Aspen Physical Property System - Physical Property Models

Where the L, M, and N are parameters that vary depending on the equation of
state and whether the temperature is above or below the critical temperature
of the component.
For Soave-Redlich-Kwong:
Subcritical T Supercritical T
L (0)
M (0)
N (0)
L (1)
M (1)
N (1)
0.544000 0.379919
1.01309 5.67342
0.935995 -0.200000
0.544306 0.0319134
0.802404 1.28756
3.10835 -8.000000
Use of Alpha Functions
The use of alpha functions in Soave-Redlich-Kwong based equation-of-state
models is given in the following table. You can verify and change the value of
possible option codes on the Properties | Property Methods | Models
sheet.
Alpha Function Model Name First Option Code
original RK ESRK0, ESRK —
standard RKS ESRKSTD0, ESRKSTD
*
standard RKS/Boston-Mathias *
ESRKSWS0, ESRKSWS
ESRKSV10, ESRKV1
ESRKSV20, ESRKSV2
Mathias/Boston-Mathias ESRKA0, ESRKA —
Extended Mathias/Boston-
Mathias
78 2 Thermodynamic Property Models
—
1, 2 (default)
0
1
1
1
ESRKU0, ESRKU —
Mathias-Copeman ESRKSV10, ESRKSV1
ESRKSV20, ESRKSV2
Schwartzentruber-Renon-
Watanasiri
ESPRWS0, ESPRWS
ESRKSV10, ESRKSV1
ESRKSV20, ESRKSV2
Twu generalized * 5
Gibbons-Laughton with Patel
extension
Mathias for T < Tc; Boston-
Mathias for T > Tc
2
2
* 3
* 4
3 (default)
3 (default)
3 (default)
* ESRKSTD0, ESRKSTD, ESRKS0, ESRKS, ESSRK, ESSRK0, ESRKSML,
ESRKSML0. The default alpha function (option code 2) for these models is the