Abstract

Two equations of state and four mixing rules are applied to the calculation of the bubble point pressure of several refrigerant mixtures. An equation of state proposed by one of the authors, known as the PTV equation, and a modified Soave-Redlich-Kwong equation of state, known as Predictive Soave-Redlich-Kwong (PSRK), have been used. The mixing rules considered in the study include the classic van der Waals mixing rule with one and with two parameters for the PTV equation, and a model that includes the excess Gibbs free energy for the PSRK equation. Eighteen data sets from the literature for five binary refrigerant mixtures containing R134A (CH2FCF3) were considered for analysis. A special program was implemented for these calculations in which the fundamental equation for phase equilibria, the equality of fugacity of each component in all phases, was applied. Correlations for the interaction parameters as functions of the acentric factor are proposed. We present conclusions about usefulness of the different models and a recommendation for the best equation of state + mixing rule combination for correlating vapor-liquid equilibrium in the refrigerant mixtures studied.