Modeling vapor-liquid equilibrium of refrigerants using an equation of state for square-well chain fluid with variable range

An equation of state developed in the authors'previous work by applying the second-order perturbation theory and Chiew's PY2 approximation of integral equation for square-well chain fluid with variable range was applied to model vapor-liquid equilibrium of pure refrigerants and their mixtures.The molecular parameters for 18 refrigerants were obtained by fitting saturated vapor pressure and liquid molar volume data.The overall average deviations of saturated vapor pressure and liquid molar volume were only 1.11% and 0.92%,respectively.Coupling with one fluid mixing rule,this model was extended to mixtures.It was found that the experimental vapor-liquid equilibrium for binary and ternary mixtures could be well predicted,except at the vicinity of critical point.When using one independent-temperature binary adjustable parameter,the correlated precisions could be greatly enhanced indicating that the new equation could be used to model vapor-liquid equilibrium of refrigerants.