1999 年 16 巻 2 号 p. 133-139
The binary mixture of two hydrofluorocarbons, R-125 and R-143a, behaves almost like an azeotrope and has been considered as a promising refrigerant to substitute R-502. In this paper, we present a thermodynamic property model for the R-125/143a system, which was developed on the basis of a new cubic equation of state proposed in our previous publications. The essential thermodynamic properties such as PVTx properties, vapor-liquid equilibrium, enthalpy, entropy, isobaric specific heat, and speed of sound are well represented simultaneously by the new model in the entire fluid-phase of theR-125/143a system including the pure components.The model is valid for any composition with thermodynamic consistency to cover a range broad enough for refrigeration engineering applications. A pressure-enthalpy diagram for the R-125/143a mixture with 50 mass% R-125 is also presented.
