Comparison between the statistical associating fluid theory for variable range potentials (SAFT-VR) and the first-order mean spherical approximation (FMSA) equations of state for Mie (α, 6) fluids

Abstract

The respective accuracies of three recent analytical equations of state (EOS) (i.e. analytical representations of the Helmholtz free energy and compressibility factor Z) for the Mie(α,6) monomer fluids are evaluated by comparing the residual Helmholtz free energy, its Barker-Henderson (BH) perturbation terms and Z with the corresponding numerical simulations for the Mie(8,6), Mie(12,6), Mie(20,6) and Mie(30,6) fluids. Two of these EOS stem from the recent enhanced statistical associating fluid theory with variable range potentials (SAFT-VR Mie 2013), with two proposed parameterizations for the free energy first-order BH perturbation term of the Sutherland potentials building up the Mie potential. The third EOS uses a new mapping between the Mie(α,6) and a two-Yukawa potential, for which the first-order mean spherical approximation (FMSA) can be used to obtain analytically the free energy and pressure of the Mie(α,6) fluids up to second order.