Analytic equation of state and thermodynamic properties for He-H2 fluid mixtures over a wide range of pressures and temperatures

The analytical expressions for the equation of state and thermo-physical quantities of Exp-6 fluid are derived based on the Ross variational perturbation theory and with the quantum effect taken into account. The formalism developed is applied to the He-H2 mixtures. The agreement of numerical results of pressure and internal energy with MC simulations is shown far better than the analytic equation of state developed by [I. Ali, S.M. Osman, N. Sulaiman, R.N. Singh, Phys. Rev. E 69 (2004) 0561045]. The isotherms for pressure, internal energy and packing factor for five concentrations and four temperatures versus volume are calculated and analyzed. The numerical results for excess Gibbs free energy and entropy of mixing are presented. The variation of the excess Gibbs free energy of mixing, and the variation of the excess entropy of mixing versus temperature and pressure are different from and similar to that of Ali et al., respectively.