Issue with ReferenceMoistAir Beyond 500°C

[aci31]

Hi,

I recently faced an issue when using Modelica.Media.Air.ReferenceMoistAir.
When using the BaseProperties (so all volume based components, like the boundary or vessel), there is a "Index out of bound" issue happening only when the temperature is beyond 500°C.

I used Dymola 25x and MSL 4.0.0 (I have the same issue in Dymola 2020x with MSL 3.2.4).

Please find below a very simple example reproducing the error:

model BugReferenceMoistAir
  //The model just bug (Index out of bounds) when temperature reaches 500°C
  package Medium=Modelica.Media.Air.ReferenceMoistAir;
  Medium.BaseProperties medium;
equation 
  medium.p=1e5;
  medium.T=273.15+time*1000;
  medium.Xi=Medium.reference_X[1:Medium.nXi];

  annotation (uses(Modelica(version="4.0.0")));
end BugReferenceMoistAir;

And the error message given by Dymola:

Error: The following error was detected at time: 0.5
Index out of bounds
Failed condition: (j >= 1) && (j <= a.dims[0])
The stack of functions is:
Modelica.Media.Air.ReferenceMoistAir.Utilities.h_dis_pTX
Modelica.Media.Air.ReferenceMoistAir.Utilities.h_pTX
Modelica.Media.Air.ReferenceMoistAir.Utilities.u_pTX(100000.0, medium.T, medium.Xi)

The error triggered by Modelica.Media.Air.ReferenceMoistAir.Utilities.h_dis_pTX() comes from the fact that the functions (like Modelica.Media.Air.ReferenceMoistAir.Utilities.u_pTX()) in BaseProperties are called using Xi instead of X. Indeed, the function Modelica.Media.Air.ReferenceMoistAir.Utilities.h_dis_pTX() that is triggering the error is using X[1] and X[2] (obviously not available when using only Xi).
I duplicated the package Modelica.Media.Air.ReferenceMoistAir, and I modified all calls in BaseProperties to use X instead of Xi and it solved the error.

I looked in different Medium.BaseProperties, and all calls to functions using Xi... maybe we should correct that ?