Current thermophysical properties research on refrigerant mixtures in Japan

This paper reviews the thermophysical properties of nonazeotropic refrigerant blends (NARBs), which are prospective working fluids, especially for advanced heat pump systems as well as for other industrial applications such as ultra-lowtemperature freezers for medical use, domestic air-conditioners, etc. After a brief introduction on the thermodynamic behavior of NARBs, the current state of thermophysical-properties research for NARBs, which are possible candidates for CFC alternatives, is reviewed. The thermophysical properties discussed in this paper include not only thermodynamic properties such asPVTx properties, vapor-liquid equilibria, critical parameters, etc., but also transport properties such as viscosity and thermal conductivity. Emphasis is placed on the most recent results resulting from an extensive research project partially supported by the Japanese Association of Refrigeration (JAR) on the occasion of its 60th foundation anniversary, celebrated in 1985. In view of the urgent demand to accumulate information on various thermophysical properties of CFC alternatives including R134a and R123, some of our current activities in Japan are presented. A task force to provide a set of reliable thermophysical properties for engineering use of CFC alternatives has been organized with partial support from the Ministry of International Trade and Industry, Japan.