Ethylene and Propylene Enthalpy function h(T,P)

[AndreChE]

Dear all

Does any know, for ethylene and propylene, the h(T,P) function without chart/table interpolations?

I'm doing an energy balance to put in the DCS to the operators regarding centrifugal ethylene and propylene compressors.

Since the first stages discharges are internally mixed with the incoming suctions, there is not possibility to calculate it as a polytropic process.

My idea is more simple, since it is a "pure" component:

Three stages (3 suctions, 1 common discharge):

m1*h1 + m2*h2 + m3*h3 - m4*h4 = Wtotal + Qloss (1/2% ??)

Range of pressure/temperature: 0 to 20 barg; -50 to 120ºC

Thank you all
AndreChE

 

[paulGENG]

if you know the mole fraction, all you need to do is find the residual enthalpy, then assume a starting temperature and integrate using Cp.
H=H_0ig+int(T_0,T)CPdT+H_residual_T.
then calculate residual enthalpy from an equation of state, such as peng-robinson.
do this for each H.
Don't worry about pressure since it is incorporated in the H_residual at temp T.
if you assume it's a pure component (instead of a mixture), this should be good ...
hope that helps