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RGP file for CO2

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Old   November 16, 2006, 04:27
Default RGP file for CO2
  #1
Alessandro
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I have to perform a calculation on a heat exchanger in which one of the fluid is CO2. I need a CFX RGP file covering the liquid, the gas and the supecritcal region of the phase state diagram. Is there anyone which has one already prepared or at least files covering pieces of the whole diagram?
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Old   November 16, 2006, 13:34
Default Re: RGP file for CO2
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Phil
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You could use the Redlich Kwong EOS, for which the solver builds the tables internally.
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Old   November 16, 2006, 16:50
Default Re: RGP file for CO2
  #3
HekLer
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So you are going to perform phase change modelling then as well?

What phase change model are you going to use?

The internal (mentioned by Phil) & presupplied tables are only appropriate for the equilibrium model.

You could pick an equation of state and create your own RGP table as well.
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Old   November 16, 2006, 17:38
Default Re: RGP file for CO2
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deLuther
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I think that CFX is suitable only to superheat region, as stated in reference to RGP-file. (at least for version 5.7). Am I wrong?
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Old   November 17, 2006, 02:22
Default Re: RGP file for CO2
  #5
HekLeR
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Certainly CFX can calculate flows of both liquids & vapours.

The doc for the RGP file certainly implies that perhaps you can only use it for superheated vapours.

However, if you carefully look at the file format you could use it for subcooled liquids as well. The file just gives material properties a f(T,p).

You just need to appropriately fill the "superheat" tables with subcooled liquid properties instead, for a liquid.

You make one material for the liquid with a liquid RGP file, one for the gas with a gas RGP file and throw the saturation properties into either, doesn't matter.

Since you can put multiple materials into a single RGP file a single file can hold liquid, vapour and saturation data.

One small caveat is that you need to add the following parameter:


PROPERITES:
..
RGP Liquid Properties = Subcooled
END


to the liquid material.
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