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Change the reference enthalpy and reference entropy of Ideal gas model

#10447  Permalink Top

Change the reference enthalpy and reference entropy of Ideal gas model

Jan-17-21 12:35:42

Given the following simple model:

Code:

 

model Test "Model based on built-in, ideal-gas model from Modelica.Media"

  package Medium = Modelica.Media.IdealGases.SingleGases.NH3 "Medium model";

  parameter Medium.AbsolutePressure p = 0.1e5;

  parameter Medium.Temperature T0 = 300;

  parameter Real dTdt (unit = "K/s") = 100;

  Medium.BaseProperties medium;

  Medium.Temperature T = medium.T;

  Medium.SpecificEnthalpy h = medium.h;

  Medium.SpecificInternalEnergy u = medium.u;

  Medium.SpecificEntropy s = Medium.specificEntropy(medium.state);

equation

  medium.p = p;

  T = T0 + dTdt * time;

  annotation(experiment(StartTime = 0, StopTime = 1, Tolerance = 0.0001, Interval = 0.0002));

end Test;

I would like to change the reference enthalpy and reference entropy of the medium. From what I could understand, the reference enthalpy is fixed in package Modelica.Media.IdealGases.Common.Functions:

Code:


constant Boolean excludeEnthalpyOfFormation=true;

constant Modelica.Media.Interfaces.Choices.ReferenceEnthalpy referenceChoice=Modelica.Media.Interfaces.Choices.ReferenceEnthalpy.ZeroAt0K;

constant Modelica.Media.Interfaces.Types.SpecificEnthalpy h_offset=0.0;

But I don't understand how to override these constants in my model.

For the reference entropy, I couldn't find where it is fixed in the code.

Thanks!

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