Fixed PartialSimpleIdealGasMedium.setState_psX

[RaphaelGebhart]

Regression test passed.

[CorentinLepais]

There was indeed a small error in the formula, even if the results do not change. From a physics point of view, I would have written it like below to keep the exponential without unit and to make more obvious that it calculates a temperature :
reference_T*exp(s/cp_const +R_gas/cp_const*Modelica.Math.log(p/reference_p))

Since this error is also in the MSL, should an issue be created in the MSL repository?

[RaphaelGebhart]

Yes i already created one: modelica/ModelicaStandardLibrary#4749

And yes Im also in favor of the version you suggested. Lets chose this one. I will run a regression test with the new version.

[RaphaelGebhart]

Regression test passed.

@CorentinLepais could you briefly check out the branch and confirm everything looks good (e.g, with the example below)?

model PartialSimleIdealGasMediumTest "Checks Modelica.Media.Air.SimpleAir.setState_psX"

  replaceable package Medium = ThermofluidStream.Media.myMedia.Air.SimpleAir;
  Medium.AbsolutePressure p=pressureSawTooth.y;
  Medium.Temperature T=temperatureSawTooth.y;
  Medium.SpecificEntropy s = Modelica.Media.Air.SimpleAir.specificEntropy_pTX(p,T, Medium.X_default);
  Medium.ThermodynamicState state = Medium.setState_psX(p,s); // This requires modification
  Medium.Temperature T1 = Medium.temperature_ps(p,s);

  Boolean check = abs(T-T1) < Modelica.Constants.eps; // Check passed

  Modelica.Blocks.Sources.SawTooth pressureSawTooth(
    amplitude=2e5,
    period=0.5,
    offset=0.5e5,
    startTime=0.1) annotation (Placement(transformation(extent={{-10,12},{10,32}})));
  Modelica.Blocks.Sources.SawTooth temperatureSawTooth(
    amplitude=200,
    period=0.5,
    offset=273.15,
    startTime=0.2) annotation (Placement(transformation(extent={{-10,-30},{10,-10}})));

end PartialSimleIdealGasMediumTest;

If you approve, we can proceed with the merge.

I also created a pull request for the MSL: modelica/ModelicaStandardLibrary#4782