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

L. Lue, J. M. Prausnitz

Research output: Contribution to journalArticle

46 Citations (Scopus)

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.
LanguageEnglish
Pages1455-1466
Number of pages12
JournalAIChE Journal
Volume44
Issue number6
DOIs
Publication statusPublished - Jun 1998

Fingerprint

Methane
Thermodynamics
Equations of state
Carbon Dioxide
Wavelength
Fluids
Butane
Phase behavior
Binary mixtures
Free energy
Integral equations
Carbon dioxide
Thermodynamic properties
butane
Experiments

Keywords

  • vapor-liquid-equilibrium
  • carbon-dioxide
  • renormalization- group
  • normal-butane
  • n-butane
  • statistical mechanics
  • differential approach
  • low-temperatures
  • critical-points
  • mode expansion

Cite this

Lue, L. ; Prausnitz, J. M. / Thermodynamics of fluid mixtures near to and far from the critical region. In: AIChE Journal. 1998 ; Vol. 44, No. 6. pp. 1455-1466.
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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.",
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Thermodynamics of fluid mixtures near to and far from the critical region. / Lue, L.; Prausnitz, J. M.

In: AIChE Journal, Vol. 44, No. 6, 06.1998, p. 1455-1466.

Research output: Contribution to journalArticle

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AU - Lue, L.

AU - Prausnitz, J. M.

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N2 - 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.

AB - 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.

KW - vapor-liquid-equilibrium

KW - carbon-dioxide

KW - renormalization- group

KW - normal-butane

KW - n-butane

KW - statistical mechanics

KW - differential approach

KW - low-temperatures

KW - critical-points

KW - mode expansion

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