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

Journal Article · Mon Jun 01 04:00:00 EDT 1998 · AIChE Journal

DOI:https://doi.org/10.1002/aic.690440622· OSTI ID:653305

Lue, L; Prausnitz, J M ^[1]

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1. Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering

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.

• Sponsoring Organization: USDOE, Washington, DC (United States); Petroleum Research Fund (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 653305
• Journal Information: AIChE Journal, Journal Name: AIChE Journal Journal Issue: 6 Vol. 44; ISSN AICEAC; ISSN 0001-1541
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
40 CHEMISTRY
BINARY MIXTURES
BUTANE
CARBON DIOXIDE
EQUATIONS OF STATE
EQUILIBRIUM
EXPERIMENTAL DATA
METHANE
PHASE STUDIES
THERMODYNAMIC PROPERTIES