Aspen Physical Property System - Physical Property Models

V. V. De Leeuw and S. Watanasiri, "Modelling Phase Equilibria and Enthalpies
of the System Water and Hydroflouric Acid Using an HF Equation-of-state in
Conjunction with the Electrolyte NRTL Activity Coefficient Model," Paper
presented at the 13th European Seminar on Applied Thermodynamics, June 9
– 12, Carry-le-Rouet, France, 1993.
R. W. Long, J. H. Hildebrand, and W. E. Morrell, "The Polymerization of
Gaseous Hydrogen and Deuterium Flourides," J. Am. Chem. Soc., Vol. 65,
(1943), pp. 182 – 187.
C. E. Vanderzee and W. WM. Rodenburg, "Gas Imperfections and
Thermodynamic Excess Properties of Gaseous Hydrogen Fluoride," J. Chem.
Thermodynamics, Vol. 2, (1970), pp. 461 – 478.
IAPWS-95 Steam Tables
The IAPWS-95 Steam Tables are implemented like any other equation-ofstate
in the Aspen Physical Property System. These steam tables can calculate
any thermodynamic property of water. The tables form the basis of the
IAPWS-95 property method. There are no parameter requirements. They are
the most accurate steam tables in the Aspen Physical Property System.
References
Wanger W. and A. Pruß, ”The IAPWS Formation 1995 for the Thermodynamic
Properties of Ordinary Water Substance for General and Scientific Use,” J.
Phys. Chem. Ref. Data, 31(2), 387- 535, 2002.
Ideal Gas
The ideal gas law (ideal gas equation-of-state) combines the laws of Boyle
and Gay-Lussac. It models a vapor as if it consisted of point masses without
any interactions. The ideal gas law is used as a reference state for equationof-state
calculations, and can be used to model gas mixtures at low pressures
(without specific gas phase interactions).
The equation is:
p = RT / Vm
Lee-Kesler
This equation-of-state model is based on the work of Lee and Kesler (1975).
In this equation, the volumetric and thermodynamic properties of fluids based
on the Curl and Pitzer approach (1958) have been analytically represented by
a modified Benedict-Webb-Rubin equation-of-state (1940). The model
calculates the molar volume, enthalpy departure, Gibbs free energy
departure, and entropy departure of a mixture at a given temperature,
pressure, and composition for either a vapor or a liquid phase. Partial
derivatives of these quantities with respect to temperature can also be
calculated.
Unlike the other equation-of-state models, this model does not calculate
fugacity coefficients.
2 Thermodynamic Property Models 29