Aspen Physical Property System - Physical Property Models

a1 is an additional, asymmetric (polar) term:
Where:
; ;
The enthalpy, entropy, Gibbs energy, and molar volume of water are
calculated from the steam tables. The total properties are mole-fraction
averages of these values with the properties calculated by the equation of
state for other components. Fugacity coefficient is not affected.
For best results, the binary parameter kij must be determined from phase
equilibrium data regression (for example, VLE data). The Aspen Physical
Property System also has built-in kij for a large number of component pairs in
the SRK-ASPEN databank, regressed by AspenTech. These parameters are
used automatically with the SRK property method. Values of kij in the
databank can be different than those used with other models such as
Standard Redlich-Kwong-Soave or Standard Redlich-Kwong-Soave, and this
can produce different results.
The model uses option codes which are described in Soave-Redlich-Kwong
Option Codes.
Parameter Symbol Default MDS Lower
Name/
Element
Limit
60 2 Thermodynamic Property Models
Upper
Limit
Units
SRKTC T ci TC x 5.0 2000.0 TEMPERATURE
SRKPC p ci PC x 10 5
SRKOMG � i
10 8
OMEGA x –0.5 2.0 —
SRKZRA z RA RKTZRA x — — —
SRKKIJ/1 k ij (1)
SRKKIJ/2 k ij (2)
SRKKIJ/3 k ij (3)
0 x — — —
PRESSURE
0 x — — TEMPERATURE
0 x — — TEMPERATURE
SRKKIJ/4 T lower 0 x — — TEMPERATURE
SRKKIJ/5 T upper 1000 x — — TEMPERATURE
SRKLIJ/1 l ij (1)
SRKLIJ/2 l ij (2)
0 x — — —
0 x — — TEMPERATURE