carlo.stenali

you can easily solve the polytropic compressor with Prode Properties,
there is a specific unit in extended version (please contact Prode at 'www.prode.com'),
that unit solves the model with the desired level of accuracy (it's a iterative procedure),
however you can obtain equivalent (or very close) results by modeling the polytropic compressor as a series of isentropic units with predetermined polytropic efficiency,
this is very simple with Prode Properties, for additional information see

'http://www.prode.com/docs/pppman.pdf'

-decide the number of steps (I suggest 5 steps) and calculate the dp as (Pout-Pin) / nr. of steps
-start from compressor inlet temperature and pressure
-at these conditions calculate cp with the method =StrGCp and cv with the method =StrGCv , calculate k = cp/cv
-calculate n (polytropic exponent) as n = polytropic efficiency * (k-1)/k
-calculate P1=Pin+dp and T1 = Tin*(P1/pin)^(n-1)/n
-at these conditions (P1,t1) calculate cp with the method =StrGCp and cv with the method =StrGCv , calculate k = cp/cv
-proceed until to complete the steps
-....
-once you have calculated the final (outlet) temperature you can calculate the enthalpy at inlet conditions (with Prode Properties) as H1 = StrH() and outlet conditions H2 = StrH() the difference being the enthalpy rise in the gas, you can then calculate the polytropic head from polytropic efficiency[/QUOTE]