A new four-parameter generalised equation of state with three reference fluids has been developed for predicting thermodynamic properties of the methane- and ethane-series refrigerants. The four chosen characteristic parameters are critical temperature, critical pressure, acentric factor, and the polarity factor proposed in this work. The three selected reference fluids are argon, n-butane and 1,1-difluoroethane (R152a). When the results of this work are compared with the refrigerant experimental data, they show significant improvement over Lee and Kesler (1975) and Wu and Stiel (1985). If the characteristic parameters of the refrigerants of interest are not available, an estimation method based on the group contribution method is given. The ideal vapour-compression refrigeration cycle was studied using the newly developed generalised equation of state to verify the accuracy of this work.

KEYWORDS: year 1995, refrigerants, R152a, methane, ethane, critical pressure, critical temperature, argon, comparing, calculating, properties, thermodynamics, replacing, thermodynamic cycles, vapours, compression refrigeration, accuracy