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Analysis of excess free energy based equations of state models
Author(s) -
Orbey Hasan,
Sandler Stanley I.
Publication year - 1996
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690420822
Subject(s) - gibbs free energy , thermodynamics , helmholtz free energy , equation of state , activity coefficient , vapor pressure , thermodynamic free energy , chemistry , energy (signal processing) , limit (mathematics) , physics , mathematics , mathematical analysis , quantum mechanics , aqueous solution
A comparison is made of the capabilities of various equation of state (EOS) + excess free energy (G ex ) models in representing the activity‐coefficient models they incorporate. Such EOS models need to reproduce the excess Gibbs free energy behavior of the activity‐coefficient models as closely as possible in order to represent low‐pressure vapor–liquid equilibrium behavior of complex mixtures accurately, and also to make accurate the vapor–liquid predictions at higher temperatures and pressures using only low‐pressure information. It is demonstrated that the EOS models that use the excess Helmholtz free energy instead of the excess Gibbs free energy, and that combine the EOS with activity‐coefficient models at the infinite pressure limit, are successful for calculations of the type just described.