Vapor Quality, Wet refrigerant, Compressor suction, R32
To evaluate performance and reliability of an air conditioner, the states of its refrigeration cycle need to be understood. Since the isentropic exponent of the next-generation refrigerant R32 is larger than that of conventional refrigerant R410A, the compressor discharge temperature of R32 is higher than that of R410A. When a wet refrigerant is entered into a compressor suction line to decrease the discharge temperature, it is generally difficult to estimate the vapor quality at the suction. This paper describes a method that estimates a vapor quality at the compressor suction by applying energy balances on the compressor with the values of suction pressure, discharge pressure, discharge temperature, etc. In the air conditioner test, the vapor qualities at the compressor suction estimated with this method agree well with those estimated with the conventional method by measuring liquid and vapor flow-rates. Moreover, this paper derives a relational expression for estimating a compressor suction state from a discharge state and discusses the characteristics of the coefficients in the expression calculated from the test results.