SPECIFIC HEAT RATIO ON HYSYS SPECIFIC HEAT RATIO ON HYSYS chimieindustrielle (Chemical) (OP) 16 Mar 16 14:07 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 apetri (Chemical) 17 Mar 16 12:37 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 tickle (Chemical) 22 Mar 16 21:58 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.