Buildings.Media.PerfectGases.Examples

Package Content

Name	Description
MoistAirComparison
MoistAirDerivativeCheck
TestMoistAir

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

Type	Name	Default	Description
replaceable package PerfectMedium		Buildings.Media.PerfectGases...
replaceable package IdealMedium		Modelica.Media.Air.MoistAir
Pressure	P	101325	Pressure [Pa]

Connectors

Type	Name	Description
replaceable package PerfectMedium
replaceable package IdealMedium

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.CelsiusTemperature 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 = 100*time;
    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 * hLiqIde = hLiqIde - hLiqPer;
    errSte * hSteIde = hSteIde - hStePer;
    errAir * hAirIde = hAirIde - hAirPer;
    errMix * hMixIde = hMixIde - hMixPer;
  
    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) < 0.01, "Error too large. Check medium model.");
  
    errT * T = T - PerfectMedium.T_phX(P, PerfectMedium.h_pTX(P, T, X), X);
    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.

Parameters

Type	Name	Default	Description
replaceable package Medium		Buildings.Media.PerfectGases...

Connectors

Type	Name	Description
replaceable package Medium

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.TestMoistAir

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium model
AbsolutePressure	p_start	Medium.p_default	Initial value of pressure [Pa]
Temperature	T_start	Medium.T_default	Initial value of temperature [K]
Density	h_start	Medium.h_default	Initial value of specific enthalpy [kg/m3]
Real	X_start[Medium.nX]	Medium.X_default	Initial value of mass fractions

Connectors

Type	Name	Description
replaceable package Medium		Medium model

Modelica definition

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