How to calculate isentropic tempera 1

[Robati2024]

How to calculate isentropic temperature exponent and isentropic valume exponent for real gases? Kv Kt

I am using LEE KESLER PLOCKER method (LKO EOS)
I have found some calculation in mr. Ludtke handbook. I also read another book " thermophysical Properties of Fluids by Marc J. Assael" to verify my Mtlab code I use exaplme in above book on page 100.But my calculation doesn't fit with the resuils !
The example ask to find isobaric heat capacity for mixture of (0.766 C3H8+ 0.234 CH4)
For a) T=310k P=1.7Mpa
b) T=420 k P=13.7 Mpa
Book results: case a Cp=2.2 kj/(kg k.
Case b Cp=3.6 KJ/KG/K
MY CALCULATION a: [z=0.8056] CPa=2.2
b: [Z=0.6159] Cpb=3.42
Densities are (a,b) : 818.73 and 6.3694E+3
Lee kealer plocker method use simple and reference fluid. It also use binary itraction parameters Kij. For this case they are 1.113
Why my calculation are incorrect ?!

 

[georgeverghese]

The last time I looked up the API Technical Databook (many years ago), there was a numerical method for computing real gas Cp. See if this helps

 

[pierreick]

Hi,
Your calculation for densities is wrong, Z are correct using Peng Robinson EOS.
Za=0.8029
Ro a = 30.83 kg/m3
Zb=0.6449
Ro b =228.32 kg/m3
Cpa = 77.720 j/mol-k
Cpb =127.829 j/mol-k
Mw= 37.532 g/mol

Pierre

 

[georgeverghese]

Agreed, those densities @robati posted are obviously wrong.

 

[PaoloPemi]

if you solve with Lee Kesler method results will be quite close to those reported in the book,
I agree with Pierreick and gergeverghese, your compressibility factors / densities are wrong,

I attach the solution calculated in Excel with Prode Properties (see prode.com) for your review