Problem with molar mass in media library

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Problem with molar mass in media library

Problem with molar mass in media library

Nov-18-16 20:06:52

Hi,

I wanted to use a gas mixture with varying composition and got a problem while looking at the molar mass. Following is a simple test:

Code:


model molarMassesTest "Test gas mixtures"

  extends Modelica.Icons.Example;

  package Medium = Modelica.Media.IdealGases.MixtureGases.SimpleNaturalGas "Medium model";

  Medium.BaseProperties medium();

  parameter Real data[:]=medium.MMX;

  Real molm "molar mass from media library";

  Real molm2 "molar mass calculated by myself";

equation

  medium.X = {0.0, 0.0, 0.0, 0.0, 0.0+time, 1.0-time};

  medium.p = 100000;

  medium.T = 300;

  molm = medium.MM;

  molm2 = 1 / sum(medium.state.X[j] / data[j] for j in 1:size(medium.state.X, 1));

end molarMassesTest;

It seems, that the molar mass from media library is constant. This shouldn't because the composition is changing. I checked MixtureGasNase and the function there is identical to the function for molm2. Did I miss something or made a mistake?

Thanks in advance for your help !