Aspen Physical Property System - Physical Property Models

; ;
The parameter ai is calculated by the standard Soave formulation at
supercritical temperatures. If the component is supercritical, the Boston-
Mathias extrapolation is used (see Soave Alpha Functions).
The model uses option codes which are described in Soave-Redlich-Kwong
Option Codes.
For best results, binary parameters kij must be determined from phaseequilibrium
data regression (for example, VLE data).
Parameter Symbol Default MDS Lower Upper Units
Name/Element
Limit Limit
TCRKS T ci TC x 5.0 2000.0 TEMPERATURE
PCRKS p ci PC x 10 5
OMGRKS � i
RKSKBV/1 k ij (1)
RKSKBV/2 k ij (2)
RKSKBV/3 k ij (3)
56 2 Thermodynamic Property Models
10 8
OMEGA x -0.5 2.0 —
0 x -5.0 5.0 —
PRESSURE
0 x — — TEMPERATURE
0 x — — TEMPERATURE
RKSKBV/4 T k,lower 0 x — — TEMPERATURE
RKSKBV/5 T k,upper 1000 x — — TEMPERATURE
RKSLBV/1 l ij (1)
RKSLBV/2 l ij (2)
RKSLBV/3 l ij (3)
0 x — — —
0 x — — TEMPERATURE
0 x — — TEMPERATURE
RKSLBV/4 T l,lower 0 x — — TEMPERATURE
RKSLBV/5 T l,upper 1000 x — — TEMPERATURE
References
G. Soave, "Equilibrium Constants for Modified Redlich-Kwong Equation-ofstate,"
Chem. Eng. Sci., Vol. 27, (1972), pp. 1196 – 1203.
Redlich-Kwong-Soave-Wong-Sandler
This equation-of-state model uses the Redlich-Kwong-Soave equation-of-state
for pure compounds. The predictive Wong-Sandler mixing rules are used.
Several alpha functions can be used in the Redlich-Kwong-Soave-Wong-
Sandler equation-of-state model for a more accurate description of the pure
component behavior. The pure component behavior and parameter
requirements are described in Standard Redlich-Kwong-Soave, and in Soave
Alpha Functions.
Note: You can choose any of the available alpha functions, but you cannot
define multiple property methods based on this model using different alpha
functions within the same run.
The Wong-Sandler mixing rules are an example of modified Huron-Vidal
mixing rules. A brief introduction is provided in Huron-Vidal Mixing Rules. For
more details, see Wong-Sandler Mixing Rules.