R32, air-conditioner refrigerant, refrigeration oil, miscibility
R32 has been widely applied as an air-conditioner refrigerant. It is known that R32 is inferior to other refrigerants such as HFC and HFO in the miscibility with refrigeration oils. In addition, when R32 dissolves in refrigeration oils, the kinematic viscosity of the oils reduces remarkably. So it is difficult to improve the miscibility of refrigeration oil while suppressing the kinematic viscosity decrease of the oil when R32 dissolves in. Various investigations have revealed that the formulation of a new base material in POE improves the miscibility with R32 without decreasing the kinematic viscosity of the oil when R32 dissolves in. By using this technology, we have developed new refrigerating oils whose phase separation temperatures were -20 degree C or less under R32 atmosphere. In addition, the kinematic viscosities of the new oils when R32 dissolves in were equal to or greater than those of POE currently used for R410A.These new refrigerating oils are expected to be developed in a large model in which oil returnability is important in a refrigeration system. In this study, we will report the method and various characteristics under HFOs.