4 replies to this topic

[breizh]

Hi ,

Consider this resource to support your work.

Hope this helps

 

Breizh

[Art Montemayor]

You cannot expect to "model" any process of this type without complete domination of the thermodyamic and phase equilibria properties of the fluid in question.  I repeat the following from a very previous thread: "More chemical engineers should use - or learn how to use - the Mollier Diagram or the equivalent Temperature-Entropy Diagram."  I highly recommend you undertake a concentrated study of this material.

 

You do not refer to "PVT" data.  Rather you should use the thermodynamic data base (as I have very, very often shown in many past threads) or use the graphical data ably furnished by Breizh.  The answer(s) to your query are all contained therein.

 

You fail to explain your query in an accurate, engineering manner.  WHAT, specifically, are you proposing to "flash"??  If you are expanding the saturated gas phase above the saturated liquid, that is NOT flashing.  You can only flash a liquid.  (and flashing liquid CO₂ produces dry ice snow - which I don't think you want)  That basic misunderstanding may be the reason for your not understanding the process.

I don't know what you call a "cannister" or who "Mosa" is, so I can only speculate that you have a small pressure cylinder filled with CO₂ liquid at saturated conditions of atmospheric temperature.  This is the normal, usual case for all CO₂ cylinders - regardless of size.  They are normally filled with liquid CO₂ at approximately 1,100 psia - which corresponds to the saturated pressure of the liquid.  The pressure vessel is filled to approximately 80-85% of liquid capacity in order to allow for a vapor space that allows for liquid expansion upon temperature increase.  This is known as high pressure liquid CO₂.  Carbonation of water or soda is done by regulating the saturated vapor over the liquid down to the usual atmospheric pressure.  This expansion of the vapor space causes an adiabatic vaporization of the liquid inside and subsequently cools down the contents (including the pressure vessel) unless the vessel is kept slightly warm or the extraction of the vapor is relatively slow.  Is that what you are trying to "model"?