An Analytical Equation of State for Saturated Liquid Refrigerant Ternary Mixtures

Document Type : Research Paper


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