Thermal Systems library - How to access gas under 200 K?

Question

Im trying to develop a model of a tuna freezer that operates a low temperatures down to -90 degree Celsius. The process is LNG ca -140 degree Celsius -> air cycle ca. -120 degree Celsius -> dry air freezing chamber -90 degree Celsius. The problem Im facing is that the minimum temperature for the dry air gas in Dymola seems to be 200 K(-73.15 degree Celsius). But also the values of the VLE Fluid seems a bit strange. Do anyone have an idea how to get a fluid with lower Kelvin.

System in Dymola

Kind regards, Sondre

score 0 · Answer 1 · answered Apr 14 '20 at 09:51

0

I see that you are using the library TIL (or ThermalSystems). I don't know the limit of the basic dryAir. But there is one valid between 13.3 - 3000K :

TSMediaXTR.DRYAIR   
Temperature range: 13.3 - 3000 Kelvin. (Thermophysical properties may differ to models with smaller range.)

You can use it via a record (Replace TS by TILMedia if you have the TIL library):

record TSMedia_DryAir2
  extends TSMedia.GasTypes.BaseGas(
    final fixedMixingRatio=false,
    final nc_propertyCalculation=1,
    final gasNames={"TSMediaXTR.DRYAIR"},
    final mixingRatio_propertyCalculation={1},
    final condensingIndex=0);
end TSMedia_DryAir2;

Regarding VLE value, what is the vle you selected ?

answered Apr 14 '20 at 09:51

Arnaud

29
1

Thank you Arnaud! I am using Refprop. Air – Sondre Seglem Bekken Apr 14 '20 at 12:03
Do you know how low temperature of Refprop.Air can go? – Sondre Seglem Bekken Apr 15 '20 at 08:12
What will triple point mean and what does (Thermophysical properties may differ to models with smaller range.) mean? – Sondre Seglem Bekken May 20 '20 at 17:29

Thermal Systems library - How to access gas under 200 K?

1 Answers1