Refrigerating Apparatus

Abstract

A refrigerant circuit ( 10 ) includes a gas-liquid separator ( 15 ) and a compressor ( 30 ) including a low pressure side compression mechanism ( 34 ) and a high pressure side compression mechanism ( 35 ) connected to each other by means of a drive shaft ( 33 ). In the refrigerant circuit ( 10 ), a two-stage compression/two-stage expansion refrigeration cycle is performed with CO 2 refrigerant utilized as that at its critical pressure. In the compressor ( 30 ), a volume ratio V2/V1 of the displacement volume V2 of the second compression mechanism ( 35 ) to that V1 of the first compression mechanism is set within a range between 0.8 and 1.3, both exclusive.

1 . A refrigerating apparatus comprising a refrigerant circuit for performing a two-stage compression/two-stage expansion refrigeration cycle in which CO 2  refrigerant at high pressure is utilized as that at its critical pressure, the refrigerant circuit including: a compressor including a low pressure side compression mechanism and a high pressure side compression mechanism connected to each other by means of a drive shaft; and a gas-liquid separator for separating refrigerant at intermediate pressure into gas refrigerant and liquid refrigerant,
 wherein a volume ratio of a displacement volume of the high pressure side compression mechanism to that of the low pressure side compression mechanism falls in a range between 0.8 and 1.3, both exclusive.   
   
   
       2 . The refrigerating apparatus of  claim 1 ,
 wherein the volume ratio falls in a range between 0.9 and 1.1, both inclusive.   
   
   
       3 . The refrigerating apparatus of  claim 2 ,
 wherein the volume ratio is 1.0.   
   
   
       4 . The refrigerating apparatus of any one of  claims 1  to  3 ,
 wherein the low pressure side compression mechanism and the high pressure side compression mechanism are rotary compression mechanisms.