An Analytical Equation of State for Saturated Liquid Refrigerant Ternary Mixtures

In this work an analytical equation of state has been employed to calculate the PVT properties ofternary refrigerant mixtures. The theoretical EoS is that of Ihm, Song and Mason, which is based onstatistical-mechanical perturbation theory, and the two constants are enthalpy of vaporization ΔHvapand molar density ρnb, both at the normal boiling temperature. The following three temperaturedependentparameters are needed to use the EoS: the second virial coefficient, B2(T), an effectivevan der Waals covolume, b(T), and a scaling factor, α(T). The second virial coefficients arecalculated from a correlation based on the heat of vaporization, Hvap, and the liquid density at thenormal boiling point, ρnb. α(T) and b(T) can also be calculated from second virial coefficients byscaling rules. This procedure predicts liquid densities ofternary mixtures at saturated state with a temperature range from 173 K to 373 K and pressure up to4.0 MPa, with very good results.