Aspen Physical Property System - Physical Property Models

Parameter
Name/Element
292 3 Transport Property Models
Symbol Default MDS Lower
Limit
Upper
Limit
SIGTDEW/2, 3, 4 C 2i, C 3i, C 4i 0 x — — —
Units
SIGTDEW/5 T c — x — — TEMPERATURE
SIGTDEW/6 nTerms 4 x — — —
SIGTDEW/7 T lower 0 x — — TEMPERATURE
SIGTDEW/8 T upper 1000 x — — TEMPERATURE
NIST TDE Expansion
This equation can be used when parameter SIGISTE is available.
Parameter
Name/Element
Symbol Default MDS Lower
Limit
Upper
Limit
Units
SIGISTE/1 C 1i — x — — N/m
SIGISTE/2, 3, 4 C 2i, C 3i, C 4i 0 x — — N/m
SIGISTE/5 T ci — x — — TEMPERATURE
SIGISTE/6 nTerms 4 x — — —
SIGISTE/7 T lower 0 x — — TEMPERATURE
SIGISTE/8 T upper 1000 x — — TEMPERATURE
References
R.C. Reid, J.M. Prausnitz, and B.E. Poling, The Properties of Gases and
Liquids, 4th. ed., (New York: McGraw-Hill, 1987), p. 638.
Onsager-Samaras
The Onsager-Samaras model calculates the correction to the liquid mixture
surface tension of a solvent mixture, due to the presence of electrolytes:
Where:
for salt concentration < 0.03
M
�solv = Surface tension of the solvent mixture calculated
by the General Pure Component Liquid Surface
Tension model
xca a
= Mole fraction of the apparent electrolyte ca
��ca = Contribution to the surface tension correction due
to apparent electrolyte ca
For each apparent electrolyte ca, the contribution to the surface tension
correction is calculated as:
(1)