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# SPECIFIC HEAT RATIO ON HYSYS

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## SPECIFIC HEAT RATIO ON HYSYS

(OP)
Hello friends ;

I'm wondering please if anyone know the difference between Cp/Cv (ent method) and Cp/Cv (gamma) on hysys

Thanks a lot !

Regards !

### RE: SPECIFIC HEAT RATIO ON HYSYS

cp and cv (for both gases and liquids) can be calculated in different ways, for example with a EOS,
if you know H and V plus derivatives vs. P, T
you can obtain (easily) cp as dH/dT and cv from cp including contributes dV/dP and dV/dT,
these are the std. methods available in my copy of Prode, see "www.prode.com/en/properties.htm"
as far as I know for cp hysys adopts a similar procedure while cv is calculated as
cp-cv = -T*(dV/dT)^2 / (dV/dT)
there is also a semi-ideal method where cp/cv = cp / (cp - R)
while in Prode to get equivalent results you select regular (ideal) method.

### RE: SPECIFIC HEAT RATIO ON HYSYS

My suggestion is to ask the Hysys helpdesk, it is very helpful. I have asked them this question myself in the past and got a fulsome response. I cannot remember the response fully but recall that cp and cv are derived from the enthalpy values, as Apetri states.

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