Buildings.Media.PerfectGases.Examples

Collection of models that illustrate model use and test models

Package Content

NameDescription
MoistAirComparison  
MoistAirDerivativeCheck  
MoistAirNonsaturatedDerivativeCheck  
Buildings.Media.PerfectGases.Examples.TestMoistAir TestMoistAir  
Buildings.Media.PerfectGases.Examples.TestMoistAirNonsaturated TestMoistAirNonsaturated  


Buildings.Media.PerfectGases.Examples.MoistAirComparison

Information


This example compares the perfect medium model Buildings.Media.PerfectGases.MoistAir with the ideal gas model from Modelica.Media.Air.MoistAir



Parameters

TypeNameDefaultDescription
PressureP101325Pressure [Pa]

Modelica definition

model MoistAirComparison

   package PerfectMedium = Buildings.Media.PerfectGases.MoistAir;
   package IdealMedium =   Modelica.Media.Air.MoistAir;

    Modelica.SIunits.SpecificEnthalpy hLiqPer "Liquid phase enthalpy";
    Modelica.SIunits.SpecificEnthalpy hLiqIde "Liquid phase enthalpy";
    Modelica.SIunits.SpecificEnthalpy hStePer "Water vapor enthalpy";
    Modelica.SIunits.SpecificEnthalpy hSteIde "Water vapor enthalpy";
    Modelica.SIunits.SpecificEnthalpy hAirPer "Air enthalpy";
    Modelica.SIunits.SpecificEnthalpy hAirIde "Air enthalpy";

    Modelica.SIunits.SpecificEnthalpy hMixPer "Mixture specific enthalpy";
    Modelica.SIunits.SpecificEnthalpy hMixIde "Mixture specific enthalpy";

    Modelica.SIunits.MassFraction X[2] = {0.01, 0.09};
    Modelica.SIunits.Temperature T "Temperature";
    Modelica.SIunits.Conversions.NonSIunits.Temperature_degC T_degC 
    "Temperature";

    Real errLiq "Error liquid phase";
    Real errSte "Error steam phase";
    Real errAir "Error gas mixture";
    Real errMix "Error gas mixture";
    Real errT 
    "Error in temperature when enthalpy-temperature relation is inverted";

    parameter Modelica.SIunits.Pressure P = 101325 "Pressure";

equation 
    T_degC = 1+99*time; // exclude 0, to avoid large relative error
    T = 273.15 + T_degC;
    hLiqPer=PerfectMedium.enthalpyOfLiquid(T);
    hStePer=PerfectMedium.enthalpyOfCondensingGas(T);
    hAirPer=PerfectMedium.enthalpyOfGas(T, X);
    hLiqIde=IdealMedium.enthalpyOfLiquid(T);
    hSteIde=IdealMedium.enthalpyOfCondensingGas(T);
    hAirIde=IdealMedium.enthalpyOfGas(T, X);

    hMixPer=PerfectMedium.h_pTX(P, T, X);
    hMixIde=IdealMedium.h_pTX(P, T, X);

    errLiq * abs(hLiqIde+1E-3) = hLiqIde - hLiqPer;
    errSte * abs(hSteIde+1E-3) = hSteIde - hStePer;
    errAir * abs(hAirIde+1E-3) = hAirIde - hAirPer;
    errMix * abs(hMixIde+1E-3) = hMixIde - hMixPer;
    errT * T = T - PerfectMedium.T_phX(P, PerfectMedium.h_pTX(P, T, X), X);

    assert( abs(errLiq) < 0.09, "Error too large. Check medium model.");
    assert( abs(errSte) < 0.01, "Error too large. Check medium model.");
    assert( abs(errAir) < 0.01, "Error too large. Check medium model.");
    assert( abs(errMix) < 2.01, "Error too large. Check medium model.");
    assert( abs(errT) < 0.01, "Error too large. Check medium model.");

end MoistAirComparison;

Buildings.Media.PerfectGases.Examples.MoistAirDerivativeCheck

Information


This example checks whether the function derivative is implemented correctly. If the derivative implementation is not correct, the model will stop with an assert statement.



Modelica definition

model MoistAirDerivativeCheck

   package Medium = Buildings.Media.PerfectGases.MoistAir;

    Modelica.SIunits.SpecificEnthalpy hLiqSym "Liquid phase enthalpy";
    Modelica.SIunits.SpecificEnthalpy hLiqCod "Liquid phase enthalpy";
    Modelica.SIunits.SpecificEnthalpy hSteSym "Water vapor enthalpy";
    Modelica.SIunits.SpecificEnthalpy hSteCod "Water vapor enthalpy";
    Modelica.SIunits.SpecificEnthalpy hAirSym "Dry air enthalpy";
    Modelica.SIunits.SpecificEnthalpy hAirCod "Dry air enthalpy";

initial equation 
     hLiqSym = hLiqCod;
     hSteSym = hSteCod;
     hAirSym = hAirCod;
equation 
    hLiqCod=Medium.enthalpyOfLiquid(time);
    der(hLiqCod)=der(hLiqSym);
    assert(abs(hLiqCod-hLiqSym) < 1E-2, "Model has an error");

    hSteCod=Medium.enthalpyOfCondensingGas(time);
    der(hSteCod)=der(hSteSym);
    assert(abs(hSteCod-hSteSym) < 1E-2, "Model has an error");

    hAirCod=Medium.enthalpyOfDryAir(time);
    der(hAirCod)=der(hAirSym);
    assert(abs(hAirCod-hAirSym) < 1E-2, "Model has an error");

end MoistAirDerivativeCheck;

Buildings.Media.PerfectGases.Examples.MoistAirNonsaturatedDerivativeCheck

Information


This example checks whether the function derivative is implemented correctly. If the derivative implementation is not correct, the model will stop with an assert statement.



Modelica definition

model MoistAirNonsaturatedDerivativeCheck

   package Medium = Buildings.Media.PerfectGases.MoistAirNonsaturated;

    Modelica.SIunits.SpecificEnthalpy hLiqSym "Liquid phase enthalpy";
    Modelica.SIunits.SpecificEnthalpy hLiqCod "Liquid phase enthalpy";
    Modelica.SIunits.SpecificEnthalpy hSteSym "Water vapor enthalpy";
    Modelica.SIunits.SpecificEnthalpy hSteCod "Water vapor enthalpy";
    Modelica.SIunits.SpecificEnthalpy hAirSym "Dry air enthalpy";
    Modelica.SIunits.SpecificEnthalpy hAirCod "Dry air enthalpy";

initial equation 
     hLiqSym = hLiqCod;
     hSteSym = hSteCod;
     hAirSym = hAirCod;
equation 
    hLiqCod=Medium.enthalpyOfLiquid(time);
    der(hLiqCod)=der(hLiqSym);
    assert(abs(hLiqCod-hLiqSym) < 1E-2, "Model has an error");

    hSteCod=Medium.enthalpyOfCondensingGas(time);
    der(hSteCod)=der(hSteSym);
    assert(abs(hSteCod-hSteSym) < 1E-2, "Model has an error");

    hAirCod=Medium.enthalpyOfDryAir(time);
    der(hAirCod)=der(hAirSym);
    assert(abs(hAirCod-hAirSym) < 1E-2, "Model has an error");

end MoistAirNonsaturatedDerivativeCheck;

Buildings.Media.PerfectGases.Examples.TestMoistAir Buildings.Media.PerfectGases.Examples.TestMoistAir

Buildings.Media.PerfectGases.Examples.TestMoistAir

Information


This is a simple test for the medium model. It uses the test model described in

Modelica.Media.UsersGuide.MediumDefinition.TestOfMedium.

Extends from Modelica.Media.Examples.Tests.Components.PartialTestModel (Basic test model to test a medium).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium model
AbsolutePressurep_startMedium.p_defaultInitial value of pressure [Pa]
TemperatureT_startMedium.T_defaultInitial value of temperature [K]
SpecificEnthalpyh_startMedium.h_defaultInitial value of specific enthalpy [J/kg]
RealX_start[Medium.nX]Medium.X_defaultInitial value of mass fractions

Connectors

TypeNameDescription
replaceable package MediumMedium model

Modelica definition

model TestMoistAir
  extends Modelica.Media.Examples.Tests.Components.PartialTestModel(
     redeclare package Medium = 
          Buildings.Media.PerfectGases.MoistAir);

end TestMoistAir;

Buildings.Media.PerfectGases.Examples.TestMoistAirNonsaturated Buildings.Media.PerfectGases.Examples.TestMoistAirNonsaturated

Buildings.Media.PerfectGases.Examples.TestMoistAirNonsaturated

Information


This is a simple test for the medium model. It uses the test model described in

Modelica.Media.UsersGuide.MediumDefinition.TestOfMedium.

Extends from Modelica.Media.Examples.Tests.Components.PartialTestModel (Basic test model to test a medium).

Parameters

TypeNameDefaultDescription
replaceable package MediumPartialMediumMedium model
AbsolutePressurep_startMedium.p_defaultInitial value of pressure [Pa]
TemperatureT_startMedium.T_defaultInitial value of temperature [K]
SpecificEnthalpyh_startMedium.h_defaultInitial value of specific enthalpy [J/kg]
RealX_start[Medium.nX]Medium.X_defaultInitial value of mass fractions

Connectors

TypeNameDescription
replaceable package MediumMedium model

Modelica definition

model TestMoistAirNonsaturated
  extends Modelica.Media.Examples.Tests.Components.PartialTestModel(
     redeclare package Medium = 
          Buildings.Media.PerfectGases.MoistAirNonsaturated);

end TestMoistAirNonsaturated;

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