# Thermodynamics of fluid mixtures near to and far from the critical region

Lue, L. and Prausnitz, J. M.
(1998)
*Thermodynamics of fluid mixtures near to and far from the critical region.*
AIChE Journal, 44 (6).
pp. 1455-1466.
ISSN 0001-1541

## Abstract

A theory for an equation of state for simple fluid mixtures valid both near to and far from critical points is presented. The base equation of state obtained from integral-equation theory using the mean-spherical approximation is used to compute the contribution of short-wavelength fluctuations to the free energy of the fluid mixture. Wilson's phase-space cell approximation, as extended by White, is used to compute the contribution of long-wavelength fluctuations.The resulting theory possesses nonclassic critical exponents similar to those observed experimentally. Far from the critical region, where long-wavelength fluctuations are not important, the theory reduces to that corresponding to the base equation of state. The complete theory is used to represent the thermodynamic properties and phase behavior of binary mixtures of methane, carbon dioxide and n-butane.In the critical region, agreement with experiment is dramatically improved upon, adding to the base equation of state corrections from long-wavelength fluctuations.

#### ORCID iDs

Lue, L. ORCID: https://orcid.org/0000-0002-4826-5337 and Prausnitz, J. M.;Item type: Article ID code: 38472 Dates: DateEventJune 1998PublishedNotes: English Article ZT298 AICHE J Keywords: vapor-liquid-equilibrium, carbon-dioxide, renormalization- group, normal-butane, n-butane, statistical mechanics, differential approach, low-temperatures, critical-points, mode expansion, Chemistry, Physical and theoretical chemistry, Chemical Engineering(all), Biotechnology, Environmental Engineering Subjects: Science > Chemistry

Science > Chemistry > Physical and theoretical chemistryDepartment: Faculty of Engineering > Chemical and Process Engineering Depositing user: Pure Administrator Date deposited: 13 Mar 2012 16:26 Last modified: 20 Jan 2021 18:51 URI: https://strathprints.strath.ac.uk/id/eprint/38472