R134a compressor equation

[chuckm1974]

I'm looking to see if there is a compressor equation other than the general isentropic ideal gas compressor equation. In particular, an isentropic equation for compressing R134A from the low pressure evaporator to the high pressure side in an HVAC system.

 

[zdas04]

What's wrong with the general isentropic compression equations? The one I use has a compressibility term so it works for a real gas.

David

 

[chuckm1974]

Thanks for responding.
What equation and compressibility factor do you use?

Chuck

 

[pmover]

to supplement zdas04, what type of compressor are you referring to?

assuming centrifugal . . .

perhaps this article "Development of a Guideline for Field Testing of Gas Turbines & Centrifugal Compressors"

at this link will help you . . .

http://www.gmrc.org/docs/index.php

as far as compressibility factor, investigate the NIST website (

http://webbook.nist.gov/chemistry/fluid/)

for properties for r134a.

we won't do the work for you, as you are suppose to be an engineer . . . next time do not ask vague questions. be more specific!

good luck!
-pmover

 

[zdas04]

Pmover,
I've never seen a refrig compressor that was not positive displacement. Lots of big ones are oil-flooded screw compressors. Small ones tend to be recips. Never seen a dynamic compressor in that service.

Using NIST (or their REFPROP program) for compressibility of R134A makes a lot more sense than trying to use one of the shortcut methods.

David

 

[pmover]

David,

Thanks & Initially, i thought recip too since the refrigerant is r134a. Then I must of had a brain spasm ("internal comm error" ) when I typed the response.

-pmover