Refrigeration apparatus

Abstract

A refrigeration apparatus includes a high-temperature side circulation circuit and a low-temperature side circulation circuit. The high-temperature side circulation circuit A is configured by connecting a high-temperature side compressor, a high-temperature side condenser, a high-temperature side expansion valve, and a high-temperature side evaporator of a cascade heat exchanger to one another. The low-temperature side circulation circuit is configured by connecting a low-temperature side compressor, a low-temperature side condenser of the cascade heat exchanger, a receiver that stores a liquid refrigerant, a solenoid valve, a low-temperature side expansion valve, and a low-temperature side evaporator to one another. A refrigerant in the low-temperature side circulation circuit includes a zeotropic refrigerant mixture containing at least CO 2 and R32. The content of R32 in the entire zeotropic refrigerant mixture is 50% to 74% by mass, and the GWP of the zeotropic refrigerant mixture is equal to or less than 500.

1 . A refrigeration apparatus comprising:
 a high-temperature side circulation circuit configured by connecting a high-temperature side compressor, a high-temperature side condenser, a high-temperature side expansion valve, and a high-temperature side evaporator of a cascade heat exchanger to one another; and   a low-temperature side circulation circuit configured by connecting a low-temperature side compressor, a low-temperature side condenser of the cascade heat exchanger, a receiver that stores a liquid refrigerant, a solenoid valve, a low-temperature side expansion valve, and a low-temperature side evaporator to one another, wherein   a refrigerant in the low-temperature side circulation circuit includes a zeotropic refrigerant mixture containing at least CO 2  and R32,   a content of R32 in the entire zeotropic refrigerant mixture is 50% to 74% by mass, and   a GWP of the zeotropic refrigerant mixture is not more than 500.   
     
     
         2 . The refrigeration apparatus of  claim 1 , further comprising:
 a composition calculation unit that obtains a composition of the refrigerant circulating in the low-temperature side circulation circuit; and   a controller that controls the low-temperature side circulation circuit based on the composition of the refrigerant obtained by the composition calculation unit.   
     
     
         3 . The refrigeration apparatus of  claim 2 , wherein
 the composition calculation unit includes   a pressure detector that detects a pressure of a liquid refrigerant in the receiver,   a temperature detector that detects a temperature of the liquid refrigerant in the receiver, and   a composition calculator that obtains the composition of the refrigerant circulating in the low-temperature side circulation circuit, based on the pressure detected by the pressure detector and the temperature detected by the temperature detector.