Liquid Oxygen Vaporization Question
Liquid Oxygen Vaporization Question
(OP)
Hello,
I have a cryogenic pipe with liquid oxygen flowing through it. Pressure = 120psia, Temp = -180 Celsius. I want to determine the increase in pressure if 28.5kJ of heat was added to the system, assuming there would be some vaporization of liquid. Any help would be much appreciated. Thank you.
I have a cryogenic pipe with liquid oxygen flowing through it. Pressure = 120psia, Temp = -180 Celsius. I want to determine the increase in pressure if 28.5kJ of heat was added to the system, assuming there would be some vaporization of liquid. Any help would be much appreciated. Thank you.





RE: Liquid Oxygen Vaporization Question
RE: Liquid Oxygen Vaporization Question
RE: Liquid Oxygen Vaporization Question
Good luck,
Latexman
RE: Liquid Oxygen Vaporization Question
I don’t want to investigate the way the energy (heat) you’ve quoted in your OP is “added to the system” and assume the whole 28.5 kJ heat up the liquid oxygen.
Now the first point is to know the amount of liquid oxygen (mol) in the system or its mass flow (mol/s). Then consider that at 120 psia oxygen will be in the liquid state up to – 156.7 °C.
You then need the specific heat of liquid oxygen (take an average value in the range -180 °C/-156.7 °C for a ballpark estimate) and check whether your system reaches saturation conditions with 28.5 kJ added.
I doubt there could be a change of phase, anyway this again depends on the amount of liquid oxygen heated. To check whether there will be a change of phase consider that the latent heat of vaporization at 120 psia and -156.7 °C is 5.7523 kJ/mol or 179.765 kJ/kg (source webbook nist).
In order to evaluate pressure increase for a trapped liquid system you can follow the procedure described by valuable member prex (http://www.eng-tips.com/faqs.cfm?fid=1339).
RE: Liquid Oxygen Vaporization Question
First of all theres is one uncertaincy at least: Is it an enclosed space. If no - then no pressure increae at all (it will just expand). You could check the webdatabook at NIST.org, they have a lot of pure component data incl heat capacity as a funtion of temperature and vapour pressure etc. (i think this is (still) free.
RE: Liquid Oxygen Vaporization Question