Aspen Physical Property System - Physical Property Models

fcn = A correlation based on API Procedures and Figures 11A4.2, 11A4.3,
and 11A4.4 (API Technical Data Book, Petroleum Refining, 1997
edition)
Vm l is obtained from the API liquid volume model.
For real components, the General model is used.
Parameter
Name/Element
252 3 Transport Property Models
Symbol Default MDS Lower
Limit
Upper
Limit
Units
TB T bi — — 4.0 2000.0 TEMPERATURE
API API i — — -60.0 500.0 —
Aspen Liquid Mixture Viscosity
The liquid mixture viscosity is calculated by the equation:
Where:
Xi = Mole fraction or weight fraction of component i
kij = Symmetric binary parameter (kij = kji)
lij = Antisymmetric binary parameter (lij = -lji)
The pure component liquid viscosity �i *,l is calculated by the General Pure
Component Liquid Viscosity model.
The binary parameters kij and lij allow accurate representation of complex
liquid mixture viscosity. Both binary parameters default to zero.
Parameter Symbol Default MDS Lower Upper Units
Name/Element
Limit Limit
MUKIJ k ij 0 — -100.0 100.0 —
MULIJ l ij 0 — 100.0 100.0 —
ASTM Liquid Mixture Viscosity
It is generally difficult to predict the viscosity of a mixture of viscous
components. For hydrocarbons, the following weighting method (ASTM †) is
known to give satisfactory results:
Where:
wi = Weight fraction of component i
�m = Absolute viscosity of the mixture (N-sec/sqm)