Crossover equation of state for the thermodynamic properties of mixtures of methane and ethane in the critical region

Povodyrev, A. A.; Jin, G. X.; Kiselev, S. B.; Sengers, J. V.

doi:10.1007/bf01439196

Cited by 43 publications

(10 citation statements)

References 49 publications

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“…For an accurate representation of the near-critical and supercritical thermodynamic behavior of fluids, non-classical crossover models [100,[102][103][104][105] should be used. These asymptotic crossover models incorporate scaling laws asymptotically close to the critical point and are transformed into the analytical Landau expansion far away from the critical point.…”

Section: Crossover Modelsmentioning

confidence: 99%

Thermodynamic Properties of Methanol in the Critical and Supercritical Regions

et al. 2005

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The isochoric heat capacity of pure methanol in the temperature range from 482 to 533 K, at near-critical densities between 274.87 and 331.59 kg · m −3 , has been measured by using a high-temperature and high-pressure nearly constant volume adiabatic calorimeter. The measurements were performed in the singleand two-phase regions including along the coexistence curve. Uncertainties of the isochoric heat capacity measurements are estimated to be within 2%. The single-and two-phase isochoric heat capacities, temperatures, and densities at saturation were extracted from experimental data for each measured isochore. The critical temperature (T c = 512.78 ± 0.02 K) and the critical density (ρ c = 277.49 ± 2 kg · m −3 ) for pure methanol were derived from the isochoric heat-capacity measurements by using the well-established method of quasi-static thermograms. The results of the C V V T measurements together with recent new experimental PVT data for pure methanol were used to develop a thermodynamically self-consistent Helmholtz free-energy parametric crossover model, CREOS97-04. The accuracy of the crossover model was confirmed by a comprehensive comparison with available experimental data for pure methanol and values calculated with various multiparameter equations of state and correlations. In the critical and supercritical regions at 0.98T c T 1.5T c and in the density range 0.35ρ c ρ 1.65ρ c , CREOS97-04 represents all available experimental thermodynamic data for pure methanol to within their experimental uncertainties.

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Section: Crossover Modelsmentioning

confidence: 99%

Thermodynamic Properties of Methanol in the Critical and Supercritical Regions

et al. 2005

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“…1990; Kiselev et al, 1991;Kiselev and Sengers, 1993;Kiselev and Kostyukova, 1993). This approach has been extended to binary fluid mixtures of type I (Leung and Griffiths, 1973;Jin et al, 1993;Povodyrev et al, 1996;Kiselev, 19971, as well as other types of mixtures (Anisimov et al, 1995a(Anisimov et al, ,b, 1996Cheng et al, 1997). Regrettably, several parameters are required to fit experimental data for each system.…”

Section: Introductionmentioning

confidence: 96%

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

Lue

Prausnitz

1998

AIChE Journal

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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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“…For mixtures with a simple phase diagram in which the critical points of the two components are connected by a continuous critical locus, this hidden field ( may be taken as a function of the difference of the critical potentials of the two components [83][84][85]. Based on this principle crossover equations have been proposed for the thermodynamic properties of a variety of fluid mixtures near the vapor-liquid critical locus [68,69,79,[86][87][88][89]. A systematic procedure for extending the application to fluids with more complex phase diagrams has been developed by Anisimov et at.…”

Section: Discussionmentioning

confidence: 99%

“…An extension of the crossover theory by retaining 6 terms in the Landau expansion has been developed [4,13,60], referred to as six-term crossover Landau model. The six-term crossover Landau model (with some minor variations) has been used to represent the thermodynamic properties of a variety of fluids in an appreciable range of temperatures and densities around the critical point including steam [4,67], carbon dioxide [4,68], ethane [4,68,69], methane [69,70], argon [71], sulfur hexafluoride [72], and a number of refrigerants like RI34a [73], R152a [74], and ammonia [75].…”

Section: Discussionmentioning

confidence: 99%