forane 141b

[pajohn]

Hey guys, I am a university student attempting to finish a refrigeration lab. Unfortunately, the refrigerant used is 141b. From what I understand, 141b is no longer being used, so why we're using it I don't know. I have a crummy photocopied p-h (mollier) diagram, but it doesn't include temperatures in the subcooled region (below saturated liquid line). I can't find this info anywhere using google, probably because it's ancient. Thanks for the help!

[US Iceman]

HI pajohn,

...but it doesn't include temperatures in the subcooled region...

The temperatures in the subcooled area of a P-H diagram are isotherms. They go straight up from the bubble point curve (the curve where the pressure and temperatures are saturated).

If the liquid is subcooled, the temperature decreases at a constant pressure (one definition). As the temperature is decreased the enthalpy also decreases.

Most P-H diagrams don't show these as they make the diagram harder to read.

...but it doesn't include temperatures in the subcooled region (below saturated liquid line).

If you are reading data below the saturated line (meaning UNDER the saturated line) you are reading a pressure decrease. The subcooled values are to the left of the bubble point curve.

[pajohn]

Thanks mate. I was looking in a textbook with 134a and they were vertical isotherms up to a certain point, but that's above the critical pressure, so I don't need to worry about that.