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Lotronex · 01-26-2005, 08:26 PM

Q: For a certain experiment, R-134a vapor is contained in a sealed glass tube at 20C. It is desired to know the pressure in this condition, but there is no means of measuring it, since the tube is sealed. However, if the tube is cooled to -20C small droplets of liquid are observed on the galss walls. What is the initial pressure?

We got this question on a HW assignment, but we never did any type of problem solving like this, it was mostly just the professor in front drawing P-T diagrams and the like.
We think that -20C is the Tsat at that pressure, but we have know idea where to go. If anyone with experience in these matters could point me in the right direction to get this solved, it would be much appreciated.

01-26-2005, 08:26 PM	#1 (permalink)
Lotronex Tilted	Help with thermodynamics Q: For a certain experiment, R-134a vapor is contained in a sealed glass tube at 20C. It is desired to know the pressure in this condition, but there is no means of measuring it, since the tube is sealed. However, if the tube is cooled to -20C small droplets of liquid are observed on the galss walls. What is the initial pressure? We got this question on a HW assignment, but we never did any type of problem solving like this, it was mostly just the professor in front drawing P-T diagrams and the like. We think that -20C is the Tsat at that pressure, but we have know idea where to go. If anyone with experience in these matters could point me in the right direction to get this solved, it would be much appreciated.