Comparison of Lorentz–Berthelot and Tang–Toennies Mixing Rules Using an Isotropic Temperature-Dependent Potential Applied to the Thermophysical Properties of Binary Gas Mixtures of CH4, CF4, SF6, and C(CH3)4with Ar, Kr, and Xe

Abstract

In this paper the isotropic temperature-dependent potential (ITDP) approach and the concepts introduced in our previous papers have been used to calculate equilibrium and transport properties of low-density gas mixtures. The twelve binary mixtures considered here are: Ar–CH4, Ar–CF4, Ar–SF6, Ar–C(CH3)4, Kr–CH4, Kr–CF4, Kr–SF6, Kr–C(CH3)4, Xe–CH4, Xe–CF4, Xe–SF6 and Xe–C(CH3)4. The (n−6) Lennard–Jones potential parameters n (repulsive parameter), R m (equilibrium distance), and ɛ (potential well depth) of the pure noble gases Ar, Kr, and Xe are obtained by a minimization of the sum of squared deviations between experimental and calculated viscosity (η), and second pVT (B) and acoustic (β) virial coefficients normalized to their relative experimental error aexp. The number of included experimental points for B, β, η was N = 305, 210, and 167 for Ar, Kr, and Xe, respectively. For the pure globular gases the potential parameters were taken from previous publications. The calculations of B, η, and ρ D12 of binary mixtures were compared with experimental data by using two different mixing rules (Lorentz–Berthelot and Tang–Toennies). Recommended sets and fitting formulae for the potential parameters that can be used for the calculation of low-pressure thermophysical properties of these mixtures are provided.