PDA

View Full Version : Pressures in simulation software?







Uni
08-05-2012, 11:52 PM
G'day everyone,

I am not sure if the simulation softwares, Evap-Cond or Refrigeration Utilities, all use Absolute Pressure inputs?

My good guess is absolute pressure because gauge pressure is just relative.

Please kindly correct me. Thank you.

aramis
09-05-2012, 12:55 AM
No, it usually is an option you can change!

Uni
09-05-2012, 03:12 AM
Aramis, not with the two I mentioned, I believe. And that caused the confusion.

Magoo
09-05-2012, 04:01 AM
Hello uni.
generally most simulation/ selection software prgs will stipulate either saturated conditions or indicate pressure conditions., options being metric or imperial.
What software are you using and referring to? .

magoo

aramis
09-05-2012, 04:09 AM
I was wrong, sorry!

Usually use RefProp that does have the choice and have enabled the use of RefProp equation set from Refrigeration Utilities but they only work with absolute kPa or Bar (both absolute), the only choices.

Cheers!

Uni
09-05-2012, 05:15 AM
Magoo, I use Evap-Cond and Refrigeration Utilities. Option is only for switching between SI units or British units.
Thanks, Aramis.

desA
09-05-2012, 06:56 AM
The norm should be pressure absolute. This corresponds to the way most steam & gas property tables are drawn up.

The problem with using gauge pressure is that it is relative to local atmospheric pressure, which changes with altitude - this would become incredibly confusing. Absolute pressure is what it is.

Uni
09-05-2012, 07:33 AM
Nice one, desA. Thank you.

desA
09-05-2012, 07:54 AM
An absolute pleasure. Have a fantastic day. :)