UmeshMathur:
You wrote: "Your numerical example shows clearly that, even for a "permanent" gas like methane, the variation in k is highly significant over modest changes in pressure and temperature. For other gases such as heavier hydrocarbons and ammonia, these errors can easily get much...
UmeshMathur:
About using k in the real-gas calculations. Let's leave aside theoretical discussion for a while and consider the isentropic process as a example. I have calculated P V^k for three cases for two points on the isentropic path each (please see the table below). All of them for pure...
The method of process calculation UmeshMathur pointed to, is pretty common. However, why cannot you integrate the equation of polytropic process as a e= v* dP/dH without all that simplifying assumptions which force you to use k and n? I agree, that usually equations of state use (P, T) as a...
I would suggest little bit more formal approach. Polytropic
efficiency for centrifugal compressor is defined as a
e=Wp/(Hs-Hd), where Wp is "net reversible process mechanical energy input"; Hs and Hp - enthalpy on the suction and discharge correspondingly. That's why I agree with DickRussell...
