(Yi p/p0)), +

    +

    + where R is the gas constant, + X is the mass fraction, + M is the molar mass, and + Y is the mole fraction. +

    +

    + To obtain the state for a given pressure, entropy and mass fraction, use + + AixLib.Media.Air.setState_psX. +

    +

    Limitations

    +

    + This function is only valid for a relative humidity below 100%. +

    + +
    • - January 26, 2016, by Michael Wetter:
      - Removed equality comparison for Real in the - assert statements as this is not allowed in Modelica. + November 27, 2013, by Michael Wetter:
      + First implementation.
      • +
    + +

    + This function returns the partial derivative of density + with respect to pressure at constant temperature. +

    + +
    • - August 12, 2014, by Michael Wetter:
      - Removed the end keyword when accessing array elements, - as this language construct caused an error in OpenModelica. + December 18, 2013, by Michael Wetter:
      + First implementation.
      • +
    + +

    + This function computes the derivative of density with respect to temperature + at constant pressure. +

    + +
    • - April 4, 2014, by Michael Wetter:
      - Moved the assignment of the flow function phi - to the model instantiation because in its base class, - the keyword input - has been added to the variable phi. + December 18, 2013, by Michael Wetter:
      + First implementation.
      • +
    + +

    + This function returns the partial derivative of density + with respect to mass fraction. + This value is zero because in this medium, density is proportional + to pressure, but independent of the species concentration. +

    + +
    • - March 26, 2014 by Michael Wetter:
      + December 18, 2013, by Michael Wetter:
      First implementation.
    --------- Corrected Code -------- -

    - Two way valve with opening characteristic that is configured through - a table. -

    -

    - The mass flow rate for the fully open valve is determined based on - the value of the parameter CvData. For the different - valve positions y ∈ [0, 1], this nominal flow rate is scaled - by the values of the parameter flowCharacteristics. The - parameter flowCharacteristics declares a table of the - form -

    - - - - - - - - - - - - - -
    - y - - 0 - - ... - - 1 -
    - φ - - l - - ... - - 1 -
    -

    - where l = Kv(y=0)/Kv(y=1) > 0 is the - valve leakage. The first row is the valve opening, and the second row - is the mass flow rate, relative to the mass flow rate of the fully - open valve, under the assumption of a constant pressure difference - across the valve. A suggested value for the valve leakage is - l=0.0001. If l = 0, then this model will replace it - with l = 10-8 for numerical reasons. For example, - if a valve has Kv=0.5 - [m3/h/bar1/2] and a linear opening - characteristics and a valve leakage of l=0.0001, then one - would set -

    -
    -  CvData=AixLib.Fluid.Types.CvTypes.Kv
-  Kv = 0.5
-  flowCharacteristics(y={0,1}, phi={0.0001,1})
-
    -

    - Note, however, that AixLib.Fluid.Actuators.Valves.TwoWayLinear - provides a more efficient implementation for this simple case. -

    -

    - The parameter flowCharacteristics must meet the - following requirements, otherwise the model stops with an error: -

    -
      -
    • Their arrays y and phi must be strictly - monotonic increasing. -
      • -
    • The first value must satisfy y[1]=0, and - phi[1] must be equal to the leakage flow rate, which - must be bigger than zero. Otherwise, a default value of - 1E-8 is used. -
      • -
    • The last values must satisfy y[end]=1 and - phi[end]=1. -
      • -
    -

    - This model is based on the partial valve model AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. - Check this model for more information, such as the regularization - near the origin. -

    -

    - For an example that specifies an opening characteristics, see - - AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable. -

    -
      -
    • June 10, 2021, by Michael Wetter:
      - Changed implementation of the filter and changed the parameter - order to a constant as most users need not change this - value.
      - This is for #1498. -
      • -
    • August 7, 2020, by Ettore Zanetti:
      - changed the computation of phi using max(0.1*l, - . ) to avoid phi=0. See issue - 1376. -
      • -
    • November 9, 2019, by Filip Jorissen:
      - Guarded the computation of phi using max(0, . - ) to avoid negative phi. See issue - 1223. -
      • -
    • January 26, 2016, by Michael Wetter:
      - Removed equality comparison for Real in the - assert statements as this is not allowed in Modelica. -
      • -
    • August 12, 2014, by Michael Wetter:
      - Removed the end keyword when accessing array elements, - as this language construct caused an error in OpenModelica. -
      • -
    • April 4, 2014, by Michael Wetter:
      - Moved the assignment of the flow function phi to the - model instantiation because in its base class, the keyword - input has been added to the variable phi. -
      • -
    • March 26, 2014 by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 14 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 - - ----- AixLib/Fluid/HeatExchangers/BaseClasses/HANaturalCylinder.mo ---- --------- HTML Code -------- - -

    - This model calculates the convection coefficient h for natural convection - from a cylinder submerged in fluid. h is calcualted using Eq 9.34 from - Incropera and DeWitt (1996). - Output of the block is the hA value. -

    -

    - The Nusselt number is computed as -

    -

    - NuD = (0.6 + (0.387 RaD(1/6))/(1+(0.559 Pr) - (9/16))(8/27))2); -

    -

    - where NuD is the Nusselt number, RaD is the - Rayleigh number and - Pr is the Prandtl number.
    - This correclation is accurate for RaD less than 1012. -

    -

    - h is then calculated from the Nusselt number. The equation is -

    -

    - h = NuD k/D -

    -

    - where k is the thermal conductivity of the fluid and D is the diameter - of the submerged cylinder. -

    -

    References

    -

    - Fundamentals of Heat and Mass Transfer (Fourth Edition), Frank Incropera and David - DeWitt, John Wiley and Sons, 1996 -

    - -
      -
    • - August 29, 2014 by Michael Wetter:
      - Refactored function calls for medium properties. -
      • +

      + The thermodynamic state record + is computed from density d, temperature T and composition X. +

      + + The + thermodynamic state record is computed from pressure p, specific enthalpy h and composition X. + + The + thermodynamic state record is computed from pressure p, temperature T and composition X. + +

      + This function returns the thermodynamic state based on pressure, + specific entropy and mass fraction. +

      +

      + The state is computed by symbolically solving + + AixLib.Media.Air.specificEntropy + for temperature. +

      + +
      • - May 10, 2013 by Michael Wetter:
        - Revised implementation to use hA_nominal as a parameter, and compute the - associated surface area A. This revision was required to have a consistent - computation of the hA values inside and outside of the coil in the - heat exchanger model of the water tank. + November 27, 2013, by Michael Wetter:
        + First implementation.
        • +
      + + Specific enthalpy as a function of temperature and species concentration. + The pressure is input for compatibility with the medium models, but the specific enthalpy + is independent of the pressure. + +
      • - February 26, 2013 by Peter Grant:
        - First implementation. + April 30, 2015, by Filip Jorissen and Michael Wetter:
        + Added Inline=true for + + issue 227.
      --------- Corrected Code -------- -

      - This model calculates the convection coefficient h for natural - convection from a cylinder submerged in fluid. h is calcualted - using Eq 9.34 from Incropera and DeWitt (1996). Output of the block - is the hA value. -

      -

      - The Nusselt number is computed as -

      -

      - NuD = (0.6 + (0.387 - RaD(1/6))/(1+(0.559 Pr) - (9/16))(8/27))2); -

      -

      - where NuD is the Nusselt number, - RaD is the Rayleigh number and Pr is the - Prandtl number.
      - This correclation is accurate for RaD less than - 1012. -

      -

      - h is then calculated from the Nusselt number. The equation is -

      -

      - h = NuD k/D -

      -

      - where k is the thermal conductivity of the fluid and D - is the diameter of the submerged cylinder. -

      -

      - References -

      -

      - Fundamentals of Heat and Mass Transfer (Fourth Edition), Frank - Incropera and David DeWitt, John Wiley and Sons, 1996 -

      -
        -
      • August 29, 2014 by Michael Wetter:
        - Refactored function calls for medium properties. -
        • -
      • May 10, 2013 by Michael Wetter:
        - Revised implementation to use hA_nominal as a - parameter, and compute the associated surface area A. - This revision was required to have a consistent computation of the - hA values inside and outside of the coil in the heat - exchanger model of the water tank. -
        • -
      • February 26, 2013 by Peter Grant:
        - First implementation. -
        • -
      - --------- Errors -------- -line 11 column 14 - Warning:

      attribute "align" not allowed for HTML5 -line 24 column 14 - Warning:

      attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Sensors/SensibleEnthalpyFlowRate.mo ---- --------- HTML Code -------- - -

      - This model outputs the sensible enthalphy flow rate of the medium in the flow - between its fluid ports. In particular, if the total enthalpy flow rate is -

      -

      - Ḣtot = Ḣsen + Ḣlat, -

      - where - Ḣsen = ṁ (1-Xw) cp,air, - then this sensor outputs Ḣ = Ḣsen. + This function computes the specific enthalpy for + an isentropic state change from the temperature + that corresponds to the state refState + to reference_T.

      -

      - If the parameter tau is non-zero, then the measured - specific sensible enthalpy hout that is used to - compute the sensible enthalpy flow rate - Ḣsen = ṁ hout - is computed using a first order differential equation. - See - AixLib.Fluid.Sensors.UsersGuide for an explanation. -

      +
        +
      • + December 18, 2013, by Michael Wetter:
        + First implementation. +
        • +
      -

      - For a sensor that measures - Ḣtot, use - - AixLib.Fluid.Sensors.EnthalpyFlowRate.
      - For a sensor that measures - Ḣlat, use - - AixLib.Fluid.Sensors.LatentEnthalpyFlowRate. -

      + Temperature is returned from the thermodynamic state record input as a simple assignment.

      - The sensor is ideal, i.e., it does not influence the fluid. - The sensor can only be used with medium models that implement the function - enthalpyOfNonCondensingGas(T).

      - + This function returns the molar mass. +

      • - October 19, 2020, by Antoine Gautier:
        - Changed default value for tau from 1 to 0.
        - This is for - #1406. + December 18, 2013, by Michael Wetter:
        + First implementation.
        • +
      + + Temperature as a function of specific enthalpy and species concentration. + The pressure is input for compatibility with the medium models, but the temperature + is independent of the pressure. + +
      • - February 25, 2020, by Michael Wetter:
        - Changed icon to display its operating state.
        - This is for - #1294. + April 30, 2015, by Filip Jorissen and Michael Wetter:
        + Added Inline=true for + + issue 227.
        • +
      + +

      + This data record contains the coefficients for perfect gases. +

      + +
      • - January 18, 2016 by Filip Jorissen:
        - Using parameter tauInv - since this now exists in - AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. + September 12, 2014, by Michael Wetter:
        + Corrected the wrong location of the preferredView + and the revisions annotation. +
        • +
      • + November 21, 2013, by Michael Wetter:
        + First implementation. +
        • +
      + +

      + This medium package models moist air using a gas law in which pressure and temperature + are independent, which often leads to significantly faster and more robust computations. + The specific heat capacities at constant pressure and at constant volume are constant. + The air is assumed to be not saturated. +

      +

      + This medium uses the gas law +

      +

      + ρ/ρstp = p/pstp, +

      +

      + where + pstd and ρstp are constant reference + temperature and density, rathern than the ideal gas law +

      +

      + ρ = p ⁄(R T), +

      +

      + where R is the gas constant and T is the temperature. +

      +

      + This formulation often leads to smaller systems of nonlinear equations + because equations for pressure and temperature are decoupled. + Therefore, if air inside a control volume such as room air is heated, it + does not increase its specific volume. Consequently, merely heating or cooling + a control volume does not affect the air flow calculations in a duct network + that may be connected to that volume. + Note that multizone air exchange simulation in which buoyancy drives the + air flow is still possible as the models in + + AixLib.Airflow.Multizone compute the mass density using the function + + AixLib.Utilities.Psychrometrics.Functions.density_pTX in which density + is a function of temperature. +

      +

      + Note that models in this package implement the equation for the internal energy as +

      +

      + u = h - pstp ⁄ ρstp, +

      +

      + where + u is the internal energy per unit mass, + h is the enthalpy per unit mass, + pstp is the static pressure and + ρstp is the mass density at standard pressure and temperature. + The reason for this implementation is that in general, +

      +

      + h = u + p v, +

      +

      + from which follows that +

      +

      + u = h - p v = h - p ⁄ ρ = h - pstp ⁄ ρstd, +

      +

      + because p ⁄ ρ = pstp ⁄ ρstp in this medium model. +

      +

      + The enthalpy is computed using the convention that h=0 + if T=0 °C and no water vapor is present. +

      + +
        +
      • + September 28, 2020, by Michael Wetter:
        + Reformulated BaseProperties to avoid event-triggering assertions.
        This is for - #372. + #1401.
      • - September 10, 2013, by Michael Wetter:
        - Changed medium declaration in the extends statement - to replaceable to avoid a translation error in - OpenModelica. + January 11, 2019 by Michael Wetter:
        + Reforulated assignment of X_int in setState_psX.
        + This is for + #1079.
      • - August 31, 2013, by Michael Wetter:
        - Removed default value tau=0 as the base class - already sets tau=1. - This change was made so that all sensors use the same default value. + October 26, 2018, by Filip Jorissen and Michael Wetter:
        + Now printing different messages if temperature is above or below its limit, + and adding instance name as JModelica does not print the full instance name in the assertion. + This is for + #1045.
      • - December 18, 2012, by Michael Wetter:
        - Moved computation of i_w to new base class - - AixLib.Fluid.BaseClasses.IndexWater. - The value of this parameter is now assigned dynamically and does not require to be specified - by the user. + November 4, 2016, by Michael Wetter:
        + Set default value for dT.start in base properties.
        + This is for + #575.
      • - November 3, 2011, by Michael Wetter:
        - Moved der(h_out) := 0; from the initial algorithm section to - the initial equation section - as this assignment does not conform to the Modelica specification. + June 6, 2015, by Michael Wetter:
        + Set AbsolutePressure(start=p_default) to avoid + a translation error if + + AixLib.Fluid.Sources.Examples.TraceSubstancesFlowSource + is translated in pedantic mode in Dymola 2016. + The reason is that pressures use Medium.p_default as start values, + but + + Modelica.Media.Interfaces.Types + sets a default value of 1E-5. + A similar change has been done for pressure. + This fixes + #266.
      • - August 10, 2011 by Michael Wetter:
        - Added parameter i_w and an assert statement to - make sure it is set correctly. Without this change, Dymola - cannot differentiate the model when reducing the index of the DAE. + June 5, 2015, by Michael Wetter:
        + Added stateSelect attribute in BaseProperties.T + to allow correct use of preferredMediumState as + described in + + Modelica.Media.Interfaces.PartialMedium. + Note that the default is preferredMediumState=false + and hence the same states are used as were used before. + This is for + #260.
      • - June 3, 2011 by Michael Wetter:
        - Revised implementation to add dynamics in such a way that - the time constant increases as the mass flow rate tends to zero. - This can improve the numerics. + May 11, 2015, by Michael Wetter:
        + Removed + p(stateSelect=if preferredMediumStates then StateSelect.prefer else StateSelect.default) + in declaration of BaseProperties. + Otherwise, when models that contain a fluid volume + are exported as an FMU, their pressure would be + differentiated with respect to time. This would require + the time derivative of the inlet pressure, which is not available, + causing the translation to stop with an error.
      • - February 22, by Michael Wetter:
        - Improved code that searches for index of 'water' in the medium model. + May 1, 2015, by Michael Wetter:
        + Added Inline=true for + + issue 227.
      • - September 9, 2009 by Michael Wetter:
        + March 20, 2015, by Michael Wetter:
        + Added missing term state.p/reference_p in function + specificEntropy. + #193. +
        • +
      • + February 3, 2015, by Michael Wetter:
        + Removed stateSelect.prefer for temperature. + This is for + #160. +
        • +
      • + July 24, 2014, by Michael Wetter:
        + Changed implementation to use + + AixLib.Utilities.Psychrometrics.Constants. + This was done to use consistent values throughout the library. +
        • +
      • + November 16, 2013, by Michael Wetter:
        + Revised and simplified the implementation. +
        • +
      • + November 14, 2013, by Michael Wetter:
        + Removed function + HeatCapacityOfWater + which is neither needed nor implemented in the + Modelica Standard Library. +
        • +
      • + November 13, 2013, by Michael Wetter:
        + Removed non-used computations in specificEnthalpy_pTX and + in temperature_phX. +
        • +
      • + March 29, 2013, by Michael Wetter:
        + Added final standardOrderComponents=true in the + BaseProperties declaration. This avoids an error + when models are checked in Dymola 2014 in the pedenatic mode. +
        • +
      • + April 12, 2012, by Michael Wetter:
        + Added keyword each to Xi(stateSelect=...). +
        • +
      • + April 4, 2012, by Michael Wetter:
        + Added redeclaration of ThermodynamicState to avoid a warning + during model check and translation. +
        • +
      • + August 3, 2011, by Michael Wetter:
        + Fixed bug in u=h-R*T, which is only valid for ideal gases. + For this medium, the function is u=h-pStd/dStp. +
        • +
      • + January 27, 2010, by Michael Wetter:
        + Fixed bug in else branch of function setState_phX + that lead to a run-time error when the constructor of this function was called. +
        • +
      • + January 22, 2010, by Michael Wetter:
        + Added implementation of function + + enthalpyOfNonCondensingGas and its derivative. +
        • +
      • + January 13, 2010, by Michael Wetter:
        + Fixed implementation of derivative functions. +
        • +
      • + August 28, 2008, by Michael Wetter:
        First implementation. - Implementation is based on enthalpy sensor of Modelica.Fluid.
      -------- Corrected Code --------

      - This model outputs the sensible enthalphy flow rate of the - medium in the flow between its fluid ports. In particular, if the - total enthalpy flow rate is -

      -

      - Ḣtot = Ḣsen + Ḣlat, + Model with basic thermodynamic properties.

      - where Ḣsen = ṁ (1-Xw) - cp,air, then this sensor outputs Ḣ = - Ḣsen. + This model provides equation for the following thermodynamic + properties:

      +
    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Variable + + Unit + + Description +
    + T + + K + + temperature +
    + p + + Pa + + absolute pressure +
    + d + + kg/m3 + + density +
    + h + + J/kg + + specific enthalpy +
    + u + + J/kg + + specific internal energy +
    + Xi[nXi] + + kg/kg + + independent mass fractions m_i/m +
    + R + + J/kg.K + + gas constant +
    + M + + kg/mol + + molar mass +
    +
      +
    • September 22, 2020, by Michael Wetter:
      + First implementation based on Modelica Standard Library, but with + noEvent added to check of bounds. +
      • +
    +Density is computed from pressure, temperature and composition in the +thermodynamic state record applying the ideal gas law.

    - If the parameter tau is non-zero, then the measured - specific sensible enthalpy hout that is used to - compute the sensible enthalpy flow rate Ḣsen = ṁ - hout is computed using a first order differential - equation. See AixLib.Fluid.Sensors.UsersGuide - for an explanation. + This function returns the dynamic viscosity.

    +

    + Implementation +

    - For a sensor that measures Ḣtot, use AixLib.Fluid.Sensors.EnthalpyFlowRate.
    - - For a sensor that measures Ḣlat, use AixLib.Fluid.Sensors.LatentEnthalpyFlowRate. + The function is based on the 5th order polynomial of Modelica.Media.Air.MoistAir.dynamicViscosity. + However, for the typical range of temperatures encountered in + building applications, a linear function sufficies. This + implementation is therefore the above 5th order polynomial, + linearized around 20°C. The relative error of this + linearization is 0.4% at -20°C, and less then + 0.2% between -5°C and +50°C. +

    +
      +
    • December 19, 2013, by Michael Wetter:
      + First implementation. +
      • +
    +The ideal gas constant for moist air is computed from thermodynamic +state assuming that all water is in the gas phase. +Pressure is returned from the thermodynamic state record input as a +simple assignment. +

    + This function returns the isobaric expansion coefficient at constant + pressure, which is zero for this medium. The isobaric expansion + coefficient at constant pressure is +

    +

    + βp = - 1 ⁄ v   (∂ v ⁄ ∂ T)p = 0,

    - The sensor is ideal, i.e., it does not influence the fluid. The - sensor can only be used with medium models that implement the - function enthalpyOfNonCondensingGas(T). + where v is the specific volume, T is the temperature + and p is the pressure.

      -
    • October 19, 2020, by Antoine Gautier:
      - Changed default value for tau from 1 to - 0.
      - This is for #1406. -
      • -
    • February 25, 2020, by Michael Wetter:
      - Changed icon to display its operating state.
      - This is for #1294. -
      • -
    • January 18, 2016 by Filip Jorissen:
      - Using parameter tauInv since this now exists in - - AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. This - is for #372. -
      • -
    • September 10, 2013, by Michael Wetter:
      - Changed medium declaration in the extends statement to - replaceable to avoid a translation error in - OpenModelica. -
      • -
    • August 31, 2013, by Michael Wetter:
      - Removed default value tau=0 as the base class already - sets tau=1. This change was made so that all sensors - use the same default value. -
      • -
    • December 18, 2012, by Michael Wetter:
      - Moved computation of i_w to new base class AixLib.Fluid.BaseClasses.IndexWater. - The value of this parameter is now assigned dynamically and does - not require to be specified by the user. -
      • -
    • November 3, 2011, by Michael Wetter:
      - Moved der(h_out) := 0; from the initial algorithm - section to the initial equation section as this assignment does not - conform to the Modelica specification. -
      • -
    • August 10, 2011 by Michael Wetter:
      - Added parameter i_w and an assert statement to make - sure it is set correctly. Without this change, Dymola cannot - differentiate the model when reducing the index of the DAE. -
      • -
    • June 3, 2011 by Michael Wetter:
      - Revised implementation to add dynamics in such a way that the time - constant increases as the mass flow rate tends to zero. This can - improve the numerics. -
      • -
    • February 22, by Michael Wetter:
      - Improved code that searches for index of 'water' in the medium - model. -
      • -
    • September 9, 2009 by Michael Wetter:
      - First implementation. Implementation is based on enthalpy sensor of - Modelica.Fluid. +
    • December 18, 2013, by Michael Wetter:
      + First implementation.
    - --------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Geothermal/Borefields/UsersGuide.mo ---- --------- HTML Code -------- -

    -This package contains borefield models. These models can simulate any arbitrary -configuration of vertical boreholes with equal lengths with both short and -long-term accuracy with an aggregation method to speed up the calculations of the ground heat transfer. Examples -of how to use the borefield models and validation cases can be found in - -AixLib.Fluid.Geothermal.Borefields.Examples -and - -AixLib.Fluid.Geothermal.Borefields.Validation, -respectively. + This function returns the isothermal compressibility coefficient. The + isothermal compressibility is +

    +

    + κT = -1 ⁄ v   (∂ v ⁄ ∂ p)T = -1 ⁄ p,

    -The major features and configurations currently supported are: + where v is the specific volume, T is the temperature + and p is the pressure. +

      -
    • User-defined borefield characteristics and geometry (borehole radius, pipe radius, shank spacing, etc.), -including single U-tube, double U-tube in parallel and double U-tube in series configurations. -
      • -
    • The resistances Rb and Ra are -either automatically calculated using the multipole method, -or the resistance Rb can be directly provided by the user. -In this case, the resistances Rb and Ra are -still evaluated internally, but their values are weighted so that the borehole -resistance matches the specified value. -
      • -
    • -User-defined vertical discretization of boreholes are supported. -However, the borehole wall temperature -is identical for each borehole, as the ground temperature response model only computes the average borehole wall temperature -for all boreholes combined. -
      • -
    • -Borefields can consist of one or many boreholes. Each borehole can be positioned -at an arbitrary position in the field using cartesian coordinates. -
      • -
    • -The resolution and precision of the load aggregation method for the ground heat transfer can be adapted. -
      • -
    • -The thermal response of the ground heat transfer is stored locally to avoid -having to recalculate it for future simulations with the same borefield configuration. -
      • -
    • -Pressure losses are calculated if the dp_nominal parameter is set to a non-zero value. -
      • +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
    -

    -The model is limited to the simulation of borefields with boreholes connected in -parallel, as shown on the figure below for a single U-tube configuration. All -boreholes have the same length hBor, the same radius -rBor, and are buried at the same depth dBor below the -ground surface (also known as the inactive borehole length). -

    -

    -\"image\" + This function computes the specific entropy.

    - -

    How to use the borefield models

    -
    Borefield data record

    -Most of the parameter values of the model are contained in the record called borFieDat. -This record is composed of three subrecords: -filDat (containing the thermal characteristics of the borehole filling material), -soiDat (containing the thermal characteristics of the surrounding soil), -and conDat (containing all others parameters, namely parameters -defining the configuration of the borefield). -The structure and default values of the record are in the package: -AixLib.Fluid.Geothermal.Borefields.Data. -The borFieDat record -can be found in the -AixLib.Fluid.Geothermal.Borefields.Data.Borefield subpackage therein. -Examples of the subrecords conDat, filDat and soiDat -can be found in - -AixLib.Fluid.Geothermal.Borefields.Data.Configuration, - -AixLib.Fluid.Geothermal.Borefields.Data.Filling and - -AixLib.Fluid.Geothermal.Borefields.Data.Soil, respectively. + The specific entropy of the mixture is obtained from

    -

    -It is important to make sure that the borCon parameter within -the conDat subrecord is compatible with the chosen borefield model. -For example, if a double U-tube -borefield model is chosen, the borCon parameter could be set -to both a parallel double U-tube configuration and a double U-tube configuration in series, -but could not be set to a single U-tube configuration. An incompatible borehole -configuration will stop the simulation. +

    + s = ss + sm,

    -
    Ground heat transfer parameters

    -Other than the parameters contained in the borFieDat record, -the borefield models have other parameters which can be modified by the user. -The tLoaAgg parameter is the time resolution of the load aggregation -for the calculation of the ground heat transfer. It represents the -frequency at which the load aggregation procedure is performed in the simulation. -Therefore, smaller values of tLoaAgg will improve -the accuracy of the model, at the cost of increased simulation times -due to a higher number of events occuring in the simulation. While a default value -is provided for this parameter, it is advisable to ensure that it is lower -than a fraction (e.g. half) of the time required for the fluid to completely circulate -through the borefield, -as increasing the value of tLoaAgg beyond this -will result in non-physical borehole wall temperatures. + where ss is the entropy change due to the state + change (relative to the reference temperature) and + sm is the entropy change due to mixing of the dry + air and water vapor.

    -The nCel parameter also affects the accuracy and simulation time -of the ground heat transfer calculations. As this parameter sets the number -of consecutive equal-size aggregation cells before increasing the size of cells, -increasing its value will result in less load aggregation, which will increase -accuracy at the cost of computation time. On the other hand, -decreasing the value of nCel (down to a minimum of 1) -will decrease accuracy but improve -computation time. The default value is chosen as a compromise between the two. + The entropy change due to change in state is obtained from

    -

    -Further information on the tLoaAgg and nCel parameters can -be found in the documentation of - -AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse. +

    + ss = cv ln(T/T0) + R + ln(v/v0)
    + = cv ln(T/T0) + R ln(ρ0/ρ)

    -
    Other parameters

    -Other parameters which can be modified include the dynamics, initial conditions, -and further information regarding the fluid flow, for example whether the flow is reversible. -It is worth noting that regardless of the energyDynamics chosen, -the dynFil parameter can be set to false -to remove the effect of the thermal capacitance -of the filling material in the borehole(s). -The nSeg parameter specifies the number of segments for the vertical discretization of the borehole(s). -Further information on this discretization can be found in the "Model description" section below. + If we assume ρ = p0/(R T), and because + cp = cv + R, we can write

    -
    Running simulations
    -

    -When running simulations using the borefield models, -the tmp/temperatureResponseMatrix directory within the current directory -will be checked to see if any of the -borefield configurations used in the simulation have already -had their ground temperature response calculated previously -If the data doesn't exist in the tmp/temperatureResponseMatrix folder, -it will be calculated during the initialization of the model -and will be saved there for future use. +

    + ss = cv ln(T/T0) + R + ln(T/T0)
    + =cp ln(T/T0).

    -

    Model description

    -The borefield models rely on the following key assumptions: -

      -
    • The thermal properties of the soil (conductivity and diffusivity) are constant, -homogenous and isotropic. -
      • -
    • -The conductivity, capacitance and density of the grout and pipe material are constant, homogenous and isotropic. -
      • -
    • -There is no heat extraction or injection prior to the simulation start. -
      • -
    • -All of the boreholes in the borefield have uniform dimensions (including the pipe dimensions). -
      • -
    • -Inside the boreholes, the non-advective heat transfer is only in the radial direction. -
      • -
    -

    -The borefield models are constructed in two main parts: the borehole(s) and the ground heat transfer. -The former is modeled as a vertical discretization of borehole segments, where a uniform temperature increase or decrease -(due to heat injection or extraction) is superimposed to the far-field ground temperature to obtain the borehole wall -temperature. The thermal effects of the circulating fluid (including the convection resistance), -of the pipes and of the filling material are all taken into consideration, which allows modeling -short-term thermal effects in the borehole. The borehole segments do not take into account axial effects, -thus only radial (horizontal) effects are considered within the borehole(s). The thermal -behavior between the pipes and borehole wall are modeled as a resistance-capacitance network, with -the grout capacitance being split in the number of pipes present in a borehole section. -The capacitance is only present if the dynFil parameter is set to true. -The figure below shows an example for a borehole section within a single U-tube configuration. + Next, the entropy of mixing is obtained from a reversible isothermal + expansion process. Hence,

    -

    -\"image\" +

    + sm = -R ∑i( Xi ⁄ Mi + ln(Yi p/p0)),

    -The second main part of the borefield models is the ground heat transfer, which shares a thermal boundary -condition at the uniform borehole wall with all of the borehole segments. The heat transfer in the ground -is modeled analytically as a convolution integral between the heat flux at the borehole wall -and the borefield's thermal response factor. -

    -

    -\"image\" + where R is the gas constant, X is the mass fraction, + M is the molar mass, and Y is the mole fraction.

    -The model uses a load aggregation technique to reduce the time required to calculate -the borehole wall temperature changes resulting from heat injection or extraction. + To obtain the state for a given pressure, entropy and mass fraction, + use AixLib.Media.Air.setState_psX.

    +

    + Limitations +

    -The ground heat transfer takes into account both the borehole axial effects and -the borehole radial effects which are a result of its cylindrical geometry. The borefield's -thermal response to a constant load, also known as its g-function, is used -to calculate the thermal response in the simulation. This g-function -is stored in the tmp/temperatureResponseMatrix subdirectory, -as discussed previously in the -"How to use the borefield models" section. Further information on the -ground heat transfer model and the thermal temperature response calculations can -be found in - -AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse -and - -AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.gFunction. + This function is only valid for a relative humidity below 100%.

    -

    References

    +
      +
    • November 27, 2013, by Michael Wetter:
      + First implementation. +
      • +

    -D. Picard, L. Helsen. -Advanced Hybrid Model for Borefield Heat -Exchanger Performance Evaluation; an Implementation in Modelica -Proc. of the 10th Intertional ModelicaConference, p. 857-866. Lund, Sweden. March 2014. -https://lirias.kuleuven.be/retrieve/270880. + This function returns the partial derivative of density with respect + to pressure at constant temperature.

    - --------- Corrected Code -------- +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - This package contains borefield models. These models can simulate any - arbitrary configuration of vertical boreholes with equal lengths with - both short and long-term accuracy with an aggregation method to speed - up the calculations of the ground heat transfer. Examples of how to - use the borefield models and validation cases can be found in - AixLib.Fluid.Geothermal.Borefields.Examples - and AixLib.Fluid.Geothermal.Borefields.Validation, - respectively. + This function computes the derivative of density with respect to + temperature at constant pressure.

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +

    - The major features and configurations currently supported are: + This function returns the partial derivative of density with respect + to mass fraction. This value is zero because in this medium, density + is proportional to pressure, but independent of the species + concentration.

      -
    • User-defined borefield characteristics and geometry (borehole - radius, pipe radius, shank spacing, etc.), including single U-tube, - double U-tube in parallel and double U-tube in series configurations. -
      • -
    • The resistances Rb and Ra are - either automatically calculated using the multipole method, or the - resistance Rb can be directly provided by the user. - In this case, the resistances Rb and - Ra are still evaluated internally, but their values - are weighted so that the borehole resistance matches the specified - value. -
      • -
    • User-defined vertical discretization of boreholes are supported. - However, the borehole wall temperature is identical for each - borehole, as the ground temperature response model only computes the - average borehole wall temperature for all boreholes combined. +
    • December 18, 2013, by Michael Wetter:
      + First implementation.
      • -
    • Borefields can consist of one or many boreholes. Each borehole - can be positioned at an arbitrary position in the field using - cartesian coordinates. +
    +

    + The + thermodynamic state record is computed from density + d, temperature T and composition + X. +

    +The +thermodynamic state record is computed from pressure p, specific +enthalpy h and composition X. +The +thermodynamic state record is computed from pressure p, temperature +T and composition X. +

    + This function returns the thermodynamic state based on pressure, + specific entropy and mass fraction. +

    +

    + The state is computed by symbolically solving AixLib.Media.Air.specificEntropy + for temperature. +

    +
      +
    • November 27, 2013, by Michael Wetter:
      + First implementation.
      • -
    • The resolution and precision of the load aggregation method for - the ground heat transfer can be adapted. +
    +Specific enthalpy as a function of temperature and species +concentration. The pressure is input for compatibility with the medium +models, but the specific enthalpy is independent of the pressure. +
      +
    • April 30, 2015, by Filip Jorissen and Michael Wetter:
      + Added Inline=true for issue 227.
      • -
    • The thermal response of the ground heat transfer is stored - locally to avoid having to recalculate it for future simulations with - the same borefield configuration. +
    +

    + This function computes the specific enthalpy for an isentropic state + change from the temperature that corresponds to the state + refState to reference_T. +

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation.
      • -
    • Pressure losses are calculated if the dp_nominal - parameter is set to a non-zero value. +
    +Temperature is returned from the thermodynamic state record input as a +simple assignment. +

    + This function returns the molar mass. +

    +
      +
    • December 18, 2013, by Michael Wetter:
      + First implementation. +
      • +
    +Temperature as a function of specific enthalpy and species +concentration. The pressure is input for compatibility with the medium +models, but the temperature is independent of the pressure. +
      +
    • April 30, 2015, by Filip Jorissen and Michael Wetter:
      + Added Inline=true for issue 227.

    - The model is limited to the simulation of borefields with boreholes - connected in parallel, as shown on the figure below for a single - U-tube configuration. All boreholes have the same length - hBor, the same radius rBor, and are buried - at the same depth dBor below the ground surface (also - known as the inactive borehole length). + This data record contains the coefficients for perfect gases.

    -

    - \"image\" +

      +
    • September 12, 2014, by Michael Wetter:
      + Corrected the wrong location of the preferredView and + the revisions annotation. +
      • +
    • November 21, 2013, by Michael Wetter:
      + First implementation. +
      • +
    +

    + This medium package models moist air using a gas law in which + pressure and temperature are independent, which often leads to + significantly faster and more robust computations. The specific heat + capacities at constant pressure and at constant volume are constant. + The air is assumed to be not saturated.

    -

    - How to use the borefield models -

    -
    - Borefield data record -

    - Most of the parameter values of the model are contained in the record - called borFieDat. This record is composed of three - subrecords: filDat (containing the thermal - characteristics of the borehole filling material), - soiDat (containing the thermal characteristics of the - surrounding soil), and conDat (containing all others - parameters, namely parameters defining the configuration of the - borefield). The structure and default values of the record are in the - package: AixLib.Fluid.Geothermal.Borefields.Data. - The borFieDat record can be found in the AixLib.Fluid.Geothermal.Borefields.Data.Borefield - subpackage therein. Examples of the subrecords conDat, - filDat and soiDat can be found in AixLib.Fluid.Geothermal.Borefields.Data.Configuration, - AixLib.Fluid.Geothermal.Borefields.Data.Filling - and AixLib.Fluid.Geothermal.Borefields.Data.Soil, - respectively. + This medium uses the gas law +

    +

    + ρ/ρstp = p/pstp,

    - It is important to make sure that the borCon parameter - within the conDat subrecord is compatible with the - chosen borefield model. For example, if a double U-tube borefield - model is chosen, the borCon parameter could be set to - both a parallel double U-tube configuration and a double U-tube - configuration in series, but could not be set to a single U-tube - configuration. An incompatible borehole configuration will stop the - simulation. + where pstd and ρstp are constant + reference temperature and density, rathern than the ideal gas law +

    +

    + ρ = p ⁄(R T),

    -
    - Ground heat transfer parameters -

    - Other than the parameters contained in the borFieDat - record, the borefield models have other parameters which can be - modified by the user. The tLoaAgg parameter is the time - resolution of the load aggregation for the calculation of the ground - heat transfer. It represents the frequency at which the load - aggregation procedure is performed in the simulation. Therefore, - smaller values of tLoaAgg will improve the accuracy of - the model, at the cost of increased simulation times due to a higher - number of events occuring in the simulation. While a default value is - provided for this parameter, it is advisable to ensure that it is - lower than a fraction (e.g. half) of the time required for the fluid - to completely circulate through the borefield, as increasing the - value of tLoaAgg beyond this will result in non-physical - borehole wall temperatures. + where R is the gas constant and T is the temperature.

    - The nCel parameter also affects the accuracy and - simulation time of the ground heat transfer calculations. As this - parameter sets the number of consecutive equal-size aggregation cells - before increasing the size of cells, increasing its value will result - in less load aggregation, which will increase accuracy at the cost of - computation time. On the other hand, decreasing the value of - nCel (down to a minimum of 1) will decrease accuracy but - improve computation time. The default value is chosen as a compromise - between the two. + This formulation often leads to smaller systems of nonlinear + equations because equations for pressure and temperature are + decoupled. Therefore, if air inside a control volume such as room air + is heated, it does not increase its specific volume. Consequently, + merely heating or cooling a control volume does not affect the air + flow calculations in a duct network that may be connected to that + volume. Note that multizone air exchange simulation in which buoyancy + drives the air flow is still possible as the models in AixLib.Airflow.Multizone + compute the mass density using the function AixLib.Utilities.Psychrometrics.Functions.density_pTX + in which density is a function of temperature.

    - Further information on the tLoaAgg and nCel - parameters can be found in the documentation of - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse. + Note that models in this package implement the equation for the + internal energy as +

    +

    + u = h - pstp ⁄ ρstp,

    -
    - Other parameters -

    - Other parameters which can be modified include the dynamics, initial - conditions, and further information regarding the fluid flow, for - example whether the flow is reversible. It is worth noting that - regardless of the energyDynamics chosen, the - dynFil parameter can be set to false to - remove the effect of the thermal capacitance of the filling material - in the borehole(s). The nSeg parameter specifies the - number of segments for the vertical discretization of the - borehole(s). Further information on this discretization can be found - in the \"Model description\" section below. + where u is the internal energy per unit mass, h is the + enthalpy per unit mass, pstp is the static pressure + and ρstp is the mass density at standard pressure + and temperature. The reason for this implementation is that in + general, +

    +

    + h = u + p v,

    -
    - Running simulations -

    - When running simulations using the borefield models, the - tmp/temperatureResponseMatrix directory within the - current directory will be checked to see if any of the borefield - configurations used in the simulation have already had their ground - temperature response calculated previously If the data doesn't exist - in the tmp/temperatureResponseMatrix folder, it will be - calculated during the initialization of the model and will be saved - there for future use. + from which follows that +

    +

    + u = h - p v = h - p ⁄ ρ = h - pstp ⁄ ρstd,

    -

    - Model description -

    - The borefield models rely on the following key assumptions: + because p ⁄ ρ = pstp ⁄ ρstp in this + medium model. +

    +

    + The enthalpy is computed using the convention that h=0 if + T=0 °C and no water vapor is present.

      -
    • The thermal properties of the soil (conductivity and diffusivity) - are constant, homogenous and isotropic. -
      • -
    • The conductivity, capacitance and density of the grout and pipe - material are constant, homogenous and isotropic. -
      • -
    • There is no heat extraction or injection prior to the simulation - start. +
    • September 28, 2020, by Michael Wetter:
      + Reformulated BaseProperties to avoid event-triggering + assertions.
      + This is for #1401.
      • -
    • All of the boreholes in the borefield have uniform dimensions - (including the pipe dimensions). +
    • January 11, 2019 by Michael Wetter:
      + Reforulated assignment of X_int in + setState_psX.
      + This is for #1079.
      • -
    • Inside the boreholes, the non-advective heat transfer is only in - the radial direction. +
    • October 26, 2018, by Filip Jorissen and Michael Wetter:
      + Now printing different messages if temperature is above or below + its limit, and adding instance name as JModelica does not print the + full instance name in the assertion. This is for #1045. +
      • +
    • November 4, 2016, by Michael Wetter:
      + Set default value for dT.start in base properties.
      + This is for #575. +
      • +
    • June 6, 2015, by Michael Wetter:
      + Set AbsolutePressure(start=p_default) to avoid a + translation error if + AixLib.Fluid.Sources.Examples.TraceSubstancesFlowSource is + translated in pedantic mode in Dymola 2016. The reason is that + pressures use Medium.p_default as start values, but + Modelica.Media.Interfaces.Types + sets a default value of 1E-5. A similar change has been done + for pressure. This fixes #266. +
      • +
    • June 5, 2015, by Michael Wetter:
      + Added stateSelect attribute in + BaseProperties.T to allow correct use of + preferredMediumState as described in Modelica.Media.Interfaces.PartialMedium. + Note that the default is preferredMediumState=false + and hence the same states are used as were used before. This is for + #260. +
      • +
    • May 11, 2015, by Michael Wetter:
      + Removed p(stateSelect=if preferredMediumStates then + StateSelect.prefer else StateSelect.default) in declaration + of BaseProperties. Otherwise, when models that contain + a fluid volume are exported as an FMU, their pressure would be + differentiated with respect to time. This would require the time + derivative of the inlet pressure, which is not available, causing + the translation to stop with an error. +
      • +
    • May 1, 2015, by Michael Wetter:
      + Added Inline=true for issue 227. +
      • +
    • March 20, 2015, by Michael Wetter:
      + Added missing term state.p/reference_p in function + specificEntropy. #193. +
      • +
    • February 3, 2015, by Michael Wetter:
      + Removed stateSelect.prefer for temperature. This is + for #160. +
      • +
    • July 24, 2014, by Michael Wetter:
      + Changed implementation to use AixLib.Utilities.Psychrometrics.Constants. + This was done to use consistent values throughout the library. +
      • +
    • November 16, 2013, by Michael Wetter:
      + Revised and simplified the implementation. +
      • +
    • November 14, 2013, by Michael Wetter:
      + Removed function HeatCapacityOfWater which is neither + needed nor implemented in the Modelica Standard Library. +
      • +
    • November 13, 2013, by Michael Wetter:
      + Removed non-used computations in specificEnthalpy_pTX + and in temperature_phX. +
      • +
    • March 29, 2013, by Michael Wetter:
      + Added final standardOrderComponents=true in the + BaseProperties declaration. This avoids an error when + models are checked in Dymola 2014 in the pedenatic mode. +
      • +
    • April 12, 2012, by Michael Wetter:
      + Added keyword each to + Xi(stateSelect=...). +
      • +
    • April 4, 2012, by Michael Wetter:
      + Added redeclaration of ThermodynamicState to avoid a + warning during model check and translation. +
      • +
    • August 3, 2011, by Michael Wetter:
      + Fixed bug in u=h-R*T, which is only valid for ideal + gases. For this medium, the function is u=h-pStd/dStp. +
      • +
    • January 27, 2010, by Michael Wetter:
      + Fixed bug in else branch of function + setState_phX that lead to a run-time error when the + constructor of this function was called. +
      • +
    • January 22, 2010, by Michael Wetter:
      + Added implementation of function + enthalpyOfNonCondensingGas and its derivative. +
      • +
    • January 13, 2010, by Michael Wetter:
      + Fixed implementation of derivative functions. +
      • +
    • August 28, 2008, by Michael Wetter:
      + First implementation.
    -

    - The borefield models are constructed in two main parts: the - borehole(s) and the ground heat transfer. The former is modeled as a - vertical discretization of borehole segments, where a uniform - temperature increase or decrease (due to heat injection or - extraction) is superimposed to the far-field ground temperature to - obtain the borehole wall temperature. The thermal effects of the - circulating fluid (including the convection resistance), of the pipes - and of the filling material are all taken into consideration, which - allows modeling short-term thermal effects in the borehole. The - borehole segments do not take into account axial effects, thus only - radial (horizontal) effects are considered within the borehole(s). - The thermal behavior between the pipes and borehole wall are modeled - as a resistance-capacitance network, with the grout capacitance being - split in the number of pipes present in a borehole section. The - capacitance is only present if the dynFil parameter is - set to true. The figure below shows an example for a - borehole section within a single U-tube configuration. -

    -

    - \"image\" -

    -

    - The second main part of the borefield models is the ground heat - transfer, which shares a thermal boundary condition at the uniform - borehole wall with all of the borehole segments. The heat transfer in - the ground is modeled analytically as a convolution integral between - the heat flux at the borehole wall and the borefield's thermal - response factor. -

    -

    - \"image\" -

    -

    - The model uses a load aggregation technique to reduce the time - required to calculate the borehole wall temperature changes resulting - from heat injection or extraction. -

    -

    - The ground heat transfer takes into account both the borehole axial - effects and the borehole radial effects which are a result of its - cylindrical geometry. The borefield's thermal response to a constant - load, also known as its g-function, is used to calculate the - thermal response in the simulation. This g-function is stored in the - tmp/temperatureResponseMatrix subdirectory, as discussed - previously in the \"How to use the borefield models\" section. Further - information on the ground heat transfer model and the thermal - temperature response calculations can be found in - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse - and - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.gFunction. -

    -

    - References -

    -

    - D. Picard, L. Helsen. Advanced Hybrid Model for Borefield Heat - Exchanger Performance Evaluation; an Implementation in Modelica - Proc. of the 10th Intertional ModelicaConference, p. 857-866. Lund, - Sweden. March 2014. https://lirias.kuleuven.be/retrieve/270880. -

    -------- Errors -------- -line 56 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 179 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 188 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 8 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 ----- AixLib/Fluid/HeatExchangers/BaseClasses/WetCoilWetRegime.mo ---- +line 7 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 21 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 37 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 19 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 43 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 54 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 60 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Sources/Outside_CpLowRise.mo ---- -------- HTML Code -------- -

      -
    • - Jan 21, 2021, by Donghun Kim:
      First implementation. -
      • -
    -

    - This model implements the calculation for a 100% wet coil. + This model describes boundary conditions for + pressure, enthalpy, and species concentration that can be obtained + from weather data. The model is identical to + + AixLib.Fluid.Sources.Outside, + except that it adds the wind pressure to the + pressure at the fluid port ports. + The correlation that is used to compute the wind pressure is based + on Swami and Chandra (1987) and valid for low-rise buildings + with rectangular shape. + The same correlation is also implemented in CONTAM (Persily and Ivy, 2001). +

    - The equations from Braun (1988) and Mitchell and Braun (2012a and b), - which are essentially the extension of the ε-NTU approach to - simultaneous sensible and latent heat transfer, are utilized. + The wind pressure coefficient is computed based on the + side ratio of the walls, which is defined as

    -

    - The mathematical equations are analogous to that of the sensible heat exchanger. - However, the key distinction is that the heat transfer is driven by an enthalpy difference - not by an temperature difference. This change in the driving potential results in re-defining - capacitances and heat transfer coefficients accordingly. +

    + s = x ⁄ y

    -

    - The total heat transfer rate is expressed as -

    -

    - Qtot=ε* C*min - (hair,in-hsat(Twat,in)), + where x is the length of the wall that will be connected to + this model, and y is the length of the adjacent wall. + The wind direction is computed relative to the azimuth of this surface, + which is equal to the parameter azi. + The surface azimuth is defined in + + AixLib.Types.Azimuth. + For example, if an exterior wall is South oriented, i.e., its outside-facing + surface is towards South, use + AixLib.Types.Azimuth.S.

    - where ε*=f(Cr*,NTU*) and f is the same ε-NTU relationships - (depending on the heat exchanger configuration) for the sensible heat exchanger. -

    -

    - hair,in and hsat(Twat,in) are - the specific enthalpies of the incoming moist air and saturated moist air - at the water inlet temperature. + Based on the surface azimuth, the wind direction and the side ratio + of the walls, the model computes how much the wind pressure + is attenuated compared to the reference wind pressure Cp0. + The reference wind pressure Cp0 is a user-defined parameter, + and must be equal to the wind pressure at zero wind incidence angle. + Swami and Chandra (1987) recommend Cp0 = 0.6 for + all low-rise buildings as this represents the average of + various values reported in the literature. + The computation of the actual wind pressure coefficient Cp + is explained in the function + + Buildings.Airflow.Multizone.BaseClasses.windPressureLowRise + that is called by this model.

    - The capacitances of water and air streams are defined as -

    -

    C*air=mair and - C*wat=mwatcp,wat/csat, + The pressure p at the port ports is computed as

    -

    - where csat is an specific heat capacity, which indicates the sensitivity - of the enthalpy of the staturated moist air w.r.t. the temperature, and is defined - here as csat=(hsat(Twat,out)-hsat(Twat,in)) - /(Twat,out-Twat,in). +

    + p = pw + Cp 1 ⁄ 2 v2 ρ,

    - The capacitance ratio and minimum capacitance are naturally defined as -

    -

    Cr*=min(C*air,C*wat)/max(C*air,C*wat) - and C*min=min(C*air,C*wat). -

    -


    - The number of transfer unit for the wet-coil is defined as NTU*=UA*/C*min, where -

    -

    - UA*=1/(1/(UAair/cp,air)+1/(UAwat/csat). + where + pw is the atmospheric pressure from the weather bus, + v is the wind speed from the weather bus, and + ρ is the fluid density.

    -

    References

    -

    - Braun, James E. 1988. - "Methodologies for the Design and Control of Central Cooling Plants". - PhD Thesis. University of Wisconsin - Madison. - Available - - online. -

    -

    - Mitchell, John W., and James E. Braun. 2012a. - Principles of heating, ventilation, and air conditioning in buildings. - Hoboken, N.J.: Wiley. -

    - Mitchell, John W., and James E. Braun. 2012b. - "Supplementary Material Chapter 2: Heat Exchangers for Cooling Applications". - Excerpt from Principles of heating, ventilation, and air conditioning in buildings. - Hoboken, N.J.: Wiley. - Available - - online. + This model differs from + AixLib.Fluid.Sources.Outside_CpData by the calculation of the wind pressure coefficient Cp,act. + The wind pressure coefficient is defined by an equation in stead of a user-defined table. + This model is only suited for low-rise rectangular buildings.

    +

    References

    + + +
      +
    • + February 2, 2022, by Michael Wetter:
      + Revised implementation.
      + This is for + IBPSA, #1436. +
      • +
    • + Jun 28, 2021, by Klaas De Jonge:
      + Documentation changes to explain the difference with + AixLib.Fluid.Sources.Outside_CpData. +
      • +
    • + January 26, 2016, by Michael Wetter:
      + Added unit and quantity attributes. +
      • +
    • + October 26, 2011 by Michael Wetter:
      + First implementation. +
      • +
    + -------- Corrected Code -------- -
      -
    • Jan 21, 2021, by Donghun Kim:
      - First implementation. -
      • -
    -

    - This model implements the calculation for a 100% wet coil. -

    -

    - The equations from Braun (1988) and Mitchell and Braun (2012a and b), - which are essentially the extension of the ε-NTU approach to - simultaneous sensible and latent heat transfer, are utilized. -

    - The mathematical equations are analogous to that of the sensible heat - exchanger. However, the key distinction is that the heat transfer is - driven by an enthalpy difference not by an temperature difference. - This change in the driving potential results in re-defining - capacitances and heat transfer coefficients accordingly. + This model describes boundary conditions for pressure, enthalpy, and + species concentration that can be obtained from weather data. The + model is identical to AixLib.Fluid.Sources.Outside, + except that it adds the wind pressure to the pressure at the fluid + port ports. The correlation that is used to compute the + wind pressure is based on Swami and Chandra (1987) and valid for + low-rise buildings with rectangular shape. The same correlation is + also implemented in CONTAM (Persily and Ivy, 2001). +

    - The total heat transfer rate is expressed as + The wind pressure coefficient is computed based on the side ratio of + the walls, which is defined as

    -

    - Qtot=ε* C*min - (hair,in-hsat(Twat,in)), +

    + s = x ⁄ y

    - where ε*=f(Cr*,NTU*) and f is the same ε-NTU - relationships (depending on the heat exchanger configuration) for the - sensible heat exchanger. + where x is the length of the wall that will be connected to + this model, and y is the length of the adjacent wall. The wind + direction is computed relative to the azimuth of this surface, which + is equal to the parameter azi. The surface azimuth is + defined in AixLib.Types.Azimuth. For + example, if an exterior wall is South oriented, i.e., its + outside-facing surface is towards South, use + AixLib.Types.Azimuth.S.

    - hair,in and - hsat(Twat,in) are the specific - enthalpies of the incoming moist air and saturated moist air at the - water inlet temperature. + Based on the surface azimuth, the wind direction and the side ratio + of the walls, the model computes how much the wind pressure is + attenuated compared to the reference wind pressure Cp0. + The reference wind pressure Cp0 is a user-defined + parameter, and must be equal to the wind pressure at zero wind + incidence angle. Swami and Chandra (1987) recommend Cp0 + = 0.6 for all low-rise buildings as this represents the average + of various values reported in the literature. The computation of the + actual wind pressure coefficient Cp is explained in + the function + Buildings.Airflow.Multizone.BaseClasses.windPressureLowRise that + is called by this model.

    - The capacitances of water and air streams are defined as -

    -

    - C*air=mair and - C*wat=mwatcp,wat/csat, + The pressure p at the port ports is computed as

    -

    - where csat is an specific heat capacity, which indicates the - sensitivity of the enthalpy of the staturated moist air w.r.t. the - temperature, and is defined here as - csat=(hsat(Twat,out)-hsat(Twat,in)) - /(Twat,out-Twat,in). +

    + p = pw + Cp 1 ⁄ 2 v2 ρ,

    - The capacitance ratio and minimum capacitance are naturally defined - as -

    -

    - Cr*=min(C*air,C*wat)/max(C*air,C*wat) - and C*min=min(C*air,C*wat). + where pw is the atmospheric pressure from the + weather bus, v is the wind speed from the weather bus, and + ρ is the fluid density.

    -
    - The number of transfer unit for the wet-coil is defined as - NTU*=UA*/C*min, where -

    -

    - UA*=1/(1/(UAair/cp,air)+1/(UAwat/csat). + This model differs from AixLib.Fluid.Sources.Outside_CpData + by the calculation of the wind pressure coefficient + Cp,act. The wind pressure coefficient is defined by an + equation in stead of a user-defined table. This model is only suited + for low-rise rectangular buildings.

    References

    -

    - Braun, James E. 1988. \"Methodologies for the Design and Control of - Central Cooling Plants\". PhD Thesis. University of Wisconsin - - Madison. Available online. -

    -

    - Mitchell, John W., and James E. Braun. 2012a. Principles of heating, - ventilation, and air conditioning in buildings. Hoboken, N.J.: Wiley. -

    -

    - Mitchell, John W., and James E. Braun. 2012b. \"Supplementary Material - Chapter 2: Heat Exchangers for Cooling Applications\". Excerpt from - Principles of heating, ventilation, and air conditioning in - buildings. Hoboken, N.J.: Wiley. Available - online. -

    - --------- Errors -------- -line 20 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 36 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 48 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 54 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Controls/Discrete/BooleanDelay.mo ---- --------- HTML Code -------- - -

    - Block that delays the boolean input signal by - one sampling interval. - For example, - if u denotes the input, - y denotes the output, and - ti and ti+1 - denote subsequent sampling - instants, then the model outputs -

    -

    - y(ti+1) = u(ti). -

    - -
      -
    • - June 6, 2015, by Michael Wetter:
      - Set start value and fixed attribute - for firstTrigger - to avoid a translation warning in pedantic mode - in Dymola 2016. - This is for - #266. -
      • -
    • - November 21, 2011, by Michael Wetter:
      - Improved documentation. -
      • -
    • - November 26, 2008, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code -------- -

    - Block that delays the boolean input signal by one sampling interval. - For example, if u denotes the input, y denotes the - output, and ti and ti+1 denote - subsequent sampling instants, then the model outputs -

    -

    - y(ti+1) = u(ti). -

    +
      +
    • February 2, 2022, by Michael Wetter:
      + Revised implementation.
      + This is for IBPSA, + #1436. +
      • +
    • Jun 28, 2021, by Klaas De Jonge:
      + Documentation changes to explain the difference with AixLib.Fluid.Sources.Outside_CpData. +
      • +
    • January 26, 2016, by Michael Wetter:
      + Added unit and quantity attributes. +
      • +
    • October 26, 2011 by Michael Wetter:
      First implementation.
    -------- Errors -------- -line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 28 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 61 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Humidifiers/SteamHumidifier_X.mo ---- +---- AixLib/Fluid/HeatExchangers/ConstantEffectiveness.mo ---- -------- HTML Code --------

    - Model for a steam humidifier with a prescribed outlet water vapor mass fraction - in kg/kg total air. -

    -

    - This model forces the outlet water mass fraction at port_b to be - no lower than the - input signal X_wSet, subject to optional limits on the - maximum water vapor mass flow rate that is added, as - described by the parameter mWatMax_flow. - By default, the model has unlimited capacity. -

    -

    - The output signal mWat_flow ≥ 0 is the moisture added - to the medium if the flow rate is from port_a to port_b. - If the flow is reversed, then mWat_flow = 0. - The outlet specific enthalpy at port_b is increased by - the enthalpy of steam at 100°C times the mass of steam that was added. - Therefore, the temperature of the leaving fluid is slightly above the inlet temperature. -

    -

    - The outlet conditions at port_a are not affected by this model, - other than for a possible pressure difference due to flow friction. + Model for a heat exchanger with constant effectiveness.

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, - the component models the dynamic response using a first order differential equation. - The time constant of the component is equal to the parameter tau. - This time constant is adjusted based on the mass flow rate using + This model transfers heat in the amount of

    - τeff = τ |ṁ| ⁄ ṁnom -

    -

    - where - τeff is the effective time constant for the given mass flow rate - ṁ and - τ is the time constant at the nominal mass flow rate - ṁnom. - This type of dynamics is equal to the dynamics that a completely mixed - control volume would have. -

    -

    - Optionally, this model can have a flow resistance. - Set dp_nominal = 0 to disable the flow friction calculation. + Q = Qmax ε,

    - For a model that uses a control signal u ∈ [0, 1] and multiplies - this with the nominal water mass flow rate, use - - AixLib.Fluid.Humidifiers.Humidifier_u - + where ε is a constant effectiveness and + Qmax is the maximum heat that can be transferred.

    -

    Limitations

    - This model only adds water vapor for the flow from - port_a to port_b. - The water vapor of the reverse flow is not affected by this model. + For a heat and moisture exchanger, use + + AixLib.Fluid.MassExchangers.ConstantEffectiveness + instead of this model.

    • - March 8, 2022, by Michael Wetter:
      - Renamed parameter massDynamics to energyDynamics for consistency with other models. + August 13, 2013 by Michael Wetter:
      + Corrected error in the documentation.
    • - May 10, 2017, by Michael Wetter:
      + July 30, 2013 by Michael Wetter:
      + Updated model to use new variable mWat_flow + in the base class. +
      • +
    • + January 28, 2010, by Michael Wetter:
      + Added regularization near zero flow. +
      • +
    • + October 2, 2009, by Michael Wetter:
      + Changed computation of inlet temperatures to use + state_*_inflow which is already known in base class. +
      • +
    • + April 28, 2008, by Michael Wetter:
      First implementation.
    -------- Corrected Code --------

    - Model for a steam humidifier with a prescribed outlet water vapor - mass fraction in kg/kg total air. -

    -

    - This model forces the outlet water mass fraction at - port_b to be no lower than the input signal - X_wSet, subject to optional limits on the maximum water - vapor mass flow rate that is added, as described by the parameter - mWatMax_flow. By default, the model has unlimited - capacity. -

    -

    - The output signal mWat_flow ≥ 0 is the moisture added to - the medium if the flow rate is from port_a to - port_b. If the flow is reversed, then mWat_flow = - 0. The outlet specific enthalpy at port_b is - increased by the enthalpy of steam at 100°C times the mass of - steam that was added. Therefore, the temperature of the leaving fluid - is slightly above the inlet temperature. -

    -

    - The outlet conditions at port_a are not affected by this - model, other than for a possible pressure difference due to flow - friction. + Model for a heat exchanger with constant effectiveness.

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, the component - models the dynamic response using a first order differential - equation. The time constant of the component is equal to the - parameter tau. This time constant is adjusted based on - the mass flow rate using + This model transfers heat in the amount of

    - τeff = τ |ṁ| ⁄ ṁnom -

    -

    - where τeff is the effective time constant for the - given mass flow rate ṁ and τ is the time constant at - the nominal mass flow rate ṁnom. This type of - dynamics is equal to the dynamics that a completely mixed control - volume would have. -

    -

    - Optionally, this model can have a flow resistance. Set - dp_nominal = 0 to disable the flow friction calculation. + Q = Qmax ε,

    - For a model that uses a control signal u ∈ [0, 1] and - multiplies this with the nominal water mass flow rate, use AixLib.Fluid.Humidifiers.Humidifier_u + where ε is a constant effectiveness and Qmax + is the maximum heat that can be transferred.

    -

    - Limitations -

    - This model only adds water vapor for the flow from - port_a to port_b. The water vapor of the - reverse flow is not affected by this model. + For a heat and moisture exchanger, use AixLib.Fluid.MassExchangers.ConstantEffectiveness + instead of this model.

      -
    • March 8, 2022, by Michael Wetter:
      - Renamed parameter massDynamics to - energyDynamics for consistency with other models. +
    • August 13, 2013 by Michael Wetter:
      + Corrected error in the documentation.
      • -
    • May 10, 2017, by Michael Wetter:
      +
    • July 30, 2013 by Michael Wetter:
      + Updated model to use new variable mWat_flow in the + base class. +
      • +
    • January 28, 2010, by Michael Wetter:
      + Added regularization near zero flow. +
      • +
    • October 2, 2009, by Michael Wetter:
      + Changed computation of inlet temperatures to use + state_*_inflow which is already known in base class. +
      • +
    • April 28, 2008, by Michael Wetter:
      First implementation.
    -------- Errors -------- -line 33 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatExchangers/EvaporatorCondenser.mo ---- +---- AixLib/Fluid/FixedResistances/BaseClasses/PlugFlowHeatLoss.mo ---- -------- HTML Code --------

    - Model for a constant temperature evaporator or condenser based on a ε-NTU - heat exchanger model. + Component that calculates the heat losses at the end of a plug flow pipe + when the flow goes in the design direction.

    +

    Main equations

    - The heat exchanger effectiveness is calculated from the number of transfer units - (NTU): + The governing equations are

    - ε = 1 - exp(UA ⁄ (ṁ cp)) + Tout = Tb + (Tin - Tb) + exp((tout - tin)/tauchar)

    - Optionally, this model can have a flow resistance. - If no flow resistance is requested, set dp_nominal=0. + with

    -

    Limitations

    -

    - This model does not consider any superheating or supercooling on the refrigerant - side. The refrigerant is considered to exchange heat at a constant temperature - throughout the heat exchanger. +

    + tauchar = R C +

    +

    Assumptions and limitations

    +

    + This model is based on the following assumptions: +

    +
      +
    • The water temperature is uniform in the cross section.
      • +
    • There is no axial heat transfer in the water or surrounding.
      • +
    • The boundary temperature along the pipe is uniform.
      • +
    • Heat losses are steady-state.
      • +
    +

    Implementation

    +

    + Heat losses are only considered in design flow direction. + For heat loss consideration in both directions, use one of these models at + both ends of a + + AixLib.Fluid.FixedResistances.BaseClasses.PlugFlow model. + The outlet temperature is calculated as in the equation above, + using the inlet temperature at port_a and the instantaneous + time delay and boundary temperature. + The boundary temperature can be either the air temperature + or the undisturbed ground temperature, depending on the definition of the + thermal resistance R.

    +

    + This component requires the delay time and the instantaneous ambient temperature + as an input. + This component is to be used in single pipes or in more advanced configurations + where no influence from other pipes is considered.

    • - March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      + December 6, 2017, by Michael Wetter:
      + Reformulated call to medium function.
      This is for - #1542. + + issue 869.
    • - May 27, 2017, by Filip Jorissen:
      - Regularised heat transfer around zero flow.
      - This is for - #769. + October 20, 2017, by Michael Wetter:
      + Revised implementation to avoid graphical and textual modeling. + Revised variable names and documentation to follow guidelines.
    • - April 12, 2017, by Michael Wetter:
      - Corrected invalid syntax for computing the specific heat capacity.
      - This is for - #707. + November 6, 2015 by Bram van der Heijde:
      + Make time delay input instead of calculation inside this model.
    • - October 11, 2016, by Massimo Cimmino:
      - First implementation. -
      • + September, 2015 by Marcus Fuchs:
      + First implementation.
    -------- Corrected Code --------

    - Model for a constant temperature evaporator or condenser based on a - ε-NTU heat exchanger model. + Component that calculates the heat losses at the end of a plug flow + pipe when the flow goes in the design direction.

    +

    + Main equations +

    - The heat exchanger effectiveness is calculated from the number of - transfer units (NTU): + The governing equations are

    - ε = 1 - exp(UA ⁄ (ṁ cp)) + Tout = Tb + (Tin - Tb) + exp((tout - tin)/tauchar)

    - Optionally, this model can have a flow resistance. If no flow - resistance is requested, set dp_nominal=0. + with +

    +

    + tauchar = R C

    - Limitations + Assumptions and limitations

    - This model does not consider any superheating or supercooling on the - refrigerant side. The refrigerant is considered to exchange heat at a - constant temperature throughout the heat exchanger. + This model is based on the following assumptions:

      -
    • March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for #1542. +
    • The water temperature is uniform in the cross section.
      • -
    • May 27, 2017, by Filip Jorissen:
      - Regularised heat transfer around zero flow.
      - This is for #769. +
    • There is no axial heat transfer in the water or surrounding.
      • -
    • April 12, 2017, by Michael Wetter:
      - Corrected invalid syntax for computing the specific heat - capacity.
      +
    • The boundary temperature along the pipe is uniform. +
      • +
    • Heat losses are steady-state. +
      • +
    +

    + Implementation +

    +

    + Heat losses are only considered in design flow direction. For heat + loss consideration in both directions, use one of these models at + both ends of a AixLib.Fluid.FixedResistances.BaseClasses.PlugFlow + model. The outlet temperature is calculated as in the equation above, + using the inlet temperature at port_a and the + instantaneous time delay and boundary temperature. The boundary + temperature can be either the air temperature or the undisturbed + ground temperature, depending on the definition of the thermal + resistance R. +

    +

    + This component requires the delay time and the instantaneous ambient + temperature as an input. This component is to be used in single pipes + or in more advanced configurations where no influence from other + pipes is considered. +

    +
      +
    • December 6, 2017, by Michael Wetter:
      + Reformulated call to medium function.
      This is for #707. + \"https://github.com/ibpsa/modelica-ibpsa/issues/869\">issue 869.
      • -
    • October 11, 2016, by Massimo Cimmino:
      +
    • October 20, 2017, by Michael Wetter:
      + Revised implementation to avoid graphical and textual modeling. + Revised variable names and documentation to follow guidelines. +
      • +
    • November 6, 2015 by Bram van der Heijde:
      + Make time delay input instead of calculation inside this model. +
      • +
    • September, 2015 by Marcus Fuchs:
      First implementation.
    -------- Errors -------- line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 17 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Media/Antifreeze/PropyleneGlycolWater.mo ---- +---- AixLib/Fluid/Geothermal/Borefields/Types.mo ---- -------- HTML Code -------- -

    - This base properties model is identical to - - Modelica.Media.Water.ConstantPropertyLiquidWater, - except that the equation - u = cv_const*(T - reference_T) - has been replaced by u=h because - cp_const=cv_const. - Also, the model checks if the mass fraction of the mixture is within the - allowed limits. -

    - -

    - Density of propylene antifreeze-water mixture at specified mass fraction - and temperature, based on Melinder (2010). -

    -

    References

    -

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary - Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: - IIR/IIF. -

    - - -

    - Dynamic viscosity of antifreeze-water mixture at specified mass fraction and - temperature, based on Melinder (2010). + Enumeration that defines the pipe configuration in the borehole.

    -

    References

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary - Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: - IIR/IIF. + The following pipe configurations are available in this enumeration:

    +
    + + + + + +
    EnumerationDescription
    SingleUTubeSingle U-tube configuration
    DoubleUTubeParallelDouble U-tube configuration with pipes connected in parallel
    DoubleUTubeSeriesDouble U-tube configuration with pipes connected in series

    +

    + This package contains type definitions. +

    + +-------- Corrected Code -------- +

    + Enumeration that defines the pipe configuration in the borehole. +

    +

    + The following pipe configurations are available in this enumeration: +

    + + + + + + + + + + + + + + + + + +
    + Enumeration + + Description +
    + SingleUTube + + Single U-tube configuration +
    + DoubleUTubeParallel + + Double U-tube configuration with pipes connected in parallel +
    + DoubleUTubeSeries + + Double U-tube configuration with pipes connected in series +
    +
      +
    • July 15, 2018, by Michael Wetter:
      + First implementation. +
      • +
    +

    + This package contains type definitions. +

    + +-------- Errors -------- +line 8 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +---- AixLib/Utilities/IO/SignalExchange/SignalTypes/SignalsForKPIs.mo ---- +-------- HTML Code -------- +

    - Fusion temperature of antifreeze-water mixture at specified mass fraction and - temperature, based on Melinder (2010). + This enumeration defines the signal types that are used by BOPTEST + to compute the key performance indices (KPI).

    -

    References

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary - Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: - IIR/IIF. + The following signal types are supported.

    +
    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    ValueDescription
    NoneNot used for KPI
    AirZoneTemperatureAir zone temperature
    RadiativeZoneTemperatureRadiative zone temperature
    OperativeZoneTemperatureOperative zone temperature
    RelativeHumidityRelative humidity
    CO2ConcentrationCO2 concentration
    ElectricPowerElectric power from grid
    DistrictHeatingPowerThermal power from district heating
    GasPowerThermal power from natural gas
    BiomassPowerThermal power from biomass
    SolarThermalPowerThermal power from solar thermal
    FreshWaterFlowRateFreshWaterFlowRate
    +-------- Corrected Code -------- +

    + This enumeration defines the signal types that are used by BOPTEST to + compute the key performance indices (KPI). +

    +

    + The following signal types are supported. +

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Value + + Description +
    + None + + Not used for KPI +
    + AirZoneTemperature + + Air zone temperature +
    + RadiativeZoneTemperature + + Radiative zone temperature +
    + OperativeZoneTemperature + + Operative zone temperature +
    + RelativeHumidity + + Relative humidity +
    + CO2Concentration + + CO2 concentration +
    + ElectricPower + + Electric power from grid +
    + DistrictHeatingPower + + Thermal power from district heating +
    + GasPower + + Thermal power from natural gas +
    + BiomassPower + + Thermal power from biomass +
    + SolarThermalPower + + Thermal power from solar thermal +
    + FreshWaterFlowRate + + FreshWaterFlowRate +
    +
      +
    • July 17, 2019, by Michael Wetter:
      + Added documentation. +
      • +
    • April 10, 2019, by Javier Arroyo:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 9 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +---- AixLib/Fluid/Humidifiers/SteamHumidifier_X.mo ---- +-------- HTML Code -------- +

    - Evaluates a thermophysical property of a mixture, based on correlations proposed - by Melinder (2010). + Model for a steam humidifier with a prescribed outlet water vapor mass fraction + in kg/kg total air.

    - The polynomial has the form -

    -

    - f = a1 (x-xm)0(y-ym)0 - + a2 (x-xm)0(y-ym)1 - + ... + - any[1] (x-xm)0(y-ym)ny[1]-1 - + ... + - any[1])+1 (x-xm)1(y-ym)0 - + ... + - any[1]+ny[2] (x-xm)1(y-ym)ny[2]-1 - + ... + This model forces the outlet water mass fraction at port_b to be + no lower than the + input signal X_wSet, subject to optional limits on the + maximum water vapor mass flow rate that is added, as + described by the parameter mWatMax_flow. + By default, the model has unlimited capacity.

    -

    References

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary - Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: - IIR/IIF. + The output signal mWat_flow ≥ 0 is the moisture added + to the medium if the flow rate is from port_a to port_b. + If the flow is reversed, then mWat_flow = 0. + The outlet specific enthalpy at port_b is increased by + the enthalpy of steam at 100°C times the mass of steam that was added. + Therefore, the temperature of the leaving fluid is slightly above the inlet temperature.

    - -
      -
    • - March 16, 2018 by Massimo Cimmino:
      - First implementation. - This function is used models in - - AixLib.Media.Antifreeze. -
      • -
    -

    - Specific heat capacity of antifreeze-water mixture at specified mass fraction - and temperature, based on Melinder (2010). + The outlet conditions at port_a are not affected by this model, + other than for a possible pressure difference due to flow friction.

    -

    References

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary - Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: - IIR/IIF. + If the parameter energyDynamics is different from + Modelica.Fluid.Types.Dynamics.SteadyState, + the component models the dynamic response using a first order differential equation. + The time constant of the component is equal to the parameter tau. + This time constant is adjusted based on the mass flow rate using +

    +

    + τeff = τ |ṁ| ⁄ ṁnom

    - - -

    - Thermal conductivity of antifreeze-water mixture at specified mass fraction and - temperature, based on Melinder (2010). -

    -

    References

    -

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids (Secondary - Refrigerants or Coolants, Heat Transfer Fluids) for Indirect Systems. Paris: - IIR/IIF. -

    - - - -

    - This medium package models propylene glycol - water mixtures. -

    -

    - The mass density, specific heat capacity, thermal conductivity and viscosity - are assumed constant and evaluated at a set temperature and mass fraction of - propylene glycol within the mixture. The dependence of the four properties - are shown on the figure below. -

    -

    - \"Relative -

    -

    - The accuracy of the thermophysical properties is dependent on the temperature - variations encountered during simulations. - The figure below shows the relative error of the the four properties over a - 10 °C range around the temperature used to evaluate the constant - properties. The maximum errors are 0.8 % for mass density, 1.5 % - for specific heat capacity, 3.2 % for thermal conductivity and 250 - % for dynamic viscosity. -

    -

    - \"Relative + where + τeff is the effective time constant for the given mass flow rate + ṁ and + τ is the time constant at the nominal mass flow rate + ṁnom. + This type of dynamics is equal to the dynamics that a completely mixed + control volume would have.

    - The figure below shows the relative error of the the four properties over a - 20 °C range around the temperature used to evaluate the constant - proepties. The maximum errors are 1.6 % for mass density, 3.0 % - for specific heat capacity, 6.2 % for thermal conductivity and 950 - % for dynamic viscosity. -

    -

    - \"Relative + Optionally, this model can have a flow resistance. + Set dp_nominal = 0 to disable the flow friction calculation.

    - The enthalpy is computed using the convention that h=0 - if T=0 °C. + For a model that uses a control signal u ∈ [0, 1] and multiplies + this with the nominal water mass flow rate, use + + AixLib.Fluid.Humidifiers.Humidifier_u +

    Limitations

    - Density, specific heat capacity, thermal conductivity and viscosity are constant. - The propylene glycol/water mixture is modeled as an incompressible liquid. - There are no phase changes. The medium is limited to temperatures below - 100 °C and mass fractions below 0.60. - As is the case for AixLib.Media.Water, - this medium package should not be used if - the simulation relies on the dynamic viscosity. -

    -

    Typical use and important parameters

    -

    - The temperature and mass fraction must be specified for the evaluation of the - constant thermophysical properties. A typical use of the package is (e.g. for - a temperature of 20 °C and a mass fraction of 0.40): -

    -

    - Medium = AixLib.Media.Antifreeze.PropyleneGlycolWater(property_T=293.15, X_a=0.40) + This model only adds water vapor for the flow from + port_a to port_b. + The water vapor of the reverse flow is not affected by this model.

    • - October 26, 2018, by Filip Jorissen and Michael Wetter:
      - Now printing different messages if temperature or mass fraction is above or below its limit, - and adding instance name as JModelica does not print the full instance name in the assertion. - This is for - #1045. + March 8, 2022, by Michael Wetter:
      + Renamed parameter massDynamics to energyDynamics for consistency with other models.
    • - March 16, 2018, by Massimo Cimmino:
      + May 10, 2017, by Michael Wetter:
      First implementation.
    -------- Corrected Code --------

    - This base properties model is identical to Modelica.Media.Water.ConstantPropertyLiquidWater, - except that the equation u = cv_const*(T - reference_T) - has been replaced by u=h because - cp_const=cv_const. Also, the model checks if the mass - fraction of the mixture is within the allowed limits. + Model for a steam humidifier with a prescribed outlet water vapor + mass fraction in kg/kg total air.

    - Density of propylene antifreeze-water mixture at specified mass - fraction and temperature, based on Melinder (2010). + This model forces the outlet water mass fraction at + port_b to be no lower than the input signal + X_wSet, subject to optional limits on the maximum water + vapor mass flow rate that is added, as described by the parameter + mWatMax_flow. By default, the model has unlimited + capacity.

    -

    - References -

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids - (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for - Indirect Systems. Paris: IIR/IIF. + The output signal mWat_flow ≥ 0 is the moisture added to + the medium if the flow rate is from port_a to + port_b. If the flow is reversed, then mWat_flow = + 0. The outlet specific enthalpy at port_b is + increased by the enthalpy of steam at 100°C times the mass of + steam that was added. Therefore, the temperature of the leaving fluid + is slightly above the inlet temperature.

    -

    - Dynamic viscosity of antifreeze-water mixture at specified mass - fraction and temperature, based on Melinder (2010). + The outlet conditions at port_a are not affected by this + model, other than for a possible pressure difference due to flow + friction.

    -

    - References -

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids - (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for - Indirect Systems. Paris: IIR/IIF. + If the parameter energyDynamics is different from + Modelica.Fluid.Types.Dynamics.SteadyState, the component + models the dynamic response using a first order differential + equation. The time constant of the component is equal to the + parameter tau. This time constant is adjusted based on + the mass flow rate using +

    +

    + τeff = τ |ṁ| ⁄ ṁnom

    -

    - Fusion temperature of antifreeze-water mixture at specified mass - fraction and temperature, based on Melinder (2010). + where τeff is the effective time constant for the + given mass flow rate ṁ and τ is the time constant at + the nominal mass flow rate ṁnom. This type of + dynamics is equal to the dynamics that a completely mixed control + volume would have. +

    +

    + Optionally, this model can have a flow resistance. Set + dp_nominal = 0 to disable the flow friction calculation. +

    +

    + For a model that uses a control signal u ∈ [0, 1] and + multiplies this with the nominal water mass flow rate, use AixLib.Fluid.Humidifiers.Humidifier_u

    - References + Limitations

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids - (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for - Indirect Systems. Paris: IIR/IIF. + This model only adds water vapor for the flow from + port_a to port_b. The water vapor of the + reverse flow is not affected by this model.

      -
    • May 2, 2018 by Massimo Cimmino:
      - First implementation. This function is used by AixLib.Media.Antifreeze.PropyleneGlycolWater. +
    • March 8, 2022, by Michael Wetter:
      + Renamed parameter massDynamics to + energyDynamics for consistency with other models. +
      • +
    • May 10, 2017, by Michael Wetter:
      + First implementation.
    + +-------- Errors -------- +line 33 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Movers/UsersGuide.mo ---- +-------- HTML Code -------- +

    - Evaluates a thermophysical property of a mixture, based on - correlations proposed by Melinder (2010). +This package contains models for fans and pumps. The same models +are used for fans or pumps.

    -

    - The polynomial has the form + +

    Model description

    +

    A detailed description of the fan and pump models can be +found in +Wetter (2013). +The models are implemented as described in this paper, except +that equation (20) is no longer used. The reason is that +the transition (24) caused the derivative

    - f = a1 (x-xm)0(y-ym)0 + - a2 (x-xm)0(y-ym)1 + ... + - any[1] (x-xm)0(y-ym)ny[1]-1 + ... + - any[1])+1 (x-xm)1(y-ym)0 + ... + - any[1]+ny[2] (x-xm)1(y-ym)ny[2]-1 + - ... + d Δp(r(t), V(t)) ⁄ d r(t)

    -

    - References -

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids - (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for - Indirect Systems. Paris: IIR/IIF. +to have an inflection point in the regularization region +r(t) ∈ (δ/2, δ). +This caused some models to not converge. +To correct this, for r(t) < δ, +the term V(t) ⁄ r(t) in (16) +has been modified so that (16) can be used for any +value of r(t).

    -
      -
    • March 16, 2018 by Massimo Cimmino:
      - First implementation. This function is used models in AixLib.Media.Antifreeze. -
      • -

    - Specific heat capacity of antifreeze-water mixture at specified mass - fraction and temperature, based on Melinder (2010). +Below, the models are briefly described.

    -

    - References -

    +
    Performance data

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids - (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for - Indirect Systems. Paris: IIR/IIF. +The models use +performance curves that compute pressure rise, +electrical power draw and efficiency as a function +of the volume flow rate and the speed. +The following performance curves are implemented:

    - -

    - Thermal conductivity of antifreeze-water mixture at specified mass - fraction and temperature, based on Melinder (2010). +

    + + + + + + + + + + + + + + + + + + + + + + + + +
    Independent variableDependent variableRecord for performance dataFunction
    Volume flow ratePressure +flowParameters +pressure
    Volume flow rateEfficiency +efficiencyParameters +efficiency
    Volume flow ratePower* +powerParameters +power
    +

    *Note: This record should not be used +(i.e. use_powerCharacteristic should be false) +for the movers that take as a control signal +the mass flow rate or the head, +unless also values for the record pressure are provided. +The reason is that for these movers the record pressure +is required to be able to compute the mover speed, +which is required to be able to compute the electrical power +correctly using similarity laws. +If a Pressure record is not provided, +the model will internally override use_powerCharacteristic=false. +In this case the efficiency records will be used. +Note that in this case an error is still introduced, +but it is smaller than when using the power records. +Compare + +AixLib.Fluid.Movers.Validation.PowerSimplified +with + +AixLib.Fluid.Movers.Validation.PowerExact +for an illustration of this error.

    -

    - References -

    - Melinder, Åke. 2010. Properties of Secondary Working Fluids - (Secondary Refrigerants or Coolants, Heat Transfer Fluids) for - Indirect Systems. Paris: IIR/IIF. +These performance curves are implemented in + +AixLib.Fluid.Movers.BaseClasses.Characteristics, +and are used in the performance records in the package + +AixLib.Fluid.Movers.Data. +The package + +AixLib.Fluid.Movers.Data +contains different data records.

    - +
    Models that use performance curves for pressure rise

    - This medium package models propylene glycol - water mixtures. +The models + +AixLib.Fluid.Movers.SpeedControlled_y and + +AixLib.Fluid.Movers.SpeedControlled_Nrpm +take as an input either a control signal between 0 and 1, or the +rotational speed in units of [1/min]. From this input and the current flow rate, +they compute the pressure rise. +This pressure rise is computed using a user-provided list of operating points that +defines the fan or pump curve at full speed. +For other speeds, similarity laws are used to scale the performance curves, as +described in + +AixLib.Fluid.Movers.BaseClasses.Characteristics.pressure.

    +

    - The mass density, specific heat capacity, thermal conductivity and - viscosity are assumed constant and evaluated at a set temperature and - mass fraction of propylene glycol within the mixture. The dependence - of the four properties are shown on the figure below. +For example, suppose a pump needs to be modeled whose pressure versus flow relation crosses, at +full speed, the points shown in the table below.

    -

    - - + + + + + + + + + + + + + + + + + +
    Volume flow rate [m3⁄s] Head [Pa]
    0.000345000
    0.000635000
    0.000815000
    +

    +Then, a declaration would be

    +
    +  AixLib.Fluid.Movers.SpeedControlled_y pum(
+    redeclare package Medium = Medium,
+    per.pressure(V_flow={0.0003,0.0006,0.0008},
+                 dp    ={45,35,15}*1000))
+    \"Circulation pump\";
+
    +

    - The accuracy of the thermophysical properties is dependent on the - temperature variations encountered during simulations. The figure - below shows the relative error of the the four properties over a - 10 °C range around the temperature used to evaluate the - constant properties. The maximum errors are 0.8 % for mass - density, 1.5 % for specific heat capacity, 3.2 % for - thermal conductivity and 250 % for dynamic viscosity. +This will model the following pump curve for the pump input signal y=1.

    - - +\"image\"

    + +
    Models that directly control the head or the mass flow rate

    - The figure below shows the relative error of the the four properties - over a 20 °C range around the temperature used to evaluate the - constant proepties. The maximum errors are 1.6 % for mass - density, 3.0 % for specific heat capacity, 6.2 % for - thermal conductivity and 950 % for dynamic viscosity. +The models +AixLib.Fluid.Movers.FlowControlled_dp and + +AixLib.Fluid.Movers.FlowControlled_m_flow +take as an input the pressure difference or the mass flow rate. +This pressure difference or mass flow rate will be provided by the fan or pump, +i.e., the fan or pump has idealized perfect control and infinite capacity. +Using these models that take as an input the head or the mass flow rate often leads +to smaller system of equations compared to using the models that take +as an input the speed.

    -

    - - +

    +These models can be configured for three different control inputs. +For + +AixLib.Fluid.Movers.FlowControlled_dp, +the head is as follows:

    +
      +

    • - The enthalpy is computed using the convention that h=0 if - T=0 °C. +If the parameter inputType==AixLib.Fluid.Types.InputType.Continuous, +the head is dp=dp_in, where dp_in is an input connector.

      -

      - Limitations -

      +
      • +

    • - Density, specific heat capacity, thermal conductivity and viscosity - are constant. The propylene glycol/water mixture is modeled as an - incompressible liquid. There are no phase changes. The medium is - limited to temperatures below 100 °C and mass fractions below - 0.60. As is the case for AixLib.Media.Water, this medium - package should not be used if the simulation relies on the dynamic - viscosity. +If the parameter inputType==AixLib.Fluid.Types.InputType.Constant, +the head is dp=constantHead, where constantHead is a parameter.

      -

      - Typical use and important parameters -

      +
      • +

    • - The temperature and mass fraction must be specified for the - evaluation of the constant thermophysical properties. A typical use - of the package is (e.g. for a temperature of 20 °C and a mass - fraction of 0.40): +If the parameter inputType==AixLib.Fluid.Types.InputType.Stages, +the head is dp=heads, where heads is a +vectorized parameter. For example, if a mover has +two stages and the head of the first stage should be 60% of the nominal head +and the second stage equal to dp_nominal, set +heads={0.6, 1}*dp_nominal. +Then, the mover will have the following heads:

      + + + + + + + + + + + + + + + + + +
      input signal stageHead [Pa]
      00
      10.6*dp_nominal
      2dp_nominal
      +
      • +

    - Medium = - AixLib.Media.Antifreeze.PropyleneGlycolWater(property_T=293.15, - X_a=0.40) +Similarly, for + +AixLib.Fluid.Movers.FlowControlled_m_flow, +the mass flow rate is as follows:

      -
    • October 26, 2018, by Filip Jorissen and Michael Wetter:
      - Now printing different messages if temperature or mass fraction is - above or below its limit, and adding instance name as JModelica - does not print the full instance name in the assertion. This is for - #1045. -
      • -
    • March 16, 2018, by Massimo Cimmino:
      - First implementation. -
      • -
    - --------- Errors -------- -line 9 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - -line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 24 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 35 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/timeGeometric.mo ---- --------- HTML Code -------- - -

    - This function attemps to build a vector of length nTim with a geometric - expansion of the time variable between dt and t_max. -

    -

    - If t_max > nTim*dt, then a geometrically expanding vector is built as -

    -

    - t = [dt, dt*(1-r2)/(1-r), ... , dt*(1-rn)/(1-r), ... , tmax], -

    -

    - where r is the geometric expansion factor. -

    -

    - If t_max < nTim*dt, then a linearly expanding vector is built as -

    -

    - t = [dt, 2*dt, ... , n*dt, ... , nTim*dt] -

    - -
      -
    • - June 28, 2018 by Massimo Cimmino:
      - First implementation. -
      • -
    - --------- Corrected Code -------- +

  • - This function attemps to build a vector of length nTim - with a geometric expansion of the time variable between - dt and t_max. +If the parameter inputType==AixLib.Fluid.Types.InputType.Continuous, +the mass flow rate is m_flow=m_flow_in, where m_flow_in is an input connector.

    +
    • +

  • - If t_max > nTim*dt, then a geometrically expanding - vector is built as +If the parameter inputType==AixLib.Fluid.Types.InputType.Constant, +the mass flow rate is m_flow=constantMassFlowRate, where constantMassFlowRate is a parameter.

    -

    - t = [dt, dt*(1-r2)/(1-r), ... , - dt*(1-rn)/(1-r), ... , tmax], +

    • +
  • +

    +If the parameter inputType==AixLib.Fluid.Types.InputType.Stages, +the mass flow rate is m_flow=massFlowRates, where massFlowRates is a +vectorized parameter. For example, if a mover has +two stages and the mass flow rate of the first stage should be 60% of the nominal mass flow rate +and the second stage equal to m_flow_nominal, set +massFlowRates={0.6, 1}*m_flow_nominal. +Then, the mover will have the following mass flow rates:

    + + + + + + + + + + + + + + + + + +
    input signal stageMass flow rates [kg/s]
    00
    10.6*m_flow_nominal
    2m_flow_nominal
    +
    • +

    - where r is the geometric expansion factor. +These two models do not need to use a performance curve for the flow +characteristics. +The reason is that

    +
      +
    • +for given pressure rise (or mass flow rate), the mass flow rate (or pressure rise) +is computed from the flow resistance of the duct or piping network, and +
      • +
    • +at zero pressure difference, solving for the flow rate and the revolution leads to a singularity. +
      • +
    +

    +However, the computation of the electrical power consumption +requires the mover speed to be known +and the computation of the mover speed requires the performance +curves for the flow and efficiency/power characteristics. +Therefore these performance curves do need to be provided +if the user desires a correct electrical power computation. +If the curves are not provided, a simplified computation is used, +where the efficiency curve is used and assumed to be correct for all speeds. +This loss of accuracy has the advantage that it allows to use the +mover models without requiring flow and efficiency/power characteristics.

    - If t_max < nTim*dt, then a linearly expanding vector - is built as +The model +AixLib.Fluid.Movers.FlowControlled_dp +has an option to control the mover such +that the pressure difference set point is obtained +across two remote points in the system. +To use this functionality +parameter prescribeSystemPressure has +to be enabled and a differential pressure measurement +must be connected to +the pump input dpMea. +This functionality is demonstrated in + +AixLib.Fluid.Movers.Validation.FlowControlled_dpSystem.

    -

    - t = [dt, 2*dt, ... , n*dt, ... , nTim*dt] +

    +The models +AixLib.Fluid.Movers.FlowControlled_dp and + +AixLib.Fluid.Movers.FlowControlled_m_flow +both have a parameter m_flow_nominal. For + +AixLib.Fluid.Movers.FlowControlled_m_flow, this parameter +is used for convenience to set a default value for the parameters +constantMassFlowRate and +massFlowRates. +For both models, the value is also used for the following:

    +
      -
    • June 28, 2018 by Massimo Cimmino:
      - First implementation. -
      • +
    • +To compute the +size of the fluid volume that can be used to approximate the +inertia of the mover if the energy dynamics is selected to be dynamic. +
      • +
    • +To compute a default pressure curve if no pressure curve has been specified +in the record per.pressure. +The default pressure curve is the line that intersects +(dp, V_flow) = (dp_nominal, 0) and +(dp, V_flow) = (m_flow_nominal/rho_default, 0). +
      • +
    • +To regularize the equations near zero flow rate to ensure a numerically +robust model. +
    - --------- Errors -------- -line 9 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 18 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Controls/SetPoints/Examples/SupplyReturnTemperatureReset.mo ---- --------- HTML Code -------- - -

    - Example that demonstrates the use of the hot water temperature reset - for a heating system. - The parameters of the block heaCur - are for a heating system with - 60°C supply water temperature and - 40°C return water temperature at - an outside temperature of - -10°C and a room temperature of - 20°C. The offset for the temperature reset is - 8 Kelvin, i.e., above - 12°C outside temperature, there is no heating load. - The figure below shows the computed supply and return water temperatures. -

    -

    - \"Supply -

    - -
      -
    • - November 21, 2011, by Michael Wetter:
      - Added documentation. -
      • -
    - --------- Corrected Code --------

    - Example that demonstrates the use of the hot water temperature reset - for a heating system. The parameters of the block heaCur - are for a heating system with 60°C supply water temperature - and 40°C return water temperature at an outside temperature of - -10°C and a room temperature of 20°C. The offset for - the temperature reset is 8 Kelvin, i.e., above 12°C - outside temperature, there is no heating load. The figure below shows - the computed supply and return water temperatures. +However, otherwise m_flow_nominal does not affect the mass flow rate of the mover as +the mass flow rate is determined by the input signal or the above explained parameters. +

    +
    Start-up and shut-down transients
    +

    +All models have a parameter use_inputFilter. This +parameter affects the fan output as follows:

    +
      +
    1. +If use_inputFilter=false, then the input signal y (or +Nrpm, m_flow_in, or dp_in) +is equal to the fan speed (or the mass flow rate or pressure rise). +Thus, a step change in the input signal causes a step change in the fan speed (or mass flow rate or pressure rise). +
      2. +
    2. +If use_inputFilter=true, which is the default, +then the fan speed (or the mass flow rate or the pressure rise) +is equal to the output of a filter. This filter is implemented +as a 2nd order differential equation and can be thought of as +approximating the inertia of the rotor and the fluid. +Thus, a step change in the fan input signal will cause a gradual change +in the fan speed. +The filter has a parameter riseTime, which by default is set to +30 seconds. +The rise time is the time required to reach 99.6% of the full speed, or, +if the fan is switched off, to reach a fan speed of 0.4%. +
      3. +
    +

    +The figure below shows for a fan with use_inputFilter=true +and riseTime=30 seconds the +speed input signal and the actual speed.

    - \"Supply +\"image\"

    -
      -
    • November 21, 2011, by Michael Wetter:
      - Added documentation. -
      • -
    - --------- Errors -------- -line 16 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Controls/Continuous/NumberOfRequests.mo ---- --------- HTML Code -------- -

    - Block that outputs the number of inputs that exceed a threshold. - The parameter kind is used to determine the kind of the - inequality. The table below shows the allowed settings. -

    - - - - - - - - - - - - - - - - - - - - - -
    Value of parameter kindOutput signal incremented by 1 for each i ∈ {1, ..., nin} if
    0u[i] > threShold
    1u[i] ≥ threShold
    2u[i] ≤ threShold
    3u[i] < threShold
    -

    - This model may be used to check how many rooms - exceed a temperature threshold. -

    - -
      -
    • - November 21, 2011, by Michael Wetter:
      - Improved documentation. -
      • -
    • - November 25, 2008, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code --------

    - Block that outputs the number of inputs that exceed a threshold. The - parameter kind is used to determine the kind of the - inequality. The table below shows the allowed settings. +Although many simulations do not require such a detailed model +that approximates the transients of fans or pumps, it turns +out that using this filter can reduce computing time and +can lead to fewer convergence problems in large system models. +With a filter, any sudden change in control signal, such as when +a fan switches on, is damped before it affects the air flow rate. +This continuous change in flow rate turns out to be easier, and in +some cases faster, to simulate compared to a step change. +For most simulations, we therefore recommend to use the default settings +of use_inputFilter=true and riseTime=30 seconds. +An exception are situations in which the fan or pump is operated at a fixed speed during +the whole simulation. In this case, set use_inputFilter=false.

    - - - - - - - - - - - - - - - - - - - - - -
    - Value of parameter kind - - Output signal incremented by 1 for each i ∈ {1, ..., nin} - if -
    - 0 - - u[i] > threShold -
    - 1 - - u[i] ≥ threShold -
    - 2 - - u[i] ≤ threShold -
    - 3 - - u[i] < threShold -

    - This model may be used to check how many rooms exceed a temperature - threshold. +Note that if the fan is part of a closed loop control, then the filter affects +the transient response of the control. +When changing the value of use_inputFilter, the control gains +may need to be retuned. +We now present values control parameters that seem to work in most cases. +Suppose there is a closed loop control with a PI-controller + +AixLib.Controls.Continuous.LimPID +and a fan or pump, configured with use_inputFilter=true and riseTime=30 seconds. +Assume that the transient response of the other dynamic elements in the control loop is fast +compared to the rise time of the filter. +Then, a proportional gain of k=0.5 and an integrator time constant of +Ti=15 seconds often yields satisfactory closed loop control performance. +These values may need to be changed for different applications as they are also a function +of the loop gain. +If the control loop shows oscillatory behavior, then reduce k and/or increase Ti. +If the control loop reacts too slow, do the opposite.

    -
      -
    • November 21, 2011, by Michael Wetter:
      - Improved documentation. -
      • -
    • November 25, 2008, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 7 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 - - ----- AixLib/Utilities/Math/Biquadratic.mo ---- --------- HTML Code -------- -

    - This block computes -

    -

    - y = a1 + a2 x1 - + a3 x12 - + a4 x2 + a5 x22 - + a6 x1 x2 -

    - -
      -
    • - Sep. 8, 2010, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code -------- +
    Efficiency and electrical power consumption

    - This block computes +All models compute the motor power draw Pele, +the hydraulic power input Whyd, the flow work +Wflo and the heat dissipated into the medium +Q. Based on the first law, the flow work is

    - y = a1 + a2 x1 + a3 - x12 + a4 x2 + - a5 x22 + a6 x1 - x2 + Wflo = | V̇ Δp |, +

    +

    +where V̇ is the volume flow rate and +Δp is the pressure rise. +The heat dissipated into the medium is as follows: +If the motor is cooled by the fluid, as indicated by +per.motorCooledByFluid=true, then the heat dissipated into the medium is +

    +

    + Q = Pele - Wflo.

    -
      -
    • Sep. 8, 2010, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 - ----- AixLib/Fluid/FMI/UsersGuide.mo ---- --------- HTML Code -------- +

    +If per.motorCooledByFluid=false, then the motor is outside the fluid stream, +and only the shaft, or hydraulic, work Whyd enters the thermodynamic +control volume. Hence, +

    +

    + Q = Whyd - Wflo. +

    +

    The efficiencies are computed as

    +

    + η = Wflo ⁄ Pele = ηhyd   ηmot
    + ηhyd = Wflo ⁄ Whyd
    + ηmot = Whyd ⁄ Pele
    +

    +

    where +ηhyd is the hydraulic efficiency, +ηmot is the motor efficiency and +Q is the heat released by the motor. +

    +

    +If per.use_powerCharacteristic=true, +then a set of data points for the power Pele for different +volume flow rates at full speed needs to be provided by the user. +Using the flow work Wflo and the electrical power input +Pele, the total efficiency is computed as +

    +

    + η = Wflo ⁄ Pele,
    +

    +

    +and the two efficiencies +ηhyd +and ηmot are computed as +

    +

    + ηhyd = 1,
    + ηmot = η. +

    +

    +However, if per.use_powerCharacteristic=false, then +performance data for +ηhyd and + ηmot need to be provided by the user, and hence +the model computes +

    +

    + η = ηhyd   ηmot
    + Pele = Wflo ⁄ η. +

    -This user's guide describes the FMI package (Wetter et al., 2015). -The FMI package has been implemented to facilitate the export -of thermofluid flow models such as HVAC components, HVAC systems -and thermal zones as Functional Mockup Units (FMUs). -This allows to export thermofluid flow models as FMUs so that they can be -imported in other simulators. -To export thermofluid flow components, a Modelica block is needed -in order for the model to only have input and output signals -rather than fluid connectors, as fluid connectors do not impose any causality -on the signal flow. -This package implements such blocks and its connectors. +The efficiency data for the motor are a list of points +V̇ and ηmot.

    + +
    Fluid volume of the component

    -The main packages are as follows: +All models can be configured to have a fluid volume at the low-pressure side. +Adding such a volume sometimes helps the solver to find a solution during +initialization and time integration of large models.

    -
    - - - - - - - - - - - - - - - - - - - -
    PackageDescription
    - - AixLib.Fluid.FMI.ExportContainers - -

    - Package with blocks to export thermofluid flow components and systems. -

    -

    - To export an HVAC component or system with a single inlet and outlet port, instantiate - - AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort - with a replaceable model, - or extend from - - AixLib.Fluid.FMI.ExportContainers.PartialTwoPort - and add components.
    - See - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.Fan - and - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ResistanceVolume. -

    -

    - To export an HVAC system that serves a single thermal zone, extend from - - AixLib.Fluid.FMI.ExportContainers.HVACZone - and add the HVAC system.
    - See - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone. -

    -

    - To export an HVAC system that serves multiple thermal zones, extend from - - AixLib.Fluid.FMI.ExportContainers.HVACZones - and add the HVAC system.
    - See - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones. -

    -

    - To export a single thermal zone, extend from - - AixLib.Fluid.FMI.ExportContainers.ThermalZone - and add the thermal zone.
    - See - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. -

    -

    - To export multiple thermal zones, extend from - - AixLib.Fluid.FMI.ExportContainers.ThermalZones - and add the thermal zone models.
    - See - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones. -

    -
    - - AixLib.Fluid.FMI.Adaptors - -

    - Package with adaptors to connect models with fluid ports to blocks that - have input and output signals. -

    -
    -

    - - AixLib.Fluid.FMI.Conversion -

    -    		 -

    - Package with blocks that convert between the signal connectors of - - AixLib.Fluid.FMI.Interfaces - and the real input and output signal connectors of the Modelica Standard Library. -

    -
    - - AixLib.Fluid.FMI.Interfaces - -

    - Package with composite connectors that have different input and output - signals. These connectors are used to export FMUs, and they contain - quantities such as mass flow rate, temperature, optional pressure, etc. -

    -
    + +
    Enthalpy change of the component

    -The package - -AixLib.Fluid.FMI.ExportContainers.Examples.FMUs -contains various examples in which HVAC components, HVAC systems -and thermal zones are exported as an FMU. +If per.motorCooledByFluid=true, then +the enthalpy change between the inlet and outlet fluid port is equal +to the electrical power Pele that is consumed by the component. +Otherwise, it is equal to the hydraulic work Whyd. +The parameter addPowerToMedium, which is by default set to +true, can be used to simplify the equations. +If addPowerToMedium = false, then no enthalpy change occurs between +inlet and outlet. +This can lead to simpler equations, but the temperature rise across the component +will be zero. In particular for fans, this simplification may not be permissible.

    -

    Typical use

    + +

    Differences to models in Modelica.Fluid.Machines

    -Users who want to export a single thermofluid flow component, or a -subsystem of thermofluid flow components, can use the block - -AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort. -This block has a fluid inlet, a fluid outlet, and a replaceable -component that can be replaced with an HVAC component or system that -has an inlet and outlet fluid port. +The models in this package differ from +Modelica.Fluid.Machines +primarily in the following points:

    +
      +
    • +They use a different base class, which allows to have zero mass flow rate. +The models in Modelica.Fluid restrict the number of revolutions, and hence the flow +rate, to be non-zero. +
      • +
    • +For the model with prescribed pressure, the input signal is the +pressure difference between the two ports, and not the absolute +pressure at port_b. +
      • +
    • +The pressure calculations are based on total pressure in Pascals instead of the pump head in meters. +This change was done to avoid ambiguities in the parameterization if the models are used as a fan +with air as the medium. The original formulation in +Modelica.Fluid.Machines converts head +to pressure using the density medium.d. Therefore, for fans, +head would be converted to pressure using the density of air. However, for pumps, +manufacturers typically publish the head in millimeters water (mmH2O). +Therefore, to avoid confusion when using these models with media other than water, +we changed the models to use total pressure in Pascals instead of head in meters. +
      • +
    • +The performance data are interpolated using cubic hermite splines instead of polynomials. +These functions are implemented in + +AixLib.Fluid.Movers.BaseClasses.Characteristics. +
      • +
    +

    References

    -Users who want to export a whole HVAC system that serves a single thermal zone -can do so by extending the partial block - -AixLib.Fluid.FMI.ExportContainers.HVACZone. -The example - -AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone -illustrates how this can be accomplished.
    -Similar export containers and examples are implemented for HVAC systems that serve multiple thermal zones. +Michael Wetter. + +Fan and pump model that has a unique solution for any pressure +boundary condition and control signal. +Proc. of the 13th Conference of the International Building Performance +Simulation Association, p. 3505-3512. Chambery, France. August 2013.

    + +-------- Corrected Code --------

    -Conversely, to export a thermal zone, users can extend the partial block - -AixLib.Fluid.FMI.ExportContainers.ThermalZone. -The example - -AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone -illustrates how this can be accomplished.
    -Similar export containers and examples are implemented for models of multiple thermal zones. + This package contains models for fans and pumps. The same models are + used for fans or pumps.

    +

    + Model description +

    -Each example and validation model has a Dymola script that -either simulates the model, or exports the model as an FMU. -The script can be invoked from the pull -down menu Commands -> Export FMU. + A detailed description of the fan and pump models can be found in + + Wetter (2013). The models are implemented as described in this + paper, except that equation (20) is no longer used. The reason is + that the transition (24) caused the derivative

    -

    Options

    -

    -In the -AixLib.Fluid package, -most models have a boolean parameter called allowFlowReversal. -If set to true, then the flow can be in either direction, -otherwise it needs to be from the inlet to the outlet port. -This parameter is also used in the -AixLib.Fluid.FMI package. -The package was designed in such a way that an FMU, -if exported with allowFlowReversal=false -has as input the mass flow rate, -pressure and fluid properties of the inflowing fluid. The outputs -are the outlet mass flow rate, outlet pressure and the fluid -properties of the outflowing medium. This allows simulators -such as Ptolemy II -to evaluate the FMUs in the direction of the mass flow by first -setting all inputs, then evaluating the model equations, -and finally retrieving the -outputs before proceeding the simulation with the next downstream -component. -If allowFlowReversal=true, then the connectors have additional -signals for the properties of the fluid if it flows backwards. +

    + d Δp(r(t), V(t)) ⁄ d r(t)

    -Most components have a boolean parameter use_p_in. -If use_p_in=true, then the pressure is used from the -connector, and based on the mass flow rate, the outlet pressure -is computed and assigned to the outlet connectors. -If use_p_in=false, then the pressure as declared -by the constant p_default of the medium model is -used, and the component computes no pressure drop. -Setting use_p_in=false therefore leads to fewer -equations, but it requires a component that specifies the mass -flow rate, such as - -AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.IdealSource_m_flow. + to have an inflection point in the regularization region r(t) ∈ + (δ/2, δ). This caused some models to not converge. To correct + this, for r(t) < δ, the term V(t) ⁄ r(t) in (16) has + been modified so that (16) can be used for any value of r(t).

    -

    Notes

    -Note the following when exporting HVAC component models as an FMU: + Below, the models are briefly described.

    -
      -
    1. +
      + Performance data +

      -For models with control volumes, -the mass balance must be configured using -massDynamics=Modelica.Fluid.Types.Dynamics.SteadyState -when used with the media - -AixLib.Media.Air. -Otherwise, the translation stops with the error -

      -
      -The model requires derivatives of some inputs as listed below:
-1 inlet.p
-
      -

      -The reason is that for - -AixLib.Media.Air, -mass is proportional to pressure and pressure is proportional -to density. Hence, dm/dt requires dp/dt, -but the time derivative of the pressure is not an input to the model. -

      -

      -For -AixLib.Media.Water, this setting is not needed -as the mass is independent of pressure. -

      -
      2. -
    2. -

      -The model - -AixLib.Fluid.Movers.FlowControlled_m_flow -cannot be exported as an FMU. -This is because it assignes the mass flow rate. -However, the input connector - -AixLib.Fluid.FMI.Interfaces.Inlet -already declares the mass flow rate as an input. -Therefore, the mass flow rate is overdetermined. -As a fall back, if a user needs to set the mass flow rate, he/she can -do so by using - -AixLib.Fluid.FMI.Source_T, -which takes as an input signal the mass flow rate. -

      -
      3. -
    -

    -When connecting fluid flow components in a loop, -be careful to avoid circular assignments for example for the temperature, -as these can of course not be simulated. -An example of such an ill-posed problem is to connect the outlet of - -AixLib.Fluid.FixedResistances.PressureDrop -to its inlet. In this situation, neither pressure, nor mass flow rate or temperature -can be computed. To model such loops, a control volume with a dynamic energy -balance must be presented, and the medium needs to be compressible. -

    -

    References

    -

    -Michael Wetter, Marcus Fuchs and Thierry Stephane Nouidui.
    - -Design choices for thermofluid flow components and systems that are exported as Functional Mockup Units.
    -Proc. of the 11th International Modelica Conference, - p. 31-41, - Versailles, France, September 2015. -

    - --------- Corrected Code -------- -

    - This user's guide describes the FMI package (Wetter et al., 2015). - The FMI package has been implemented to facilitate the export of - thermofluid flow models such as HVAC components, HVAC systems and - thermal zones as Functional Mockup Units (FMUs). This allows to - export thermofluid flow models as FMUs so that they can be imported - in other simulators. To export thermofluid flow components, a - Modelica block is needed in order for the model to only have input - and output signals rather than fluid connectors, as fluid connectors - do not impose any causality on the signal flow. This package - implements such blocks and its connectors. -

    -

    - The main packages are as follows: + The models use performance curves that compute pressure rise, + electrical power draw and efficiency as a function of the volume flow + rate and the speed. The following performance curves are implemented:

    + + + + + + - -
    - Package + Independent variable - Description + Dependent variable + + Record for performance data + + Function
    + Volume flow rate + + Pressure + AixLib.Fluid.FMI.ExportContainers + \"modelica://AixLib.Fluid.Movers.BaseClasses.Characteristics.flowParameters\"> + flowParameters -

    - Package with blocks to export thermofluid flow components and - systems. -

    -

    - To export an HVAC component or system with a single inlet and - outlet port, instantiate - AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort with a - replaceable model, or extend from AixLib.Fluid.FMI.ExportContainers.PartialTwoPort - and add components.
    - See - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.Fan and - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ResistanceVolume. -

    -

    - To export an HVAC system that serves a single thermal zone, - extend from AixLib.Fluid.FMI.ExportContainers.HVACZone - and add the HVAC system.
    - See - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone. -

    -

    - To export an HVAC system that serves multiple thermal zones, - extend from AixLib.Fluid.FMI.ExportContainers.HVACZones - and add the HVAC system.
    - See - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones. -

    -

    - To export a single thermal zone, extend from AixLib.Fluid.FMI.ExportContainers.ThermalZone - and add the thermal zone.
    - See - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. -

    -

    - To export multiple thermal zones, extend from AixLib.Fluid.FMI.ExportContainers.ThermalZones - and add the thermal zone models.
    - See - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones. -

    + + pressure
    + Volume flow rate + + Efficiency + AixLib.Fluid.FMI.Adaptors + \"modelica://AixLib.Fluid.Movers.BaseClasses.Characteristics.efficiencyParameters\"> + efficiencyParameters -

    - Package with adaptors to connect models with fluid ports to - blocks that have input and output signals. -

    + + efficiency
    -

    - AixLib.Fluid.FMI.Conversion -

    + Volume flow rate     		-

    - Package with blocks that convert between the signal connectors - of AixLib.Fluid.FMI.Interfaces - and the real input and output signal connectors of the Modelica - Standard Library. -

    + Power*
    AixLib.Fluid.FMI.Interfaces + \"modelica://AixLib.Fluid.Movers.BaseClasses.Characteristics.powerParameters\"> + powerParameters -

    - Package with composite connectors that have different input and - output signals. These connectors are used to export FMUs, and - they contain quantities such as mass flow rate, temperature, - optional pressure, etc. -

    + + power

    + *Note: This record should not be used (i.e. + use_powerCharacteristic should be false) + for the movers that take as a control signal the mass flow rate or + the head, unless also values for the record pressure are + provided. The reason is that for these movers the record + pressure is required to be able to compute the mover + speed, which is required to be able to compute the electrical power + correctly using similarity laws. If a Pressure record is + not provided, the model will internally override + use_powerCharacteristic=false. In this case the + efficiency records will be used. Note that in this case an error is + still introduced, but it is smaller than when using the power + records. Compare AixLib.Fluid.Movers.Validation.PowerSimplified + with AixLib.Fluid.Movers.Validation.PowerExact + for an illustration of this error. +

    +

    + These performance curves are implemented in AixLib.Fluid.Movers.BaseClasses.Characteristics, + and are used in the performance records in the package AixLib.Fluid.Movers.Data. The package AixLib.Fluid.FMI.ExportContainers.Examples.FMUs - contains various examples in which HVAC components, HVAC systems and - thermal zones are exported as an FMU. + \"modelica://AixLib.Fluid.Movers.Data\">AixLib.Fluid.Movers.Data + contains different data records.

    -

    - Typical use -

    +
    + Models that use performance curves for pressure rise +

    - Users who want to export a single thermofluid flow component, or a - subsystem of thermofluid flow components, can use the block AixLib.Fluid.FMI.ExportContainers.ReplaceableTwoPort. - This block has a fluid inlet, a fluid outlet, and a replaceable - component that can be replaced with an HVAC component or system that - has an inlet and outlet fluid port. + The models AixLib.Fluid.Movers.SpeedControlled_y + and AixLib.Fluid.Movers.SpeedControlled_Nrpm + take as an input either a control signal between 0 and + 1, or the rotational speed in units of [1/min]. From + this input and the current flow rate, they compute the pressure rise. + This pressure rise is computed using a user-provided list of + operating points that defines the fan or pump curve at full speed. + For other speeds, similarity laws are used to scale the performance + curves, as described in + AixLib.Fluid.Movers.BaseClasses.Characteristics.pressure.

    - Users who want to export a whole HVAC system that serves a single - thermal zone can do so by extending the partial block AixLib.Fluid.FMI.ExportContainers.HVACZone. - The example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone - illustrates how this can be accomplished.
    - Similar export containers and examples are implemented for HVAC - systems that serve multiple thermal zones. + For example, suppose a pump needs to be modeled whose pressure versus + flow relation crosses, at full speed, the points shown in the table + below.

    + + + + + + + + + + + + + + + + + +
    + Volume flow rate [m3⁄s] + + Head [Pa] +
    + 0.0003 + + 45000 +
    + 0.0006 + + 35000 +
    + 0.0008 + + 15000 +

    - Conversely, to export a thermal zone, users can extend the partial - block AixLib.Fluid.FMI.ExportContainers.ThermalZone. - The example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone - illustrates how this can be accomplished.
    - Similar export containers and examples are implemented for models of - multiple thermal zones. + Then, a declaration would be

    +
    +  AixLib.Fluid.Movers.SpeedControlled_y pum(
+    redeclare package Medium = Medium,
+    per.pressure(V_flow={0.0003,0.0006,0.0008},
+                 dp    ={45,35,15}*1000))
+    \"Circulation pump\";
+

    - Each example and validation model has a Dymola script that either - simulates the model, or exports the model as an FMU. The script can - be invoked from the pull down menu Commands -> Export - FMU. + This will model the following pump curve for the pump input signal + y=1.

    -

    - Options -

    -

    - In the AixLib.Fluid package, - most models have a boolean parameter called - allowFlowReversal. If set to true, then the - flow can be in either direction, otherwise it needs to be from the - inlet to the outlet port. This parameter is also used in the AixLib.Fluid.FMI package. The - package was designed in such a way that an FMU, if exported with - allowFlowReversal=false has as input the mass flow rate, - pressure and fluid properties of the inflowing fluid. The outputs are - the outlet mass flow rate, outlet pressure and the fluid properties - of the outflowing medium. This allows simulators such as Ptolemy II - to evaluate the FMUs in the direction of the mass flow by first - setting all inputs, then evaluating the model equations, and finally - retrieving the outputs before proceeding the simulation with the next - downstream component. If allowFlowReversal=true, then - the connectors have additional signals for the properties of the - fluid if it flows backwards. +

    + \"image\"

    +
    + Models that directly control the head or the mass flow rate +

    - Most components have a boolean parameter use_p_in. If - use_p_in=true, then the pressure is used from the - connector, and based on the mass flow rate, the outlet pressure is - computed and assigned to the outlet connectors. If - use_p_in=false, then the pressure as declared by the - constant p_default of the medium model is used, and the - component computes no pressure drop. Setting - use_p_in=false therefore leads to fewer equations, but - it requires a component that specifies the mass flow rate, such as - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.IdealSource_m_flow. + The models AixLib.Fluid.Movers.FlowControlled_dp + and AixLib.Fluid.Movers.FlowControlled_m_flow + take as an input the pressure difference or the mass flow rate. This + pressure difference or mass flow rate will be provided by the fan or + pump, i.e., the fan or pump has idealized perfect control and + infinite capacity. Using these models that take as an input the head + or the mass flow rate often leads to smaller system of equations + compared to using the models that take as an input the speed.

    -

    - Notes -

    - Note the following when exporting HVAC component models as an FMU: + These models can be configured for three different control inputs. + For AixLib.Fluid.Movers.FlowControlled_dp, + the head is as follows:

    -
      +

      • - For models with control volumes, the mass balance must be - configured using - massDynamics=Modelica.Fluid.Types.Dynamics.SteadyState - when used with the media AixLib.Media.Air. Otherwise, - the translation stops with the error -

        - 
        -The model requires derivatives of some inputs as listed below:
-1 inlet.p
-
        -

        - The reason is that for AixLib.Media.Air, mass is - proportional to pressure and pressure is proportional to density. - Hence, dm/dt requires dp/dt, but the time - derivative of the pressure is not an input to the model. + If the parameter + inputType==AixLib.Fluid.Types.InputType.Continuous, + the head is dp=dp_in, where dp_in is an + input connector.

        +
        • +

      • - For AixLib.Media.Water, this - setting is not needed as the mass is independent of pressure. + If the parameter + inputType==AixLib.Fluid.Types.InputType.Constant, + the head is dp=constantHead, where + constantHead is a parameter.

      • - The model AixLib.Fluid.Movers.FlowControlled_m_flow - cannot be exported as an FMU. This is because it assignes the - mass flow rate. However, the input connector AixLib.Fluid.FMI.Interfaces.Inlet - already declares the mass flow rate as an input. Therefore, the - mass flow rate is overdetermined. As a fall back, if a user needs - to set the mass flow rate, he/she can do so by using AixLib.Fluid.FMI.Source_T, - which takes as an input signal the mass flow rate. + If the parameter + inputType==AixLib.Fluid.Types.InputType.Stages, the + head is dp=heads, where heads is a + vectorized parameter. For example, if a mover has two stages and + the head of the first stage should be 60% of the nominal + head and the second stage equal to dp_nominal, set + heads={0.6, 1}*dp_nominal. Then, the mover will have + the following heads:

        + + + + + + + + + + + + + + + + + +
        + input signal stage + + Head [Pa] +
        + 0 + + 0 +
        + 1 + + 0.6*dp_nominal +
        + 2 + + dp_nominal +
        • -
    -

    - When connecting fluid flow components in a loop, be careful to avoid - circular assignments for example for the temperature, as these can of - course not be simulated. An example of such an ill-posed problem is - to connect the outlet of AixLib.Fluid.FixedResistances.PressureDrop - to its inlet. In this situation, neither pressure, nor mass flow rate - or temperature can be computed. To model such loops, a control volume - with a dynamic energy balance must be presented, and the medium needs - to be compressible. -

    -

    - References -

    +

    - Michael Wetter, Marcus Fuchs and Thierry Stephane Nouidui.
    - - Design choices for thermofluid flow components and systems that are - exported as Functional Mockup Units.
    - Proc. of the 11th International Modelica Conference, p. 31-41, - Versailles, France, September 2015. + Similarly, for AixLib.Fluid.Movers.FlowControlled_m_flow, + the mass flow rate is as follows:

    - --------- Errors -------- -line 18 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 - - ----- AixLib/Fluid/FMI/ExportContainers/ThermalZones.mo ---- --------- HTML Code -------- - -

    - Model that is used as a container for a multiple thermal zones - that are to be exported as an FMU. -

    -

    Typical use and important parameters

    -

    - To use this model as a container for an FMU, extend - from this model, rather than instantiate it, - add your thermal zones. For each thermal zone, - add a vector of mass flow rate sensors. - By extending from this model, the top-level - signal connectors on the left stay at the top-level, and hence - will be visible at the FMI interface. -

    - - Note that -
      -
    • - A vector of mass flow rate sensors is used to connect - one element of the thermal zone adapter with one thermal zone. -
      • -
    • - The size of the thermal zone adapter must be the same as the number - of vectors of mass flow rate sensors. -
      • -
    • - The vector of mass flow rate sensors must have the size nPorts. -
      • -
    • - All fluid ports of the mass flow rate sensor must be connected. -
      • -
    • - If mass flow rate sensors are not used, and your themal zone - has fluid ports which are autosized, then a direct connection between - an element of the thermal zone adpater theZonAda and your thermal - zone will be rejected. The reason is because autosized fluid ports - can only be connected to vector of ports whose sizes are literal. -
      • -
    - -

    - The example - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones - shows how multiple simple thermal zones can be implemented and exported as - an FMU. - -

    - -

    - The conversion between the fluid ports and signal ports is done - in the thermal zone adapter theZonAda[nZon]. - This adapter has a vector of fluid ports called ports[nPorts] - which needs to be connected to the air volume of the thermal zones. - At this port, air exchanged between the thermal zones, the HVAC system - and any infiltration flow paths. -

    -

    - This model has input signals fluPor[nZon, nPorts] which carry - the mass flow rate for each flow that is connected to ports[1:nPorts] - for the respective zone, together with its - temperature, water vapor mass fraction per total mass of the air (not per kg dry - air), and trace substances. These quantities are always as if the flow - enters the respective room, even if the flow is zero or negative. - If a medium has no moisture, e.g., if Medium.nXi=0, or - if it has no trace substances, e.g., if Medium.nC=0, then - the output signal for these properties are removed. - Thus, a thermal zone model that uses these signals to compute the - heat added by the HVAC system need to implement an equation such as -

    -

    - Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), -

    -

    - where - Qsen is the sensible heat flow rate added to the thermal zone, - ṁsup is the supply air mass flow rate from - the port fluPor (which is negative if it is an exhaust), - cp is the specific heat capacity at constant pressure, - Tsup is the supply air temperature and - Tair,zon is the zone air temperature. - Note that without the max(·, ·), the energy - balance would be wrong. - For example, - - the control volumes in - - AixLib.Fluid.MixingVolumes - implement such a max(·, ·) function. -

    -

    - For each zone, its air temperature, - water vapor mass fraction per total mass of the air (unless Medium.nXi=0) - and trace substances (unless Medium.nC=0) - can be obtained from the outupt connector - fluPor[1:nZon].backward. - These signals are the same as the inflowing fluid stream(s) - at the port theAdaZon[1:nZon].ports[1:nPorts]. - The fluid connector ports[nPorts] has a prescribed mass flow rate, but - it does not set any pressure. -

    -

    - This model has a user-defined parameter nPorts - which sets the number of fluid ports, which in turn is used - for the ports fluPor and ports. - All zones must have the same number of fluid ports nPorts. - All nPorts - ports[1:nPorts] need to be connected as demonstrated in the example - - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones. -

    -

    - -

    - -
      -
    • - January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air. - See #1050. -
      • -
    • - September 20, 2016, by Thierry S. Nouidui:
      - Revised documentation to explain the rationale - of needing mass flow rate sensors. -
      • -
    • - June 29, 2016, by Michael Wetter:
      - Revised implementation and documentation. -
      • -
    • - April 27, 2016, by Thierry S. Nouidui:
      - First implementation. -
      • -
    - --------- Corrected Code -------- -

    - Model that is used as a container for a multiple thermal zones that - are to be exported as an FMU. -

    -

    - Typical use and important parameters -

    -

    - To use this model as a container for an FMU, extend from this model, - rather than instantiate it, add your thermal zones. For each thermal - zone, add a vector of mass flow rate sensors. By extending from this - model, the top-level signal connectors on the left stay at the - top-level, and hence will be visible at the FMI interface. -

    Note that
      -
    • A vector of mass flow rate sensors is used to connect one element - of the thermal zone adapter with one thermal zone. -
      • -
    • The size of the thermal zone adapter must be the same as the - number of vectors of mass flow rate sensors. -
      • -
    • The vector of mass flow rate sensors must have the size - nPorts. +
    • +

      + If the parameter + inputType==AixLib.Fluid.Types.InputType.Continuous, + the mass flow rate is m_flow=m_flow_in, where + m_flow_in is an input connector. +

      • -
    • All fluid ports of the mass flow rate sensor must be connected. +
    • +

      + If the parameter + inputType==AixLib.Fluid.Types.InputType.Constant, + the mass flow rate is m_flow=constantMassFlowRate, + where constantMassFlowRate is a parameter. +

      • -
    • If mass flow rate sensors are not used, and your themal zone has - fluid ports which are autosized, then a direct connection between an - element of the thermal zone adpater theZonAda and your - thermal zone will be rejected. The reason is because autosized fluid - ports can only be connected to vector of ports whose sizes are - literal. +
    • +

      + If the parameter + inputType==AixLib.Fluid.Types.InputType.Stages, the + mass flow rate is m_flow=massFlowRates, where + massFlowRates is a vectorized parameter. For + example, if a mover has two stages and the mass flow rate of the + first stage should be 60% of the nominal mass flow rate + and the second stage equal to m_flow_nominal, set + massFlowRates={0.6, 1}*m_flow_nominal. Then, the + mover will have the following mass flow rates: +

      +
    + + + + + + + + + + + + + + + + +
    + input signal stage + + Mass flow rates [kg/s] +
    + 0 + + 0 +
    + 1 + + 0.6*m_flow_nominal +
    + 2 + + m_flow_nominal +

    - The example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones - shows how multiple simple thermal zones can be implemented and - exported as an FMU. + These two models do not need to use a performance curve for the flow + characteristics. The reason is that

    +
      +
    • for given pressure rise (or mass flow rate), the mass flow rate + (or pressure rise) is computed from the flow resistance of the duct + or piping network, and +
      • +
    • at zero pressure difference, solving for the flow rate and the + revolution leads to a singularity. +
      • +

    - The conversion between the fluid ports and signal ports is done in - the thermal zone adapter theZonAda[nZon]. This adapter - has a vector of fluid ports called ports[nPorts] which - needs to be connected to the air volume of the thermal zones. At this - port, air exchanged between the thermal zones, the HVAC system and - any infiltration flow paths. -

    -

    - This model has input signals fluPor[nZon, nPorts] which - carry the mass flow rate for each flow that is connected to - ports[1:nPorts] for the respective zone, together with - its temperature, water vapor mass fraction per total mass of the air - (not per kg dry air), and trace substances. These quantities are - always as if the flow enters the respective room, even if the flow is - zero or negative. If a medium has no moisture, e.g., if - Medium.nXi=0, or if it has no trace substances, e.g., if - Medium.nC=0, then the output signal for these properties - are removed. Thus, a thermal zone model that uses these signals to - compute the heat added by the HVAC system need to implement an - equation such as -

    -

    - Qsen = max(0, ṁsup)   cp   - (Tsup - Tair,zon), -

    -

    - where Qsen is the sensible heat flow rate added to - the thermal zone, ṁsup is the supply air mass flow - rate from the port fluPor (which is negative if it is an - exhaust), cp is the specific heat capacity at - constant pressure, Tsup is the supply air - temperature and Tair,zon is the zone air - temperature. Note that without the max(·, ·), the energy - balance would be wrong. For example, - the control volumes in AixLib.Fluid.MixingVolumes - implement such a max(·, ·) function. -

    -

    - For each zone, its air temperature, water vapor mass fraction per - total mass of the air (unless Medium.nXi=0) and trace - substances (unless Medium.nC=0) can be obtained from the - outupt connector fluPor[1:nZon].backward. These signals - are the same as the inflowing fluid stream(s) at the port - theAdaZon[1:nZon].ports[1:nPorts]. The fluid connector - ports[nPorts] has a prescribed mass flow rate, but it - does not set any pressure. + However, the computation of the electrical power consumption requires + the mover speed to be known and the computation of the mover speed + requires the performance curves for the flow and efficiency/power + characteristics. Therefore these performance curves do need to be + provided if the user desires a correct electrical power computation. + If the curves are not provided, a simplified computation is used, + where the efficiency curve is used and assumed to be correct for all + speeds. This loss of accuracy has the advantage that it allows to use + the mover models without requiring flow and efficiency/power + characteristics.

    - This model has a user-defined parameter nPorts which - sets the number of fluid ports, which in turn is used for the ports - fluPor and ports. All zones must have the - same number of fluid ports nPorts. All - nPorts ports[1:nPorts] need to be connected - as demonstrated in the example - AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZones. + The model AixLib.Fluid.Movers.FlowControlled_dp + has an option to control the mover such that the pressure difference + set point is obtained across two remote points in the system. To use + this functionality parameter prescribeSystemPressure has + to be enabled and a differential pressure measurement must be + connected to the pump input dpMea. This functionality is + demonstrated in AixLib.Fluid.Movers.Validation.FlowControlled_dpSystem.

    - + The models AixLib.Fluid.Movers.FlowControlled_dp + and AixLib.Fluid.Movers.FlowControlled_m_flow + both have a parameter m_flow_nominal. For AixLib.Fluid.Movers.FlowControlled_m_flow, + this parameter is used for convenience to set a default value for the + parameters constantMassFlowRate and + massFlowRates. For both models, the value is also used + for the following:

      -
    • January 18, 2019, by Jianjun Hu:
      - Limited the media choice to moist air. See #1050. -
      • -
    • September 20, 2016, by Thierry S. Nouidui:
      - Revised documentation to explain the rationale of needing mass flow - rate sensors. -
      • -
    • June 29, 2016, by Michael Wetter:
      - Revised implementation and documentation. -
      • -
    • April 27, 2016, by Thierry S. Nouidui:
      - First implementation. -
      • -
    - --------- Errors -------- -line 78 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/ThermalZones/ReducedOrder/RC/TwoElements.mo ---- --------- HTML Code -------- - -

      -
    • - March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for - #1542. -
      • -
    • - July 11, 2019, by Katharina Brinkmann:
      - Renamed alphaInt to hConInt, - alphaIntWall to hConIntWall -
      • -
    • - January 25, 2019, by Michael Wetter:
      - Added start value to avoid warning in JModelica. -
      • -
    • - April 18, 2015, by Moritz Lauster:
      - First implementation. -
      • -
    - -

    This model distinguishes between internal - thermal masses and exterior walls. While exterior walls contribute to heat - transfer to the ambient, adiabatic conditions apply to internal masses. - Parameters for the internal wall element are the length of the RC-chain - nInt, the vector of the capacities - CInt[nInt] and the vector of the resistances RInt[nInt]. - This approach allows considering the dynamic behaviour induced by internal - heat storage. -

    -

    - The image below shows the RC-network of this model. -

    -

    - \"image\"/ -

    - --------- Corrected Code -------- -
      -
    • March 7, 2022, by Michael Wetter:
      - Removed massDynamics.
      - This is for #1542. -
      • -
    • July 11, 2019, by Katharina Brinkmann:
      - Renamed alphaInt to hConInt, - alphaIntWall to hConIntWall +
    • To compute the size of the fluid volume that can be used to + approximate the inertia of the mover if the energy dynamics is + selected to be dynamic.
      • -
    • January 25, 2019, by Michael Wetter:
      - Added start value to avoid warning in JModelica. +
    • To compute a default pressure curve if no pressure curve has been + specified in the record per.pressure. The default + pressure curve is the line that intersects (dp, V_flow) = + (dp_nominal, 0) and (dp, V_flow) = + (m_flow_nominal/rho_default, 0).
      • -
    • April 18, 2015, by Moritz Lauster:
      - First implementation. +
    • To regularize the equations near zero flow rate to ensure a + numerically robust model.

    - This model distinguishes between internal thermal masses and exterior - walls. While exterior walls contribute to heat transfer to the - ambient, adiabatic conditions apply to internal masses. Parameters - for the internal wall element are the length of the RC-chain - nInt, the vector of the capacities - CInt[nInt] and the vector of the resistances - RInt[nInt]. This approach allows considering the dynamic - behaviour induced by internal heat storage. + However, otherwise m_flow_nominal does not affect the + mass flow rate of the mover as the mass flow rate is determined by + the input signal or the above explained parameters.

    +
    + Start-up and shut-down transients +

    - The image below shows the RC-network of this model. -

    -

    - \"image\" + All models have a parameter use_inputFilter. This + parameter affects the fan output as follows:

    - --------- Errors -------- -line 14 column 4 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Utilities/Math/Polynomial.mo ---- --------- HTML Code -------- - -

    This block computes a polynomial of arbitrary order. The polynomial has the form

    -

    y = a1 + a2 x + a3 x2 + ...

    - -
      -
    • - September 21, 2021, by Michael Wetter:
      - Renamed class to correct typo in class name.
      - This is for - IBPSA, #1524. -
      • -
    • - November 28, 2013, by Marcus Fuchs:
      - First implementation. -
      • -
    - --------- Corrected Code -------- +
      +
    1. If use_inputFilter=false, then the input signal + y (or Nrpm, m_flow_in, or + dp_in) is equal to the fan speed (or the mass flow rate + or pressure rise). Thus, a step change in the input signal causes a + step change in the fan speed (or mass flow rate or pressure rise). +
      2. +
    2. If use_inputFilter=true, which is the default, then + the fan speed (or the mass flow rate or the pressure rise) is equal + to the output of a filter. This filter is implemented as a 2nd order + differential equation and can be thought of as approximating the + inertia of the rotor and the fluid. Thus, a step change in the fan + input signal will cause a gradual change in the fan speed. The filter + has a parameter riseTime, which by default is set to + 30 seconds. The rise time is the time required to reach + 99.6% of the full speed, or, if the fan is switched off, to + reach a fan speed of 0.4%. +
      3. +

    - This block computes a polynomial of arbitrary order. The polynomial - has the form + The figure below shows for a fan with + use_inputFilter=true and riseTime=30 + seconds the speed input signal and the actual speed.

    - y = a1 + a2 x + a3 x2 + ... + \"image\"

    -
      -
    • September 21, 2021, by Michael Wetter:
      - Renamed class to correct typo in class name.
      - This is for IBPSA, - #1524. -
      • -
    • November 28, 2013, by Marcus Fuchs:
      - First implementation. -
      • -
    - --------- Errors -------- -line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Humidifiers/SprayAirWasher_X.mo ---- --------- HTML Code -------- - -

    - Model for a spray air washer with a prescribed outlet water vapor mass fraction - in kg/kg total air. -

    -

    - This model forces the outlet water mass fraction at port_b to be - no lower than the - input signal X_wSet, subject to optional limits on the - maximum water vapor mass flow rate that is added, as - described by the parameter mWatMax_flow. - By default, the model has unlimited capacity. -

    -

    - The output signal mWat_flow ≥ 0 is the moisture added - to the medium if the flow rate is from port_a to port_b. - If the flow is reversed, then mWat_flow = 0. - The outlet specific enthalpy at port_b is increased by - the enthalpy of liquid water at 10°C times the mass of water that was added. - Therefore, the temperature of the leaving fluid is below the inlet temperature. -

    -

    - The outlet conditions at port_a are not affected by this model, - other than for a possible pressure difference due to flow friction. -

    -

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, - the component models the dynamic response using a first order differential equation. - The time constant of the component is equal to the parameter tau. - This time constant is adjusted based on the mass flow rate using -

    -

    - τeff = τ |ṁ| ⁄ ṁnom -

    -

    - where - τeff is the effective time constant for the given mass flow rate - ṁ and - τ is the time constant at the nominal mass flow rate - ṁnom. - This type of dynamics is equal to the dynamics that a completely mixed - control volume would have. -

    -

    - Optionally, this model can have a flow resistance. - Set dp_nominal = 0 to disable the flow friction calculation. -

    -

    - For a model that uses a control signal u ∈ [0, 1] and multiplies - this with the nominal water mass flow rate, use - - AixLib.Fluid.Humidifiers.Humidifier_u - -

    -

    Limitations

    -

    - This model only adds water vapor for the flow from - port_a to port_b. - The water vapor of the reverse flow is not affected by this model. -

    -

    - This model does not affect the enthalpy of the air. Therefore, - if water is added, the temperature will decrease, e.g., the humidification - is adiabatic. -

    - -
      -
    • - March 8, 2022, by Michael Wetter:
      - Renamed parameter massDynamics to energyDynamics for consistency with other models. -
      • -
    • - December 14, 2018, by Michael Wetter:
      - Restricted base class for medium to one that implements - the function enthalpyOfLiquid.
      - This is for - #1057. -
      • -
    • - May 3, 2017, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Corrected Code --------

    - Model for a spray air washer with a prescribed outlet water vapor - mass fraction in kg/kg total air. + Although many simulations do not require such a detailed model that + approximates the transients of fans or pumps, it turns out that using + this filter can reduce computing time and can lead to fewer + convergence problems in large system models. With a filter, any + sudden change in control signal, such as when a fan switches on, is + damped before it affects the air flow rate. This continuous change in + flow rate turns out to be easier, and in some cases faster, to + simulate compared to a step change. For most simulations, we + therefore recommend to use the default settings of + use_inputFilter=true and riseTime=30 + seconds. An exception are situations in which the fan or pump is + operated at a fixed speed during the whole simulation. In this case, + set use_inputFilter=false.

    - This model forces the outlet water mass fraction at - port_b to be no lower than the input signal - X_wSet, subject to optional limits on the maximum water - vapor mass flow rate that is added, as described by the parameter - mWatMax_flow. By default, the model has unlimited - capacity. + Note that if the fan is part of a closed loop control, then the + filter affects the transient response of the control. When changing + the value of use_inputFilter, the control gains may need + to be retuned. We now present values control parameters that seem to + work in most cases. Suppose there is a closed loop control with a + PI-controller AixLib.Controls.Continuous.LimPID + and a fan or pump, configured with use_inputFilter=true + and riseTime=30 seconds. Assume that the transient + response of the other dynamic elements in the control loop is fast + compared to the rise time of the filter. Then, a proportional gain of + k=0.5 and an integrator time constant of + Ti=15 seconds often yields satisfactory closed loop + control performance. These values may need to be changed for + different applications as they are also a function of the loop gain. + If the control loop shows oscillatory behavior, then reduce + k and/or increase Ti. If the control loop + reacts too slow, do the opposite.

    +
    + Efficiency and electrical power consumption +

    - The output signal mWat_flow ≥ 0 is the moisture added to - the medium if the flow rate is from port_a to - port_b. If the flow is reversed, then mWat_flow = - 0. The outlet specific enthalpy at port_b is - increased by the enthalpy of liquid water at 10°C times the - mass of water that was added. Therefore, the temperature of the - leaving fluid is below the inlet temperature. + All models compute the motor power draw Pele, the + hydraulic power input Whyd, the flow work + Wflo and the heat dissipated into the medium + Q. Based on the first law, the flow work is +

    +

    + Wflo = | V̇ Δp |,

    - The outlet conditions at port_a are not affected by this - model, other than for a possible pressure difference due to flow - friction. + where V̇ is the volume flow rate and Δp is the pressure + rise. The heat dissipated into the medium is as follows: If the motor + is cooled by the fluid, as indicated by + per.motorCooledByFluid=true, then the heat dissipated + into the medium is +

    +

    + Q = Pele - Wflo.

    - If the parameter energyDynamics is different from - Modelica.Fluid.Types.Dynamics.SteadyState, the component - models the dynamic response using a first order differential - equation. The time constant of the component is equal to the - parameter tau. This time constant is adjusted based on - the mass flow rate using + If per.motorCooledByFluid=false, then the motor is + outside the fluid stream, and only the shaft, or hydraulic, work + Whyd enters the thermodynamic control volume. + Hence,

    - τeff = τ |ṁ| ⁄ ṁnom + Q = Whyd - Wflo.

    - where τeff is the effective time constant for the - given mass flow rate ṁ and τ is the time constant at - the nominal mass flow rate ṁnom. This type of - dynamics is equal to the dynamics that a completely mixed control - volume would have. + The efficiencies are computed as +

    +

    + η = Wflo ⁄ Pele = ηhyd   + ηmot
    + ηhyd = Wflo ⁄ Whyd
    + ηmot = Whyd ⁄ Pele

    - Optionally, this model can have a flow resistance. Set - dp_nominal = 0 to disable the flow friction calculation. + where ηhyd is the hydraulic efficiency, + ηmot is the motor efficiency and Q is the + heat released by the motor.

    - For a model that uses a control signal u ∈ [0, 1] and - multiplies this with the nominal water mass flow rate, use AixLib.Fluid.Humidifiers.Humidifier_u + If per.use_powerCharacteristic=true, then a set of data + points for the power Pele for different volume flow + rates at full speed needs to be provided by the user. Using the flow + work Wflo and the electrical power input + Pele, the total efficiency is computed as +

    +

    + η = Wflo ⁄ Pele,

    -

    - Limitations -

    - This model only adds water vapor for the flow from - port_a to port_b. The water vapor of the - reverse flow is not affected by this model. + and the two efficiencies ηhyd and + ηmot are computed as +

    +

    + ηhyd = 1,
    + ηmot = η.

    - This model does not affect the enthalpy of the air. Therefore, if - water is added, the temperature will decrease, e.g., the - humidification is adiabatic. + However, if per.use_powerCharacteristic=false, then + performance data for ηhyd and + ηmot need to be provided by the user, and hence the + model computes

    -
      -
    • March 8, 2022, by Michael Wetter:
      - Renamed parameter massDynamics to - energyDynamics for consistency with other models. -
      • -
    • December 14, 2018, by Michael Wetter:
      - Restricted base class for medium to one that implements the - function enthalpyOfLiquid.
      - This is for #1057. -
      • -
    • May 3, 2017, by Michael Wetter:
      - First implementation. -
      • -
    - --------- Errors -------- -line 33 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Movers/BaseClasses/Characteristics/pressure.mo ---- --------- HTML Code -------- - -

    - This function computes the fan static - pressure raise as a function of volume flow rate and revolution in the form -

    -

    - Δp = rN2   s(V̇/rN, d), -

    -

    - where - Δp is the pressure rise, - rN is the normalized fan speed, - V̇ is the volume flow rate and - d are performance data for fan or pump power consumption at rN=1. -

    -

    Implementation

    +

    + η = ηhyd   ηmot
    + Pele = Wflo ⁄ η. +

    +

    + The efficiency data for the motor are a list of points V̇ and + ηmot. +

    +
    + Fluid volume of the component +
    +

    + All models can be configured to have a fluid volume at the + low-pressure side. Adding such a volume sometimes helps the solver to + find a solution during initialization and time integration of large + models. +

    +
    + Enthalpy change of the component +
    +

    + If per.motorCooledByFluid=true, then the enthalpy change + between the inlet and outlet fluid port is equal to the electrical + power Pele that is consumed by the component. + Otherwise, it is equal to the hydraulic work Whyd. + The parameter addPowerToMedium, which is by default set + to true, can be used to simplify the equations. If + addPowerToMedium = false, then no enthalpy change occurs + between inlet and outlet. This can lead to simpler equations, but the + temperature rise across the component will be zero. In particular for + fans, this simplification may not be permissible. +

    +

    + Differences to models in Modelica.Fluid.Machines +

    +

    + The models in this package differ from Modelica.Fluid.Machines primarily in + the following points: +

    +
      +
    • They use a different base class, which allows to have zero mass + flow rate. The models in Modelica.Fluid restrict the + number of revolutions, and hence the flow rate, to be non-zero. +
      • +
    • For the model with prescribed pressure, the input signal is the + pressure difference between the two ports, and not the absolute + pressure at port_b. +
      • +
    • The pressure calculations are based on total pressure in Pascals + instead of the pump head in meters. This change was done to avoid + ambiguities in the parameterization if the models are used as a fan + with air as the medium. The original formulation in Modelica.Fluid.Machines converts head + to pressure using the density medium.d. Therefore, for + fans, head would be converted to pressure using the density of air. + However, for pumps, manufacturers typically publish the head in + millimeters water (mmH2O). Therefore, to avoid confusion + when using these models with media other than water, we changed the + models to use total pressure in Pascals instead of head in meters. +
      • +
    • The performance data are interpolated using cubic hermite splines + instead of polynomials. These functions are implemented in AixLib.Fluid.Movers.BaseClasses.Characteristics. +
      • +
    +

    + References +

    +

    + Michael Wetter. + Fan and pump model that has a unique solution for any pressure + boundary condition and control signal. Proc. of the 13th + Conference of the International Building Performance Simulation + Association, p. 3505-3512. Chambery, France. August 2013. +

    + +-------- Errors -------- +line 38 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 +line 126 column 3 - Warning: The summary attribute on the
    element is obsolete in HTML5 +line 205 column 3 - Warning: The summary attribute on the
    element is obsolete in HTML5 +line 254 column 3 - Warning: The summary attribute on the
    element is obsolete in HTML5 +line 15 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 158 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 380 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 425 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 435 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 444 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 448 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 465 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 473 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 484 column 1 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Utilities/Math/Biquadratic.mo ---- +-------- HTML Code -------- +

    - The function s(·, ·) is a cubic hermite spline. - If the data d define a monotone decreasing sequence, then - s(·, d) is a monotone decreasing function. + This block computes

    -

    - The function allows rN to be zero. +

    + y = a1 + a2 x1 + + a3 x12 + + a4 x2 + a5 x22 + + a6 x1 x2

    • - September 8, 2016, by Michael Wetter and Filip Jorissen:
      - Changed implementation to allow r_N = 0.
      - This is - for #458. -
      • -
    • - September 7, 2016, by Michael Wetter:
      - Moved function which was a protected function to make it public, as it - is now called by - - AixLib.Fluid.Movers.BaseClasses.FlowMachineInterface. + Sep. 8, 2010, by Michael Wetter:
      + First implementation.
    -------- Corrected Code --------

    - This function computes the fan static pressure raise as a function of - volume flow rate and revolution in the form + This block computes

    - Δp = rN2   s(V̇/rN, d), -

    -

    - where Δp is the pressure rise, rN is the - normalized fan speed, V̇ is the volume flow rate and d - are performance data for fan or pump power consumption at - rN=1. -

    -

    - Implementation -

    -

    - The function s(·, ·) is a cubic hermite spline. If the data - d define a monotone decreasing sequence, then s(·, d) - is a monotone decreasing function. -

    -

    - The function allows rN to be zero. + y = a1 + a2 x1 + a3 + x12 + a4 x2 + + a5 x22 + a6 x1 + x2

      -
    • September 8, 2016, by Michael Wetter and Filip Jorissen:
      - Changed implementation to allow r_N = 0.
      - This is for #458. -
      • -
    • September 7, 2016, by Michael Wetter:
      - Moved function which was a protected function to make it public, as - it is now called by AixLib.Fluid.Movers.BaseClasses.FlowMachineInterface. +
    • Sep. 8, 2010, by Michael Wetter:
      + First implementation.
    -------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/BoundaryConditions/Validation/BESTEST/WD300.mo ---- +---- AixLib/Fluid/FixedResistances/Validation/PlugFlowPipes/MSLAIT2Nodes.mo ---- -------- HTML Code -------- +

    The example contains + + experimental data from a real district heating network. + This data is used to validate this library's + plug flow pipe model + in + AixLib.Fluid.FixedResistances.Validation.PlugFlowPipes.PlugFlowAIT. +

    +

    + Note that these three models are identical, except for the pipe model that is used: +

    +

    + This comparison between different discretization levels and pipe models is made + to check the influence of the discretization and pipe model on computation time + and simulation accuracy. +

    +

    The pipes' temperatures are not initialized, thus results of outflow temperature + before approximately the first 10000 seconds should not be considered. +

    +

    Test bench schematic

    +

    \"Schematic

    +

    Calibration

    +

    + To calculate the length specific thermal resistance R of the pipe, + the thermal resistance of the surrounding ground is added. +

    +

    + R=1/(0.208)+1/(2   lambdag Modelica.Constants.pi)   log(1/0.18) +

    +

    + Where the thermal conductivity of the ground lambda_g = 2.4 W/(m K). +

    + +
      +
    • + March 7, 2020, by Michael Wetter:
      + Replaced measured data from specification in Modelica file to external table, + as this reduces the computing time.
      This is for - IBPSA, #1477. + #1289.
    • - March 11, 2020, by Ettore Zanetti:
      - First implementation. + May 15, 2019, by Jianjun Hu:
      + Replaced fluid source. This is for + #1072. +
      • +
    • November 28, 2016 by Bram van der Heijde:
      Remove pipVol.
    • - April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request - #1339. + August 24, 2016 by Bram van der Heijde:
      + Implement validation with MSL pipes for comparison, based on AIT validation.
    • - May 2, 2021, by Ettore Zanetti:
      - Updated weather file as explained in #1478. + July 4, 2016 by Bram van der Heijde:
      Added parameters to test the + influence of allowFlowReversal and the presence of explicit volumes in the pipe.
      • +
    • January 26, 2016 by Carles Ribas:
      First implementation.
    -

    WD300: Southern Hemisphere Case

    -

    Weather data file : WD300.epw

    -

    Table 1: Site Data for Weather file WD300.epw

    -
    - - - - - - - - - - - - - - - -

    Latitude

    33.393° south

    Longitude

    70.786° west

    Altitude

    474 m

    Time Zone

    -4

    - -------- Corrected Code -------- +

    + The example contains + experimental data from a real district heating network. This data + is used to validate this library's plug flow + pipe model in + AixLib.Fluid.FixedResistances.Validation.PlugFlowPipes.PlugFlowAIT. +

    +

    + Note that these three models are identical, except for the pipe model + that is used: +

    +

    + This comparison between different discretization levels and pipe + models is made to check the influence of the discretization and pipe + model on computation time and simulation accuracy. +

    +

    + The pipes' temperatures are not initialized, thus results of outflow + temperature before approximately the first 10000 seconds should not + be considered. +

    - WD300: Southern Hemisphere Case + Test bench schematic

    - Weather data file : WD300.epw + \"Schematic

    +

    + Calibration +

    - Table 1: Site Data for Weather file WD300.epw + To calculate the length specific thermal resistance R of + the pipe, the thermal resistance of the surrounding ground is added.

    - - - - - - - - - - - - - - - - - -
    -

    - Latitude -

    -     		-

    - 33.393° south -

    -
    -

    - Longitude -

    -     		-

    - 70.786° west -

    -
    -

    - Altitude -

    -     		-

    - 474 m -

    -
    -

    - Time Zone -

    -     		-

    - -4 -

    -
    +

    + R=1/(0.208)+1/(2   lambdag Modelica.Constants.pi) +   log(1/0.18) +

    +

    + Where the thermal conductivity of the ground lambda_g = + 2.4 W/(m K). +

    +
      +
    • March 7, 2020, by Michael Wetter:
      + Replaced measured data from specification in Modelica file to + external table, as this reduces the computing time.
      + This is for #1289. +
      • +
    • May 15, 2019, by Jianjun Hu:
      + Replaced fluid source. This is for #1072. +
      • +
    • November 28, 2016 by Bram van der Heijde:
      + Remove pipVol. +
      • +
    • August 24, 2016 by Bram van der Heijde:
      + Implement validation with MSL pipes for comparison, based on AIT + validation. +
      • +
    • July 4, 2016 by Bram van der Heijde:
      + Added parameters to test the influence of allowFlowReversal and the + presence of explicit volumes in the pipe. +
      • +
    • January 26, 2016 by Carles Ribas:
      + First implementation. +
      • +
    -------- Errors -------- -line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 +line 51 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/gFunction.mo ---- +---- AixLib/Fluid/FixedResistances/PressureDrop.mo ---- -------- HTML Code --------

    - This function implements the g-function evaluation method introduced by - Cimmino and Bernier (see: Cimmino and Bernier (2014), and Cimmino (2018)) based - on the g-function function concept first introduced by Eskilson (1987). - The g-function gives the relation between the variation of the borehole - wall temperature at a time t and the heat extraction and injection rates - at all times preceding time t as + Model of a flow resistance with a fixed flow coefficient. + The mass flow rate is

    -

    - \"image\" +

    + ṁ = k + √ΔP,

    - where Tb is the borehole wall temperature, - Tg is the undisturbed ground temperature, Q is the - heat injection rate into the ground through the borehole wall per unit borehole - length, ks is the soil thermal conductivity and g is - the g-function. + where + k is a constant and + ΔP is the pressure drop. + The constant k is equal to + k=m_flow_nominal/sqrt(dp_nominal), + where m_flow_nominal and dp_nominal + are parameters.

    +

    Assumptions

    - The g-function is constructed from the combination of the combination of - the finite line source (FLS) solution (see - - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource), - the cylindrical heat source (CHS) solution (see - - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource), - and the infinite line source (ILS) solution (see - - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.infiniteLineSource). - To obtain the g-function of a bore field, each borehole is divided into a - series of nSeg segments of equal length, each modeled as a line - source of finite length. The finite line source solution is superimposed in - space to obtain a system of equations that gives the relation between the heat - injection rate at each of the segments and the borehole wall temperature at each - of the segments. The system is solved to obtain the uniform borehole wall - temperature required at any time to maintain a constant total heat injection - rate (Qtot = 2πksHtot) into the bore - field. The uniform borehole wall temperature is then equal to the finite line - source based g-function. + In the region + abs(m_flow) < m_flow_turbulent, + the square root is replaced by a differentiable function + with finite slope. + The value of m_flow_turbulent is + computed as + m_flow_turbulent = deltaM * abs(m_flow_nominal), + where deltaM=0.3 and + m_flow_nominal are parameters that can be set by the user.

    - Since this g-function is based on line sources of heat, rather than - cylinders, the g-function is corrected to consider the cylindrical - geometry. The correction factor is then the difference between the cylindrical - heat source solution and the infinite line source solution, as proposed by - Li et al. (2014) as + The figure below shows the pressure drop for the parameters + m_flow_nominal=5 kg/s, + dp_nominal=10 Pa and + deltaM=0.3.

    - g(t) = gFLS + (gCHS - gILS) -

    -

    Implementation

    -

    - The calculation of the g-function is separated into two regions: the - short-time region and the long-time region. In the short-time region, - corresponding to times t < 1 hour, heat interaction between boreholes - and axial variations of heat injection rate are not considered. The - g-function is calculated using only one borehole and one segment. In the - long-time region, corresponding to times t > 1 hour, all boreholes - are represented as series of nSeg line segments and the - g-function is evaluated as described above. + \"image\"

    -

    References

    +

    Important parameters

    - Cimmino, M. and Bernier, M. 2014. A semi-analytical method to generate - g-functions for geothermal bore fields. International Journal of Heat and - Mass Transfer 70: 641-650. + The parameter from_dp is used to determine + whether the mass flow rate is computed as a function of the + pressure drop (if from_dp=true), or vice versa. + This setting can affect the size of the nonlinear system of equations.

    - Cimmino, M. 2018. Fast calculation of the g-functions of geothermal borehole - fields using similarities in the evaluation of the finite line source - solution. Journal of Building Performance Simulation. DOI: - 10.1080/19401493.2017.1423390. + If the parameter linearized is set to true, + then the pressure drop is computed as a linear function of the + mass flow rate.

    - Eskilson, P. 1987. Thermal analysis of heat extraction boreholes. Ph.D. - Thesis. Department of Mathematical Physics. University of Lund. Sweden. + Setting allowFlowReversal=false can lead to simpler + equations. However, this should only be set to false + if one can guarantee that the flow never reverses its direction. + This can be difficult to guarantee, as pressure imbalance after + the initialization, or due to medium expansion and contraction, + can lead to reverse flow.

    - Li, M., Li, P., Chan, V. and Lai, A.C.K. 2014. Full-scale temperature - response function (G-function) for heat transfer by borehole heat exchangers - (GHEs) from sub-hour to decades. Applied Energy 136: 197-205. + If the parameter + show_T is set to true, + then the model will compute the + temperature at its ports. Note that this can lead to state events + when the mass flow rate approaches zero, + which can increase computing time. +

    +

    Notes

    +

    + For more detailed models that compute the actual flow friction, + models from the package + + Modelica.Fluid + can be used and combined with models from the + AixLib library. +

    +

    + For a model that uses the hydraulic parameter and flow velocity at nominal conditions + as a parameter, use + + AixLib.Fluid.FixedResistances.HydraulicDiameter. +

    +

    Implementation

    +

    + The pressure drop is computed by calling a function in the package + + AixLib.Fluid.BaseClasses.FlowModels, + This package contains regularized implementations of the equation +

    +

    + m = sign(Δp) k √ Δp   +

    +

    + and its inverse function. +

    +

    + To decouple the energy equation from the mass equations, + the pressure drop is a function of the mass flow rate, + and not the volume flow rate. + This leads to simpler equations.

    • - March 22, 2018 by Massimo Cimmino:
      + September 21, 2018, by Michael Wetter:
      + Decrease value of deltaM(min=...) attribute. + See #1026. +
      • +
    • + February 3, 2018, by Filip Jorissen:
      + Revised implementation of pressure drop equation + such that it depends on from_dp + when linearized=true. + See #884. +
      • +
    • + December 1, 2016, by Michael Wetter:
      + Simplified model by removing the geometry dependent parameters into the new + model + + AixLib.Fluid.FixedResistances.HydraulicDiameter. +
      • +
    • + November 23, 2016, by Filip Jorissen:
      + Removed dp_nominal and + m_flow_nominal labels from icon. +
      • +
    • + October 14, 2016, by Michael Wetter:
      + Updated comment for parameter use_dh. +
      • +
    • + November 26, 2014, by Michael Wetter:
      + Added the required annotation(Evaluate=true) so + that the system of nonlinear equations in + + AixLib.Fluid.FixedResistances.Validation.PressureDropsExplicit + remains the same. +
      • +
    • + November 20, 2014, by Michael Wetter:
      + Rewrote the warning message using an assert with + AssertionLevel.warning + as this is the proper way to write warnings in Modelica. +
      • +
    • + August 5, 2014, by Michael Wetter:
      + Corrected error in documentation of computation of k. +
      • +
    • + May 29, 2014, by Michael Wetter:
      + Removed undesirable annotation Evaluate=true. +
      • +
    • + October 8, 2013, by Michael Wetter:
      + Removed parameter show_V_flow. +
      • +
    • + December 14, 2012 by Michael Wetter:
      + Renamed protected parameters for consistency with the naming conventions. +
      • +
    • + January 16, 2012 by Michael Wetter:
      + To simplify object inheritance tree, revised base classes + AixLib.Fluid.BaseClasses.PartialResistance, + AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve, + AixLib.Fluid.Actuators.BaseClasses.PartialDamperExponential, + AixLib.Fluid.Actuators.BaseClasses.PartialActuator + and model + AixLib.Fluid.FixedResistances.PressureDrop. +
      • +
    • + May 30, 2008 by Michael Wetter:
      + Added parameters use_dh and deltaM for easier parameterization. +
      • +
    • + July 20, 2007 by Michael Wetter:
      First implementation.
    -------- Corrected Code --------

    - This function implements the g-function evaluation method - introduced by Cimmino and Bernier (see: Cimmino and Bernier (2014), - and Cimmino (2018)) based on the g-function function concept - first introduced by Eskilson (1987). The g-function gives the - relation between the variation of the borehole wall temperature at a - time t and the heat extraction and injection rates at all - times preceding time t as + Model of a flow resistance with a fixed flow coefficient. The mass + flow rate is

    -

    - \"image\" +

    + ṁ = k √ΔP,

    - where Tb is the borehole wall temperature, - Tg is the undisturbed ground temperature, Q - is the heat injection rate into the ground through the borehole wall - per unit borehole length, ks is the soil thermal - conductivity and g is the g-function. + where k is a constant and ΔP is the pressure drop. The + constant k is equal to + k=m_flow_nominal/sqrt(dp_nominal), where + m_flow_nominal and dp_nominal are + parameters.

    +

    + Assumptions +

    - The g-function is constructed from the combination of the - combination of the finite line source (FLS) solution (see - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource), - the cylindrical heat source (CHS) solution (see - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource), - and the infinite line source (ILS) solution (see - AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.infiniteLineSource). - To obtain the g-function of a bore field, each borehole is - divided into a series of nSeg segments of equal length, - each modeled as a line source of finite length. The finite line - source solution is superimposed in space to obtain a system of - equations that gives the relation between the heat injection rate at - each of the segments and the borehole wall temperature at each of the - segments. The system is solved to obtain the uniform borehole wall - temperature required at any time to maintain a constant total heat - injection rate (Qtot = - 2πksHtot) into the bore field. The uniform - borehole wall temperature is then equal to the finite line source - based g-function. + In the region abs(m_flow) < m_flow_turbulent, the + square root is replaced by a differentiable function with finite + slope. The value of m_flow_turbulent is computed as + m_flow_turbulent = deltaM * abs(m_flow_nominal), where + deltaM=0.3 and m_flow_nominal are + parameters that can be set by the user.

    - Since this g-function is based on line sources of heat, rather - than cylinders, the g-function is corrected to consider the - cylindrical geometry. The correction factor is then the difference - between the cylindrical heat source solution and the infinite line - source solution, as proposed by Li et al. (2014) as + The figure below shows the pressure drop for the parameters + m_flow_nominal=5 kg/s, dp_nominal=10 Pa and + deltaM=0.3.

    - g(t) = gFLS + (gCHS - gILS) + \"image\"

    - Implementation + Important parameters

    - The calculation of the g-function is separated into two - regions: the short-time region and the long-time region. In the - short-time region, corresponding to times t < 1 hour, heat - interaction between boreholes and axial variations of heat injection - rate are not considered. The g-function is calculated using - only one borehole and one segment. In the long-time region, - corresponding to times t > 1 hour, all boreholes are - represented as series of nSeg line segments and the - g-function is evaluated as described above. + The parameter from_dp is used to determine whether the + mass flow rate is computed as a function of the pressure drop (if + from_dp=true), or vice versa. This setting can affect + the size of the nonlinear system of equations. +

    +

    + If the parameter linearized is set to true, + then the pressure drop is computed as a linear function of the mass + flow rate. +

    +

    + Setting allowFlowReversal=false can lead to simpler + equations. However, this should only be set to false if + one can guarantee that the flow never reverses its direction. This + can be difficult to guarantee, as pressure imbalance after the + initialization, or due to medium expansion and contraction, can lead + to reverse flow. +

    +

    + If the parameter show_T is set to true, + then the model will compute the temperature at its ports. Note that + this can lead to state events when the mass flow rate approaches + zero, which can increase computing time.

    - References + Notes

    - Cimmino, M. and Bernier, M. 2014. A semi-analytical method to - generate g-functions for geothermal bore fields. International - Journal of Heat and Mass Transfer 70: 641-650. + For more detailed models that compute the actual flow friction, + models from the package Modelica.Fluid can be used and + combined with models from the AixLib library.

    - Cimmino, M. 2018. Fast calculation of the g-functions of - geothermal borehole fields using similarities in the evaluation of - the finite line source solution. Journal of Building Performance - Simulation. DOI: 10.1080/19401493.2017.1423390. + For a model that uses the hydraulic parameter and flow velocity at + nominal conditions as a parameter, use AixLib.Fluid.FixedResistances.HydraulicDiameter.

    +

    + Implementation +

    - Eskilson, P. 1987. Thermal analysis of heat extraction - boreholes. Ph.D. Thesis. Department of Mathematical Physics. - University of Lund. Sweden. + The pressure drop is computed by calling a function in the package + AixLib.Fluid.BaseClasses.FlowModels, + This package contains regularized implementations of the equation +

    +

    + m = sign(Δp) k √ Δp +  

    - Li, M., Li, P., Chan, V. and Lai, A.C.K. 2014. Full-scale - temperature response function (G-function) for heat transfer by - borehole heat exchangers (GHEs) from sub-hour to decades. Applied - Energy 136: 197-205. + and its inverse function. +

    +

    + To decouple the energy equation from the mass equations, the pressure + drop is a function of the mass flow rate, and not the volume flow + rate. This leads to simpler equations.

      -
    • March 22, 2018 by Massimo Cimmino:
      +
    • September 21, 2018, by Michael Wetter:
      + Decrease value of deltaM(min=...) attribute. See + #1026. +
      • +
    • February 3, 2018, by Filip Jorissen:
      + Revised implementation of pressure drop equation such that it + depends on from_dp when linearized=true. + See #884. +
      • +
    • December 1, 2016, by Michael Wetter:
      + Simplified model by removing the geometry dependent parameters into + the new model AixLib.Fluid.FixedResistances.HydraulicDiameter. +
      • +
    • November 23, 2016, by Filip Jorissen:
      + Removed dp_nominal and m_flow_nominal + labels from icon. +
      • +
    • October 14, 2016, by Michael Wetter:
      + Updated comment for parameter use_dh. +
      • +
    • November 26, 2014, by Michael Wetter:
      + Added the required annotation(Evaluate=true) so that + the system of nonlinear equations in + AixLib.Fluid.FixedResistances.Validation.PressureDropsExplicit + remains the same. +
      • +
    • November 20, 2014, by Michael Wetter:
      + Rewrote the warning message using an assert with + AssertionLevel.warning as this is the proper way to + write warnings in Modelica. +
      • +
    • August 5, 2014, by Michael Wetter:
      + Corrected error in documentation of computation of k. +
      • +
    • May 29, 2014, by Michael Wetter:
      + Removed undesirable annotation Evaluate=true. +
      • +
    • October 8, 2013, by Michael Wetter:
      + Removed parameter show_V_flow. +
      • +
    • December 14, 2012 by Michael Wetter:
      + Renamed protected parameters for consistency with the naming + conventions. +
      • +
    • January 16, 2012 by Michael Wetter:
      + To simplify object inheritance tree, revised base classes + AixLib.Fluid.BaseClasses.PartialResistance, + AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve, + AixLib.Fluid.Actuators.BaseClasses.PartialDamperExponential, + AixLib.Fluid.Actuators.BaseClasses.PartialActuator and + model AixLib.Fluid.FixedResistances.PressureDrop. +
      • +
    • May 30, 2008 by Michael Wetter:
      + Added parameters use_dh and deltaM for + easier parameterization. +
      • +
    • July 20, 2007 by Michael Wetter:
      First implementation.
    -------- Errors -------- -line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 49 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 37 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 90 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/BoundaryConditions/Validation/BESTEST/WD200.mo ---- +---- AixLib/Fluid/Movers/BaseClasses/Characteristics/efficiency.mo ---- -------- HTML Code -------- +

    + This function computes the fan or pump efficiency for given normalized volume flow rate + and performance data. The efficiency is +

    +

    + η = s(V̇/rN, d), +

    +

    + where + η is the efficiency, + rN is the normalized fan speed, + V̇ is the volume flow rate, and + d are performance data for fan or pump efficiency. +

    +

    Implementation

    +

    + The function s(·, ·) is a cubic hermite spline. + If the data d define a monotone decreasing sequence, then + s(·, d) is a monotone decreasing function. +

    +
    • - September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the weather data bus.
      + December 2, 2016, by Michael Wetter:
      + Removed min attribute as otherwise numerical noise can cause + the assertion on the limit to fail.
      This is for - IBPSA, #1477. + #606.
    • - March 11, 2020, by Ettore Zanetti:
      - First implementation. + November 22, 2014, by Michael Wetter:
      + Corrected documentation as curve uses V̇ + as an independent variable.
    • - April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request - #1339. + September 30, 2014, by Filip Jorissen:
      + Changed polynomial to be evaluated at V_flow + instead of r_V.
    • - May 2, 2021, by Ettore Zanetti:
      - Updated weather file as explained in #1478. + April 19, 2014, by Filip Jorissen:
      + Changed polynomial to be evaluated at r_V/r_N + instead of r_V to properly account for the + scaling law. See + #202 + for a discussion and validation. +
      • +
    • + September 28, 2011, by Michael Wetter:
      + First implementation.
    -

    WD200: Low Elevation, Hot and Humid Case.

    -

    Weather data file : WD200.epw

    -

    Table 1: Site Data for Weather file WD200.epw

    -
    - - - - - - - - - - - - - - - -

    Latitude

    33.633° north

    Longitude

    84.433° west

    Altitude

    308 m

    Time Zone

    -5

    - -------- Corrected Code -------- +

    + This function computes the fan or pump efficiency for given + normalized volume flow rate and performance data. The efficiency is +

    +

    + η = s(V̇/rN, d), +

    +

    + where η is the efficiency, rN is the + normalized fan speed, V̇ is the volume flow rate, and d + are performance data for fan or pump efficiency. +

    +

    + Implementation +

    +

    + The function s(·, ·) is a cubic hermite spline. If the data + d define a monotone decreasing sequence, then s(·, d) + is a monotone decreasing function. +

      -
    • September 6, 2021, by Ettore Zanetti:
      - Removed parameter lat as it is now obtained from the - weather data bus.
      +
    • December 2, 2016, by Michael Wetter:
      + Removed min attribute as otherwise numerical noise can + cause the assertion on the limit to fail.
      This is for IBPSA, - #1477. + \"https://github.com/ibpsa/modelica-ibpsa/issues/606\">#606.
      • -
    • March 11, 2020, by Ettore Zanetti:
      - First implementation. +
    • November 22, 2014, by Michael Wetter:
      + Corrected documentation as curve uses V̇ as an independent + variable.
      • -
    • April 14, 2020, by Ettore Zanetti:
      - Rework after comments from pull request #1339. +
    • September 30, 2014, by Filip Jorissen:
      + Changed polynomial to be evaluated at V_flow instead + of r_V.
      • -
    • May 2, 2021, by Ettore Zanetti:
      - Updated weather file as explained in #1478. +
    • April 19, 2014, by Filip Jorissen:
      + Changed polynomial to be evaluated at r_V/r_N instead + of r_V to properly account for the scaling law. See + #202 + for a discussion and validation. +
      • +
    • September 28, 2011, by Michael Wetter:
      + First implementation.
    -

    - WD200: Low Elevation, Hot and Humid Case. -

    -

    - Weather data file : WD200.epw -

    -

    - Table 1: Site Data for Weather file WD200.epw -

    - - - - - - - - - - - - - - - - - -
    -

    - Latitude -

    -     		-

    - 33.633° north -

    -
    -

    - Longitude -

    -     		-

    - 84.433° west -

    -
    -

    - Altitude -

    -     		-

    - 308 m -

    -
    -

    - Time Zone -

    -     		-

    - -5 -

    -
    -------- Errors -------- -line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatPumps/Compressors/ReciprocatingCompressor.mo ---- +---- AixLib/Fluid/Movers/Data/Pumps/Wilo/Stratos25slash1to6.mo ---- -------- HTML Code -------- -

    - Model for a reciprocating processor, as detailed in Jin (2002). The rate of heat transferred to the evaporator is given by: -

    -

    - Q̇Eva = ṁref ( hVap(TEva) - hLiq(TCon) ). -

    -

    - The power consumed by the compressor is given by a linear efficiency relation: -

    -

    - P = PTheoretical / η + PLoss,constant. -

    -

    - Variable speed is acheived by multiplying the full load piston displacement - by the normalized compressor speed. The power and heat transfer rates are forced - to zero if the resulting heat pump state has higher evaporating pressure than - condensing pressure. +

    Data from + + http://productfinder.wilo.com/en/COM/product/00000018000028040002003a/fc_product_datasheet

    -

    Assumptions and limitations

    - The compression process is assumed isentropic. The thermal energy - of superheating is ignored in the evaluation of the heat transferred to the refrigerant - in the evaporator. There is no supercooling. + The nominal rpm is arbitrarily chosen as the rpm of the pump curve + in the data sheet that has the highest rpm, + without being limited by the maximum power limitation + (see dotted curve on figure below). + Pump curves (H(m_flow) and P(m_flow)) from the data sheets + are digitized using + web plot digitizer.

    -

    References

    +

    Limitations:

    +
      +
    • The pump curve cap at high rpm that can be seen is not enforced + by the model. +
      • +
    • + The pump curve may be altered slightly to guarantee that dp/dm<0 +
      • +

    - H. Jin. - - Parameter estimation based models of water source heat pumps. - - PhD Thesis. Oklahoma State University. Stillwater, Oklahoma, USA. 2002. + The figure below illustrates a digitized pump curve.

    +

    + \"Pump

    • - January 25, 2019, by Michael Wetter:
      - Added start value to avoid warning in JModelica. + February 17, 2016, by Michael Wetter:
      + Updated parameter names for + #396.
    • - May 30, 2017, by Filip Jorissen:
      - Removed pressure_error as - this is replaced by - - AixLib.Fluid.HeatPumps.Compressors.BaseClasses.TemperatureProtection. - See #769. + December 12, 2014, by Michael Wetter:
      + Added defaultComponentPrefixes and + defaultComponentName annotations.
      • -
    • - November 14, 2016, by Massimo Cimmino:
      - First implementation. +
    • April 17, 2014 + by Filip Jorissen:
      + Initial version
    -------- Corrected Code --------

    - Model for a reciprocating processor, as detailed in Jin (2002). The - rate of heat transferred to the evaporator is given by: -

    -

    - Q̇Eva = ṁref ( - hVap(TEva) - hLiq(TCon) - ). -

    -

    - The power consumed by the compressor is given by a linear efficiency - relation: -

    -

    - P = PTheoretical / η + PLoss,constant. + Data from + http://productfinder.wilo.com/en/COM/product/00000018000028040002003a/fc_product_datasheet

    - Variable speed is acheived by multiplying the full load piston - displacement by the normalized compressor speed. The power and heat - transfer rates are forced to zero if the resulting heat pump state - has higher evaporating pressure than condensing pressure. + The nominal rpm is arbitrarily chosen as the rpm of the pump curve in + the data sheet that has the highest rpm, without being limited by the + maximum power limitation (see dotted curve on figure below). Pump + curves (H(m_flow) and P(m_flow)) from the data sheets are digitized + using web plot + digitizer.

    - Assumptions and limitations + Limitations:

    +
      +
    • The pump curve cap at high rpm that can be seen is not enforced + by the model. +
      • +
    • The pump curve may be altered slightly to guarantee that + dp/dm<0 +
      • +

    - The compression process is assumed isentropic. The thermal energy of - superheating is ignored in the evaluation of the heat transferred to - the refrigerant in the evaporator. There is no supercooling. + The figure below illustrates a digitized pump curve.

    -

    - References -

    -

    - H. Jin. Parameter estimation based models of water source heat - pumps. PhD Thesis. Oklahoma State University. Stillwater, - Oklahoma, USA. 2002. +

    + \"Pump

      -
    • January 25, 2019, by Michael Wetter:
      - Added start value to avoid warning in JModelica. +
    • February 17, 2016, by Michael Wetter:
      + Updated parameter names for #396.
      • -
    • May 30, 2017, by Filip Jorissen:
      - Removed pressure_error as this is replaced by - AixLib.Fluid.HeatPumps.Compressors.BaseClasses.TemperatureProtection. - See #769. +
    • December 12, 2014, by Michael Wetter:
      + Added defaultComponentPrefixes and + defaultComponentName annotations.
      • -
    • November 14, 2016, by Massimo Cimmino:
      - First implementation. +
    • April 17, 2014 by Filip Jorissen:
      + Initial version
    -------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 27 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/infiniteLineSource.mo ---- +---- AixLib/Fluid/FixedResistances/CheckValve.mo ---- -------- HTML Code --------

    - This function evaluates the infinite line source solution. This solution gives - the relation between the constant heat transfer rate (per unit length) injected - by a line heat source of infinite length and the temperature raise in the - medium. The infinite line source solution is defined by + Implementation of a hydraulic check valve. + Note that the small reverse flows can still occur with this model.

    -

    - \"image\" +

    Main equations

    +

    + The basic flow function +

    +

    + m = sign(Δp) k √ Δp  ,

    - where ΔT(t,r) is the temperature raise after a time t of - constant heat injection and at a distance r from the line source, - Q' is the heat injection rate per unit length, ks is - the soil thermal conductivity and hILS is the infinite line - source solution. + with regularization near the origin, is used to compute the pressure drop. + The flow coefficient +

    +

    + k = m ⁄ √ Δp  

    - The infinite line source solution is given by the exponential integral + is increased from l*KV_Si to KV_Si, + where KV_Si is equal to Kv but in SI units. + Therefore, the flow coefficient k is set to a value close to zero for negative pressure differences, thereby + restricting reverse flow to a small value. + The flow coefficient k saturates to its maximum value at the pressure dpValve_closing. + For larger pressure drops, the pressure drop is a quadratic function of the flow rate.

    -

    - \"image\" +

    Typical use and important parameters

    +

    + The parameters m_flow_nominal and dpValve_nominal + determine the flow coefficient of the check valve when it is fully opened. + A typical value for a nominal flow rate of 1 m/s is + dpValve_nominal = 3400 Pa. + The leakage ratio l determines the minimum flow coefficient, + for negative pressure differences. + The parameter dpFixed_nominal allows to include a series + pressure drop with a fixed flow coefficient into the model. + The parameter dpValve_closing determines when the + flow coefficient starts to increase, + which is typically in the order of dpValve_nominal.

    +

    Implementation

    - where αs is the ground thermal diffusivity. The - exponential integral is implemented in - AixLib.Utilities.Math.Functions.exponentialIntegralE1. + The check valve implementation approximates the physics + where a forward pressure difference opens the valve such that + the valve opening increases, causing a growing orifice area + and thus increasing the flow coefficient. + Near dp=dpValve_closing, the valve is fully open and the flow coefficient saturates + to the flow coefficient value determined by dpValve_nominal and m_flow_nominal. + For typical valve diameters, the check valve is only fully open + near nominal mass flow rate. Therefore, the model sets dpValve_closing=dpValve_nominal/2 + by default.

    • - March 22, 2018 by Massimo Cimmino:
      - First implementation. + September 16, 2019, by Kristoff Six and Filip Jorissen:
      + Implementation of a hydraulic check valve. This is for + issue 1198.
    -------- Corrected Code --------

    - This function evaluates the infinite line source solution. This - solution gives the relation between the constant heat transfer rate - (per unit length) injected by a line heat source of infinite length - and the temperature raise in the medium. The infinite line source - solution is defined by -

    -

    - \"image\" + Implementation of a hydraulic check valve. Note that the small + reverse flows can still occur with this model.

    +

    + Main equations +

    - where ΔT(t,r) is the temperature raise after a time t - of constant heat injection and at a distance r from the line - source, Q' is the heat injection rate per unit length, - ks is the soil thermal conductivity and - hILS is the infinite line source solution. + The basic flow function +

    +

    + m = sign(Δp) k √ Δp +  ,

    - The infinite line source solution is given by the exponential - integral + with regularization near the origin, is used to compute the pressure + drop. The flow coefficient

    -

    - \"image\" +

    + k = m ⁄ √ Δp +  

    - where αs is the ground thermal diffusivity. The - exponential integral is implemented in AixLib.Utilities.Math.Functions.exponentialIntegralE1. -

    -
      -
    • March 22, 2018 by Massimo Cimmino:
      - First implementation. + is increased from l*KV_Si to KV_Si, where + KV_Si is equal to Kv but in SI units. + Therefore, the flow coefficient k is set to a value + close to zero for negative pressure differences, thereby restricting + reverse flow to a small value. The flow coefficient k + saturates to its maximum value at the pressure + dpValve_closing. For larger pressure drops, the pressure + drop is a quadratic function of the flow rate. +

      +

      + Typical use and important parameters +

      +

      + The parameters m_flow_nominal and + dpValve_nominal determine the flow coefficient of the + check valve when it is fully opened. A typical value for a nominal + flow rate of 1 m/s is dpValve_nominal = 3400 Pa. + The leakage ratio l determines the minimum flow + coefficient, for negative pressure differences. The parameter + dpFixed_nominal allows to include a series pressure drop + with a fixed flow coefficient into the model. The parameter + dpValve_closing determines when the flow coefficient + starts to increase, which is typically in the order of + dpValve_nominal. +

      +

      + Implementation +

      +

      + The check valve implementation approximates the physics where a + forward pressure difference opens the valve such that the valve + opening increases, causing a growing orifice area and thus increasing + the flow coefficient. Near dp=dpValve_closing, the valve + is fully open and the flow coefficient saturates to the flow + coefficient value determined by dpValve_nominal and + m_flow_nominal. For typical valve diameters, the check + valve is only fully open near nominal mass flow rate. Therefore, the + model sets dpValve_closing=dpValve_nominal/2 by default. +

      +
        +
      • September 16, 2019, by Kristoff Six and Filip Jorissen:
        + Implementation of a hydraulic check valve. This is for issue + 1198.
      -------- Errors -------- -line 8 column 2 - Warning:

      attribute "align" not allowed for HTML5 -line 21 column 2 - Warning:

      attribute "align" not allowed for HTML5 +line 10 column 2 - Warning:

      attribute "align" not allowed for HTML5 +line 17 column 2 - Warning:

      attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Interfaces/PrescribedOutlet.mo ---- +---- AixLib/Fluid/HeatExchangers/BaseClasses/HANaturalCylinder.mo ---- -------- HTML Code -------- -

      - This model sets the temperature or the water vapor mass fraction - of the medium that leaves port_a - to the value given by the input TSet or X_wSet, - subject to optional limitations on the capacity - for heating and cooling, or limitations on the humidification or dehumidification - moisture mass flow rate. - Also, optionally the model allows to take into account first order dynamics. -

      -

      - If the parameters energyDynamics is not equal to - Modelica.Fluid.Types.Dynamics.SteadyState, - the component models the dynamic response using a first order differential equation. - The time constant of the component is equal to the parameter tau. - This time constant is adjusted based on the mass flow rate using -

      -

      - τeff = τ |ṁ| ⁄ ṁnom -

      -

      - where - τeff is the effective time constant for the given mass flow rate - ṁ and - τ is the time constant at the nominal mass flow rate - ṁnom. - This type of dynamics is equal to the dynamics that a completely mixed - control volume would have. -

      -

      - This model has no pressure drop. - See - AixLib.Fluid.HeatExchangers.PrescribedOutlet - for a model that instantiates this model and that has a pressure drop. -

      -

      - In case of reverse flow, - the fluid that leaves port_a has the same - properties as the fluid that enters port_b. -

      - -
        -
      • - March 3, 2022, by Michael Wetter:
        - Removed massDynamics.
        - This is for - issue 1542. -
        • -
      • - April 29, 2021, by Michael Wetter:
        - Removed duplicate declaration of m_flow_nominal which is already - declared in the base class.
        -
        • -
      • - March 19, 2018, by Michael Wetter:
        - Added bugfix as the old model did not track TSet and X_wSet - simultaneously.
        - This is for - #893. -
        • +

        + This model calculates the convection coefficient h for natural convection + from a cylinder submerged in fluid. h is calcualted using Eq 9.34 from + Incropera and DeWitt (1996). + Output of the block is the hA value. +

        +

        + The Nusselt number is computed as +

        +

        + NuD = (0.6 + (0.387 RaD(1/6))/(1+(0.559 Pr) + (9/16))(8/27))2); +

        +

        + where NuD is the Nusselt number, RaD is the + Rayleigh number and + Pr is the Prandtl number.
        + This correclation is accurate for RaD less than 1012. +

        +

        + h is then calculated from the Nusselt number. The equation is +

        +

        + h = NuD k/D +

        +

        + where k is the thermal conductivity of the fluid and D is the diameter + of the submerged cylinder. +

        +

        References

        +

        + Fundamentals of Heat and Mass Transfer (Fourth Edition), Frank Incropera and David + DeWitt, John Wiley and Sons, 1996 +

        + +
        • - May 3, 2017, by Michael Wetter:
          - Refactored model to allow X_wSet as an input.
          - This is for - #763. + August 29, 2014 by Michael Wetter:
          + Refactored function calls for medium properties.
        • - January 26, 2016, by Michael Wetter:
          - Removed inequality comparison of real numbers in restrictCool - and in restrictHeat as this is not allowed in Modelica. + May 10, 2013 by Michael Wetter:
          + Revised implementation to use hA_nominal as a parameter, and compute the + associated surface area A. This revision was required to have a consistent + computation of the hA values inside and outside of the coil in the + heat exchanger model of the water tank.
        • - November 10, 2014, by Michael Wetter:
          + February 26, 2013 by Peter Grant:
          First implementation.
        -------- Corrected Code --------

        - This model sets the temperature or the water vapor mass fraction of - the medium that leaves port_a to the value given by the - input TSet or X_wSet, subject to optional - limitations on the capacity for heating and cooling, or limitations - on the humidification or dehumidification moisture mass flow rate. - Also, optionally the model allows to take into account first order - dynamics. + This model calculates the convection coefficient h for natural + convection from a cylinder submerged in fluid. h is calcualted + using Eq 9.34 from Incropera and DeWitt (1996). Output of the block + is the hA value.

        - If the parameters energyDynamics is not equal to - Modelica.Fluid.Types.Dynamics.SteadyState, the component - models the dynamic response using a first order differential - equation. The time constant of the component is equal to the - parameter tau. This time constant is adjusted based on - the mass flow rate using + The Nusselt number is computed as

        - τeff = τ |ṁ| ⁄ ṁnom + NuD = (0.6 + (0.387 + RaD(1/6))/(1+(0.559 Pr) + (9/16))(8/27))2);

        - where τeff is the effective time constant for the - given mass flow rate ṁ and τ is the time constant at - the nominal mass flow rate ṁnom. This type of - dynamics is equal to the dynamics that a completely mixed control - volume would have. + where NuD is the Nusselt number, + RaD is the Rayleigh number and Pr is the + Prandtl number.
        + This correclation is accurate for RaD less than + 1012.

        - This model has no pressure drop. See AixLib.Fluid.HeatExchangers.PrescribedOutlet - for a model that instantiates this model and that has a pressure - drop. + h is then calculated from the Nusselt number. The equation is +

        +

        + h = NuD k/D

        - In case of reverse flow, the fluid that leaves port_a - has the same properties as the fluid that enters port_b. + where k is the thermal conductivity of the fluid and D + is the diameter of the submerged cylinder. +

        +

        + References +

        +

        + Fundamentals of Heat and Mass Transfer (Fourth Edition), Frank + Incropera and David DeWitt, John Wiley and Sons, 1996

          -
        • March 3, 2022, by Michael Wetter:
          - Removed massDynamics.
          - This is for issue - 1542. -
          • -
        • April 29, 2021, by Michael Wetter:
          - Removed duplicate declaration of m_flow_nominal which - is already declared in the base class.
          -
          • -
        • March 19, 2018, by Michael Wetter:
          - Added bugfix as the old model did not track TSet and - X_wSet simultaneously.
          - This is for #893. -
          • -
        • May 3, 2017, by Michael Wetter:
          - Refactored model to allow X_wSet as an input.
          - This is for #763. +
        • August 29, 2014 by Michael Wetter:
          + Refactored function calls for medium properties.
          • -
        • January 26, 2016, by Michael Wetter:
          - Removed inequality comparison of real numbers in - restrictCool and in restrictHeat as this - is not allowed in Modelica. +
        • May 10, 2013 by Michael Wetter:
          + Revised implementation to use hA_nominal as a + parameter, and compute the associated surface area A. + This revision was required to have a consistent computation of the + hA values inside and outside of the coil in the heat + exchanger model of the water tank.
          • -
        • November 10, 2014, by Michael Wetter:
          +
        • February 26, 2013 by Peter Grant:
          First implementation.
        -------- Errors -------- -line 18 column 2 - Warning:

        attribute "align" not allowed for HTML5 +line 11 column 14 - Warning:

        attribute "align" not allowed for HTML5 +line 24 column 14 - Warning:

        attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Sensors/LatentEnthalpyFlowRate.mo ---- +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/Cylindrical.mo ---- -------- HTML Code --------

        - This model outputs the latent enthalphy flow rate of the medium in the flow - between its fluid ports. In particular, if the total enthalpy flow rate is + Model for radial heat transfer in a hollow cylinder. +

        +

        + If the heat capacity of the material is non-zero, then this model computes transient heat conduction, i.e., it + computes a numerical approximation to the solution of the heat equation

        - Ḣtot = Ḣsen + Ḣlat, + ρ c ( ∂ T(r,t) ⁄ ∂t ) = + k ( ∂² T(r,t) ⁄ ∂r² + 1 ⁄ r   ∂ T(r,t) ⁄ ∂r ),

        - where - Ḣsen = ṁ (1-Xw) cp,air, - then this sensor outputs Ḣ = Ḣlat. + where + ρ + is the mass density, + c + is the specific heat capacity per unit mass, + T + is the temperature at location r and time t and + k is the heat conductivity. + At the locations r=ra and r=rb, + the temperature and heat flow rate are equal to the + temperature and heat flow rate of the heat ports.

        - If the parameter tau is non-zero, then the measured - specific latent enthalpy hout that is used to - compute the latent enthalpy flow rate - Ḣlat = ṁ hout - is computed using a first order differential equation. - See - AixLib.Fluid.Sensors.UsersGuide for an explanation. + If the heat capacity of the material is set to zero, then steady-state heat flow is computed using +

        +

        + Q = 2 π k (Ta-Tb)⁄ ln(ra ⁄ rb),

        - For a sensor that measures - Ḣtot, use - - AixLib.Fluid.Sensors.EnthalpyFlowRate.
        - For a sensor that measures - Ḣsen, use - - AixLib.Fluid.Sensors.SensibleEnthalpyFlowRate. + where + ra is the internal radius, + rb is the external radius, + Ta is the temperature at port a and + Tb is the temperature at port b.

        +

        Implementation

        - The sensor is ideal, i.e., it does not influence the fluid. - The sensor can only be used with medium models that implement the function - enthalpyOfNonCondensingGas(T). + To spatially discretize the heat equation, the construction is + divided into compartments with nSta ≥ 1 state variables. + The state variables are connected to each other through thermal conductors. + There is also a thermal conductor + between the surfaces and the outermost state variables. Thus, to obtain + the surface temperature, use port_a.T (or port_b.T) + and not the variable T[1].

        • - October 19, 2020, by Antoine Gautier:
          - Changed default value for tau from 1 to 0.
          - This is for - #1406. -
          • -
        • - February 25, 2020, by Michael Wetter:
          - Changed icon to display its operating state.
          - This is for - #1294. -
          • -
        • - January 18, 2016 by Filip Jorissen:
          - Using parameter tauInv - since this now exists in - AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. - This is for - #372. -
          • -
        • - September 10, 2013, by Michael Wetter:
          - Changed medium declaration in the extends statement - to replaceable to avoid a translation error in - OpenModelica. -
          • -
        • - August 31, 2013, by Michael Wetter:
          - Removed default value tau=0 as the base class - already sets tau=1. - This change was made so that all sensors use the same default value. -
          • -
        • - December 18, 2012, by Michael Wetter:
          - Moved computation of i_w to new base class - - AixLib.Fluid.BaseClasses.IndexWater. - The value of this parameter is now assigned dynamically and does not require to be specified - by the user. -
          • -
        • - November 3, 2011, by Michael Wetter:
          - Moved der(h_out) := 0; from the initial algorithm section to - the initial equation section - as this assignment does not conform to the Modelica specification. -
          • -
        • - August 10, 2011 by Michael Wetter:
          - Added parameter i_w and an assert statement to - make sure it is set correctly. Without this change, Dymola - cannot differentiate the model when reducing the index of the DAE. -
          • -
        • - June 3, 2011 by Michael Wetter:
          - Revised implementation to add dynamics in such a way that - the time constant increases as the mass flow rate tends to zero. - This can improve the numerics. + January, 2014, by Damien Picard:
          + Modify the discretization of the cilindrical layer so that the first three layers have an equal thickness the following an exponentionally growing thickness. + This follows the guidelines of Eskilson (P. Eskilson. Thermal analysis of heat extraction + boreholes. PhD thesis, Dep. of Mathematical + Physics, University of Lund, Sweden, 1987).
        • - February 22, by Michael Wetter:
          - Improved code that searches for index of 'water' in medium model. + March 9, 2012, by Michael Wetter:
          + Removed protected variable der_T as it is not required.
        • - September 9, 2009 by Michael Wetter:
          + April 14 2011, by Pierre Vigouroux:
          First implementation. - Implementation is based on enthalpy sensor of Modelica.Fluid.
        -------- Corrected Code --------

        - This model outputs the latent enthalphy flow rate of the - medium in the flow between its fluid ports. In particular, if the - total enthalpy flow rate is + Model for radial heat transfer in a hollow cylinder. +

        +

        + If the heat capacity of the material is non-zero, then this model + computes transient heat conduction, i.e., it computes a numerical + approximation to the solution of the heat equation

        - Ḣtot = Ḣsen + Ḣlat, + ρ c ( ∂ T(r,t) ⁄ ∂t ) = k ( ∂² T(r,t) ⁄ ∂r² + 1 ⁄ r   ∂ T(r,t) ⁄ + ∂r ),

        - where Ḣsen = ṁ (1-Xw) - cp,air, then this sensor outputs Ḣ = - Ḣlat. + where ρ is the mass density, c is the specific heat + capacity per unit mass, T is the temperature at location + r and time t and k is the heat conductivity. At + the locations r=ra and r=rb, the + temperature and heat flow rate are equal to the temperature and heat + flow rate of the heat ports.

        - If the parameter tau is non-zero, then the measured - specific latent enthalpy hout that is used to - compute the latent enthalpy flow rate Ḣlat = ṁ - hout is computed using a first order differential - equation. See AixLib.Fluid.Sensors.UsersGuide - for an explanation. + If the heat capacity of the material is set to zero, then + steady-state heat flow is computed using +

        +

        + Q = 2 π k (Ta-Tb)⁄ ln(ra ⁄ + rb),

        - For a sensor that measures Ḣtot, use AixLib.Fluid.Sensors.EnthalpyFlowRate.
        - - For a sensor that measures Ḣsen, use AixLib.Fluid.Sensors.SensibleEnthalpyFlowRate. + where ra is the internal radius, + rb is the external radius, Ta is + the temperature at port a and Tb is the temperature + at port b.

        +

        + Implementation +

        - The sensor is ideal, i.e., it does not influence the fluid. The - sensor can only be used with medium models that implement the - function enthalpyOfNonCondensingGas(T). + To spatially discretize the heat equation, the construction is + divided into compartments with nSta ≥ 1 state variables. + The state variables are connected to each other through thermal + conductors. There is also a thermal conductor between the surfaces + and the outermost state variables. Thus, to obtain the surface + temperature, use port_a.T (or port_b.T) and + not the variable T[1].

          -
        • October 19, 2020, by Antoine Gautier:
          - Changed default value for tau from 1 to - 0.
          - This is for #1406. -
          • -
        • February 25, 2020, by Michael Wetter:
          - Changed icon to display its operating state.
          - This is for #1294. -
          • -
        • January 18, 2016 by Filip Jorissen:
          - Using parameter tauInv since this now exists in - - AixLib.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. This - is for #372. -
          • -
        • September 10, 2013, by Michael Wetter:
          - Changed medium declaration in the extends statement to - replaceable to avoid a translation error in - OpenModelica. -
          • -
        • August 31, 2013, by Michael Wetter:
          - Removed default value tau=0 as the base class already - sets tau=1. This change was made so that all sensors - use the same default value. -
          • -
        • December 18, 2012, by Michael Wetter:
          - Moved computation of i_w to new base class AixLib.Fluid.BaseClasses.IndexWater. - The value of this parameter is now assigned dynamically and does - not require to be specified by the user. -
          • -
        • November 3, 2011, by Michael Wetter:
          - Moved der(h_out) := 0; from the initial algorithm - section to the initial equation section as this assignment does not - conform to the Modelica specification. -
          • -
        • August 10, 2011 by Michael Wetter:
          - Added parameter i_w and an assert statement to make - sure it is set correctly. Without this change, Dymola cannot - differentiate the model when reducing the index of the DAE. -
          • -
        • June 3, 2011 by Michael Wetter:
          - Revised implementation to add dynamics in such a way that the time - constant increases as the mass flow rate tends to zero. This can - improve the numerics. +
        • January, 2014, by Damien Picard:
          + Modify the discretization of the cilindrical layer so that the + first three layers have an equal thickness the following an + exponentionally growing thickness. This follows the guidelines of + Eskilson (P. Eskilson. Thermal analysis of heat extraction + boreholes. PhD thesis, Dep. of Mathematical Physics, University of + Lund, Sweden, 1987).
          • -
        • February 22, by Michael Wetter:
          - Improved code that searches for index of 'water' in medium model. +
        • March 9, 2012, by Michael Wetter:
          + Removed protected variable der_T as it is not + required.
          • -
        • September 9, 2009 by Michael Wetter:
          - First implementation. Implementation is based on enthalpy sensor of - Modelica.Fluid. +
        • April 14 2011, by Pierre Vigouroux:
          + First implementation.
        -------- Errors -------- -line 6 column 2 - Warning:

        attribute "align" not allowed for HTML5 +line 9 column 2 - Warning:

        attribute "align" not allowed for HTML5 +line 29 column 2 - Warning:

        attribute "align" not allowed for HTML5 ----- AixLib/BoundaryConditions/WeatherData/ReaderTMY3.mo ---- +---- AixLib/Fluid/HeatPumps/Compressors/ReciprocatingCompressor.mo ---- -------- HTML Code --------

        - Block to output the latitude of the location. - This block is added so that the latitude is displayed - with a comment in the GUI of the weather bus connector. + Model for a reciprocating processor, as detailed in Jin (2002). The rate of heat transferred to the evaporator is given by: +

        +

        + Q̇Eva = ṁref ( hVap(TEva) - hLiq(TCon) ).

        -

        Implementation

        - If - - Modelica.Blocks.Sources.Constant where used, then - the comment for the latitude would be \"Connector of Real output signal\". - As this documentation string cannot be overwritten, a new block - was implemented. + The power consumed by the compressor is given by a linear efficiency relation: +

        +

        + P = PTheoretical / η + PLoss,constant. +

        +

        + Variable speed is acheived by multiplying the full load piston displacement + by the normalized compressor speed. The power and heat transfer rates are forced + to zero if the resulting heat pump state has higher evaporating pressure than + condensing pressure. +

        +

        Assumptions and limitations

        +

        + The compression process is assumed isentropic. The thermal energy + of superheating is ignored in the evaluation of the heat transferred to the refrigerant + in the evaporator. There is no supercooling. +

        +

        References

        +

        + H. Jin. + + Parameter estimation based models of water source heat pumps. + + PhD Thesis. Oklahoma State University. Stillwater, Oklahoma, USA. 2002.

        +-------- Corrected Code -------- +

        + Model for a reciprocating processor, as detailed in Jin (2002). The + rate of heat transferred to the evaporator is given by: +

        +

        + Q̇Eva = ṁref ( + hVap(TEva) - hLiq(TCon) + ). +

        +

        + The power consumed by the compressor is given by a linear efficiency + relation: +

        +

        + P = PTheoretical / η + PLoss,constant. +

        +

        + Variable speed is acheived by multiplying the full load piston + displacement by the normalized compressor speed. The power and heat + transfer rates are forced to zero if the resulting heat pump state + has higher evaporating pressure than condensing pressure. +

        +

        + Assumptions and limitations +

        +

        + The compression process is assumed isentropic. The thermal energy of + superheating is ignored in the evaluation of the heat transferred to + the refrigerant in the evaporator. There is no supercooling. +

        +

        + References +

        +

        + H. Jin. Parameter estimation based models of water source heat + pumps. PhD Thesis. Oklahoma State University. Stillwater, + Oklahoma, USA. 2002. +

        + + +-------- Errors -------- +line 5 column 2 - Warning:

        attribute "align" not allowed for HTML5 +line 11 column 2 - Warning:

        attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/cylindricalHeatSource.mo ---- +-------- HTML Code -------- +

        - Block to output the longitude of the location. - This block is added so that the longitude is displayed - with a comment in the GUI of the weather bus connector. + This function evaluates the cylindrical heat source solution. This solution + gives the relation between the constant heat transfer rate (per unit length) + injected by a cylindrical heat source of infinite length and the temperature + raise in the medium. The cylindrical heat source solution is defined by +

        +

        + \"image\"

        -

        Implementation

        - If - - Modelica.Blocks.Sources.Constant where used, then - the comment for the longitude would be \"Connector of Real output signal\". - As this documentation string cannot be overwritten, a new block - was implemented. + where ΔT(t,r) is the temperature raise after a time t of + constant heat injection and at a distance r from the cylindrical source, + Q' is the heat injection rate per unit length, ks is + the soil thermal conductivity, Fo is the Fourier number, + aSois is the ground thermal diffusivity, + rb is the radius of the cylindrical source and G + is the cylindrical heat source solution. +

        +

        + The cylindrical heat source solution is given by: +

        +

        + \"image\" +

        +

        + The integral is solved numerically, with the integrand defined in + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource_Integrand.

        • - January 4, 2016, by Michael Wetter:
          + March 22, 2018 by Massimo Cimmino:
          First implementation.
        +-------- Corrected Code -------- +

        + This function evaluates the cylindrical heat source solution. This + solution gives the relation between the constant heat transfer rate + (per unit length) injected by a cylindrical heat source of infinite + length and the temperature raise in the medium. The cylindrical heat + source solution is defined by +

        +

        + \"image\" +

        +

        + where ΔT(t,r) is the temperature raise after a time t + of constant heat injection and at a distance r from the + cylindrical source, Q' is the heat injection rate per unit + length, ks is the soil thermal conductivity, + Fo is the Fourier number, aSois is the + ground thermal diffusivity, rb is the radius of the + cylindrical source and G is the cylindrical heat source + solution. +

        +

        + The cylindrical heat source solution is given by: +

        +

        + \"image\" +

        +

        + The integral is solved numerically, with the integrand defined in + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource_Integrand. +

        +
          +
        • March 22, 2018 by Massimo Cimmino:
          + First implementation. +
          • +
        + +-------- Errors -------- +line 8 column 2 - Warning:

        attribute "align" not allowed for HTML5 +line 23 column 2 - Warning:

        attribute "align" not allowed for HTML5 + + +---- AixLib/Controls/Continuous/Examples/SignalRanker.mo ---- +-------- HTML Code -------- +

        - Block to output the altitude of the location. - This block is added so that the altitude is displayed - with a comment in the GUI of the weather bus connector. + Example that demonstrates the use of the signal ranker model. + The figure below shows the input and output signals of the block. + Note that + sigRan.y[1] ≥ sigRan.y[2] ≥ sigRan.y[3].

        -

        Implementation

        -

        - If - - Modelica.Blocks.Sources.Constant where used, then - the comment for the Altitude would be \"Connector of Real output signal\". - As this documentation string cannot be overwritten, a new block - was implemented. +

        + \"Input
        + \"Output

        • - May 2, 2021, by Ettore Zanetti:
          - First implementation. + October 15, 2021, by Michael Wetter:
          + Moved start time of sine input signal to avoid simultaneous state event and time event.
          + This is for + IBPSA, #1534. +
          • +
        • + November 21, 2011, by Michael Wetter:
          + Added documentation.
        -

        - This component reads TMY3 weather data (Wilcox and Marion, 2008) or user specified weather data. - The Modelica built-in variable time determines what row - of the weather file is read. - The value of time is the number of seconds - that have passed since January 1st at midnight (00:00) in the local time zone. - The local time zone value, longitude and latitute are also read from the weather data, - such that the solar position computations are consistent with the weather data. -

        -

        - The weather data format is the Typical Meteorological Year (TMY3) - as obtained from the EnergyPlus web site at - - http://energyplus.net/weather. These - data, which are in the EnergyPlus format, need to be converted as described - below. -

        - -

        Output to weaBus

        -

        - The following variables serve as output and are accessible via weaBus: -

        -
    - - - - - - +-------- Corrected Code -------- +

    + Example that demonstrates the use of the signal ranker model. The + figure below shows the input and output signals of the block. Note + that sigRan.y[1] ≥ sigRan.y[2] ≥ sigRan.y[3]. +

    +

    + \"Input
    + \"Output +

    +
      +
    • October 15, 2021, by Michael Wetter:
      + Moved start time of sine input signal to avoid simultaneous state + event and time event.
      + This is for IBPSA, + #1534. +
      • +
    • November 21, 2011, by Michael Wetter:
      + Added documentation. +
      • +
    + +-------- Errors -------- +line 8 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/HeatExchangers/EvaporatorCondenser.mo ---- +-------- HTML Code -------- + +

    + Model for a constant temperature evaporator or condenser based on a ε-NTU + heat exchanger model. +

    +

    + The heat exchanger effectiveness is calculated from the number of transfer units + (NTU): +

    +

    + ε = 1 - exp(UA ⁄ (ṁ cp)) +

    +

    + Optionally, this model can have a flow resistance. + If no flow resistance is requested, set dp_nominal=0. +

    +

    Limitations

    +

    + This model does not consider any superheating or supercooling on the refrigerant + side. The refrigerant is considered to exchange heat at a constant temperature + throughout the heat exchanger. +

    + +
      +
    • + March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      + This is for + #1542. +
      • +
    • + May 27, 2017, by Filip Jorissen:
      + Regularised heat transfer around zero flow.
      + This is for + #769. +
      • +
    • + April 12, 2017, by Michael Wetter:
      + Corrected invalid syntax for computing the specific heat capacity.
      + This is for + #707. +
      • +
    • + October 11, 2016, by Massimo Cimmino:
      + First implementation. +
      • +
    + +-------- Corrected Code -------- +

    + Model for a constant temperature evaporator or condenser based on a + ε-NTU heat exchanger model. +

    +

    + The heat exchanger effectiveness is calculated from the number of + transfer units (NTU): +

    +

    + ε = 1 - exp(UA ⁄ (ṁ cp)) +

    +

    + Optionally, this model can have a flow resistance. If no flow + resistance is requested, set dp_nominal=0. +

    +

    + Limitations +

    +

    + This model does not consider any superheating or supercooling on the + refrigerant side. The refrigerant is considered to exchange heat at a + constant temperature throughout the heat exchanger. +

    +
      +
    • March 7, 2022, by Michael Wetter:
      + Removed massDynamics.
      + This is for #1542. +
      • +
    • May 27, 2017, by Filip Jorissen:
      + Regularised heat transfer around zero flow.
      + This is for #769. +
      • +
    • April 12, 2017, by Michael Wetter:
      + Corrected invalid syntax for computing the specific heat + capacity.
      + This is for #707. +
      • +
    • October 11, 2016, by Massimo Cimmino:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Movers/Validation/PowerSimplified.mo ---- +-------- HTML Code -------- + +

    + This example compares the power consumed by pumps that + take three different control signals. + Each pump has identical mass flow rate and pressure rise. +

    +

    + Note that for the instances + + AixLib.Fluid.Movers.FlowControlled_dp + and + + AixLib.Fluid.Movers.FlowControlled_m_flow, + we had to assign the efficiencies (otherwise the default constant + efficiency of 0.7 would have been used). + In these models, the power consumption is computed + using similarity laws, but using the mass flow rate as opposed + to the speed, because speed is not known in these two models. + This is an approximation at operating points in which + the speed is different from the nominal speed N_nominal + because similarity laws are valid for speed and not for + mass flow rate. +

    +

    + The figure below shows the approximation error for the + power calculation where the speed Nrpm differs from + the nominal speed Nnominal. +

    +

    + \"image\" +

    + +
      +
    • + October 15, 2021, by Hongxiang Fu:
      + Fixed the image in the documentation which was cut off + at the y-axis. This is for + IBPSA, #1533. +
      • +
    • + March 11, 2016, by Michael Wetter:
      + Revised implementation by assigning the data record directly in the + instances pump_dp and pump_m_flow, because + using a parameter and assigning this parameter leads + in OpenModelica to the error message + expected subtype of record AixLib.Fluid.Movers.Data.Generic. +
      • +
    • + March 2, 2016, by Filip Jorissen:
      + Revised implementation for + #417. +
      • +
    • + November 5, 2015, by Michael Wetter:
      + Changed parameters since the power is no longer a parameter for the movers + that take mass flow rate or head as an input. + This is for + issue 457. +
      • +
    • + November 22, 2014, by Michael Wetter:
      + Revised implementation. +
      • +
    + +-------- Corrected Code -------- +

    + This example compares the power consumed by pumps that take three + different control signals. Each pump has identical mass flow rate and + pressure rise. +

    +

    + Note that for the instances AixLib.Fluid.Movers.FlowControlled_dp + and AixLib.Fluid.Movers.FlowControlled_m_flow, + we had to assign the efficiencies (otherwise the default constant + efficiency of 0.7 would have been used). In these models, the + power consumption is computed using similarity laws, but using the + mass flow rate as opposed to the speed, because speed is not known in + these two models. This is an approximation at operating points in + which the speed is different from the nominal speed + N_nominal because similarity laws are valid for speed + and not for mass flow rate. +

    +

    + The figure below shows the approximation error for the power + calculation where the speed Nrpm differs from the + nominal speed Nnominal. +

    +

    + \"image\" +

    +
      +
    • October 15, 2021, by Hongxiang Fu:
      + Fixed the image in the documentation which was cut off at the + y-axis. This is for IBPSA, + #1533. +
      • +
    • March 11, 2016, by Michael Wetter:
      + Revised implementation by assigning the data record directly in the + instances pump_dp and pump_m_flow, + because using a parameter and assigning this + parameter leads in OpenModelica to the error message + expected subtype of record + AixLib.Fluid.Movers.Data.Generic. +
      • +
    • March 2, 2016, by Filip Jorissen:
      + Revised implementation for #417. +
      • +
    • November 5, 2015, by Michael Wetter:
      + Changed parameters since the power is no longer a parameter for the + movers that take mass flow rate or head as an input. This is for + issue + 457. +
      • +
    • November 22, 2014, by Michael Wetter:
      + Revised implementation. +
      • +
    + +-------- Errors -------- +line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Chillers/BaseClasses/Carnot.mo ---- +-------- HTML Code -------- + +

    + This is the base class for the Carnot chiller and the Carnot heat pump + whose coefficient of performance COP changes + with temperatures in the same way as the Carnot efficiency changes. +

    +

    + The model allows to either specify the Carnot effectivness + ηCarnot,0, or + a COP0 + at the nominal conditions, together with + the evaporator temperature Teva,0 and + the condenser temperature Tcon,0, in which + case the model computes the Carnot effectivness as +

    +

    + ηCarnot,0 = + COP0 + ⁄ (Tuse,0 ⁄ (Tcon,0-Teva,0)), +

    +

    + where + Tuse is the temperature of the the useful heat, + e.g., the evaporator temperature for a chiller or the condenser temperature + for a heat pump. +

    +

    + The COP is computed as the product +

    +

    + COP = ηCarnot,0 COPCarnot ηPL, +

    +

    + where COPCarnot is the Carnot efficiency and + ηPL is the part load efficiency, expressed using + a polynomial. + This polynomial has the form +

    +

    + ηPL = a1 + a2 y + a3 y2 + ... +

    +

    + where y ∈ [0, 1] is + either the part load for cooling in case of a chiller, or the part load of heating in + case of a heat pump, and the coefficients ai + are declared by the parameter a. +

    +

    Implementation

    +

    + To make this base class applicable to chiller or heat pumps, it uses + the boolean constant COP_is_for_cooling. + Depending on its value, the equations for the coefficient of performance + and the part load ratio are set up. +

    + +
      +
    • + April 14, 2020, by Michael Wetter:
      + Changed homotopyInitialization to a constant.
      + This is for + IBPSA, #1341. +
      • +
    • + September 12, 2019, by Michael Wetter:
      + Corrected value of evaluate_etaPL and how it is used. + This correction only affects protected variables and does not affect the results.
      + This is for + #1200. +
      • +
    • + June 16, 2017, by Michael Wetter:
      + Added temperature difference between fluids in condenser and evaporator + for computation of nominal COP and effectiveness.
      + This is for + #698. +
      • +
    • + March 28, 2017, by Felix Buenning:
      + Added temperature difference between fluids in condenser and evaporator. + The difference is based on discussions with Emerson Climate Technologies.
      + This is for + #698. +
      • +
    • + January 2, 2017, by Filip Jorissen:
      + Removed option for choosing what temperature + should be used to compute the Carnot efficiency. + This is for + + issue 497. +
      • +
    • + January 26, 2016, by Michael Wetter:
      + First implementation of this base class. +
      • +
    + +-------- Corrected Code -------- +

    + This is the base class for the Carnot chiller and the Carnot heat + pump whose coefficient of performance COP changes with temperatures + in the same way as the Carnot efficiency changes. +

    +

    + The model allows to either specify the Carnot effectivness + ηCarnot,0, or a COP0 at the + nominal conditions, together with the evaporator temperature + Teva,0 and the condenser temperature + Tcon,0, in which case the model computes the Carnot + effectivness as +

    +

    + ηCarnot,0 = COP0 ⁄ (Tuse,0 ⁄ + (Tcon,0-Teva,0)), +

    +

    + where Tuse is the temperature of the the useful + heat, e.g., the evaporator temperature for a chiller or the condenser + temperature for a heat pump. +

    +

    + The COP is computed as the product +

    +

    + COP = ηCarnot,0 COPCarnot ηPL, +

    +

    + where COPCarnot is the Carnot efficiency and + ηPL is the part load efficiency, expressed using a + polynomial. This polynomial has the form +

    +

    + ηPL = a1 + a2 y + a3 + y2 + ... +

    +

    + where y ∈ [0, 1] is either the part load for cooling in case + of a chiller, or the part load of heating in case of a heat pump, and + the coefficients ai are declared by the parameter + a. +

    +

    + Implementation +

    +

    + To make this base class applicable to chiller or heat pumps, it uses + the boolean constant COP_is_for_cooling. Depending on + its value, the equations for the coefficient of performance and the + part load ratio are set up. +

    +
      +
    • April 14, 2020, by Michael Wetter:
      + Changed homotopyInitialization to a constant.
      + This is for IBPSA, + #1341. +
      • +
    • September 12, 2019, by Michael Wetter:
      + Corrected value of evaluate_etaPL and how it is used. + This correction only affects protected variables and does not + affect the results.
      + This is for #1200. +
      • +
    • June 16, 2017, by Michael Wetter:
      + Added temperature difference between fluids in condenser and + evaporator for computation of nominal COP and effectiveness.
      + This is for #698. +
      • +
    • March 28, 2017, by Felix Buenning:
      + Added temperature difference between fluids in condenser and + evaporator. The difference is based on discussions with Emerson + Climate Technologies.
      + This is for #698. +
      • +
    • January 2, 2017, by Filip Jorissen:
      + Removed option for choosing what temperature should be used to + compute the Carnot efficiency. This is for issue 497. +
      • +
    • January 26, 2016, by Michael Wetter:
      + First implementation of this base class. +
      • +
    + +-------- Errors -------- +line 16 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 30 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 39 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/BoundaryConditions/Validation/BESTEST/WD200.mo ---- +-------- HTML Code -------- + +

      +
    • + September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the weather data bus.
      + This is for + IBPSA, #1477. +
      • +
    • + March 11, 2020, by Ettore Zanetti:
      + First implementation. +
      • +
    • + April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request + #1339. +
      • +
    • + May 2, 2021, by Ettore Zanetti:
      + Updated weather file as explained in #1478. +
      • +
    + +

    WD200: Low Elevation, Hot and Humid Case.

    +

    Weather data file : WD200.epw

    +

    Table 1: Site Data for Weather file WD200.epw

    +
    Name - Unit - Description -
    + + + + + + + + + + + + + + + +

    Latitude

    33.633° north

    Longitude

    84.433° west

    Altitude

    308 m

    Time Zone

    -5

    + +-------- Corrected Code -------- +
      +
    • September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the + weather data bus.
      + This is for IBPSA, + #1477. +
      • +
    • March 11, 2020, by Ettore Zanetti:
      + First implementation. +
      • +
    • April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request #1339. +
      • +
    • May 2, 2021, by Ettore Zanetti:
      + Updated weather file as explained in #1478. +
      • +
    +

    + WD200: Low Elevation, Hot and Humid Case. +

    +

    + Weather data file : WD200.epw +

    +

    + Table 1: Site Data for Weather file WD200.epw +

    + + + + + + + + + + + + + + + + + +
    +

    + Latitude +

    +     		+

    + 33.633° north +

    +
    +

    + Longitude +

    +     		+

    + 84.433° west +

    +
    +

    + Altitude +

    +     		+

    + 308 m +

    +
    +

    + Time Zone +

    +     		+

    + -5 +

    +
    + +-------- Errors -------- +line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +---- AixLib/Fluid/FMI/ExportContainers/ThermalZone.mo ---- +-------- HTML Code -------- + +

    + Model that is used as a container for a single thermal zone + that is to be exported as an FMU. +

    +

    Typical use and important parameters

    +

    + To use this model as a container for an FMU, extend + from this model, rather than instantiate it, + add your thermal zone and a vector of mass flow rate sensors. + By extending from this model, the top-level + signal connectors on the left stay at the top-level, and hence + will be visible at the FMI interface. +

    + + Note that +
      +
    • + The vector of mass flow rate sensors is used to connect + the thermal zone adapter and your thermal zone. +
      • +
    • + The vector of mass flow rate sensors must have the size nPorts. +
      • +
    • + All fluid ports of the mass flow rate sensor must be connected. +
      • +
    • + If the vector of mass flow rate sensors is not used, and your themal zone + has fluid ports which are autosized, then a direct connection between + the thermal zone adpater theZonAda and your thermal + zone will be rejected. The reason is because autosized fluid ports + can only be connected to vector of ports whose sizes are literal. +
      • +
    + +

    + The example + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone + shows how a simple thermal zone can be implemented and exported as + an FMU. + +

    + +

    + The conversion between the fluid ports and signal ports is done + in the thermal zone adapter theZonAda. + This adapter has a vector of fluid ports called ports[nPorts] + which needs to be connected to the air volume of the thermal zone. + At this port, air exchanged between the thermal zone, the HVAC system + and any infiltration flow paths. +

    +

    + This model has input signals fluPor[nPorts], which carry + the mass flow rate for each flow that is connected to ports, together with its + temperature, water vapor mass fraction per total mass of the air (not per kg dry + air), and trace substances. These quantities are always as if the flow + enters the room, even if the flow is zero or negative. + If a medium has no moisture, e.g., if Medium.nXi=0, or + if it has no trace substances, e.g., if Medium.nC=0, then + the output signal for these properties are removed. + Thus, a thermal zone model that uses these signals to compute the + heat added by the HVAC system need to implement an equation such as +

    +

    + Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), +

    +

    + where + Qsen is the sensible heat flow rate added to the thermal zone, + ṁsup is the supply air mass flow rate from + the port fluPor (which is negative if it is an exhaust), + cp is the specific heat capacity at constant pressure, + Tsup is the supply air temperature and + Tair,zon is the zone air temperature. + Note that without the max(·, ·), the energy + balance would be wrong. + For example, + + the control volumes in + + AixLib.Fluid.MixingVolumes + implement such a max(·, ·) function. +

    +

    + The zone air temperature, + the water vapor mass fraction per total mass of the air (unless Medium.nXi=0) + and trace substances (unless Medium.nC=0) + can be obtained from the outupt connector + fluPor.backward. + These signals are the same as the inflowing fluid stream(s) + at the port theAdaZon.ports[1:nPorts]. + The fluid connector ports[nPorts] has a prescribed mass flow rate, but + it does not set any pressure. +

    +

    + This model has a user-defined parameter nPorts + which sets the number of fluid ports, which in turn is used + for the ports fluPor and ports. + All nPorts + ports[1:nPorts] need to be connected as demonstrated in the example + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. +

    +

    + +

    + +
      +
    • + January 18, 2019, by Jianjun Hu:
      + Limited the media choice to moist air. + See #1050. +
      • +
    • + September 20, 2016, by Thierry S. Nouidui:
      + Revised documentation to explain the rationale + of needing mass flow rate sensors. +
      • +
    • + June 29, 2016, by Michael Wetter:
      + Revised implementation and documentation. +
      • +
    • + April 27, 2016, by Thierry S. Nouidui:
      + First implementation. +
      • +
    + +-------- Corrected Code -------- +

    + Model that is used as a container for a single thermal zone that is + to be exported as an FMU. +

    +

    + Typical use and important parameters +

    +

    + To use this model as a container for an FMU, extend from this model, + rather than instantiate it, add your thermal zone and a vector of + mass flow rate sensors. By extending from this model, the top-level + signal connectors on the left stay at the top-level, and hence will + be visible at the FMI interface. +

    Note that +
      +
    • The vector of mass flow rate sensors is used to connect the + thermal zone adapter and your thermal zone. +
      • +
    • The vector of mass flow rate sensors must have the size + nPorts. +
      • +
    • All fluid ports of the mass flow rate sensor must be connected. +
      • +
    • If the vector of mass flow rate sensors is not used, and your + themal zone has fluid ports which are autosized, then a direct + connection between the thermal zone adpater theZonAda + and your thermal zone will be rejected. The reason is because + autosized fluid ports can only be connected to vector of ports whose + sizes are literal. +
      • +
    +

    + The example + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone shows + how a simple thermal zone can be implemented and exported as an FMU. + +

    +

    + The conversion between the fluid ports and signal ports is done in + the thermal zone adapter theZonAda. This adapter has a + vector of fluid ports called ports[nPorts] which needs + to be connected to the air volume of the thermal zone. At this port, + air exchanged between the thermal zone, the HVAC system and any + infiltration flow paths. +

    +

    + This model has input signals fluPor[nPorts], which carry + the mass flow rate for each flow that is connected to + ports, together with its temperature, water vapor mass + fraction per total mass of the air (not per kg dry air), and trace + substances. These quantities are always as if the flow enters the + room, even if the flow is zero or negative. If a medium has no + moisture, e.g., if Medium.nXi=0, or if it has no trace + substances, e.g., if Medium.nC=0, then the output signal + for these properties are removed. Thus, a thermal zone model that + uses these signals to compute the heat added by the HVAC system need + to implement an equation such as +

    +

    + Qsen = max(0, ṁsup)   cp   + (Tsup - Tair,zon), +

    +

    + where Qsen is the sensible heat flow rate added to + the thermal zone, ṁsup is the supply air mass flow + rate from the port fluPor (which is negative if it is an + exhaust), cp is the specific heat capacity at + constant pressure, Tsup is the supply air + temperature and Tair,zon is the zone air + temperature. Note that without the max(·, ·), the energy + balance would be wrong. For example, + the control volumes in AixLib.Fluid.MixingVolumes + implement such a max(·, ·) function. +

    +

    + The zone air temperature, the water vapor mass fraction per total + mass of the air (unless Medium.nXi=0) and trace + substances (unless Medium.nC=0) can be obtained from the + outupt connector fluPor.backward. These signals are the + same as the inflowing fluid stream(s) at the port + theAdaZon.ports[1:nPorts]. The fluid connector + ports[nPorts] has a prescribed mass flow rate, but it + does not set any pressure. +

    +

    + This model has a user-defined parameter nPorts which + sets the number of fluid ports, which in turn is used for the ports + fluPor and ports. All nPorts + ports[1:nPorts] need to be connected as demonstrated in + the example + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone. +

    +

    + +

    +
      +
    • January 18, 2019, by Jianjun Hu:
      + Limited the media choice to moist air. See #1050. +
      • +
    • September 20, 2016, by Thierry S. Nouidui:
      + Revised documentation to explain the rationale of needing mass flow + rate sensors. +
      • +
    • June 29, 2016, by Michael Wetter:
      + Revised implementation and documentation. +
      • +
    • April 27, 2016, by Thierry S. Nouidui:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 72 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/Boreholes/BaseClasses/Functions/convectionResistanceCircularPipe.mo ---- +-------- HTML Code -------- + +

    + This model computes the convection resistance in the pipes of a borehole segment + with heigth hSeg using correlations suggested by Bergman et al. (2011). +

    +

    + If the flow is laminar (Re ≤ 2300, with Re being the Reynolds number of the flow), + the Nusselt number of the flow is assumed to be constant at 3.66. If the flow is turbulent (Re > 2300), + the correlation of Dittus-Boelter is used to find the convection heat transfer coefficient as +

    +

    + Nu = 0.023   Re0.8   Prn, +

    +

    + where Nu is the Nusselt number and + Pr is the Prandlt number. + A value of n=0.35 is used, as the reference uses n=0.4 for heating and + n=0.3 for cooling. To ensure that the function is continuously differentiable, + a smooth transition between the laminar and turbulent values is created for the + range 2300 < Re < 2400. +

    +

    References

    +

    + Bergman, T. L., Incropera, F. P., DeWitt, D. P., & Lavine, A. S. (2011). Fundamentals of heat and mass + transfer (7th ed.). New York: John Wiley & Sons. +

    + +
      +
    • + July 10, 2018, by Alex Laferrière:
      + Added laminar flow and smooth laminar-turbulent transition. + Revised documentation. +
      • +
    • + February 14, 2014, by Michael Wetter:
      + Removed unused input rBor. + Revised documentation. +
      • +
    • + January 24, 2014, by Michael Wetter:
      + Revised implementation. + Changed cpFluid to cpMed to use consistent notation. + Added regularization for computation of convective heat transfer coefficient to + avoid an event and a non-differentiability. +
      • +
    • + January 23, 2014, by Damien Picard:
      + First implementation. +
      • +
    + +-------- Corrected Code -------- +

    + This model computes the convection resistance in the pipes of a + borehole segment with heigth hSeg using + correlations suggested by Bergman et al. (2011). +

    +

    + If the flow is laminar (Re ≤ 2300, with Re being the + Reynolds number of the flow), the Nusselt number of the flow is + assumed to be constant at 3.66. If the flow is turbulent (Re > + 2300), the correlation of Dittus-Boelter is used to find the + convection heat transfer coefficient as +

    +

    + Nu = 0.023   Re0.8   Prn, +

    +

    + where Nu is the Nusselt number and Pr is the Prandlt + number. A value of n=0.35 is used, as the reference uses + n=0.4 for heating and n=0.3 for cooling. To ensure that + the function is continuously differentiable, a smooth transition + between the laminar and turbulent values is created for the range + 2300 < Re < 2400. +

    +

    + References +

    +

    + Bergman, T. L., Incropera, F. P., DeWitt, D. P., & Lavine, A. S. + (2011). Fundamentals of heat and mass transfer (7th ed.). New + York: John Wiley & Sons. +

    +
      +
    • July 10, 2018, by Alex Laferrière:
      + Added laminar flow and smooth laminar-turbulent transition. Revised + documentation. +
      • +
    • February 14, 2014, by Michael Wetter:
      + Removed unused input rBor. Revised documentation. +
      • +
    • January 24, 2014, by Michael Wetter:
      + Revised implementation. Changed cpFluid to + cpMed to use consistent notation. Added regularization + for computation of convective heat transfer coefficient to avoid an + event and a non-differentiability. +
      • +
    • January 23, 2014, by Damien Picard:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Actuators/Valves/TwoWayTable.mo ---- +-------- HTML Code -------- + +

    + Two way valve with opening characteristic that is configured through + a table. +

    +

    + The mass flow rate for the fully open valve is determined based + on the value of the parameter CvData. + For the different valve positions y ∈ [0, 1], this nominal flow rate is + scaled by the values of the parameter + flowCharacteristics. + The parameter flowCharacteristics declares a table of the form +

    +
    + + + + + + +
    y 0 ... 1
    φ l ... 1
    +

    + where l = Kv(y=0)/Kv(y=1) > 0 is the valve leakage. + The first row is the valve opening, and the second row is the + mass flow rate, relative to the mass flow rate of the fully open + valve, under the assumption of a constant pressure difference across the + valve. + A suggested value for the valve leakage is l=0.0001. + If l = 0, then this model will replace it with + l = 10-8 for numerical reasons. + For example, if a valve has Kv=0.5 [m3/h/bar1/2] and + a linear opening characteristics and + a valve leakage of l=0.0001, then one would set +

    + 
    +  CvData=AixLib.Fluid.Types.CvTypes.Kv
+  Kv = 0.5
+  flowCharacteristics(y={0,1}, phi={0.0001,1})
+
    +

    + Note, however, that + + AixLib.Fluid.Actuators.Valves.TwoWayLinear provides a more + efficient implementation for this simple case. +

    +

    + The parameter flowCharacteristics must meet the following + requirements, otherwise the model stops with an error: +

    +
      +
    • + Their arrays + y and phi + must be strictly monotonic increasing. +
      • +
    • + The first value must satisfy + y[1]=0, and + phi[1] must be equal to the + leakage flow rate, which must be bigger than zero. + Otherwise, a default value of 1E-8 is used. +
      • +
    • + The last values must satisfy + y[end]=1 and + phi[end]=1. +
      • +
    +

    + This model is based on the partial valve model + + AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. + Check this model for more information, such + as the regularization near the origin. +

    +

    + For an example that specifies an opening characteristics, see + + AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable. +

    + +
      +
    • + June 10, 2021, by Michael Wetter:
      + Changed implementation of the filter and changed the parameter order to a constant + as most users need not change this value.
      + This is for + #1498. +
      • +
    • + August 7, 2020, by Ettore Zanetti:
      + changed the computation of phi using + max(0.1*l, . ) to avoid + phi=0. + See + issue 1376. +
      • +
    • + November 9, 2019, by Filip Jorissen:
      + Guarded the computation of phi using + max(0, . ) to avoid + negative phi. + See + issue 1223. +
      • +
    • + January 26, 2016, by Michael Wetter:
      + Removed equality comparison for Real in the + assert statements as this is not allowed in Modelica. +
      • +
    • + August 12, 2014, by Michael Wetter:
      + Removed the end keyword when accessing array elements, + as this language construct caused an error in OpenModelica. +
      • +
    • + April 4, 2014, by Michael Wetter:
      + Moved the assignment of the flow function phi + to the model instantiation because in its base class, + the keyword input + has been added to the variable phi. +
      • +
    • + March 26, 2014 by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Corrected Code -------- +

    + Two way valve with opening characteristic that is configured through + a table. +

    +

    + The mass flow rate for the fully open valve is determined based on + the value of the parameter CvData. For the different + valve positions y ∈ [0, 1], this nominal flow rate is scaled + by the values of the parameter flowCharacteristics. The + parameter flowCharacteristics declares a table of the + form +

    + + + + + + + + + + + + + +
    + y + + 0 + + ... + + 1 +
    + φ + + l + + ... + + 1 +
    +

    + where l = Kv(y=0)/Kv(y=1) > 0 is the + valve leakage. The first row is the valve opening, and the second row + is the mass flow rate, relative to the mass flow rate of the fully + open valve, under the assumption of a constant pressure difference + across the valve. A suggested value for the valve leakage is + l=0.0001. If l = 0, then this model will replace it + with l = 10-8 for numerical reasons. For example, + if a valve has Kv=0.5 + [m3/h/bar1/2] and a linear opening + characteristics and a valve leakage of l=0.0001, then one + would set +

    +
    +  CvData=AixLib.Fluid.Types.CvTypes.Kv
+  Kv = 0.5
+  flowCharacteristics(y={0,1}, phi={0.0001,1})
+
    +

    + Note, however, that AixLib.Fluid.Actuators.Valves.TwoWayLinear + provides a more efficient implementation for this simple case. +

    +

    + The parameter flowCharacteristics must meet the + following requirements, otherwise the model stops with an error: +

    +
      +
    • Their arrays y and phi must be strictly + monotonic increasing. +
      • +
    • The first value must satisfy y[1]=0, and + phi[1] must be equal to the leakage flow rate, which + must be bigger than zero. Otherwise, a default value of + 1E-8 is used. +
      • +
    • The last values must satisfy y[end]=1 and + phi[end]=1. +
      • +
    +

    + This model is based on the partial valve model AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve. + Check this model for more information, such as the regularization + near the origin. +

    +

    + For an example that specifies an opening characteristics, see + + AixLib.Fluid.Actuators.Valves.Examples.TwoWayValveTable. +

    +
      +
    • June 10, 2021, by Michael Wetter:
      + Changed implementation of the filter and changed the parameter + order to a constant as most users need not change this + value.
      + This is for #1498. +
      • +
    • August 7, 2020, by Ettore Zanetti:
      + changed the computation of phi using max(0.1*l, + . ) to avoid phi=0. See issue + 1376. +
      • +
    • November 9, 2019, by Filip Jorissen:
      + Guarded the computation of phi using max(0, . + ) to avoid negative phi. See issue + 1223. +
      • +
    • January 26, 2016, by Michael Wetter:
      + Removed equality comparison for Real in the + assert statements as this is not allowed in Modelica. +
      • +
    • August 12, 2014, by Michael Wetter:
      + Removed the end keyword when accessing array elements, + as this language construct caused an error in OpenModelica. +
      • +
    • April 4, 2014, by Michael Wetter:
      + Moved the assignment of the flow function phi to the + model instantiation because in its base class, the keyword + input has been added to the variable phi. +
      • +
    • March 26, 2014 by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 14 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +---- AixLib/BoundaryConditions/WeatherData/ReaderTMY3.mo ---- +-------- HTML Code -------- + +

    + Block to output the latitude of the location. + This block is added so that the latitude is displayed + with a comment in the GUI of the weather bus connector. +

    +

    Implementation

    +

    + If + + Modelica.Blocks.Sources.Constant where used, then + the comment for the latitude would be \"Connector of Real output signal\". + As this documentation string cannot be overwritten, a new block + was implemented. +

    + +
      +
    • + January 4, 2016, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + Block to output the longitude of the location. + This block is added so that the longitude is displayed + with a comment in the GUI of the weather bus connector. +

    +

    Implementation

    +

    + If + + Modelica.Blocks.Sources.Constant where used, then + the comment for the longitude would be \"Connector of Real output signal\". + As this documentation string cannot be overwritten, a new block + was implemented. +

    + +
      +
    • + January 4, 2016, by Michael Wetter:
      + First implementation. +
      • +
    + +

    + Block to output the altitude of the location. + This block is added so that the altitude is displayed + with a comment in the GUI of the weather bus connector. +

    +

    Implementation

    +

    + If + + Modelica.Blocks.Sources.Constant where used, then + the comment for the Altitude would be \"Connector of Real output signal\". + As this documentation string cannot be overwritten, a new block + was implemented. +

    + +
      +
    • + May 2, 2021, by Ettore Zanetti:
      + First implementation. +
      • +
    + +

    + This component reads TMY3 weather data (Wilcox and Marion, 2008) or user specified weather data. + The Modelica built-in variable time determines what row + of the weather file is read. + The value of time is the number of seconds + that have passed since January 1st at midnight (00:00) in the local time zone. + The local time zone value, longitude and latitute are also read from the weather data, + such that the solar position computations are consistent with the weather data. +

    +

    + The weather data format is the Typical Meteorological Year (TMY3) + as obtained from the EnergyPlus web site at + + http://energyplus.net/weather. These + data, which are in the EnergyPlus format, need to be converted as described + below. +

    + +

    Output to weaBus

    +

    + The following variables serve as output and are accessible via weaBus: +

    +
    + + + + + + - - - + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    Name + Unit + Description +
    @@ -20611,4403 +19446,5568 @@ style=\"border-collapse:collapse;\">
    - lat - - rad - - Latitude of the location. - + lat + + rad + + Latitude of the location. +
    + lon + + rad + + Longitude of the location. +
    + nOpa + + 1 + + Opaque sky cover [0, 1]. +
    + nTot + + 1 + + Total sky Cover [0, 1]. +
    + pAtm + + Pa + + Atmospheric pressure. +
    + relHum + + 1 + + Relative humidity. +
    + solAlt + + rad + + Altitude angle. +
    + solDec + + rad + + Declination angle. +
    + solHouAng + + rad + + Solar hour angle. +
    + solTim + + s + + Solar time. +
    + solZen + + rad + + Zenith angle. +
    + winDir + + rad + + Wind direction. +
    + winSpe + + m/s + + Wind speed. +
    +

    + Adding new weather data +

    +

    + To add new weather data, proceed as follows: +

    +
      +
    1. Download the weather data file with the epw + extension from http://energyplus.net/weather. +
      2. +
    2. Add the file to AixLib/Resources/weatherdata (or to + any directory for which you have write permission). +
      3. +
    3. On a console window, type + 
      +   cd AixLib/Resources/weatherdata
+   java -jar ../bin/ConvertWeatherData.jar inputFile.epw
+
      if inputFile contains space in the name: + 
      +   java -jar ../bin/ConvertWeatherData.jar \"inputFile .epw\"
+
      This will generate the weather data file +inputFile.mos, which can be read by the model AixLib.BoundaryConditions.WeatherData.ReaderTMY3. +
      4. +
    +

    + Location data that are read automatically from the weather data file +

    +

    + The following location data are automatically read from the weather + file: +

    +
      +
    • The latitude of the weather station, lat, +
      • +
    • the longitude of the weather station, lon, and +
      • +
    • the time zone relative to Greenwich Mean Time, + timZone. +
      • +
    +

    + Wet bulb temperature +

    +

    + By default, the data bus contains the wet bulb temperature. This + introduces a nonlinear equation. However, we have not observed an + increase in computing time because of this equation. To disable the + computation of the wet bulb temperature, set + computeWetBulbTemperature=false. +

    +

    + Using constant or user-defined input signals for weather data +

    +

    + This model has the option of using a constant value, using the data + from the weather file, or using data from an input connector for the + following variables: +

    +
      +
    • The atmospheric pressure, +
      • +
    • the ceiling height, +
      • +
    • the total sky cover, +
      • +
    • the opaque sky cover, +
      • +
    • the dry bulb temperature, +
      • +
    • the dew point temperature, +
      • +
    • the sky black body temperature, +
      • +
    • the relative humidity, +
      • +
    • the wind direction, +
      • +
    • the wind speed, +
      • +
    • the global horizontal radiation, direct normal and diffuse + horizontal radiation, and +
      • +
    • the infrared horizontal radiation. +
      • +
    +

    + By default, all data are obtained from the weather data file, except + for the atmospheric pressure, which is set to the parameter + pAtm=101325 Pascals. +

    +

    + The parameter *Sou configures the source of the data. + For the atmospheric pressure, temperatures, relative humidity, wind + speed and wind direction, the enumeration AixLib.BoundaryConditions.Types.DataSource + is used as follows: +

    + + + + + - - - - + +
    + Parameter *Sou + + Data used to compute weather data. +
    - lon - - rad + File - Longitude of the location. + Use data from file.
    - nOpa - - 1 + Parameter - Opaque sky cover [0, 1]. + Use value specified by the parameter.
    - nTot - - 1 + Input - Total sky Cover [0, 1]. + Use value from the input connector.
    +

    + Because global, diffuse and direct radiation are related to each + other, the parameter HSou is treated differently. It is + set to a value of the enumeration AixLib.BoundaryConditions.Types.RadiationDataSource, + and allows the following configurations: +

    + + - - - + + - - - + - - + - - + +
    - pAtm - - Pa - - Atmospheric pressure. - + Parameter HSou + + Data used to compute weather data. +
    - relHum - - 1 + File - Relative humidity. + Use data from file.
    - solAlt - - rad + Input_HGloHor_HDifHor - Altitude angle. + Use global horizontal and diffuse horizontal radiation from input + connector.
    - solDec - - rad + Input_HDirNor_HDifHor - Declination angle. + Use direct normal and diffuse horizontal radiation from input + connector.
    - solHouAng - - rad + Input_HDirNor_HGloHor - Solar hour angle. + Use direct normal and global horizontal radiation from input + connector.
    +

    + Length of weather data and simulation period +

    +

    + If weather data span a year, which is the default for TMY3 data, or + multiple years, then this model can be used for simulations that span + multiple years. The simulation start time needs to be set to the + clock time of the respective start time. For example, to start at + January 2 at 10am, set start time to t=(24+10)*3600 + seconds. For this computation, the used date and time (here January + 2, 10 am) must be expressed in the same time zone as the one that is + used to define the TMY3 file. This is usually the local (winter) time + zone. The parameter `timZon` represents the TMY3 file time zone, + expressed in seconds compared to UTC. +

    +

    + Moreover, weather data need not span a whole year, or it can span + across New Year. In this case, the simulation cannot exceed the time + of the weather data file. Otherwise, the simulation stops with an + error. +

    +

    + As weather data have one entry at the start of the time interval, the + end time of the weather data file is computed as the last time entry + plus the average time increment of the file. For example, an hourly + weather data file has 8760 entries, starting on January 1 at 0:00. + The last entry in the file will be for December 31 at 23:00. As the + time increment is 1 hour, the model assumes the weather file to end + at December 31 at 23:00 plus 1 hour, e.g., at January 1 at 0:00. +

    +

    + Notes +

    +
      +
    1. +

      + In HVAC systems, when the fan is off, changes in atmospheric + pressure can cause small air flow rates in the duct system due to + change in pressure and hence in the mass of air that is stored in + air volumes (such as in fluid junctions or in the room model). + This may increase computing time. Therefore, the default value + for the atmospheric pressure is set to a constant. Furthermore, + if the initial pressure of air volumes are different from the + atmospheric pressure, then fast pressure transients can happen in + the first few seconds of the simulation. This can cause numerical + problems for the solver. To avoid this problem, set the + atmospheric pressure to the same value as the medium default + pressure, which is typically set to the parameter + Medium.p_default. For medium models for moist air + and dry air, the default is Medium.p_default=101325 + Pascals. +

      +
      2. +
    2. +

      + Different units apply depending on whether data are obtained from + a file, or from a parameter or an input connector: +

      +
        +
      • When using TMY3 data from a file (e.g. + USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.mos), the + units must be the same as the original TMY3 file used by + EnergyPlus (e.g. + USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.epw). The + TMY3 data used by EnergyPlus are in both SI units and non-SI + units. If Resources/bin/ConvertWeatherData.jar is + used to convert the .epw file to an + .mos file, the units of the TMY3 data are preserved + and the file can be directly used by this data reader. The data + reader will automatically convert units to the SI units used by + Modelica. For example, the dry bulb temperature + TDryBul in TMY3 is in degree Celsius. The data + reader will automatically convert the data to Kelvin. The wind + direction winDir in TMY3 is degrees and will be + automatically converted to radians. +
        • +
      • When using data from a parameter or from an input connector, + the data must be in the SI units used by Modelica. For instance, + the unit must be Pa for pressure, K for + temperature, W/m2 for solar radiations and + rad for wind direction. +
        • +
      +
      3. +
    3. +

      + Hourly and subhourly timestamp are handled in a different way in + .epw files. From the EnergyPlus Auxiliary Programs + Document (v9.3.0, p. 63): In hourly data the minute field can be + 00 or 60. In this case as mentioned in + the previous section, the weather data is reported at the hourly + value and the minute field has to be ignored, writing 1, + 60 or 1, 00 is equivalent. If the minute + field is between 00 and 60, the file + becomes subhourly, in this case the timestamp corresponds to the + minute field in the considered hour. For example: 1, + 30 is equivalent to 00:30 and 3, 45 is + equivalent to 02:45.
      + (Note the offset in the hour digit.) +

      +
      4. +
    4. The ReaderTMY3 should only be used with TMY3 data. It contains a + time shift for solar radiation data that is explained below. This + time shift needs to be removed if the user may want to use the + ReaderTMY3 for other weather data types. +
      5. +
    +

    + Implementation +

    +
    + Start and end data for annual weather data files +
    +

    + The TMY3 weather data, as well as the EnergyPlus weather data, start + at 1:00 AM on January 1, and provide hourly data until midnight on + December 31. Thus, the first entry for temperatures, humidity, wind + speed etc. are values at 1:00 AM and not at midnight. Furthermore, + the TMY3 weather data files can have values at midnight of December + 31 that may be significantly different from the values at 1:00 AM on + January 1. Since annual simulations require weather data that start + at 0:00 on January 1, data need to be provided for this hour. Due to + the possibly large change in weatherdata between 1:00 AM on January 1 + and midnight at December 31, the weather data files in the AixLib + library do not use the data entry from midnight at December 31 as the + value for t=0. Rather, the value from 1:00 AM on January 1 is + duplicated and used for 0:00 on January 1. To maintain a data record + with 8760 hours, the weather data record from midnight at + December 31 is deleted. These changes in the weather data file are + done in the Java program + AixLib/Resources/bin/ConvertWeatherData.jar that + converts EnergyPlus weather data file to Modelica weather data files, + and which is described above. The length of the weather data is + calculated as the end time stamp minus start time stamp plus average + increment, where the average increment is equal to the end time stamp + minus start time stamp divided by the number of rows minus 1. This + only works correctly for weather files with equidistant time stamps. +

    +
    + Time shift for solar radiation data +
    +

    + To read weather data from the TMY3 weather data file, there are two + data readers in this model. One data reader obtains all data except + solar radiation, and the other data reader reads only the solar + radiation data, shifted by 30 minutes. The reason for this + time shift is as follows: The TMY3 weather data file contains for + solar radiation the \"...radiation received on a horizontal surface + during the 60-minute period ending at the timestamp.\" Thus, as the + figure below shows, a more accurate interpolation is obtained if time + is shifted by 30 minutes prior to reading the weather data. +

    +

    + \"image\" +

    +

    + References +

    +
      +
    • Wilcox S. and W. Marion. Users Manual for TMY3 Data Sets. + Technical Report, NREL/TP-581-43156, revised May 2008. +
      • +
    +
      +
    • September 6, 2021, by Ettore Zanetti:
      + Changed alt and lat to real inputs.
      + This is for IBPSA, + #1477. +
      • +
    • May 2, 2021, by Ettore Zanetti:
      + Added altitude to parameters.
      + This is for IBPSA, + #1477. +
      • +
    • October 4, 2020, by Ettore Zanetti:
      + Updated documentation for Java weather file generator.
      + This is for #1396. +
      • +
    • August 20, 2019, by Filip Jorissen:
      + Better clarified the meaning of time in the + documentation.
      + This is for #1192. +
      • +
    • March 5, 2019, by Michael Wetter:
      + Updated documentation.
      + This is for #842. +
      • +
    • September 20, 2018, by Michael Wetter:
      + Corrected documentation.
      + This is for #1022. +
      • +
    • December 4, 2017, by Michael Wetter:
      + Removed function call to getAbsolutePath, as this + causes in Dymola 2018FD01 the error \"A call of loadResource with a + non-literal string remains in the generated code; it will not work + for an URI.\" when exporting + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.ThermalZone as + an FMU. Instead, if the weather file is specified as a Modelica, + URI, syntax such as + Modelica.Utilities.Files.loadResource(\"modelica://AixLib/Resources/weatherdata/USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.mos\") + should be used.
      + This is for #867. +
      • +
    • February 18, 2017, by Filip Jorissen:
      + Infrared radiation on horizontal surface is now delayed by 30 + minutes such that the results in + TBlaSky are consistent. This is for #648. +
      • +
    • December 06, 2016, by Thierry S. Nouidui:
      + Constrained the direct normal radiation to not be bigger than the + solar constant when using global and diffuse solar radiation data + provided via the inputs connectors. This is for #608. +
      • +
    • April 21, 2016, by Michael Wetter:
      + Introduced absFilNam to avoid multiple calls to + + AixLib.BoundaryConditions.WeatherData.BaseClasses.getAbsolutePath. + This is for Buildings, + #506. +
      • +
    • January 6, 2016, by Moritz Lauster:
      + Changed output radHorIR to HHorIR. This + is for #376. +
      • +
    • January 4, 2016, by Moritz Lauster:
      + Added a table in documentation with output variables accessible via + weaBus. This is for #376. +
      • +
    • December 15, 2015, by Michael Wetter:
      + Added the block cheTemBlaSky. This also allows to + graphically connect the black body sky temperature to the weather + bus, which is required in Dymola 2016 for the variable + weaBus.TBlaSky to appear in the graphical editor. This + is for #377. +
      • +
    • September 24, 2015, by Marcus Fuchs:
      + Replace Dymola specific annotation by loadSelector for + MSL compliancy as reported by @tbeu at RWTH-EBC/AixLib#107 +
      • +
    • June 6, 2015, by Michael Wetter:
      + Removed redundant but consistent connect(TBlaSkyCom.TBlaSky, + weaBus.TBlaSky) statement. This avoids a warning if + AixLib.BoundaryConditions.SolarIrradiation.BaseClasses.Examples.SkyClearness + is translated in pedantic mode in Dymola 2016. This is for #266. +
      • +
    • March 26, 2015, by Michael Wetter:
      + Added option to obtain the black body sky temperature from a + parameter or an input signal. +
      • +
    • October 17, 2014, by Michael Wetter:
      + Corrected error that led the total and opaque sky cover to be ten + times too low if its value was obtained from the parameter or the + input connector. For the standard configuration in which the sky + cover is obtained from the weather data file, the model was + correct. This error only affected the other two possible + configurations. +
      • +
    • September 12, 2014, by Michael Wetter:
      + Removed redundant connection connect(conHorRad.HOut, + cheHorRad.HIn);. +
      • +
    • May 30, 2014, by Michael Wetter:
      + Removed undesirable annotation Evaluate=true. +
      • +
    • May 5, 2013, by Thierry S. Nouidui:
      + Added the option to use a constant, an input signal or the weather + file as the source for the ceiling height, the total sky cover, the + opaque sky cover, the dew point temperature, and the infrared + horizontal radiation HInfHor. +
      • +
    • October 8, 2013, by Michael Wetter:
      + Improved the algorithm that determines the absolute path of the + file. Now weather files are searched in the path specified, and if + not found, the urls file://, modelica:// + and modelica://AixLib are added in this order to + search for the weather file. This allows using the data reader + without having to specify an absolute path, as long as the + AixLib library is on the MODELICAPATH. + This change was implemented in + AixLib.BoundaryConditions.WeatherData.BaseClasses.getAbsolutePath + and improves this weather data reader. +
      • +
    • May 2, 2013, by Michael Wetter:
      + Added function call to getAbsolutePath. +
      • +
    • October 16, 2012, by Michael Wetter:
      + Added computation of the wet bulb temperature. Computing the wet + bulb temperature introduces a nonlinear equation. As we have not + observed an increase in computing time because of computing the wet + bulb temperature, it is computed by default. By setting the + parameter computeWetBulbTemperature=false, the + computation of the wet bulb temperature can be removed. Revised + documentation. +
      • +
    • August 11, 2012, by Wangda Zuo:
      + Renamed radHor to radHorIR and improved + the optional inputs for radiation data. +
      • +
    • July 24, 2012, by Wangda Zuo:
      + Corrected the notes of SI unit requirements for input files. +
      • +
    • July 13, 2012, by Michael Wetter:
      + Removed assignment of HGloHor_in in its declaration, + because this gives an overdetermined system if the input connector + is used. Removed non-required assignments of attribute + displayUnit. +
      • +
    • February 25, 2012, by Michael Wetter:
      + Added subbus for solar position, which is needed by irradition and + shading model. +
      • +
    • November 29, 2011, by Michael Wetter:
      + Fixed wrong display unit for pAtm_in_internal and made + propagation of parameter final. +
      • +
    • October 27, 2011, by Wangda Zuo:
      +
        +
      1. Added optional connectors for dry bulb temperature, relative + humidity, wind speed, wind direction, global horizontal + radiation, diffuse horizontal radiation.
        +
        2. +
      2. Separate the unit conversion for TMY3 data and data validity + check. +
        3. +
      +
      • +
    • October 3, 2011, by Michael Wetter:
      + Propagated value for sky temperature calculation to make it + accessible as a parameter. +
      • +
    • July 20, 2011, by Michael Wetter:
      + Added the option to use a constant, an input signal or the weather + file as the source for the atmospheric pressure. +
      • +
    • March 15, 2011, by Wangda Zuo:
      + Delete the wet bulb temperature since it may cause numerical + problem. +
      • +
    • March 7, 2011, by Wangda Zuo:
      + Added wet bulb temperature. Changed reader to read only needed + columns. Added explanation for 30 minutes shift for radiation data. +
      • +
    • March 5, 2011, by Michael Wetter:
      + Changed implementation to obtain longitude and time zone directly + from weather file. +
      • +
    • June 25, 2010, by Wangda Zuo:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 24 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 +line 425 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 +line 469 column 2 - Warning: The summary attribute on the
    element is obsolete in HTML5 +line 640 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Actuators/BaseClasses/exponentialDamper.mo ---- +-------- HTML Code -------- + +

    + This function computes the opening characteristics of an exponential damper. +

    + The function is used by the model + + AixLib.Fluid.Actuators.Dampers.Exponential. +

    + For yL < y < yU, the damper characteristics is +

    +

    + kd(y) = exp(a+b (1-y)). +

    +

    + Outside this range, the damper characteristic is defined by a quadratic polynomial. +

    +

    + Note that this implementation returns sqrt(kd(y)) instead of kd(y). + This is done for numerical reason since otherwise kd(y) may be an iteration + variable, which may cause a lot of warnings and slower convergence if the solver + attempts kd(y) < 0 during the iterative solution procedure. +

    + +
      +
    • + April 14, 2014 by Michael Wetter:
      + Improved documentation. +
      • +
    • + July 1, 2011 by Michael Wetter:
      + Added constraint to control input to avoid using a number outside + 0 and 1 in case that the control input + has a numerical integration error. +
      • +
    • + April 4, 2010 by Michael Wetter:
      + Reformulated implementation. The new implementation computes + sqrt(kTheta). This avoid having kTheta in + the iteration variables, which caused warnings when the solver attempted + kTheta < 0. +
      • +
    • + June 22, 2008 by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Corrected Code -------- +

    + This function computes the opening characteristics of an exponential + damper. +

    +

    + The function is used by the model AixLib.Fluid.Actuators.Dampers.Exponential. +

    +

    + For yL < y < yU, the damper characteristics is +

    +

    + kd(y) = exp(a+b (1-y)). +

    +

    + Outside this range, the damper characteristic is defined by a + quadratic polynomial. +

    +

    + Note that this implementation returns sqrt(kd(y)) + instead of kd(y). This is done for numerical reason + since otherwise kd(y) may be an iteration variable, + which may cause a lot of warnings and slower convergence if the + solver attempts kd(y) < 0 during the iterative + solution procedure. +

    +
      +
    • April 14, 2014 by Michael Wetter:
      + Improved documentation. +
      • +
    • July 1, 2011 by Michael Wetter:
      + Added constraint to control input to avoid using a number outside + 0 and 1 in case that the control input + has a numerical integration error. +
      • +
    • April 4, 2010 by Michael Wetter:
      + Reformulated implementation. The new implementation computes + sqrt(kTheta). This avoid having kTheta in + the iteration variables, which caused warnings when the solver + attempted kTheta < 0. +
      • +
    • June 22, 2008 by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/BoundaryConditions/Validation/BESTEST/WD500.mo ---- +-------- HTML Code -------- + +

      +
    • + September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the weather data bus.
      + This is for + IBPSA, #1477. +
      • +
    • + March 11, 2020, by Ettore Zanetti:
      + First implementation. +
      • +
    • + April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request + #1339. +
      • +
    • + May 2, 2021, by Ettore Zanetti:
      + Updated weather file as explained in #1478. +
      • +
    + +

    WD500: Time Zone Case

    +

    Weather data file : WD500.epw

    +

    Table 1: Site Data for Weather file WD500epw

    +
    + + + + + + + + + + + + + + + +

    Latitude

    28.567° north

    Longitude

    77.103° east

    Altitude

    236.9 m

    Time Zone

    5.5

    + +-------- Corrected Code -------- +
      +
    • September 6, 2021, by Ettore Zanetti:
      + Removed parameter lat as it is now obtained from the + weather data bus.
      + This is for IBPSA, + #1477. +
      • +
    • March 11, 2020, by Ettore Zanetti:
      + First implementation. +
      • +
    • April 14, 2020, by Ettore Zanetti:
      + Rework after comments from pull request #1339. +
      • +
    • May 2, 2021, by Ettore Zanetti:
      + Updated weather file as explained in #1478. +
      • +
    +

    + WD500: Time Zone Case +

    +

    + Weather data file : WD500.epw +

    +

    + Table 1: Site Data for Weather file WD500epw +

    + - - + - - + - - + - -
    - solTim - - s +

    + Latitude +

    		- Solar time. +

    + 28.567° north +

    - solZen - - rad +

    + Longitude +

    		- Zenith angle. +

    + 77.103° east +

    - winDir - - rad +

    + Altitude +

    		- Wind direction. +

    + 236.9 m +

    - winSpe - - m/s +

    + Time Zone +

    		- Wind speed. +

    + 5.5 +

    -

    - Adding new weather data -

    -

    - To add new weather data, proceed as follows: -

    -
      -
    1. Download the weather data file with the epw - extension from http://energyplus.net/weather. -
      2. -
    2. Add the file to AixLib/Resources/weatherdata (or to - any directory for which you have write permission). -
      3. -
    3. On a console window, type - 
      -   cd AixLib/Resources/weatherdata
-   java -jar ../bin/ConvertWeatherData.jar inputFile.epw
-
      if inputFile contains space in the name: - 
      -   java -jar ../bin/ConvertWeatherData.jar \"inputFile .epw\"
-
      This will generate the weather data file -inputFile.mos, which can be read by the model AixLib.BoundaryConditions.WeatherData.ReaderTMY3. -
      4. -
    -

    - Location data that are read automatically from the weather data file -

    +
    + +-------- Errors -------- +line 5 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 + + +---- AixLib/Controls/SetPoints/Examples/SupplyReturnTemperatureReset.mo ---- +-------- HTML Code -------- + +

    + Example that demonstrates the use of the hot water temperature reset + for a heating system. + The parameters of the block heaCur + are for a heating system with + 60°C supply water temperature and + 40°C return water temperature at + an outside temperature of + -10°C and a room temperature of + 20°C. The offset for the temperature reset is + 8 Kelvin, i.e., above + 12°C outside temperature, there is no heating load. + The figure below shows the computed supply and return water temperatures. +

    +

    + \"Supply +

    + + + +-------- Corrected Code --------

    - The following location data are automatically read from the weather - file: + Example that demonstrates the use of the hot water temperature reset + for a heating system. The parameters of the block heaCur + are for a heating system with 60°C supply water temperature + and 40°C return water temperature at an outside temperature of + -10°C and a room temperature of 20°C. The offset for + the temperature reset is 8 Kelvin, i.e., above 12°C + outside temperature, there is no heating load. The figure below shows + the computed supply and return water temperatures.

    - -

    - Wet bulb temperature -

    -

    - By default, the data bus contains the wet bulb temperature. This - introduces a nonlinear equation. However, we have not observed an - increase in computing time because of this equation. To disable the - computation of the wet bulb temperature, set - computeWetBulbTemperature=false. -

    -

    - Using constant or user-defined input signals for weather data -

    -

    - This model has the option of using a constant value, using the data - from the weather file, or using data from an input connector for the - following variables: +

    + \"Supply

    + +-------- Errors -------- +line 16 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Actuators/BaseClasses/PartialDamperExponential.mo ---- +-------- HTML Code -------- + +

    + Partial model for air dampers with exponential opening characteristics. + This is the base model for air dampers. + The model implements the functions that relate the opening signal and the + flow coefficient. + The model also defines parameters that are used by different air damper + models. +

    +

    + The model is as in ASHRAE 825-RP except that a control signal of + y=0 means the damper is closed, and y=1 means + the damper is open. + This is opposite of the implementation of ASHRAE 825-RP, but used here + for consistency within this library. +

    +

    + For yL < y < yU, the damper characteristics is: +

    +

    + kd(y) = exp(a+b (1-y)) +

    +

    + where kd is the loss coefficient (total pressure drop divided + by dynamic pressure) and y is the fractional opening. +

    +

    + Outside this range, the damper characteristics is defined by a quadratic polynomial that + matches the damper resistance at y=0 and y=yL or + y=yU and y=1, respectively. + In addition, the polynomials are such that kd(y) is differentiable in + y and the derivative is continuous. +

    +

    + The damper characteristics is then used to compute the flow coefficient k(y) as: +

    +

    + k(y) = (2 ρ ⁄ kd(y))1/2 A +

    +

    + where A is the face area, which is computed using the nominal + mass flow rate m_flow_nominal, the nominal velocity + v_nominal and the density of the medium. +

    +

    + ASHRAE 825-RP lists the following parameter values as typical (note that the + default values in the model correspond to opposed blades). +
    +

    +
    + + + + + + + + + + + + + + + + + + +
    opposed bladessingle blades
    yL15/9015/90
    yU55/9065/90
    k10.2 to 0.50.2 to 0.5
    a-1.51-1.51
    b0.105*900.0842*90
    +

    + (The loss coefficient in fully closed position k0 is computed based on the leakage coefficient + and the coefficient in fully open position.) +

    +

    References

    +

    + P. Haves, L. K. Norford, M. DeSimone and L. Mei, + A Standard Simulation Testbed for the Evaluation of Control Algorithms & Strategies, + ASHRAE Final Report 825-RP, Atlanta, GA. +

    + + + +-------- Corrected Code --------

    - By default, all data are obtained from the weather data file, except - for the atmospheric pressure, which is set to the parameter - pAtm=101325 Pascals. + Partial model for air dampers with exponential opening + characteristics. This is the base model for air dampers. The model + implements the functions that relate the opening signal and the flow + coefficient. The model also defines parameters that are used by + different air damper models.

    - The parameter *Sou configures the source of the data. - For the atmospheric pressure, temperatures, relative humidity, wind - speed and wind direction, the enumeration AixLib.BoundaryConditions.Types.DataSource - is used as follows: + The model is as in ASHRAE 825-RP except that a control signal of + y=0 means the damper is closed, and y=1 + means the damper is open. This is opposite of the implementation of + ASHRAE 825-RP, but used here for consistency within this library.

    - - - - - - - - - - - - - - - - - - -
    - Parameter *Sou - - Data used to compute weather data. -
    - File - - Use data from file. -
    - Parameter - - Use value specified by the parameter. -
    - Input - - Use value from the input connector. -

    - Because global, diffuse and direct radiation are related to each - other, the parameter HSou is treated differently. It is - set to a value of the enumeration AixLib.BoundaryConditions.Types.RadiationDataSource, - and allows the following configurations: + For yL < y < yU, the damper characteristics is:

    - - - - - - - - - - - - - - - - - - - - - - -
    - Parameter HSou - - Data used to compute weather data. -
    - File - - Use data from file. -
    - Input_HGloHor_HDifHor - - Use global horizontal and diffuse horizontal radiation from input - connector. -
    - Input_HDirNor_HDifHor - - Use direct normal and diffuse horizontal radiation from input - connector. -
    - Input_HDirNor_HGloHor - - Use direct normal and global horizontal radiation from input - connector. -
    -

    - Length of weather data and simulation period -

    -

    - If weather data span a year, which is the default for TMY3 data, or - multiple years, then this model can be used for simulations that span - multiple years. The simulation start time needs to be set to the - clock time of the respective start time. For example, to start at - January 2 at 10am, set start time to t=(24+10)*3600 - seconds. For this computation, the used date and time (here January - 2, 10 am) must be expressed in the same time zone as the one that is - used to define the TMY3 file. This is usually the local (winter) time - zone. The parameter `timZon` represents the TMY3 file time zone, - expressed in seconds compared to UTC. +

    + kd(y) = exp(a+b (1-y))

    - Moreover, weather data need not span a whole year, or it can span - across New Year. In this case, the simulation cannot exceed the time - of the weather data file. Otherwise, the simulation stops with an - error. + where kd is the loss coefficient (total pressure drop divided + by dynamic pressure) and y is the fractional opening.

    - As weather data have one entry at the start of the time interval, the - end time of the weather data file is computed as the last time entry - plus the average time increment of the file. For example, an hourly - weather data file has 8760 entries, starting on January 1 at 0:00. - The last entry in the file will be for December 31 at 23:00. As the - time increment is 1 hour, the model assumes the weather file to end - at December 31 at 23:00 plus 1 hour, e.g., at January 1 at 0:00. -

    -

    - Notes -

    -
      -
    1. -

      - In HVAC systems, when the fan is off, changes in atmospheric - pressure can cause small air flow rates in the duct system due to - change in pressure and hence in the mass of air that is stored in - air volumes (such as in fluid junctions or in the room model). - This may increase computing time. Therefore, the default value - for the atmospheric pressure is set to a constant. Furthermore, - if the initial pressure of air volumes are different from the - atmospheric pressure, then fast pressure transients can happen in - the first few seconds of the simulation. This can cause numerical - problems for the solver. To avoid this problem, set the - atmospheric pressure to the same value as the medium default - pressure, which is typically set to the parameter - Medium.p_default. For medium models for moist air - and dry air, the default is Medium.p_default=101325 - Pascals. -

      -
      2. -
    2. -

      - Different units apply depending on whether data are obtained from - a file, or from a parameter or an input connector: -

      -
        -
      • When using TMY3 data from a file (e.g. - USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.mos), the - units must be the same as the original TMY3 file used by - EnergyPlus (e.g. - USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.epw). The - TMY3 data used by EnergyPlus are in both SI units and non-SI - units. If Resources/bin/ConvertWeatherData.jar is - used to convert the .epw file to an - .mos file, the units of the TMY3 data are preserved - and the file can be directly used by this data reader. The data - reader will automatically convert units to the SI units used by - Modelica. For example, the dry bulb temperature - TDryBul in TMY3 is in degree Celsius. The data - reader will automatically convert the data to Kelvin. The wind - direction winDir in TMY3 is degrees and will be - automatically converted to radians. -
        • -
      • When using data from a parameter or from an input connector, - the data must be in the SI units used by Modelica. For instance, - the unit must be Pa for pressure, K for - temperature, W/m2 for solar radiations and - rad for wind direction. -
        • -
      -
      3. -
    3. -

      - Hourly and subhourly timestamp are handled in a different way in - .epw files. From the EnergyPlus Auxiliary Programs - Document (v9.3.0, p. 63): In hourly data the minute field can be - 00 or 60. In this case as mentioned in - the previous section, the weather data is reported at the hourly - value and the minute field has to be ignored, writing 1, - 60 or 1, 00 is equivalent. If the minute - field is between 00 and 60, the file - becomes subhourly, in this case the timestamp corresponds to the - minute field in the considered hour. For example: 1, - 30 is equivalent to 00:30 and 3, 45 is - equivalent to 02:45.
      - (Note the offset in the hour digit.) -

      -
      4. -
    4. The ReaderTMY3 should only be used with TMY3 data. It contains a - time shift for solar radiation data that is explained below. This - time shift needs to be removed if the user may want to use the - ReaderTMY3 for other weather data types. -
      5. -
    -

    - Implementation -

    -
    - Start and end data for annual weather data files -
    + Outside this range, the damper characteristics is defined by a + quadratic polynomial that matches the damper resistance at + y=0 and y=yL or y=yU and + y=1, respectively. In addition, the polynomials are such + that kd(y) is differentiable in y and the + derivative is continuous. +

    - The TMY3 weather data, as well as the EnergyPlus weather data, start - at 1:00 AM on January 1, and provide hourly data until midnight on - December 31. Thus, the first entry for temperatures, humidity, wind - speed etc. are values at 1:00 AM and not at midnight. Furthermore, - the TMY3 weather data files can have values at midnight of December - 31 that may be significantly different from the values at 1:00 AM on - January 1. Since annual simulations require weather data that start - at 0:00 on January 1, data need to be provided for this hour. Due to - the possibly large change in weatherdata between 1:00 AM on January 1 - and midnight at December 31, the weather data files in the AixLib - library do not use the data entry from midnight at December 31 as the - value for t=0. Rather, the value from 1:00 AM on January 1 is - duplicated and used for 0:00 on January 1. To maintain a data record - with 8760 hours, the weather data record from midnight at - December 31 is deleted. These changes in the weather data file are - done in the Java program - AixLib/Resources/bin/ConvertWeatherData.jar that - converts EnergyPlus weather data file to Modelica weather data files, - and which is described above. The length of the weather data is - calculated as the end time stamp minus start time stamp plus average - increment, where the average increment is equal to the end time stamp - minus start time stamp divided by the number of rows minus 1. This - only works correctly for weather files with equidistant time stamps. + The damper characteristics is then used to compute the flow + coefficient k(y) as: +

    +

    + k(y) = (2 ρ ⁄ kd(y))1/2 A

    -
    - Time shift for solar radiation data -

    - To read weather data from the TMY3 weather data file, there are two - data readers in this model. One data reader obtains all data except - solar radiation, and the other data reader reads only the solar - radiation data, shifted by 30 minutes. The reason for this - time shift is as follows: The TMY3 weather data file contains for - solar radiation the \"...radiation received on a horizontal surface - during the 60-minute period ending at the timestamp.\" Thus, as the - figure below shows, a more accurate interpolation is obtained if time - is shifted by 30 minutes prior to reading the weather data. + where A is the face area, which is computed using the nominal + mass flow rate m_flow_nominal, the nominal velocity + v_nominal and the density of the medium.

    -

    - \"image\" +

    + ASHRAE 825-RP lists the following parameter values as typical (note + that the default values in the model correspond to opposed + blades).

    -

    - References -

    - -

    -Similarly, for - -AixLib.Fluid.Movers.FlowControlled_m_flow, -the mass flow rate is as follows: + The parameter filterOpening is set to + false, as this model is used to plot the flow at + different opening signals without taking into account the travel time + of the actuator.

    + +-------- Errors -------- +line 8 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 +line 24 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/ThermalResponseFactors/gFunction.mo ---- +-------- HTML Code -------- + +

    + This function implements the g-function evaluation method introduced by + Cimmino and Bernier (see: Cimmino and Bernier (2014), and Cimmino (2018)) based + on the g-function function concept first introduced by Eskilson (1987). + The g-function gives the relation between the variation of the borehole + wall temperature at a time t and the heat extraction and injection rates + at all times preceding time t as +

    +

    + \"image\" +

    +

    + where Tb is the borehole wall temperature, + Tg is the undisturbed ground temperature, Q is the + heat injection rate into the ground through the borehole wall per unit borehole + length, ks is the soil thermal conductivity and g is + the g-function. +

    +

    + The g-function is constructed from the combination of the combination of + the finite line source (FLS) solution (see + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource), + the cylindrical heat source (CHS) solution (see + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource), + and the infinite line source (ILS) solution (see + + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.infiniteLineSource). + To obtain the g-function of a bore field, each borehole is divided into a + series of nSeg segments of equal length, each modeled as a line + source of finite length. The finite line source solution is superimposed in + space to obtain a system of equations that gives the relation between the heat + injection rate at each of the segments and the borehole wall temperature at each + of the segments. The system is solved to obtain the uniform borehole wall + temperature required at any time to maintain a constant total heat injection + rate (Qtot = 2πksHtot) into the bore + field. The uniform borehole wall temperature is then equal to the finite line + source based g-function. +

    +

    + Since this g-function is based on line sources of heat, rather than + cylinders, the g-function is corrected to consider the cylindrical + geometry. The correction factor is then the difference between the cylindrical + heat source solution and the infinite line source solution, as proposed by + Li et al. (2014) as +

    +

    + g(t) = gFLS + (gCHS - gILS) +

    +

    Implementation

    +

    + The calculation of the g-function is separated into two regions: the + short-time region and the long-time region. In the short-time region, + corresponding to times t < 1 hour, heat interaction between boreholes + and axial variations of heat injection rate are not considered. The + g-function is calculated using only one borehole and one segment. In the + long-time region, corresponding to times t > 1 hour, all boreholes + are represented as series of nSeg line segments and the + g-function is evaluated as described above. +

    +

    References

    +

    + Cimmino, M. and Bernier, M. 2014. A semi-analytical method to generate + g-functions for geothermal bore fields. International Journal of Heat and + Mass Transfer 70: 641-650. +

    +

    + Cimmino, M. 2018. Fast calculation of the g-functions of geothermal borehole + fields using similarities in the evaluation of the finite line source + solution. Journal of Building Performance Simulation. DOI: + 10.1080/19401493.2017.1423390. +

    +

    + Eskilson, P. 1987. Thermal analysis of heat extraction boreholes. Ph.D. + Thesis. Department of Mathematical Physics. University of Lund. Sweden. +

    +

    + Li, M., Li, P., Chan, V. and Lai, A.C.K. 2014. Full-scale temperature + response function (G-function) for heat transfer by borehole heat exchangers + (GHEs) from sub-hour to decades. Applied Energy 136: 197-205. +

    + + + +-------- Corrected Code --------

    -If the parameter inputType==AixLib.Fluid.Types.InputType.Continuous, -the mass flow rate is m_flow=m_flow_in, where m_flow_in is an input connector. + This function implements the g-function evaluation method + introduced by Cimmino and Bernier (see: Cimmino and Bernier (2014), + and Cimmino (2018)) based on the g-function function concept + first introduced by Eskilson (1987). The g-function gives the + relation between the variation of the borehole wall temperature at a + time t and the heat extraction and injection rates at all + times preceding time t as

    - -
  • -

    -If the parameter inputType==AixLib.Fluid.Types.InputType.Constant, -the mass flow rate is m_flow=constantMassFlowRate, where constantMassFlowRate is a parameter. +

    + \"image\"

    -
    • -

  • -If the parameter inputType==AixLib.Fluid.Types.InputType.Stages, -the mass flow rate is m_flow=massFlowRates, where massFlowRates is a -vectorized parameter. For example, if a mover has -two stages and the mass flow rate of the first stage should be 60% of the nominal mass flow rate -and the second stage equal to m_flow_nominal, set -massFlowRates={0.6, 1}*m_flow_nominal. -Then, the mover will have the following mass flow rates: + where Tb is the borehole wall temperature, + Tg is the undisturbed ground temperature, Q + is the heat injection rate into the ground through the borehole wall + per unit borehole length, ks is the soil thermal + conductivity and g is the g-function.

    -
    • - - - - - - - - - - - - - - - - -
    input signal stageMass flow rates [kg/s]
    00
    10.6*m_flow_nominal
    2m_flow_nominal
    - - -

    -These two models do not need to use a performance curve for the flow -characteristics. -The reason is that

    -

    -However, the computation of the electrical power consumption -requires the mover speed to be known -and the computation of the mover speed requires the performance -curves for the flow and efficiency/power characteristics. -Therefore these performance curves do need to be provided -if the user desires a correct electrical power computation. -If the curves are not provided, a simplified computation is used, -where the efficiency curve is used and assumed to be correct for all speeds. -This loss of accuracy has the advantage that it allows to use the -mover models without requiring flow and efficiency/power characteristics. + The g-function is constructed from the combination of the + combination of the finite line source (FLS) solution (see + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.finiteLineSource), + the cylindrical heat source (CHS) solution (see + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.cylindricalHeatSource), + and the infinite line source (ILS) solution (see + AixLib.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.ThermalResponseFactors.infiniteLineSource). + To obtain the g-function of a bore field, each borehole is + divided into a series of nSeg segments of equal length, + each modeled as a line source of finite length. The finite line + source solution is superimposed in space to obtain a system of + equations that gives the relation between the heat injection rate at + each of the segments and the borehole wall temperature at each of the + segments. The system is solved to obtain the uniform borehole wall + temperature required at any time to maintain a constant total heat + injection rate (Qtot = + 2πksHtot) into the bore field. The uniform + borehole wall temperature is then equal to the finite line source + based g-function.

    -The model -AixLib.Fluid.Movers.FlowControlled_dp -has an option to control the mover such -that the pressure difference set point is obtained -across two remote points in the system. -To use this functionality -parameter prescribeSystemPressure has -to be enabled and a differential pressure measurement -must be connected to -the pump input dpMea. -This functionality is demonstrated in - -AixLib.Fluid.Movers.Validation.FlowControlled_dpSystem. + Since this g-function is based on line sources of heat, rather + than cylinders, the g-function is corrected to consider the + cylindrical geometry. The correction factor is then the difference + between the cylindrical heat source solution and the infinite line + source solution, as proposed by Li et al. (2014) as

    -

    -The models -AixLib.Fluid.Movers.FlowControlled_dp and - -AixLib.Fluid.Movers.FlowControlled_m_flow -both have a parameter m_flow_nominal. For - -AixLib.Fluid.Movers.FlowControlled_m_flow, this parameter -is used for convenience to set a default value for the parameters -constantMassFlowRate and -massFlowRates. -For both models, the value is also used for the following: +

    + g(t) = gFLS + (gCHS - gILS)

    - - +

    + Implementation +

    -However, otherwise m_flow_nominal does not affect the mass flow rate of the mover as -the mass flow rate is determined by the input signal or the above explained parameters. + The calculation of the g-function is separated into two + regions: the short-time region and the long-time region. In the + short-time region, corresponding to times t < 1 hour, heat + interaction between boreholes and axial variations of heat injection + rate are not considered. The g-function is calculated using + only one borehole and one segment. In the long-time region, + corresponding to times t > 1 hour, all boreholes are + represented as series of nSeg line segments and the + g-function is evaluated as described above.

    -
    Start-up and shut-down transients
    +

    + References +

    -All models have a parameter use_inputFilter. This -parameter affects the fan output as follows: + Cimmino, M. and Bernier, M. 2014. A semi-analytical method to + generate g-functions for geothermal bore fields. International + Journal of Heat and Mass Transfer 70: 641-650.

    -
      -
    1. -If use_inputFilter=false, then the input signal y (or -Nrpm, m_flow_in, or dp_in) -is equal to the fan speed (or the mass flow rate or pressure rise). -Thus, a step change in the input signal causes a step change in the fan speed (or mass flow rate or pressure rise). -
      2. -
    2. -If use_inputFilter=true, which is the default, -then the fan speed (or the mass flow rate or the pressure rise) -is equal to the output of a filter. This filter is implemented -as a 2nd order differential equation and can be thought of as -approximating the inertia of the rotor and the fluid. -Thus, a step change in the fan input signal will cause a gradual change -in the fan speed. -The filter has a parameter riseTime, which by default is set to -30 seconds. -The rise time is the time required to reach 99.6% of the full speed, or, -if the fan is switched off, to reach a fan speed of 0.4%. -
      3. -

    -The figure below shows for a fan with use_inputFilter=true -and riseTime=30 seconds the -speed input signal and the actual speed.

    -

    -\"image\" + Cimmino, M. 2018. Fast calculation of the g-functions of + geothermal borehole fields using similarities in the evaluation of + the finite line source solution. Journal of Building Performance + Simulation. DOI: 10.1080/19401493.2017.1423390.

    -

    -Although many simulations do not require such a detailed model -that approximates the transients of fans or pumps, it turns -out that using this filter can reduce computing time and -can lead to fewer convergence problems in large system models. -With a filter, any sudden change in control signal, such as when -a fan switches on, is damped before it affects the air flow rate. -This continuous change in flow rate turns out to be easier, and in -some cases faster, to simulate compared to a step change. -For most simulations, we therefore recommend to use the default settings -of use_inputFilter=true and riseTime=30 seconds. -An exception are situations in which the fan or pump is operated at a fixed speed during -the whole simulation. In this case, set use_inputFilter=false. + Eskilson, P. 1987. Thermal analysis of heat extraction + boreholes. Ph.D. Thesis. Department of Mathematical Physics. + University of Lund. Sweden.

    -Note that if the fan is part of a closed loop control, then the filter affects -the transient response of the control. -When changing the value of use_inputFilter, the control gains -may need to be retuned. -We now present values control parameters that seem to work in most cases. -Suppose there is a closed loop control with a PI-controller - -AixLib.Controls.Continuous.LimPID -and a fan or pump, configured with use_inputFilter=true and riseTime=30 seconds. -Assume that the transient response of the other dynamic elements in the control loop is fast -compared to the rise time of the filter. -Then, a proportional gain of k=0.5 and an integrator time constant of -Ti=15 seconds often yields satisfactory closed loop control performance. -These values may need to be changed for different applications as they are also a function -of the loop gain. -If the control loop shows oscillatory behavior, then reduce k and/or increase Ti. -If the control loop reacts too slow, do the opposite. + Li, M., Li, P., Chan, V. and Lai, A.C.K. 2014. Full-scale + temperature response function (G-function) for heat transfer by + borehole heat exchangers (GHEs) from sub-hour to decades. Applied + Energy 136: 197-205.

    + -
    Efficiency and electrical power consumption
    +-------- Errors -------- +line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 49 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/HeatExchangers/DryCoilEffectivenessNTU.mo ---- +-------- HTML Code -------- + +

    + Model of a coil without humidity condensation. + This model transfers heat in the amount of +

    +

    + Q̇ = Q̇max ε
    + ε = f(NTU, Z, flowRegime), +

    +

    + where + Q̇max is the maximum heat that can be transferred, + ε is the heat transfer effectiveness, + NTU is the Number of Transfer Units, + Z is the ratio of minimum to maximum capacity flow rate and + flowRegime is the heat exchanger flow regime. + such as + parallel flow, cross flow or counter flow. +

    +

    + The flow regimes depend on the heat exchanger configuration. All configurations + defined in + + AixLib.Fluid.Types.HeatExchangerConfiguration + are supported. +

    +

    + The convective heat transfer coefficients scale proportional to + (ṁ/ṁ0)n, where + ṁ is the mass flow rate, + ṁ0 is the nominal mass flow rate, and + n=0.8 on the air-side and n=0.85 on the water side. +

    +

    + For a heat and moisture exchanger, use + + AixLib.Fluid.MassExchangers.ConstantEffectiveness. +

    + + + +-------- Corrected Code --------

    -All models compute the motor power draw Pele, -the hydraulic power input Whyd, the flow work -Wflo and the heat dissipated into the medium -Q. Based on the first law, the flow work is + Model of a coil without humidity condensation. This model transfers + heat in the amount of

    - Wflo = | V̇ Δp |, + Q̇ = Q̇max ε
    + ε = f(NTU, Z, flowRegime),

    -where V̇ is the volume flow rate and -Δp is the pressure rise. -The heat dissipated into the medium is as follows: -If the motor is cooled by the fluid, as indicated by -per.motorCooledByFluid=true, then the heat dissipated into the medium is -

    -

    - Q = Pele - Wflo. + where Q̇max is the maximum heat that can be + transferred, ε is the heat transfer effectiveness, NTU + is the Number of Transfer Units, Z is the ratio of minimum to + maximum capacity flow rate and flowRegime is the heat + exchanger flow regime. such as parallel flow, cross flow or counter + flow.

    -

    -If per.motorCooledByFluid=false, then the motor is outside the fluid stream, -and only the shaft, or hydraulic, work Whyd enters the thermodynamic -control volume. Hence, -

    -

    - Q = Whyd - Wflo. + The flow regimes depend on the heat exchanger configuration. All + configurations defined in AixLib.Fluid.Types.HeatExchangerConfiguration + are supported.

    -

    The efficiencies are computed as

    -

    - η = Wflo ⁄ Pele = ηhyd   ηmot
    - ηhyd = Wflo ⁄ Whyd
    - ηmot = Whyd ⁄ Pele
    +

    + The convective heat transfer coefficients scale proportional to + (ṁ/ṁ0)n, where ṁ is the mass + flow rate, ṁ0 is the nominal mass flow rate, and + n=0.8 on the air-side and n=0.85 on the water side.

    -

    where -ηhyd is the hydraulic efficiency, -ηmot is the motor efficiency and -Q is the heat released by the motor. +

    + For a heat and moisture exchanger, use AixLib.Fluid.MassExchangers.ConstantEffectiveness.

    + + +-------- Errors -------- +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/HeatPumps/ReciprocatingWaterToWater.mo ---- +-------- HTML Code -------- + +

    + Model for a water to water heat pump with a reciprocating compressor, as + described in Jin (2002). The thermodynamic heat pump cycle is represented below. +

    +

    + \"image\" +

    +

    + The rate of heat transferred to the evaporator is given by: +

    +

    + Q̇Eva = ṁref ( hVap(TEva) - hLiq(TCon) ). +

    +

    + The power consumed by the compressor is given by a linear efficiency relation: +

    +

    + P = PTheoretical / η + PLoss,constant. +

    +

    + Heat transfer in the evaporator and condenser is calculated using an + ε-NTU method, assuming constant refrigerant temperature and constant heat + transfer coefficient between fluid and refrigerant. +

    +

    + Variable speed is acheived by multiplying the full load piston displacement + by the normalized compressor speed. The power and heat transfer rates are forced + to zero if the resulting heat pump state has higher evaporating pressure than + condensing pressure. +

    +

    Options

    +

    + Parameters TConMax and TEvaMin + may be used to set an upper or lower bound for the + condenser and evaporator. + The compressor is disabled when these conditions + are not satisfied, or when the + evaporator temperature is larger + than the condenser temperature. + This mimics the temperature protection + of heat pumps and moreover it avoids + non-converging algebraic loops of equations, + or freezing of evaporator medium. + This option can be disabled by setting + enable_temperature_protection = false. +

    +

    Assumptions and limitations

    +

    + The compression process is assumed isentropic. The thermal energy + of superheating is ignored in the evaluation of the heat transferred to the refrigerant + in the evaporator. There is no supercooling. +

    +

    References

    +

    + H. Jin. + + Parameter estimation based models of water source heat pumps. + + PhD Thesis. Oklahoma State University. Stillwater, Oklahoma, USA. 2002. +

    + + + +-------- Corrected Code --------

    -If per.use_powerCharacteristic=true, -then a set of data points for the power Pele for different -volume flow rates at full speed needs to be provided by the user. -Using the flow work Wflo and the electrical power input -Pele, the total efficiency is computed as + Model for a water to water heat pump with a reciprocating compressor, + as described in Jin (2002). The thermodynamic heat pump cycle is + represented below.

    -

    - η = Wflo ⁄ Pele,
    +

    + \"image\"

    -and the two efficiencies -ηhyd -and ηmot are computed as + The rate of heat transferred to the evaporator is given by:

    - ηhyd = 1,
    - ηmot = η. + Q̇Eva = ṁref ( + hVap(TEva) - hLiq(TCon) + ).

    -However, if per.use_powerCharacteristic=false, then -performance data for -ηhyd and - ηmot need to be provided by the user, and hence -the model computes + The power consumed by the compressor is given by a linear efficiency + relation:

    - η = ηhyd   ηmot
    - Pele = Wflo ⁄ η. + P = PTheoretical / η + PLoss,constant.

    -

    -The efficiency data for the motor are a list of points -V̇ and ηmot. + Heat transfer in the evaporator and condenser is calculated using an + ε-NTU method, assuming constant refrigerant temperature and constant + heat transfer coefficient between fluid and refrigerant.

    - -
    Fluid volume of the component

    -All models can be configured to have a fluid volume at the low-pressure side. -Adding such a volume sometimes helps the solver to find a solution during -initialization and time integration of large models. + Variable speed is acheived by multiplying the full load piston + displacement by the normalized compressor speed. The power and heat + transfer rates are forced to zero if the resulting heat pump state + has higher evaporating pressure than condensing pressure.

    - -
    Enthalpy change of the component
    +

    + Options +

    -If per.motorCooledByFluid=true, then -the enthalpy change between the inlet and outlet fluid port is equal -to the electrical power Pele that is consumed by the component. -Otherwise, it is equal to the hydraulic work Whyd. -The parameter addPowerToMedium, which is by default set to -true, can be used to simplify the equations. -If addPowerToMedium = false, then no enthalpy change occurs between -inlet and outlet. -This can lead to simpler equations, but the temperature rise across the component -will be zero. In particular for fans, this simplification may not be permissible. + Parameters TConMax and TEvaMin may be used + to set an upper or lower bound for the condenser and evaporator. The + compressor is disabled when these conditions are not satisfied, or + when the evaporator temperature is larger than the condenser + temperature. This mimics the temperature protection of heat pumps and + moreover it avoids non-converging algebraic loops of equations, or + freezing of evaporator medium. This option can be disabled by setting + enable_temperature_protection = false.

    - -

    Differences to models in Modelica.Fluid.Machines

    +

    + Assumptions and limitations +

    -The models in this package differ from -Modelica.Fluid.Machines -primarily in the following points: + The compression process is assumed isentropic. The thermal energy of + superheating is ignored in the evaluation of the heat transferred to + the refrigerant in the evaporator. There is no supercooling.

    - -

    References

    +

    + References +

    -Michael Wetter. - -Fan and pump model that has a unique solution for any pressure -boundary condition and control signal. -Proc. of the 13th Conference of the International Building Performance -Simulation Association, p. 3505-3512. Chambery, France. August 2013. + H. Jin. Parameter estimation based models of water source heat + pumps. PhD Thesis. Oklahoma State University. Stillwater, + Oklahoma, USA. 2002.

    + + +-------- Errors -------- +line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 18 column 2 - Warning:

    attribute "align" not allowed for HTML5 + +---- AixLib/Fluid/HeatExchangers/Radiators/RadiatorEN442_2.mo ---- +-------- HTML Code -------- + +

    + This is a model of a radiator that can be used as a dynamic or steady-state model. + The required parameters are data that are typically available from + manufacturers that follow the European Norm EN 442-2. +

    +

    + However, to allow for varying mass flow rates, the transferred heat is computed + using a discretization along the water flow path, and heat is exchanged between + each compartment and a uniform room air and radiation temperature. + This discretization is different from the computation in EN 442-2, which + may yield water outlet temperatures that are below + the room temperature at low mass flow rates. + Furthermore, rather than using only one room temperature, this model uses + a room air and room radiation temperature. +

    +

    + The transferred heat is modeled as follows: + Let N denote the number of elements used to discretize the radiator model. + For each element i ∈ {1, … , N}, + the convective and radiative heat transfer + Qic and + Qir + from the radiator to the room is +

    +

    + Qic = sign(Ti-Ta) + (1-fr) UA ⁄ N |Ti-Ta|n +

    + Qir = sign(Ti-Tr) + fr UA ⁄ N |Ti-Tr|n +

    +

    + where + Ti is the water temperature of the element, + Ta is the temperature of the room air, + Tr is the radiative temperature, + 0 < fr < 1 is the fraction of radiant to total heat transfer, + UA is the UA-value of the radiator, + and + n is an exponent for the heat transfer. + The model computes the UA-value by numerically solving the above equations + for given + nominal heating power, nominal temperatures, fraction radiant to total heat transfer + and exponent for heat transfer. +

    +

    + The parameter energyDynamics (in the Assumptions tab), + determines whether the model computes the dynamic or the steady-state response. + For the transient response, heat storage is computed using a + finite volume approach for the + water and the metal mass, which are both assumed to be at the same + temperature. +

    +

    + The default parameters for the heat capacities are valid for a flat plate radiator without fins, + with one plate of water carying fluid, and a height of 0.42 meters. +

    + + + -------- Corrected Code --------

    - This package contains models for fans and pumps. The same models are - used for fans or pumps. -

    -

    - Model description -

    -

    - A detailed description of the fan and pump models can be found in - - Wetter (2013). The models are implemented as described in this - paper, except that equation (20) is no longer used. The reason is - that the transition (24) caused the derivative -

    -

    - d Δp(r(t), V(t)) ⁄ d r(t) -

    -

    - to have an inflection point in the regularization region r(t) ∈ - (δ/2, δ). This caused some models to not converge. To correct - this, for r(t) < δ, the term V(t) ⁄ r(t) in (16) has - been modified so that (16) can be used for any value of r(t). -

    -

    - Below, the models are briefly described. -

    -
    - Performance data -
    -

    - The models use performance curves that compute pressure rise, - electrical power draw and efficiency as a function of the volume flow - rate and the speed. The following performance curves are implemented: -

    - - - - - - - - - - - - - - - - - - - - - - - - - -
    - Independent variable - - Dependent variable - - Record for performance data - - Function -
    - Volume flow rate - - Pressure - - - flowParameters - - - pressure -
    - Volume flow rate - - Efficiency - - - efficiencyParameters - - - efficiency -
    - Volume flow rate - - Power* - - - powerParameters - - - power -
    -

    - *Note: This record should not be used (i.e. - use_powerCharacteristic should be false) - for the movers that take as a control signal the mass flow rate or - the head, unless also values for the record pressure are - provided. The reason is that for these movers the record - pressure is required to be able to compute the mover - speed, which is required to be able to compute the electrical power - correctly using similarity laws. If a Pressure record is - not provided, the model will internally override - use_powerCharacteristic=false. In this case the - efficiency records will be used. Note that in this case an error is - still introduced, but it is smaller than when using the power - records. Compare AixLib.Fluid.Movers.Validation.PowerSimplified - with AixLib.Fluid.Movers.Validation.PowerExact - for an illustration of this error. -

    -

    - These performance curves are implemented in AixLib.Fluid.Movers.BaseClasses.Characteristics, - and are used in the performance records in the package AixLib.Fluid.Movers.Data. - The package AixLib.Fluid.Movers.Data - contains different data records. -

    -
    - Models that use performance curves for pressure rise -
    -

    - The models AixLib.Fluid.Movers.SpeedControlled_y - and AixLib.Fluid.Movers.SpeedControlled_Nrpm - take as an input either a control signal between 0 and - 1, or the rotational speed in units of [1/min]. From - this input and the current flow rate, they compute the pressure rise. - This pressure rise is computed using a user-provided list of - operating points that defines the fan or pump curve at full speed. - For other speeds, similarity laws are used to scale the performance - curves, as described in - AixLib.Fluid.Movers.BaseClasses.Characteristics.pressure. + This is a model of a radiator that can be used as a dynamic or + steady-state model. The required parameters are data that are + typically available from manufacturers that follow the European Norm + EN 442-2.

    - For example, suppose a pump needs to be modeled whose pressure versus - flow relation crosses, at full speed, the points shown in the table - below. + However, to allow for varying mass flow rates, the transferred heat + is computed using a discretization along the water flow path, and + heat is exchanged between each compartment and a uniform room air and + radiation temperature. This discretization is different from the + computation in EN 442-2, which may yield water outlet temperatures + that are below the room temperature at low mass flow rates. + Furthermore, rather than using only one room temperature, this model + uses a room air and room radiation temperature.

    - - - - - - - - - - - - - - - - - -
    - Volume flow rate [m3⁄s] - - Head [Pa] -
    - 0.0003 - - 45000 -
    - 0.0006 - - 35000 -
    - 0.0008 - - 15000 -

    - Then, a declaration would be + The transferred heat is modeled as follows: Let N denote the + number of elements used to discretize the radiator model. For each + element i ∈ {1, … , N}, the convective and radiative heat + transfer Qic and + Qir from the radiator to the room is

    -
    -  AixLib.Fluid.Movers.SpeedControlled_y pum(
-    redeclare package Medium = Medium,
-    per.pressure(V_flow={0.0003,0.0006,0.0008},
-                 dp    ={45,35,15}*1000))
-    \"Circulation pump\";
-
    -

    - This will model the following pump curve for the pump input signal - y=1. +

    + Qic = sign(Ti-Ta) + (1-fr) UA ⁄ N + |Ti-Ta|n
    +
    + Qir = sign(Ti-Tr) + fr UA ⁄ N |Ti-Tr|n

    -

    - \"image\" +

    + where Ti is the water temperature of the element, + Ta is the temperature of the room air, + Tr is the radiative temperature, 0 < + fr < 1 is the fraction of radiant to total heat + transfer, UA is the UA-value of the radiator, and n is + an exponent for the heat transfer. The model computes the UA-value by + numerically solving the above equations for given nominal heating + power, nominal temperatures, fraction radiant to total heat transfer + and exponent for heat transfer.

    -
    - Models that directly control the head or the mass flow rate -

    - The models AixLib.Fluid.Movers.FlowControlled_dp - and AixLib.Fluid.Movers.FlowControlled_m_flow - take as an input the pressure difference or the mass flow rate. This - pressure difference or mass flow rate will be provided by the fan or - pump, i.e., the fan or pump has idealized perfect control and - infinite capacity. Using these models that take as an input the head - or the mass flow rate often leads to smaller system of equations - compared to using the models that take as an input the speed. + The parameter energyDynamics (in the Assumptions tab), + determines whether the model computes the dynamic or the steady-state + response. For the transient response, heat storage is computed using + a finite volume approach for the water and the metal mass, which are + both assumed to be at the same temperature.

    - These models can be configured for three different control inputs. - For AixLib.Fluid.Movers.FlowControlled_dp, - the head is as follows: + The default parameters for the heat capacities are valid for a flat + plate radiator without fins, with one plate of water carying fluid, + and a height of 0.42 meters.

    -

    - Similarly, for AixLib.Fluid.Movers.FlowControlled_m_flow, - the mass flow rate is as follows: -

    - -

    - These two models do not need to use a performance curve for the flow - characteristics. The reason is that -

    - -

    - However, the computation of the electrical power consumption requires - the mover speed to be known and the computation of the mover speed - requires the performance curves for the flow and efficiency/power - characteristics. Therefore these performance curves do need to be - provided if the user desires a correct electrical power computation. - If the curves are not provided, a simplified computation is used, - where the efficiency curve is used and assumed to be correct for all - speeds. This loss of accuracy has the advantage that it allows to use - the mover models without requiring flow and efficiency/power - characteristics. -

    -

    - The model AixLib.Fluid.Movers.FlowControlled_dp - has an option to control the mover such that the pressure difference - set point is obtained across two remote points in the system. To use - this functionality parameter prescribeSystemPressure has - to be enabled and a differential pressure measurement must be - connected to the pump input dpMea. This functionality is - demonstrated in AixLib.Fluid.Movers.Validation.FlowControlled_dpSystem. -

    -

    - The models AixLib.Fluid.Movers.FlowControlled_dp - and AixLib.Fluid.Movers.FlowControlled_m_flow - both have a parameter m_flow_nominal. For AixLib.Fluid.Movers.FlowControlled_m_flow, - this parameter is used for convenience to set a default value for the - parameters constantMassFlowRate and - massFlowRates. For both models, the value is also used - for the following: -

    - + +-------- Errors -------- +line 26 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/FMI/ExportContainers/HVACZone.mo ---- +-------- HTML Code -------- + +

    + Model that is used as a container for an HVAC system that is + to be exported as an FMU and that serves a single zone. +

    +

    Typical use and important parameters

    +

    + To use this model as a container for an FMU, extend + from this model, rather than instantiate it, + and add your HVAC system. By extending from this model, the top-level + signal connectors on the right stay at the top-level, and hence + will be visible at the FMI interface. + The example + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone + shows how a simple HVAC system can be implemented and exported as + an FMU. + +

    +

    + The conversion between the fluid ports and signal ports is done + in the HVAC adapter hvacAda. + This adapter has a vector of fluid ports called ports. + The supply and return air ducts, including any resistance model for the inlet + diffusor or exhaust grill, need to be connected to these ports. + Also, if a thermal zone has interzonal air exchange or air infiltration, + these flows need to be connected to ports. + This model outputs at the port fluPor the mass flow rate for + each flow that is connected to ports, together with its + temperature, water vapor mass fraction per total mass of the air (not per kg dry + air), and trace substances. These quantities are always as if the flow + enters the room, even if the flow is zero or negative. + If a medium has no moisture, e.g., if Medium.nXi=0, or + if it has no trace substances, e.g., if Medium.nC=0, then + the output signal for these properties are removed. + These quantities are always as if the flow + enters the room, even if the flow is zero or negative. + Thus, a thermal zone model that uses these signals to compute the + heat added by the HVAC system needs to implement an equation such as +

    +

    + Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), +

    +

    + where + Qsen is the sensible heat flow rate added to the thermal zone, + ṁsup is the supply air mass flow rate from + the port fluPor (which is negative if it is an exhaust), + cp is the specific heat capacity at constant pressure, + Tsup is the supply air temperature and + Tair,zon is the zone air temperature. + Note that without the max(·, ·), the energy + balance would be wrong. +

    +

    + The input signals of this model are the zone radiative temperature. + The the zone air temperature, + the water vapor mass fraction per total mass of the air (unless Medium.nXi=0) + and trace substances (unless Medium.nC=0) are obtained from the connector + fluPor.backward. + The outflowing fluid stream(s) at the port ports will be at the + states obtained from fluPor.backward. + All fluid streams at port ports are at the same + pressure. + For convenience, the instance hvacAda also outputs the + properties obtained from fluPor.backward. These can be used + to connect a controller. The properties are available for each flow path in + fluPor.backward. For a thermal zone with mixed air, these are + all equal, while for a stratified room model, they can be different. +

    + +

    + See + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone + for a model that uses this model. +

    +

    + For models that multiple thermal zones connected to the HVAC system, + use the model + + AixLib.Fluid.FMI.ExportContainers.HVACZones. +

    +

    Assumption and limitations

    +

    + The mass flow rates at ports sum to zero, hence this + model conserves mass. +

    +

    + This model does not impose any pressure, other than setting the pressure + of all fluid connections to ports to be equal. + The reason is that setting a pressure can lead to non-physical system models, + for example if a mass flow rate is imposed and the HVAC system is connected + to a model that sets a pressure boundary condition such as + + AixLib.Fluid.Sources.Outside. + Also, setting a pressure would make it impossible to use multiple instances + of this model (one for each thermal zone) and build in Modelica an airflow network + model with pressure driven mass flow rates. +

    +

    + The model has no pressure drop. Hence, the pressure drop + of an air diffuser or of an exhaust grill needs to be modelled + in models that are connected to ports. +

    + + + +-------- Corrected Code --------

    - However, otherwise m_flow_nominal does not affect the - mass flow rate of the mover as the mass flow rate is determined by - the input signal or the above explained parameters. + Model that is used as a container for an HVAC system that is to be + exported as an FMU and that serves a single zone.

    -
    - Start-up and shut-down transients -
    +

    + Typical use and important parameters +

    - All models have a parameter use_inputFilter. This - parameter affects the fan output as follows: + To use this model as a container for an FMU, extend from this model, + rather than instantiate it, and add your HVAC system. By extending + from this model, the top-level signal connectors on the right stay at + the top-level, and hence will be visible at the FMI interface. The + example + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone shows + how a simple HVAC system can be implemented and exported as an FMU. +

    -
      -
    1. If use_inputFilter=false, then the input signal - y (or Nrpm, m_flow_in, or - dp_in) is equal to the fan speed (or the mass flow rate - or pressure rise). Thus, a step change in the input signal causes a - step change in the fan speed (or mass flow rate or pressure rise). -
      2. -
    2. If use_inputFilter=true, which is the default, then - the fan speed (or the mass flow rate or the pressure rise) is equal - to the output of a filter. This filter is implemented as a 2nd order - differential equation and can be thought of as approximating the - inertia of the rotor and the fluid. Thus, a step change in the fan - input signal will cause a gradual change in the fan speed. The filter - has a parameter riseTime, which by default is set to - 30 seconds. The rise time is the time required to reach - 99.6% of the full speed, or, if the fan is switched off, to - reach a fan speed of 0.4%. -
      3. -

    - The figure below shows for a fan with - use_inputFilter=true and riseTime=30 - seconds the speed input signal and the actual speed. + The conversion between the fluid ports and signal ports is done in + the HVAC adapter hvacAda. This adapter has a vector of + fluid ports called ports. The supply and return air + ducts, including any resistance model for the inlet diffusor or + exhaust grill, need to be connected to these ports. Also, if a + thermal zone has interzonal air exchange or air infiltration, these + flows need to be connected to ports. This model outputs + at the port fluPor the mass flow rate for each flow that + is connected to ports, together with its temperature, + water vapor mass fraction per total mass of the air (not per kg dry + air), and trace substances. These quantities are always as if the + flow enters the room, even if the flow is zero or negative. If a + medium has no moisture, e.g., if Medium.nXi=0, or if it + has no trace substances, e.g., if Medium.nC=0, then the + output signal for these properties are removed. These quantities are + always as if the flow enters the room, even if the flow is zero or + negative. Thus, a thermal zone model that uses these signals to + compute the heat added by the HVAC system needs to implement an + equation such as

    -

    - \"image\" +

    + Qsen = max(0, ṁsup)   cp   + (Tsup - Tair,zon),

    - Although many simulations do not require such a detailed model that - approximates the transients of fans or pumps, it turns out that using - this filter can reduce computing time and can lead to fewer - convergence problems in large system models. With a filter, any - sudden change in control signal, such as when a fan switches on, is - damped before it affects the air flow rate. This continuous change in - flow rate turns out to be easier, and in some cases faster, to - simulate compared to a step change. For most simulations, we - therefore recommend to use the default settings of - use_inputFilter=true and riseTime=30 - seconds. An exception are situations in which the fan or pump is - operated at a fixed speed during the whole simulation. In this case, - set use_inputFilter=false. + where Qsen is the sensible heat flow rate added to + the thermal zone, ṁsup is the supply air mass flow + rate from the port fluPor (which is negative if it is an + exhaust), cp is the specific heat capacity at + constant pressure, Tsup is the supply air + temperature and Tair,zon is the zone air + temperature. Note that without the max(·, ·), the energy + balance would be wrong.

    - Note that if the fan is part of a closed loop control, then the - filter affects the transient response of the control. When changing - the value of use_inputFilter, the control gains may need - to be retuned. We now present values control parameters that seem to - work in most cases. Suppose there is a closed loop control with a - PI-controller AixLib.Controls.Continuous.LimPID - and a fan or pump, configured with use_inputFilter=true - and riseTime=30 seconds. Assume that the transient - response of the other dynamic elements in the control loop is fast - compared to the rise time of the filter. Then, a proportional gain of - k=0.5 and an integrator time constant of - Ti=15 seconds often yields satisfactory closed loop - control performance. These values may need to be changed for - different applications as they are also a function of the loop gain. - If the control loop shows oscillatory behavior, then reduce - k and/or increase Ti. If the control loop - reacts too slow, do the opposite. + The input signals of this model are the zone radiative temperature. + The the zone air temperature, the water vapor mass fraction per total + mass of the air (unless Medium.nXi=0) and trace + substances (unless Medium.nC=0) are obtained from the + connector fluPor.backward. The outflowing fluid + stream(s) at the port ports will be at the states + obtained from fluPor.backward. All fluid streams at port + ports are at the same pressure. For convenience, the + instance hvacAda also outputs the properties obtained + from fluPor.backward. These can be used to connect a + controller. The properties are available for each flow path in + fluPor.backward. For a thermal zone with mixed air, + these are all equal, while for a stratified room model, they can be + different.

    -
    - Efficiency and electrical power consumption -

    - All models compute the motor power draw Pele, the - hydraulic power input Whyd, the flow work - Wflo and the heat dissipated into the medium - Q. Based on the first law, the flow work is + See + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZone for a + model that uses this model.

    -

    - Wflo = | V̇ Δp |, +

    + For models that multiple thermal zones connected to the HVAC system, + use the model AixLib.Fluid.FMI.ExportContainers.HVACZones.

    +

    + Assumption and limitations +

    - where V̇ is the volume flow rate and Δp is the pressure - rise. The heat dissipated into the medium is as follows: If the motor - is cooled by the fluid, as indicated by - per.motorCooledByFluid=true, then the heat dissipated - into the medium is + The mass flow rates at ports sum to zero, hence this + model conserves mass.

    -

    - Q = Pele - Wflo. +

    + This model does not impose any pressure, other than setting the + pressure of all fluid connections to ports to be equal. + The reason is that setting a pressure can lead to non-physical system + models, for example if a mass flow rate is imposed and the HVAC + system is connected to a model that sets a pressure boundary + condition such as AixLib.Fluid.Sources.Outside. + Also, setting a pressure would make it impossible to use multiple + instances of this model (one for each thermal zone) and build in + Modelica an airflow network model with pressure driven mass flow + rates.

    - If per.motorCooledByFluid=false, then the motor is - outside the fluid stream, and only the shaft, or hydraulic, work - Whyd enters the thermodynamic control volume. - Hence, + The model has no pressure drop. Hence, the pressure drop of an air + diffuser or of an exhaust grill needs to be modelled in models that + are connected to ports.

    -

    - Q = Whyd - Wflo. +

    + +-------- Errors -------- +line 47 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/FixedResistances/Validation/PlugFlowPipes/PlugFlowULg.mo ---- +-------- HTML Code -------- + +

    + The example contains + experimental data from a real district heating network. +

    +

    + This model compares the results with the original Modelica Standard Library pipes. +

    +

    The pipes' temperatures are not initialized. Therefore, results of + outflow temperature before approximately the first 10000 seconds should not be + considered. +

    +

    Test bench schematic

    +

    \"Schematic

    +

    Calibration

    +

    + There are some uncertainties about the heat loss coefficient between pipe and + surrounding air as well as regarding the heat conductivity of the insulation + material. + With the + given data, the length specific thermal resistance is R = 2.164 + ((m K)/W), calculated as follows: +

    +

    + R=((1/(2*pipe.kIns)*log((0.0603+2*pipe.dIns)/(0.0603)))+1/(5*(0.0603+2*pipe.dIns)))/Modelica.Constants.pi

    +

    + U = 1/R = 0.462 W/(m K)

    + + + +-------- Corrected Code -------- +

    + The example contains experimental data from a real district heating + network.

    - The efficiencies are computed as + This model compares the results with the original Modelica Standard + Library pipes.

    -

    - η = Wflo ⁄ Pele = ηhyd   - ηmot
    - ηhyd = Wflo ⁄ Whyd
    - ηmot = Whyd ⁄ Pele
    +

    + The pipes' temperatures are not initialized. Therefore, results of + outflow temperature before approximately the first 10000 seconds + should not be considered.

    +

    + Test bench schematic +

    - where ηhyd is the hydraulic efficiency, - ηmot is the motor efficiency and Q is the - heat released by the motor. + \"Schematic

    +

    + Calibration +

    - If per.use_powerCharacteristic=true, then a set of data - points for the power Pele for different volume flow - rates at full speed needs to be provided by the user. Using the flow - work Wflo and the electrical power input - Pele, the total efficiency is computed as + There are some uncertainties about the heat loss coefficient between + pipe and surrounding air as well as regarding the heat conductivity + of the insulation material. With the + given data, the length specific thermal resistance is R = + 2.164 ((m K)/W), calculated as follows:

    - η = Wflo ⁄ Pele,
    + R=((1/(2*pipe.kIns)*log((0.0603+2*pipe.dIns)/(0.0603)))+1/(5*(0.0603+2*pipe.dIns)))/Modelica.Constants.pi

    +

    + U = 1/R = 0.462 W/(m K) +

    + + +-------- Errors -------- +line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 27 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/FixedResistances/BaseClasses/PlugFlow.mo ---- +-------- HTML Code -------- + +

    + +

    + Model that computes the temperature propagation of + a fluid flow through a pipe, idealized as a plug flow. +

    +

    Main equation

    +

    + The transport delay is computed using the one-dimensional wave equation + without source or sink terms, +

    + ∂z(x,t)/∂t + v(t) ∂z(x,t)/∂x = 0, +

    +

    where z(x,t) is the spatial distribution as a function of time of any + property z of the fluid. + For the temperature propagation, z will be replaced by T. +

    +

    Assumptions

    +

    + This model is based on the following assumptions: +

    + + +-------- Corrected Code -------- +

    - and the two efficiencies ηhyd and - ηmot are computed as -

    -

    - ηhyd = 1,
    - ηmot = η. + Model that computes the temperature propagation of a fluid flow + through a pipe, idealized as a plug flow.

    +

    + Main equation +

    - However, if per.use_powerCharacteristic=false, then - performance data for ηhyd and - ηmot need to be provided by the user, and hence the - model computes + The transport delay is computed using the one-dimensional wave + equation without source or sink terms,

    - η = ηhyd   ηmot
    - Pele = Wflo ⁄ η. -

    -

    - The efficiency data for the motor are a list of points V̇ and - ηmot. -

    -
    - Fluid volume of the component -
    -

    - All models can be configured to have a fluid volume at the - low-pressure side. Adding such a volume sometimes helps the solver to - find a solution during initialization and time integration of large - models. + ∂z(x,t)/∂t + v(t) ∂z(x,t)/∂x = 0,

    -
    - Enthalpy change of the component -

    - If per.motorCooledByFluid=true, then the enthalpy change - between the inlet and outlet fluid port is equal to the electrical - power Pele that is consumed by the component. - Otherwise, it is equal to the hydraulic work Whyd. - The parameter addPowerToMedium, which is by default set - to true, can be used to simplify the equations. If - addPowerToMedium = false, then no enthalpy change occurs - between inlet and outlet. This can lead to simpler equations, but the - temperature rise across the component will be zero. In particular for - fans, this simplification may not be permissible. + where z(x,t) is the spatial distribution as a function of time + of any property z of the fluid. For the temperature + propagation, z will be replaced by T.

    - Differences to models in Modelica.Fluid.Machines + Assumptions

    - The models in this package differ from Modelica.Fluid.Machines primarily in - the following points: + This model is based on the following assumptions:

    -

    - References -

    -

    - Michael Wetter. - Fan and pump model that has a unique solution for any pressure - boundary condition and control signal. Proc. of the 13th - Conference of the International Building Performance Simulation - Association, p. 3505-3512. Chambery, France. August 2013. -

    -------- Errors -------- -line 38 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 -line 126 column 3 - Warning: The summary attribute on the
    element is obsolete in HTML5 -line 205 column 3 - Warning: The summary attribute on the
    element is obsolete in HTML5 -line 254 column 3 - Warning: The summary attribute on the
    element is obsolete in HTML5 -line 15 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 158 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 380 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 425 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 435 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 444 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 448 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 465 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 473 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 484 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Controls/Continuous/Examples/NumberOfRequests.mo ---- +---- AixLib/Utilities/Math/Bicubic.mo ---- -------- HTML Code -------- +

    + This block computes +

    +

    + y = a1 + + a2 x1 + a3 x12 + + a4 x2 + a5 x22 + + a6 x1 x2 + + a7 x1^3 + + a8 x2^3 + + a9 x12 x2 + + a10 x1 x22 +

    + +-------- Corrected Code -------- +

    + This block computes +

    +

    + y = a1 + a2 x1 + a3 + x12 + a4 x2 + + a5 x22 + a6 x1 + x2 + a7 x1^3 + a8 + x2^3 + a9 x12 + x2 + a10 x1 + x22 +

    + + +-------- Errors -------- +line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/FMI/ExportContainers/HVACZones.mo ---- +-------- HTML Code -------- + +

    + Model that is used as a container for an HVAC system that is + to be exported as an FMU and that serves multiple zones. +

    +

    Typical use and important parameters

    +

    + To use this model as a container for an FMU, simply extend + from this model, rather than instantiate it, + and add your HVAC system. By extending from this model, the top-level + signal connectors on the right stay at the top-level, and hence + will be visible at the FMI interface. + The example + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones + shows how a simple HVAC system that serves two rooms can be implemented and exported as + an FMU. + +

    +

    + The following two parameters need to be assigned by the user: + Set nZon to the number of thermal zones to which the + FMU will be connected. + Set nPorts to the largest number of fluid ports + that the thermal zones has. For example, + if nZon=2 and zone 1 has one inlet and one outlet + (hence it has 2 ports), + and zone 2 has one inlets and two outlets + (hence it has 3 ports), then + set nPorts=3. This will add more fluid ports than are needed + for zone 1, but this causes no overhead if they are not connected. +

    +

    + The conversion between the fluid ports and signal ports is done + in the HVAC adapter hvacAda. + This adapter has a vector of fluid ports called ports. + The supply and return air ducts, including any resistance model for the inlet + diffusor or exhaust grill, need to be connected to these ports. + Also, if a thermal zone has interzonal air exchange or air infiltration, + these flows need to be connected to ports. + This model outputs at the port fluPor the mass flow rate for + each flow that is connected to ports, together with its + temperature, water vapor mass fraction per total mass of the air (not per kg dry + air), and trace substances. These quantities are always as if the flow + enters the room, even if the flow is zero or negative. + If a medium has no moisture, e.g., if Medium.nXi=0, or + if it has no trace substances, e.g., if Medium.nC=0, then + the output signal for these properties are removed. + These quantities are always as if the flow + enters the room, even if the flow is zero or negative. + Thus, a thermal zone model that uses these signals to compute the + heat added by the HVAC system need to implement an equation such as +

    +

    + Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), +

    +

    + where + Qsen is the sensible heat flow rate added to the thermal zone, + ṁsup is the supply air mass flow rate from + the port fluPor (which is negative if it is an exhaust), + cp is the specific heat capacity at constant pressure, + Tsup is the supply air temperature and + Tair,zon is the zone air temperature. + Note that without the max(·, ·), the energy + balance would be wrong. +

    +

    - Example that demonstrates the use of the block - - AixLib.Controls.Continuous.NumberOfRequests. - The parameters of the block are such that the output is incremented - for each input signal that is strictly larger than 0. - The figure below shows the inputs and the output of the block. + The input signals of this model are the radiative temperature of each zone. + The the zone air temperatures, + the water vapor mass fractions per total mass of the air (unless Medium.nXi=0) + and trace substances (unless Medium.nC=0) are obtained from the connector + fluPor.backward. + The outflowing fluid stream(s) at the port ports will be at the + states obtained from fluPor.backward. + For any given izon ∈ {1, ..., nzon}, + for each iports ∈ {1, ..., nports} + all fluid streams at port ports[izon, iports] are at the same + pressure. + For convenience, the instance hvacAda also outputs the + properties obtained from fluPor.backward. These can be used + to connect a controller. The properties are available for each flow path in + fluPor.backward. For a thermal zone with mixed air, these are + all equal, while for a stratified room model, they can be different.

    -

    - \"Simulation +

    + See + + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones + for a model that uses this model.

    - --------- Corrected Code -------- - -

    - Example that demonstrates the use of the block AixLib.Controls.Continuous.NumberOfRequests. - The parameters of the block are such that the output is incremented - for each input signal that is strictly larger than 0. The - figure below shows the inputs and the output of the block. -

    -

    - \"Simulation -

    - --------- Errors -------- -line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Movers/BaseClasses/Characteristics/power.mo ---- --------- HTML Code -------- -

    - This function computes the fan power consumption for given volume flow rate, - speed and performance data. The power consumption is + For models that only have one thermal zone connected to the HVAC system, + use the simpler model + + AixLib.Fluid.FMI.ExportContainers.HVACZone.

    -

    - P = rN3   s(V̇/rN, d), +

    Assumption and limitations

    +

    + The mass flow rates at ports sum to zero, hence this + model conserves mass for each thermal zone.

    - where - P is the power consumption, - rN is the normalized fan speed, - V̇ is the volume flow rate and - d are performance data for fan or pump power consumption at rN=1. + This model does not impose any pressure, other than, + for any given izon ∈ {1, ..., nzon} and + for each j,k ∈ {1, ..., nports}, + setting the pressure of ports[izon, j].p = ports[izon, k].p + to be the same. + The reason is that setting a pressure can lead to non-physical system models, + for example if a mass flow rate is imposed and the HVAC system is connected + to a model that sets a pressure boundary condition such as + + AixLib.Fluid.Sources.Outside. + Also, setting a pressure would make it impossible to use multiple instances + of this model (one for each thermal zone) and build in Modelica an airflow network + model with pressure driven mass flow rates.

    -

    Implementation

    - The function s(·, ·) is a cubic hermite spline. - If the data d define a monotone decreasing sequence, then - s(·, d) is a monotone decreasing function. + The model has no pressure drop. Hence, the pressure drop + of an air diffuser or of an exhaust grill needs to be modelled + in models that are connected to ports.

    -------- Corrected Code --------

    - This function computes the fan power consumption for given volume - flow rate, speed and performance data. The power consumption is + Model that is used as a container for an HVAC system that is to be + exported as an FMU and that serves multiple zones. +

    +

    + Typical use and important parameters +

    +

    + To use this model as a container for an FMU, simply extend from this + model, rather than instantiate it, and add your HVAC system. By + extending from this model, the top-level signal connectors on the + right stay at the top-level, and hence will be visible at the FMI + interface. The example + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones shows + how a simple HVAC system that serves two rooms can be implemented and + exported as an FMU. +

    +

    + The following two parameters need to be assigned by the user: Set + nZon to the number of thermal zones to which the FMU + will be connected. Set nPorts to the largest number of + fluid ports that the thermal zones has. For example, if + nZon=2 and zone 1 has one inlet and one outlet + (hence it has 2 ports), and zone 2 has one inlets and two + outlets (hence it has 3 ports), then set nPorts=3. This + will add more fluid ports than are needed for zone 1, but this + causes no overhead if they are not connected. +

    +

    + The conversion between the fluid ports and signal ports is done in + the HVAC adapter hvacAda. This adapter has a vector of + fluid ports called ports. The supply and return air + ducts, including any resistance model for the inlet diffusor or + exhaust grill, need to be connected to these ports. Also, if a + thermal zone has interzonal air exchange or air infiltration, these + flows need to be connected to ports. This model outputs + at the port fluPor the mass flow rate for each flow that + is connected to ports, together with its temperature, + water vapor mass fraction per total mass of the air (not per kg dry + air), and trace substances. These quantities are always as if the + flow enters the room, even if the flow is zero or negative. If a + medium has no moisture, e.g., if Medium.nXi=0, or if it + has no trace substances, e.g., if Medium.nC=0, then the + output signal for these properties are removed. These quantities are + always as if the flow enters the room, even if the flow is zero or + negative. Thus, a thermal zone model that uses these signals to + compute the heat added by the HVAC system need to implement an + equation such as

    - P = rN3   s(V̇/rN, d), + Qsen = max(0, ṁsup)   cp   + (Tsup - Tair,zon),

    - where P is the power consumption, rN is the - normalized fan speed, V̇ is the volume flow rate and d - are performance data for fan or pump power consumption at - rN=1. + where Qsen is the sensible heat flow rate added to + the thermal zone, ṁsup is the supply air mass flow + rate from the port fluPor (which is negative if it is an + exhaust), cp is the specific heat capacity at + constant pressure, Tsup is the supply air + temperature and Tair,zon is the zone air + temperature. Note that without the max(·, ·), the energy + balance would be wrong. +

    +

    + The input signals of this model are the radiative temperature of each + zone. The the zone air temperatures, the water vapor mass fractions + per total mass of the air (unless Medium.nXi=0) and + trace substances (unless Medium.nC=0) are obtained from + the connector fluPor.backward. The outflowing fluid + stream(s) at the port ports will be at the states + obtained from fluPor.backward. For any given + izon ∈ {1, ..., nzon}, for each + iports ∈ {1, ..., nports} all fluid + streams at port ports[izon, + iports] are at the same pressure. For convenience, + the instance hvacAda also outputs the properties + obtained from fluPor.backward. These can be used to + connect a controller. The properties are available for each flow path + in fluPor.backward. For a thermal zone with mixed air, + these are all equal, while for a stratified room model, they can be + different. +

    +

    + See + AixLib.Fluid.FMI.ExportContainers.Examples.FMUs.HVACZones for a + model that uses this model. +

    +

    + For models that only have one thermal zone connected to the HVAC + system, use the simpler model AixLib.Fluid.FMI.ExportContainers.HVACZone.

    - Implementation + Assumption and limitations

    - The function s(·, ·) is a cubic hermite spline. If the data - d define a monotone decreasing sequence, then s(·, d) - is a monotone decreasing function. + The mass flow rates at ports sum to zero, hence this + model conserves mass for each thermal zone. +

    +

    + This model does not impose any pressure, other than, for any given + izon ∈ {1, ..., nzon} and for each + j,k ∈ {1, ..., nports}, setting the pressure of + ports[izon, j].p = ports[izon, + k].p to be the same. The reason is that setting a pressure can + lead to non-physical system models, for example if a mass flow rate + is imposed and the HVAC system is connected to a model that sets a + pressure boundary condition such as AixLib.Fluid.Sources.Outside. + Also, setting a pressure would make it impossible to use multiple + instances of this model (one for each thermal zone) and build in + Modelica an airflow network model with pressure driven mass flow + rates. +

    +

    + The model has no pressure drop. Hence, the pressure drop of an air + diffuser or of an exhaust grill needs to be modelled in models that + are connected to ports.

    -------- Errors -------- -line 6 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 60 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow.mo ---- +---- AixLib/Fluid/HeatExchangers/BaseClasses/WetCoilWetRegime.mo ---- -------- HTML Code -------- +

    +

    - Function that computes the pressure drop of flow elements as + This model implements the calculation for a 100% wet coil.

    -

    - Δp = sign(m) (m ⁄ k)2 +

    + The equations from Braun (1988) and Mitchell and Braun (2012a and b), + which are essentially the extension of the ε-NTU approach to + simultaneous sensible and latent heat transfer, are utilized.

    - with regularization near the origin. - Therefore, the flow coefficient is + The mathematical equations are analogous to that of the sensible heat exchanger. + However, the key distinction is that the heat transfer is driven by an enthalpy difference + not by an temperature difference. This change in the driving potential results in re-defining + capacitances and heat transfer coefficients accordingly.

    -

    - k = m ⁄ √ Δp   + +

    + The total heat transfer rate is expressed as +

    +

    + Qtot=ε* C*min + (hair,in-hsat(Twat,in)),

    - The input m_flow_turbulent determines the location of the regularization. + where ε*=f(Cr*,NTU*) and f is the same ε-NTU relationships + (depending on the heat exchanger configuration) for the sensible heat exchanger. +

    +

    + hair,in and hsat(Twat,in) are + the specific enthalpies of the incoming moist air and saturated moist air + at the water inlet temperature. +

    +

    + The capacitances of water and air streams are defined as +

    +

    C*air=mair and + C*wat=mwatcp,wat/csat, +

    +

    + where csat is an specific heat capacity, which indicates the sensitivity + of the enthalpy of the staturated moist air w.r.t. the temperature, and is defined + here as csat=(hsat(Twat,out)-hsat(Twat,in)) + /(Twat,out-Twat,in). +

    +

    + The capacitance ratio and minimum capacitance are naturally defined as +

    +

    Cr*=min(C*air,C*wat)/max(C*air,C*wat) + and C*min=min(C*air,C*wat). +

    +


    + The number of transfer unit for the wet-coil is defined as NTU*=UA*/C*min, where +

    +

    + UA*=1/(1/(UAair/cp,air)+1/(UAwat/csat).

    - +

    References

    +

    + Braun, James E. 1988. + "Methodologies for the Design and Control of Central Cooling Plants". + PhD Thesis. University of Wisconsin - Madison. + Available + + online. +

    +

    + Mitchell, John W., and James E. Braun. 2012a. + Principles of heating, ventilation, and air conditioning in buildings. + Hoboken, N.J.: Wiley. +

    +

    + Mitchell, John W., and James E. Braun. 2012b. + "Supplementary Material Chapter 2: Heat Exchangers for Cooling Applications". + Excerpt from Principles of heating, ventilation, and air conditioning in buildings. + Hoboken, N.J.: Wiley. + Available + + online. +

    -------- Corrected Code -------- +

    - Function that computes the pressure drop of flow elements as + This model implements the calculation for a 100% wet coil.

    -

    - Δp = sign(m) (m ⁄ k)2 +

    + The equations from Braun (1988) and Mitchell and Braun (2012a and b), + which are essentially the extension of the ε-NTU approach to + simultaneous sensible and latent heat transfer, are utilized.

    - with regularization near the origin. Therefore, the flow coefficient - is + The mathematical equations are analogous to that of the sensible heat + exchanger. However, the key distinction is that the heat transfer is + driven by an enthalpy difference not by an temperature difference. + This change in the driving potential results in re-defining + capacitances and heat transfer coefficients accordingly.

    -

    - k = m ⁄ √ Δp -   +

    + The total heat transfer rate is expressed as +

    +

    + Qtot=ε* C*min + (hair,in-hsat(Twat,in)),

    - The input m_flow_turbulent determines the location of - the regularization. + where ε*=f(Cr*,NTU*) and f is the same ε-NTU + relationships (depending on the heat exchanger configuration) for the + sensible heat exchanger. +

    +

    + hair,in and + hsat(Twat,in) are the specific + enthalpies of the incoming moist air and saturated moist air at the + water inlet temperature. +

    +

    + The capacitances of water and air streams are defined as +

    +

    + C*air=mair and + C*wat=mwatcp,wat/csat, +

    +

    + where csat is an specific heat capacity, which indicates the + sensitivity of the enthalpy of the staturated moist air w.r.t. the + temperature, and is defined here as + csat=(hsat(Twat,out)-hsat(Twat,in)) + /(Twat,out-Twat,in). +

    +

    + The capacitance ratio and minimum capacitance are naturally defined + as +

    +

    + Cr*=min(C*air,C*wat)/max(C*air,C*wat) + and C*min=min(C*air,C*wat). +

    +

    +
    + The number of transfer unit for the wet-coil is defined as + NTU*=UA*/C*min, where +

    +

    + UA*=1/(1/(UAair/cp,air)+1/(UAwat/csat). +

    +

    + References +

    +

    + Braun, James E. 1988. \"Methodologies for the Design and Control of + Central Cooling Plants\". PhD Thesis. University of Wisconsin - + Madison. Available online. +

    +

    + Mitchell, John W., and James E. Braun. 2012a. Principles of heating, + ventilation, and air conditioning in buildings. Hoboken, N.J.: Wiley. +

    +

    + Mitchell, John W., and James E. Braun. 2012b. \"Supplementary Material + Chapter 2: Heat Exchangers for Cooling Applications\". Excerpt from + Principles of heating, ventilation, and air conditioning in + buildings. Hoboken, N.J.: Wiley. Available + online.

    - -------- Errors -------- -line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 12 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 20 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 36 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 48 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 54 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Utilities/Math/Functions/quadraticLinear.mo ---- +---- AixLib/ThermalZones/ReducedOrder/RC/ThreeElements.mo ---- -------- HTML Code -------- - This function computes -

    - y = a1 + a2 x1 - + a3 x12 - + (a4 + a5 x1 - + a6 x12) x2 -

    - +

    This model adds one further element for + the floor plate. Long-term effects dominate the excitation of the floor plate + and thus the excitation fundamentally differs from excitation of outer walls. + Adding an extra element for the floor plate leads to a finer resolution of the + dynamic behaviour but increases calculation times. The floor plate is + parameterized via the length of the RC-chain nFloor, + the vector of the capacities + CFloor[nFloor], the vector of the resistances + RFloor[nFloor] + and the remaining resistance RFloorRem. +

    +

    + The image below shows the RC-network of this model. +

    +

    + \"image\"/ +

    + -------- Corrected Code -------- -This function computes -

    - y = a1 + a2 x1 + a3 - x12 + (a4 + a5 - x1 + a6 x12) - x2 -

    - --------- Errors -------- -line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 - - ----- AixLib/Fluid/Storage/UsersGuide.mo ---- --------- HTML Code -------- -

    -This user's guide describes the storage tank models. -There are three storage tank models in the this package. + This model adds one further element for the floor plate. Long-term + effects dominate the excitation of the floor plate and thus the + excitation fundamentally differs from excitation of outer walls. + Adding an extra element for the floor plate leads to a finer + resolution of the dynamic behaviour but increases calculation times. + The floor plate is parameterized via the length of the RC-chain + nFloor, the vector of the capacities + CFloor[nFloor], the vector of the resistances + RFloor[nFloor] and the remaining resistance + RFloorRem.

    -
    - - - - - - - - - - - - - -
    Model name Description
    - -AixLib.Fluid.Storage.Stratified -

    -This is a model of a stratified storage tank as shown in the figure below. + The image below shows the RC-network of this model.

    -\"Image -

    -

    -The tank uses several volumes to model the stratification. -Heat conduction is modeled between the volumes through the fluid, -and between the volumes and the ambient. + \"image\"

    + +-------- Errors -------- +line 16 column 4 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/FMI/Adaptors/HVAC.mo ---- +-------- HTML Code -------- + +

    + The (time varying) vector Real output signal of this block can be defined in its + parameter menu via variable y. The purpose is to support the + easy definition of vector-valued Real expressions in a block diagram. +

    + +

    + Adaptor that can be used to connect an HVAC system (with acausal ports) + to input/output signals, which then can be exposed in an FMI interface. +

    +

    + The adaptor has a vector of fluid ports called ports. + The supply and return air ducts need to be connected to these ports. + Also, if a thermal zone has interzonal air exchange or air infiltration, + these flow paths also need be connected to ports. +

    +

    + This model outputs at the port fluPor the mass flow rate for + each flow that is connected to ports, together with its + temperature, water vapor mass fraction per total mass of the air (not per kg dry + air), and trace substances. These quantities are always as if the flow + enters the room, even if the flow is zero or negative. + If a medium has no moisture, e.g., if Medium.nXi=0, or + if it has no trace substances, e.g., if Medium.nC=0, then + the output signal for these properties are removed. + These quantities are always as if the flow + enters the room, even if the flow is zero or negative. + Thus, a thermal zone model that uses these signals to compute the + heat added by the HVAC system need to implement an equation such as +

    +

    + Qsen = max(0, ṁsup)   cp   (Tsup - Tair,zon), +

    +

    + where + Qsen is the sensible heat flow rate added to the thermal zone, + ṁsup is the supply air mass flow rate from + the port fluPor (which is negative if it is an exhaust), + cp is the specific heat capacity at constant pressure, + Tsup is the supply air temperature and + Tair,zon is the zone air temperature. + Note that without the max(·, ·) function, the energy + balance would be wrong. +

    +

    + The output signals of this model are the zone air temperature, + the water vapor mass fraction per total mass of the air (unless Medium.nXi=0) + and trace substances (unless Medium.nC=0). + These output connectors can be used to connect to a controller. + These values are obtained from the fluid stream(s) that flow into this component + at the port fluPor, e.g., from the connector + fluPor.backward. + Note that there are nPorts of these signals. + For a completely mixed room, they will all have the same value, but + for a room with non-uniform temperatures, they can have different values. +

    +

    Assumption and limitations

    +

    + The mass flow rates at ports sum to zero, hence this + model conserves mass. +

    +

    + This model does not impose any pressure, other than setting the pressure + of all fluid connections to ports to be equal. + The reason is that setting a pressure can lead to non-physical system models, + for example if a mass flow rate is imposed and the HVAC system is connected + to a model that sets a pressure boundary condition such as + + AixLib.Fluid.Sources.Outside. + Also, setting a pressure would make it impossible to use multiple instances + of this model (one for each thermal zone) and build in Modelica an airflow network + model with pressure driven mass flow rates. +

    +

    + The model has no pressure drop. Hence, the pressure drop + of an air diffuser or of an exhaust grill need to be modelled + in models that are connected to ports. +

    +

    Typical use and important parameters

    +

    + See + + AixLib.Fluid.FMI.ExportContainers.HVACZone + for a model that uses this model. +

    + +
      +
    • + January 18, 2019, by Jianjun Hu:
      + Limited the media choice to moist air only. + See #1050. +
      • +
    • + September 13, 2017, by Michael Wetter:
      + Removed erroneous each. +
      • +
    • + October 4, 2016, by Michael Wetter:
      + Corrected assignment of quantity in CZon. +
      • +
    • + June 29, 2016, by Michael Wetter:
      + Revised implementation. +
      • +
    • + April 14, 2016, by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Corrected Code --------

    -The heat port heaPorVol may be used to connect a temperature sensor -that measures the fluid temperature of an individual volume. It may also -be used to add heat to individual volumes, for example if the tank contains -an electrical resistance heater. + The (time varying) vector Real output signal of this + block can be defined in its parameter menu via variable + y. The purpose is to support the easy definition of + vector-valued Real expressions in a block diagram.

    -Similarly, the fluid port fluPorVol may be used to connect a fluid pipe -to an individual volume. This allows for example to draw water from that volume whose temperature -is close to the temperature required by the consumer. -Conversely, water could be added to that tank volume whose temperature is close to the -inlet water temperature. -If you don't use such a pipe, simply leave the ports unconnected. + Adaptor that can be used to connect an HVAC system (with acausal + ports) to input/output signals, which then can be exposed in an FMI + interface.

    -The tank has nSeg fluid volumes. The top segment has the index 1. -Thus, to add a heating element to the bottom element, connect a heat input to -heaPorVol[nSeg]. + The adaptor has a vector of fluid ports called ports. + The supply and return air ducts need to be connected to these ports. + Also, if a thermal zone has interzonal air exchange or air + infiltration, these flow paths also need be connected to + ports.

    -The heat ports outside the tank insulation can be -used to specify an ambient temperature. -Leave these ports unconnected to force adiabatic boundary conditions. -Note, however, that all heat conduction elements through the tank wall (but not the top and bottom) are connected to the -heat port heaPorSid. Thus, not connecting -heaPorSid means an adiabatic boundary condition in the sense -that heaPorSid.Q_flow = 0. This, however, still allows heat to flow -through the tank walls, modeled by conWal, from one fluid volume -to another one. + This model outputs at the port fluPor the mass flow rate + for each flow that is connected to ports, together with + its temperature, water vapor mass fraction per total mass of the air + (not per kg dry air), and trace substances. These quantities are + always as if the flow enters the room, even if the flow is zero or + negative. If a medium has no moisture, e.g., if + Medium.nXi=0, or if it has no trace substances, e.g., if + Medium.nC=0, then the output signal for these properties + are removed. These quantities are always as if the flow enters the + room, even if the flow is zero or negative. Thus, a thermal zone + model that uses these signals to compute the heat added by the HVAC + system need to implement an equation such as

    -
    - -AixLib.Fluid.Storage.StratifiedEnhanced - -

    -The model is identical to - -AixLib.Fluid.Storage.Stratified, -except for the following: +

    + Qsen = max(0, ṁsup)   cp   + (Tsup - Tair,zon),

    -
      -
    • -It adds a correction that reduces the numerical dissipation. -
      • -
    • -It does not contain the fluid ports fluPorVol that -connect from the outside to the individual volumes. -
      • -

    -The correction uses a third order upwind scheme to compute the -outlet temperatures of the segments in the tank. This model -is implemented in - -AixLib.Fluid.Storage.BaseClasses.ThirdOrderStratifier. + where Qsen is the sensible heat flow rate added to + the thermal zone, ṁsup is the supply air mass flow + rate from the port fluPor (which is negative if it is an + exhaust), cp is the specific heat capacity at + constant pressure, Tsup is the supply air + temperature and Tair,zon is the zone air + temperature. Note that without the max(·, ·) function, the + energy balance would be wrong.

    -
    - -AixLib.Fluid.Storage.StratifiedEnhancedInternalHex -

    -This model is identical to - -AixLib.Fluid.Storage.StratifiedEnhanced -except that it adds a heat exchanger to the tank. + The output signals of this model are the zone air temperature, the + water vapor mass fraction per total mass of the air (unless + Medium.nXi=0) and trace substances (unless + Medium.nC=0). These output connectors can be used to + connect to a controller. These values are obtained from the fluid + stream(s) that flow into this component at the port + fluPor, e.g., from the connector + fluPor.backward. Note that there are nPorts + of these signals. For a completely mixed room, they will all have the + same value, but for a room with non-uniform temperatures, they can + have different values.

    +

    + Assumption and limitations +

    -The modifications consist of adding a heat exchanger -and fluid ports to connect to the heat exchanger. -The modifications allow to run a fluid through the tank causing heat transfer to the stored fluid. -A typical example is a storage tank in a solar hot water system. + The mass flow rates at ports sum to zero, hence this + model conserves mass.

    -The heat exchanger model assumes flow through the inside of a helical coil heat exchanger, -and stagnant fluid on the outside. Parameters are used to describe the -heat transfer on the inside of the heat exchanger at nominal conditions, and -geometry of the outside of the heat exchanger. This information is used to compute -an hA-value for each side of the coil. -Convection calculations are then performed to identify heat transfer -between the heat transfer fluid and the fluid in the tank. + This model does not impose any pressure, other than setting the + pressure of all fluid connections to ports to be equal. + The reason is that setting a pressure can lead to non-physical system + models, for example if a mass flow rate is imposed and the HVAC + system is connected to a model that sets a pressure boundary + condition such as AixLib.Fluid.Sources.Outside. + Also, setting a pressure would make it impossible to use multiple + instances of this model (one for each thermal zone) and build in + Modelica an airflow network model with pressure driven mass flow + rates.

    -The location of the heat exchanger can be parameterized as follows: -The parameters hHex_a and hHex_b are the heights -of the heat exchanger ports portHex_a and portHex_b, -measured from the bottom of the tank. -For example, to place the port portHex_b at the bottom of the tank, -set hHexB_b=0. -The parameters hHex_a and hHex_b are then used to provide -a default value for the parameters -segHex_a and segHex_b, which are the numbers of the tank -segments to which the heat exchanger ports portHex_a and portHex_b -are connected. -

    -

    -\"Image + The model has no pressure drop. Hence, the pressure drop of an air + diffuser or of an exhaust grill need to be modelled in models that + are connected to ports.

    +

    + Typical use and important parameters +

    -Optionally, this model computes a dynamic response of the heat exchanger. -This can be configured using the parameters -energyDynamicsHexSolid, -energyDynamicsHex and -massDynamicsHex. -For this computation, the fluid volume inside the heat exchanger -and the heat capacity of the heat -exchanger wall CHex are approximated. -Both depend on the length lHex -of the heat exchanger. -The model provides default values for these -parameters, as well as for the heat exchanger material which is -assumed to be steel. These default values can be overwritten by the user. -The default values for the heat exchanger geometry are computed assuming -that there is a cylindrical heat exchanger -made of steel whose diameter is half the diameter of the tank, e.g., -rHex=rTan/2. -Hence, the length of the heat exchanger is approximated as -lHex = 2 rHex π h = 2 rTan/2 π h, -where h is the distance between the heat exchanger inlet and outlet. -The wall thickness is assumed to be 10% of the heat exchanger -outer diameter. -For typical applications, users do not need to change these values. + See AixLib.Fluid.FMI.ExportContainers.HVACZone + for a model that uses this model.

    +
      +
    • January 18, 2019, by Jianjun Hu:
      + Limited the media choice to moist air only. See #1050. +
      • +
    • September 13, 2017, by Michael Wetter:
      + Removed erroneous each. +
      • +
    • October 4, 2016, by Michael Wetter:
      + Corrected assignment of quantity in CZon. +
      • +
    • June 29, 2016, by Michael Wetter:
      + Revised implementation. +
      • +
    • April 14, 2016, by Michael Wetter:
      + First implementation. +
      • +
    + +-------- Errors -------- +line 26 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Fluid/Geothermal/Borefields/BaseClasses/HeatTransfer/LoadAggregation/Validation/ShiftAggregationCells.mo ---- +-------- HTML Code -------- + +

    + This validation case replicates the load-shifting procedure illustred in the figure below by Cimmino (2014). +

    +

    + \"image\" +

    +

    References

    +

    + Cimmino, M. 2014. Développement et validation expérimentale de facteurs de réponse + thermique pour champs de puits géothermiques, + Ph.D. Thesis, École Polytechnique de Montréal. +

    + +
      +
    • + July 18, 2018, by Alex Laferrière:
      + First implementation. +
      • +
    + +-------- Corrected Code --------

    -Setting energyDynamicsHexSolid to a dynamic balance and -energyDynamicsHex to a steady-state balance may be of interest -to remove very fast dynamics of the fluid, while still modeling slower -dynamics that arises from the metal of the heat exchanger. -By default, energyDynamicsHexSolid is set -to the same value as energyDynamicsHex -as this seems to be the typical configuration. + This validation case replicates the load-shifting procedure illustred + in the figure below by Cimmino (2014).

    -

    -The heat exchanger is implemented in - -AixLib.Fluid.Storage.BaseClasses.IndirectTankHeatExchanger. +

    + \"image\"

    -
    - --------- Corrected Code -------- +

    + References +

    - This user's guide describes the storage tank models. There are three - storage tank models in the this package. + Cimmino, M. 2014. Développement et validation expérimentale de + facteurs de réponse thermique pour champs de puits géothermiques, + Ph.D. Thesis, École Polytechnique de Montréal.

    - - - - - - - - - - - - - - - - - -
    - Model name - - Description -
    - AixLib.Fluid.Storage.Stratified - -

    - This is a model of a stratified storage tank as shown in the - figure below. -

    -

    - \"Image -

    -

    - The tank uses several volumes to model the stratification. Heat - conduction is modeled between the volumes through the fluid, - and between the volumes and the ambient. -

    -

    - The heat port heaPorVol may be used to connect a - temperature sensor that measures the fluid temperature of an - individual volume. It may also be used to add heat to - individual volumes, for example if the tank contains an - electrical resistance heater. -

    -

    - Similarly, the fluid port fluPorVol may be used to - connect a fluid pipe to an individual volume. This allows for - example to draw water from that volume whose temperature is - close to the temperature required by the consumer. Conversely, - water could be added to that tank volume whose temperature is - close to the inlet water temperature. If you don't use such a - pipe, simply leave the ports unconnected. -

    -

    - The tank has nSeg fluid volumes. The top segment - has the index 1. Thus, to add a heating element to - the bottom element, connect a heat input to - heaPorVol[nSeg]. -

    -

    - The heat ports outside the tank insulation can be used to - specify an ambient temperature. Leave these ports unconnected - to force adiabatic boundary conditions. Note, however, that all - heat conduction elements through the tank wall (but not the top - and bottom) are connected to the heat port - heaPorSid. Thus, not connecting - heaPorSid means an adiabatic boundary condition in - the sense that heaPorSid.Q_flow = 0. This, - however, still allows heat to flow through the tank walls, - modeled by conWal, from one fluid volume to - another one. -

    -
    - AixLib.Fluid.Storage.StratifiedEnhanced - -

    - The model is identical to AixLib.Fluid.Storage.Stratified, - except for the following: -

    -
      -
    • It adds a correction that reduces the numerical - dissipation. -
      • -
    • It does not contain the fluid ports fluPorVol - that connect from the outside to the individual volumes. -
      • -
    -

    - The correction uses a third order upwind scheme to compute the - outlet temperatures of the segments in the tank. This model is - implemented in - AixLib.Fluid.Storage.BaseClasses.ThirdOrderStratifier. -

    -
    - AixLib.Fluid.Storage.StratifiedEnhancedInternalHex - -

    - This model is identical to AixLib.Fluid.Storage.StratifiedEnhanced - except that it adds a heat exchanger to the tank. -

    -

    - The modifications consist of adding a heat exchanger and fluid - ports to connect to the heat exchanger. The modifications allow - to run a fluid through the tank causing heat transfer to the - stored fluid. A typical example is a storage tank in a solar - hot water system. -

    -

    - The heat exchanger model assumes flow through the inside of a - helical coil heat exchanger, and stagnant fluid on the outside. - Parameters are used to describe the heat transfer on the inside - of the heat exchanger at nominal conditions, and geometry of - the outside of the heat exchanger. This information is used to - compute an hA-value for each side of the coil. - Convection calculations are then performed to identify heat - transfer between the heat transfer fluid and the fluid in the - tank. -

    -

    - The location of the heat exchanger can be parameterized as - follows: The parameters hHex_a and - hHex_b are the heights of the heat exchanger ports - portHex_a and portHex_b, measured - from the bottom of the tank. For example, to place the port - portHex_b at the bottom of the tank, set - hHexB_b=0. The parameters hHex_a and - hHex_b are then used to provide a default value - for the parameters segHex_a and - segHex_b, which are the numbers of the tank - segments to which the heat exchanger ports - portHex_a and portHex_b are - connected. -

    -

    - \"Image -

    -

    - Optionally, this model computes a dynamic response of the heat - exchanger. This can be configured using the parameters - energyDynamicsHexSolid, - energyDynamicsHex and - massDynamicsHex. For this computation, the fluid - volume inside the heat exchanger and the heat capacity of the - heat exchanger wall CHex are approximated. Both - depend on the length lHex of the heat exchanger. - The model provides default values for these parameters, as well - as for the heat exchanger material which is assumed to be - steel. These default values can be overwritten by the user. The - default values for the heat exchanger geometry are computed - assuming that there is a cylindrical heat exchanger made of - steel whose diameter is half the diameter of the tank, e.g., - rHex=rTan/2. Hence, the length of - the heat exchanger is approximated as lHex = 2 - rHex π h = 2 rTan/2 π h, where - h is the distance between the heat exchanger inlet and - outlet. The wall thickness is assumed to be 10% of the - heat exchanger outer diameter. For typical applications, users - do not need to change these values. -

    -

    - Setting energyDynamicsHexSolid to a dynamic - balance and energyDynamicsHex to a steady-state - balance may be of interest to remove very fast dynamics of the - fluid, while still modeling slower dynamics that arises from - the metal of the heat exchanger. By default, - energyDynamicsHexSolid is set to the same value as - energyDynamicsHex as this seems to be the typical - configuration. -

    -

    - The heat exchanger is implemented in AixLib.Fluid.Storage.BaseClasses.IndirectTankHeatExchanger. -

    -
    + + +-------- Errors -------- +line 5 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Utilities/Math/Functions/Examples/CubicHermite.mo ---- +-------- HTML Code -------- + +

    + This example demonstrates the use of the function for cubic hermite interpolation + and linear extrapolation. + The example use interpolation with two different settings: One settings + produces a monotone cubic hermite, whereas the other setting + does not enforce monotonicity. + The resulting plot should look as shown below, where for better visibility, the support points have been marked with black dots. + Notice that the red curve is monotone increasing. +

    +

    \"image\"

    + + + +-------- Corrected Code -------- +

    + This example demonstrates the use of the function for cubic hermite + interpolation and linear extrapolation. The example use interpolation + with two different settings: One settings produces a monotone cubic + hermite, whereas the other setting does not enforce monotonicity. The + resulting plot should look as shown below, where for better + visibility, the support points have been marked with black dots. + Notice that the red curve is monotone increasing. +

    +

    + \"image\" +

    + -------- Errors -------- -line 6 column 1 - Warning: The summary attribute on the element is obsolete in HTML5 -line 17 column 1 - Warning:

    attribute "align" not allowed for HTML5 -line 129 column 1 - Warning:

    attribute "align" not allowed for HTML5 +line 11 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/FixedResistances/BaseClasses/PlugFlowHeatLoss.mo ---- +---- AixLib/Fluid/FixedResistances/Validation/PlugFlowPipes/PlugFlowAIT.mo ---- -------- HTML Code --------

    - Component that calculates the heat losses at the end of a plug flow pipe - when the flow goes in the design direction. -

    -

    Main equations

    -

    - The governing equations are -

    -

    - Tout = Tb + (Tin - Tb) - exp((tout - tin)/tauchar) -

    -

    - with + The example contains + experimental data from a real district heating network.

    -

    - tauchar = R C +

    The pipes' temperatures are not initialized. Therefore, results of + outflow temperature before approximately the first 10000 seconds should not be + considered.

    -

    Assumptions and limitations

    - This model is based on the following assumptions: + Note that these three models are identical, except for the pipe model that is used:

    -

    Implementation

    - Heat losses are only considered in design flow direction. - For heat loss consideration in both directions, use one of these models at - both ends of a - - AixLib.Fluid.FixedResistances.BaseClasses.PlugFlow model. - The outlet temperature is calculated as in the equation above, - using the inlet temperature at port_a and the instantaneous - time delay and boundary temperature. - The boundary temperature can be either the air temperature - or the undisturbed ground temperature, depending on the definition of the - thermal resistance R. + This comparison between different discretization levels and pipe models is made + to check the influence of the discretization and pipe model on computation time + and simulation accuracy. +

    +

    Test bench schematic

    +

    \"Schematic +

    +

    Calibration

    +

    To calculate the length specific thermal resistance R of the pipe, + the thermal resistance of the surrounding ground is added, which yields

    +

    + R=1/(0.208)+1/(2   lambda_g   Modelica.Constants.pi)   log(1/0.18),

    +

    where the thermal conductivity of the ground lambda_g = 2.4 W/(m K).

    -

    - This component requires the delay time and the instantaneous ambient temperature - as an input. - This component is to be used in single pipes or in more advanced configurations - where no influence from other pipes is considered.

    -------- Corrected Code --------

    - Component that calculates the heat losses at the end of a plug flow - pipe when the flow goes in the design direction. + The example contains experimental data from a real district heating + network.

    -

    - Main equations -

    - The governing equations are + The pipes' temperatures are not initialized. Therefore, results of + outflow temperature before approximately the first 10000 seconds + should not be considered.

    -

    - Tout = Tb + (Tin - Tb) - exp((tout - tin)/tauchar) +

    + Note that these three models are identical, except for the pipe model + that is used:

    +

    - with + This comparison between different discretization levels and pipe + models is made to check the influence of the discretization and pipe + model on computation time and simulation accuracy.

    -

    - tauchar = R C +

    + Test bench schematic +

    +

    + \"Schematic

    - Assumptions and limitations + Calibration

    - This model is based on the following assumptions: + To calculate the length specific thermal resistance R of + the pipe, the thermal resistance of the surrounding ground is added, + which yields +

    +

    + R=1/(0.208)+1/(2   lambda_g   Modelica.Constants.pi)   + log(1/0.18), +

    +

    + where the thermal conductivity of the ground lambda_g = + 2.4 W/(m K).

    -

    - Implementation -

    -

    - Heat losses are only considered in design flow direction. For heat - loss consideration in both directions, use one of these models at - both ends of a AixLib.Fluid.FixedResistances.BaseClasses.PlugFlow - model. The outlet temperature is calculated as in the equation above, - using the inlet temperature at port_a and the - instantaneous time delay and boundary temperature. The boundary - temperature can be either the air temperature or the undisturbed - ground temperature, depending on the definition of the thermal - resistance R. -

    -

    - This component requires the delay time and the instantaneous ambient - temperature as an input. This component is to be used in single pipes - or in more advanced configurations where no influence from other - pipes is considered. + +-------- Errors -------- +line 48 column 2 - Warning:

    attribute "align" not allowed for HTML5 + + +---- AixLib/Utilities/Math/Functions/quadraticLinear.mo ---- +-------- HTML Code -------- + + This function computes +

    + y = a1 + a2 x1 + + a3 x12 + + (a4 + a5 x1 + + a6 x12) x2 +

    + + + +-------- Corrected Code -------- +This function computes +

    + y = a1 + a2 x1 + a3 + x12 + (a4 + a5 + x1 + a6 x12) + x2

    -------- Errors -------- -line 10 column 2 - Warning:

    attribute "align" not allowed for HTML5 -line 17 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 3 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Utilities/IO/SignalExchange/SignalTypes/SignalsForKPIs.mo ---- +---- AixLib/Fluid/FixedResistances/BaseClasses/PlugFlowTransportDelay.mo ---- -------- HTML Code --------

    - This enumeration defines the signal types that are used by BOPTEST - to compute the key performance indices (KPI). + Calculates time delay at both sides of the pipe as the difference between the + current simulation time and the inlet time of the fluid at both ends of the pipe. +

    +

    Main equation

    +

    + ∂z(x,t)/∂t + v(t) ∂z(x,t)/∂x = 0,

    - The following signal types are supported. + where z(x,t) is the spatial distribution as a function of time of any + property z of the fluid. For the inlet time propagation, z will + be replaced by the inlet time of the fluid tin. +

    +

    Implementation

    +

    + The inlet time is approached as a fluid property and its propagation follows + the one-dimensional wave equation, implemented using the spatialDistribution + function. This components requires the mass flow through the pipe and the pipe + dimensions in order to derive information about the fluid propagation. +

    +

    + The component calculates the delay time at the inlet and the outlet port of the pipe. + For the forward flow, the time delay is exposed at the output tau, + and for the backward flow, the time delay is exposed at the output tauRev. +

    +

    Assumption

    +

    + No axial mixing takes place in the pipe.

    -
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    ValueDescription
    NoneNot used for KPI
    AirZoneTemperatureAir zone temperature
    RadiativeZoneTemperatureRadiative zone temperature
    OperativeZoneTemperatureOperative zone temperature
    RelativeHumidityRelative humidity
    CO2ConcentrationCO2 concentration
    ElectricPowerElectric power from grid
    DistrictHeatingPowerThermal power from district heating
    GasPowerThermal power from natural gas
    BiomassPowerThermal power from biomass
    SolarThermalPowerThermal power from solar thermal
    FreshWaterFlowRateFreshWaterFlowRate
    -------- Corrected Code --------

    - This enumeration defines the signal types that are used by BOPTEST to - compute the key performance indices (KPI). + Calculates time delay at both sides of the pipe as the difference + between the current simulation time and the inlet time of the fluid + at both ends of the pipe. +

    +

    + Main equation +

    +

    + ∂z(x,t)/∂t + v(t) ∂z(x,t)/∂x = 0,

    - The following signal types are supported. + where z(x,t) is the spatial distribution as a function of time + of any property z of the fluid. For the inlet time + propagation, z will be replaced by the inlet time of the fluid + tin. +

    +

    + Implementation +

    +

    + The inlet time is approached as a fluid property and its propagation + follows the one-dimensional wave equation, implemented using the + spatialDistribution function. This components requires the mass flow + through the pipe and the pipe dimensions in order to derive + information about the fluid propagation. +

    +

    + The component calculates the delay time at the inlet and the outlet + port of the pipe. For the forward flow, the time delay is exposed at + the output tau, and for the backward flow, the time + delay is exposed at the output tauRev. +

    +

    + Assumption +

    +

    + No axial mixing takes place in the pipe.

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    - Value - - Description -
    - None - - Not used for KPI -
    - AirZoneTemperature - - Air zone temperature -
    - RadiativeZoneTemperature - - Radiative zone temperature -
    - OperativeZoneTemperature - - Operative zone temperature -
    - RelativeHumidity - - Relative humidity -
    - CO2Concentration - - CO2 concentration -
    - ElectricPower - - Electric power from grid -
    - DistrictHeatingPower - - Thermal power from district heating -
    - GasPower - - Thermal power from natural gas -
    - BiomassPower - - Thermal power from biomass -
    - SolarThermalPower - - Thermal power from solar thermal -
    - FreshWaterFlowRate - - FreshWaterFlowRate -
    -------- Errors -------- -line 9 column 2 - Warning: The summary attribute on the element is obsolete in HTML5 +line 7 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/FixedResistances/Validation/PlugFlowPipes/MSLAIT.mo ---- +---- AixLib/Fluid/HeatExchangers/Heater_T.mo ---- -------- HTML Code --------

    - The example contains - - experimental data from a real district heating network. - This data is used to validate this library's - - AixLib.Fluid.FixedResistances.PlugFlowPipe in - - AixLib.Fluid.FixedResistances.Validation.PlugFlowPipes.PlugFlowAIT. - This model compares its performance with the original Modelica Standard Library - pipes, using one discretization element per unit length of pipe. - For a coarser discretization, please refer to - - MSLAIT2Nodes. + Model for an ideal heater that controls its outlet temperature to + a prescribed outlet temperature.

    - Note that these three models are identical, except for the pipe model that is used: + This model forces the outlet temperature at port_b to be + no lower than the temperature of the input signal + TSet, subject to optional limits on the + capacity. + By default, the model has unlimited heating capacity.

    -

    - This comparison between different discretization levels and pipe models is made - to check the influence of the discretization and pipe model on computation time - and simulation accuracy. + The output signal Q_flow is the heat added + to the medium if the mass flow rate is from port_a to port_b. + If the flow is reversed, then Q_flow=0.

    -

    The pipes' temperatures are not initialized, thus results of outflow - temperature before approximately the first 10000 seconds should not be considered. +

    + The outlet conditions at port_a are not affected by this model, + other than for a possible pressure difference due to flow friction.

    -

    Test bench schematic

    -

    \"Schematic

    -

    Calibration

    -

    To calculate the length specific thermal resistance R of the - pipe, the thermal resistance of the surrounding ground is added.

    -

    - R=1/(0.208)+1/(2   lambda_g   Modelica.Constants.pi)   log(1/0.18)

    - Where the thermal conductivity of the ground lambda_g = 2.4 W/(m K). + If the parameter energyDynamics is different from + Modelica.Fluid.Types.Dynamics.SteadyState, + the component models the dynamic response using a first order differential equation. + The time constant of the component is equal to the parameter tau. + This time constant is adjusted based on the mass flow rate using +

    +

    + τeff = τ |ṁ| ⁄ ṁnom +

    +

    + where + τeff is the effective time constant for the given mass flow rate + ṁ and + τ is the time constant at the nominal mass flow rate + ṁnom. + This type of dynamics is equal to the dynamics that a completely mixed + control volume would have. +

    +

    + Optionally, this model can have a flow resistance. + Set dp_nominal = 0 to disable the flow friction calculation. +

    +

    + For a similar model that is a sensible cooling device, use + + AixLib.Fluid.HeatExchangers.SensibleCooler_T. + For a model that uses a control signal u ∈ [0, 1] and multiplies + this with the nominal heating or cooling power, use + + AixLib.Fluid.HeatExchangers.HeaterCooler_u + +

    +

    Limitations

    +

    + If the flow is from port_b to port_a, + then the enthalpy of the medium is not affected by this model. +

    +

    Validation

    +

    + The model has been validated against the analytical solution in + the examples + + AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet + and + + AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic.

    -------- Corrected Code --------

    - The example contains - experimental data from a real district heating network. This data - is used to validate this library's AixLib.Fluid.FixedResistances.PlugFlowPipe - in - AixLib.Fluid.FixedResistances.Validation.PlugFlowPipes.PlugFlowAIT. - This model compares its performance with the original Modelica - Standard Library pipes, using one discretization element per unit - length of pipe. For a coarser discretization, please refer to - - MSLAIT2Nodes. + Model for an ideal heater that controls its outlet temperature to a + prescribed outlet temperature.

    - Note that these three models are identical, except for the pipe model - that is used: + This model forces the outlet temperature at port_b to be + no lower than the temperature of the input signal TSet, + subject to optional limits on the capacity. By default, the model has + unlimited heating capacity.

    -

    - This comparison between different discretization levels and pipe - models is made to check the influence of the discretization and pipe - model on computation time and simulation accuracy. + The output signal Q_flow is the heat added to the medium + if the mass flow rate is from port_a to + port_b. If the flow is reversed, then + Q_flow=0. +

    +

    + The outlet conditions at port_a are not affected by this + model, other than for a possible pressure difference due to flow + friction. +

    +

    + If the parameter energyDynamics is different from + Modelica.Fluid.Types.Dynamics.SteadyState, the component + models the dynamic response using a first order differential + equation. The time constant of the component is equal to the + parameter tau. This time constant is adjusted based on + the mass flow rate using +

    +

    + τeff = τ |ṁ| ⁄ ṁnom +

    +

    + where τeff is the effective time constant for the + given mass flow rate ṁ and τ is the time constant at + the nominal mass flow rate ṁnom. This type of + dynamics is equal to the dynamics that a completely mixed control + volume would have. +

    +

    + Optionally, this model can have a flow resistance. Set + dp_nominal = 0 to disable the flow friction calculation.

    - The pipes' temperatures are not initialized, thus results of outflow - temperature before approximately the first 10000 seconds should not - be considered. + For a similar model that is a sensible cooling device, use AixLib.Fluid.HeatExchangers.SensibleCooler_T. + For a model that uses a control signal u ∈ [0, 1] and + multiplies this with the nominal heating or cooling power, use + AixLib.Fluid.HeatExchangers.HeaterCooler_u

    - Test bench schematic + Limitations

    - \"Schematic + If the flow is from port_b to port_a, then + the enthalpy of the medium is not affected by this model.

    - Calibration + Validation

    - To calculate the length specific thermal resistance R of - the pipe, the thermal resistance of the surrounding ground is added. -

    -

    - R=1/(0.208)+1/(2   lambda_g   Modelica.Constants.pi)   - log(1/0.18) -

    -

    - Where the thermal conductivity of the ground lambda_g = - 2.4 W/(m K). + The model has been validated against the analytical solution in the + examples AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet + and + AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic.

    -------- Errors -------- -line 56 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 29 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/HeatExchangers/PrescribedOutlet.mo ---- +---- AixLib/Media/Specialized/Air/PerfectGas.mo ---- -------- HTML Code -------- + Function to set the state for given pressure, enthalpy and species concentration. + + The thermodynamic state record + is computed from density d, temperature T and composition X. + + Saturation pressure of water above the triple point temperature is computed from temperature. It's range of validity is between + 273.16 and 373.16 K. Outside these limits a less accurate result is returned. + + Derivative function of + + AixLib.Media.Specialized.Air.PerfectGas.saturationPressureLiquid + + Pressure is returned from the thermodynamic state record input as a simple assignment. + + Temperature is returned from the thermodynamic state record input as a simple assignment. + + Density is computed from pressure, temperature and composition in the thermodynamic state record applying the ideal gas law. + + Specific entropy is calculated from the thermodynamic state record, assuming ideal gas behavior and including entropy of mixing. Liquid or solid water is not taken into account, the entire water content X[1] is assumed to be in the vapor state (relative humidity below 1.0). + + Temperature as a function of specific enthalpy and species concentration. + The pressure is input for compatibility with the medium models, but the temperature + is independent of the pressure. +

    - Model that allows specifying the temperature and mass fraction of the fluid - that leaves the model from port_b. + This data record contains the coefficients for perfect gases.

    + + +

    - This model forces the outlet temperature at port_b to be equal to the temperature - of the input signal TSet, subject to optional limits on the - heating or cooling capacity QMax_flow ≥ 0 and QMin_flow ≤ 0. - Similarly than for the temperature, - this model also forces the outlet water mass fraction at port_b to be - no lower than the - input signal X_wSet, subject to optional limits on the - maximum water vapor mass flow rate that is added, as - described by the parameter mWatMax_flow. - By default, the model has unlimited capacity, but control of temperature - and humidity can be subject to capacity limits, or be disabled. + This package contains a thermally perfect model of moist air.

    - The output signal Q_flow is the heat added (for heating) or subtracted (for cooling) - to the medium if the flow rate is from port_a to port_b. - If the flow is reversed, then Q_flow=0. + A medium is called thermally perfect if

    +

    - The outlet conditions at port_a are not affected by this model. + In addition, this medium model is calorically perfect, i.e., the + specific heat capacities at constant pressure cp + and constant volume cv are both constant (Bower 1998).

    - If the parameter energyDynamics is not equal to - Modelica.Fluid.Types.Dynamics.SteadyState, - the component models the dynamic response using a first order differential equation. - The time constant of the component is equal to the parameter tau. - This time constant is adjusted based on the mass flow rate using + This medium uses the ideal gas law

    - τeff = τ |ṁ| ⁄ ṁnom + ρ = p ⁄(R T),

    where - τeff is the effective time constant for the given mass flow rate - ṁ and - τ is the time constant at the nominal mass flow rate - ṁnom. - This type of dynamics is equal to the dynamics that a completely mixed - control volume would have. -

    -

    - Optionally, this model can have a flow resistance. - If no flow resistance is requested, set dp_nominal=0. -

    -

    - For a model that uses a control signal u ∈ [0, 1] and multiplies - this with the nominal heating or cooling power, use - - AixLib.Fluid.HeatExchangers.HeaterCooler_u - -

    -

    Limitations

    -

    - This model only adds or removes heat or water vapor for the flow from - port_a to port_b. - The enthalpy of the reverse flow is not affected by this model. + ρ is the density, + p is the pressure, + R is the gas constant and + T is the temperature.

    - If this model is used to cool air below the dew point temperature, the water mass fraction - will not change. + The enthalpy is computed using the convention that h=0 + if T=0 °C and no water vapor is present.

    - Note that for use_TSet = false, the enthalpy of the leaving fluid - will not be changed, even if moisture is added. The enthalpy added (or removed) - by the change in humidity is neglected. To properly account for change in enthalpy - due to humidification, use instead - - AixLib.Fluid.Humidifiers.SprayAirWasher_X. + Note that for typical building simulations, the media + AixLib.Media.Air + should be used as it leads generally to faster simulation.

    -

    Validation

    +

    References

    - The model has been validated against the analytical solution in - the examples - - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet - and - - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic. + Bower, William B. A primer in fluid mechanics: Dynamics of flows in one + space dimension. CRC Press. 1998.

    -------- Corrected Code -------- +Function to set the state for given pressure, enthalpy and species +concentration. +The thermodynamic state record is computed from density d, temperature +T and composition X. +Saturation pressure of water above the triple point temperature is +computed from temperature. It's range of validity is between 273.16 and +373.16 K. Outside these limits a less accurate result is returned. +Derivative function of +AixLib.Media.Specialized.Air.PerfectGas.saturationPressureLiquid +Pressure is returned from the thermodynamic state record input as a +simple assignment. +Temperature is returned from the thermodynamic state record input as a +simple assignment. +Density is computed from pressure, temperature and composition in the +thermodynamic state record applying the ideal gas law. +Specific entropy is calculated from the thermodynamic state record, +assuming ideal gas behavior and including entropy of mixing. Liquid or +solid water is not taken into account, the entire water content X[1] is +assumed to be in the vapor state (relative humidity below 1.0). +Temperature as a function of specific enthalpy and species +concentration. The pressure is input for compatibility with the medium +models, but the temperature is independent of the pressure.

    - Model that allows specifying the temperature and mass fraction of the - fluid that leaves the model from port_b. + This data record contains the coefficients for perfect gases.

    +

    - This model forces the outlet temperature at port_b to be - equal to the temperature of the input signal TSet, - subject to optional limits on the heating or cooling capacity - QMax_flow ≥ 0 and QMin_flow ≤ 0. Similarly - than for the temperature, this model also forces the outlet water - mass fraction at port_b to be no lower than the input - signal X_wSet, subject to optional limits on the maximum - water vapor mass flow rate that is added, as described by the - parameter mWatMax_flow. By default, the model has - unlimited capacity, but control of temperature and humidity can be - subject to capacity limits, or be disabled. + This package contains a thermally perfect model of moist air.

    - The output signal Q_flow is the heat added (for heating) - or subtracted (for cooling) to the medium if the flow rate is from - port_a to port_b. If the flow is reversed, - then Q_flow=0. + A medium is called thermally perfect if

    +

    - The outlet conditions at port_a are not affected by this - model. + In addition, this medium model is calorically perfect, i.e., + the specific heat capacities at constant pressure + cp and constant volume cv are + both constant (Bower 1998).

    - If the parameter energyDynamics is not equal to - Modelica.Fluid.Types.Dynamics.SteadyState, the component - models the dynamic response using a first order differential - equation. The time constant of the component is equal to the - parameter tau. This time constant is adjusted based on - the mass flow rate using + This medium uses the ideal gas law

    - τeff = τ |ṁ| ⁄ ṁnom -

    -

    - where τeff is the effective time constant for the - given mass flow rate ṁ and τ is the time constant at - the nominal mass flow rate ṁnom. This type of - dynamics is equal to the dynamics that a completely mixed control - volume would have. -

    -

    - Optionally, this model can have a flow resistance. If no flow - resistance is requested, set dp_nominal=0. -

    -

    - For a model that uses a control signal u ∈ [0, 1] and - multiplies this with the nominal heating or cooling power, use - AixLib.Fluid.HeatExchangers.HeaterCooler_u + ρ = p ⁄(R T),

    -

    - Limitations -

    - This model only adds or removes heat or water vapor for the flow from - port_a to port_b. The enthalpy of the - reverse flow is not affected by this model. + where ρ is the density, p is the pressure, R is + the gas constant and T is the temperature.

    - If this model is used to cool air below the dew point temperature, - the water mass fraction will not change. + The enthalpy is computed using the convention that h=0 if + T=0 °C and no water vapor is present.

    - Note that for use_TSet = false, the enthalpy of the - leaving fluid will not be changed, even if moisture is added. The - enthalpy added (or removed) by the change in humidity is neglected. - To properly account for change in enthalpy due to humidification, use - instead AixLib.Fluid.Humidifiers.SprayAirWasher_X. + Note that for typical building simulations, the media AixLib.Media.Air should be used as + it leads generally to faster simulation.

    - Validation + References

    - The model has been validated against the analytical solution in the - examples AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet - and - AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic. + Bower, William B. A primer in fluid mechanics: Dynamics of flows + in one space dimension. CRC Press. 1998.

    -------- Errors -------- -line 34 column 2 - Warning:

    attribute "align" not allowed for HTML5 +line 25 column 2 - Warning:

    attribute "align" not allowed for HTML5 ----- AixLib/Fluid/Actuators/BaseClasses/PartialDamperExponential.mo ---- +---- AixLib/BoundaryConditions/Validation/BESTEST/WD100.mo ---- -------- HTML Code -------- -

    - Partial model for air dampers with exponential opening characteristics. - This is the base model for air dampers. - The model implements the functions that relate the opening signal and the - flow coefficient. - The model also defines parameters that are used by different air damper - models. -

    -

    - The model is as in ASHRAE 825-RP except that a control signal of - y=0 means the damper is closed, and y=1 means - the damper is open. - This is opposite of the implementation of ASHRAE 825-RP, but used here - for consistency within this library. -

    -

    - For yL < y < yU, the damper characteristics is: -

    -

    - kd(y) = exp(a+b (1-y)) -

    -

    - where kd is the loss coefficient (total pressure drop divided - by dynamic pressure) and y is the fractional opening. -

    -

    - Outside this range, the damper characteristics is defined by a quadratic polynomial that - matches the damper resistance at y=0 and y=yL or - y=yU and y=1, respectively. - In addition, the polynomials are such that kd(y) is differentiable in - y and the derivative is continuous. -

    -

    - The damper characteristics is then used to compute the flow coefficient k(y) as: -

    -

    - k(y) = (2 ρ ⁄ kd(y))1/2 A -

    -

    - where A is the face area, which is computed using the nominal - mass flow rate m_flow_nominal, the nominal velocity - v_nominal and the density of the medium. -

    -

    - ASHRAE 825-RP lists the following parameter values as typical (note that the - default values in the model correspond to opposed blades). -
    -

    -
    - - - - - - - - +

    WD100: Base Case

    +

    Weather data file : WD100.epw

    +

    Table 1: Site Data for Weather file WD100.epw

    +
    opposed bladessingle blades
    yL15/9015/90
    yU55/9065/90
    + + - + + - + + - + +

    Latitude

    39.833° north
    k10.2 to 0.50.2 to 0.5

    Longitude

    104.65° west
    a-1.51-1.51

    Altitude

    1650 m
    b0.105*900.0842*90

    Time Zone

    -7
    -

    - (The loss coefficient in fully closed position k0 is computed based on the leakage coefficient - and the coefficient in fully open position.) -

    -

    References

    -

    - P. Haves, L. K. Norford, M. DeSimone and L. Mei, - A Standard Simulation Testbed for the Evaluation of Control Algorithms & Strategies, - ASHRAE Final Report 825-RP, Atlanta, GA. -

    +

    This model is a template for all the other test cases. + It allows to extrapolate all the weather data from the Reader TMY3 for a specific location, incliation and azimuth. + The model + AixLib.BoundaryConditions.Validation.IsotropicAndPerezDiffuseRadiation + outputs radiation data using the available Isotropic and Perez methodlogies. + The sky temperature is calculated using both the Horizontal radiation model, + from data reader weaBusHorRad and the dew point temperature plus sky cover model from the datareader weaBusSkyCovDewTem.

    -------- Corrected Code -------- +

    + WD100: Base Case +

    - Partial model for air dampers with exponential opening - characteristics. This is the base model for air dampers. The model - implements the functions that relate the opening signal and the flow - coefficient. The model also defines parameters that are used by - different air damper models. -

    -

    - The model is as in ASHRAE 825-RP except that a control signal of - y=0 means the damper is closed, and y=1 - means the damper is open. This is opposite of the implementation of - ASHRAE 825-RP, but used here for consistency within this library. -

    -

    - For yL < y < yU, the damper characteristics is: -

    -

    - kd(y) = exp(a+b (1-y)) -

    -

    - where kd is the loss coefficient (total pressure drop divided - by dynamic pressure) and y is the fractional opening. -

    -

    - Outside this range, the damper characteristics is defined by a - quadratic polynomial that matches the damper resistance at - y=0 and y=yL or y=yU and - y=1, respectively. In addition, the polynomials are such - that kd(y) is differentiable in y and the - derivative is continuous. -

    -

    - The damper characteristics is then used to compute the flow - coefficient k(y) as: -

    -

    - k(y) = (2 ρ ⁄ kd(y))1/2 A -

    -

    - where A is the face area, which is computed using the nominal - mass flow rate m_flow_nominal, the nominal velocity - v_nominal and the density of the medium. + Weather data file : WD100.epw

    - ASHRAE 825-RP lists the following parameter values as typical (note - that the default values in the model correspond to opposed - blades).
    + Table 1: Site Data for Weather file WD100.epw

    - - - - - - - - - - - +
    - opposed blades - - single blades -
    - yL - - 15/90 - - 15/90 -
    - - - -
    - yU - - 55/90 +

    + Latitude +

    		- 65/90 +

    + 39.833° north +

    - k1 - - 0.2 to 0.5 +

    + Longitude +

    		- 0.2 to 0.5 +

    + 104.65° west +

    - a - - -1.51 +

    + Altitude +

    		- -1.51 +

    + 1650 m +

    - b - - 0.105*90 +

    + Time Zone +

    		- 0.0842*90 +

    + -7 +

    - (The loss coefficient in fully closed position k0 is - computed based on the leakage coefficient and the coefficient in - fully open position.) -

    -

    - References -

    -

    - P. Haves, L. K. Norford, M. DeSimone and L. Mei, A Standard - Simulation Testbed for the Evaluation of Control Algorithms & - Strategies, ASHRAE Final Report 825-RP, Atlanta, GA. -

    -