Generalized SAFT-DFT/DMT model for the thermodynamic, interfacial, and transport properties of associating fluids: Application for n-alkanols.

Published

July 2, 2005

Author(s)

Sergei B. Kiselev, James F. Ely, Ilmutdin Abdulagatov, Marcia L. Huber

Abstract

We have developed a ¿global¿ crossover (GC) statistical associating fluid theory (SAFT) equation of state (EOS) for associating fluids, which incorporates non-analytic scaling laws in the critical region and in the limit of low densities is transformed into the ideal gas equation EOS. Unlike the crossover SAFT EOS developed earlier, the new GC SAFT EOS contains a so-called kernel term and reproduces the asymptotic scaling behavior of the isochoric heat capacity in the one- and two-phase regions. In addition, we develop on the basis the density functional theory (DFT) a GC SAFT-DFT model for the surface tension. In the second step, using the GC SAFT equation of state and the decoupled-mode theory (DMT) we have developed a generalized GC SAFT-DMT model for transport coefficients, which reproduces the singular behavior of the thermal conductivity of pure fluids in the critical region. Unlike the DMT model based on the asymptotic crossover equation of state, the GC SAFT-DMT model is valid in the entire fluid state region at T greater than or equal to Tb (where Tb is the binodal temperature), and at densities approaching zero reproduces the dilute gas contributions for the transport coefficients. A comparison was made with experimental data for methanol, ethanol, and higher n-alkanols. For n-akanols the GC SAFT-DFT/DMT model contains the same number of the adjustable parameters as original - classical SAFT EOS, but reproduces the PVT, VLE, isochoric and isobaric specific heats, surface tension, and thermal conductivity data close to and far away from the critical point with high accuracy.

Citation

Industrial and Engineering Chemistry Research

Pub Type

Journals

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Keywords

Associating fluids, Critical region, Crossover theory, Equation of state, Ethanol, Methanol, n-alkanols, Surface tension, Thermal conductivity, Thermodynamic properties, Transport coefficients

Citation

Kiselev, S. , Ely, J. , Abdulagatov, I. and Huber, M. (2005), Generalized SAFT-DFT/DMT model for the thermodynamic, interfacial, and transport properties of associating fluids: Application for n-alkanols., Industrial and Engineering Chemistry Research, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=30052 (Accessed June 1, 2024)