Refrigeration apparatus

Abstract

There is disclosed a refrigeration apparatus capable of decreasing a load on a compressor and improving an operation efficiency. According to the present invention, in a refrigeration apparatus 1 of a so-called two-dimensional multistage system, an evaporator 34 of a high-temperature-side refrigerant circuit 25 and a condensing pipe 42 of a low-temperature-side refrigerant circuit 38 constitute a cascade heat exchanger 43, and an evaporation pipe 62 of the low-temperature-side refrigerant circuit 38 obtains an extremely low temperature. The apparatus includes an oil separator 43 provided on the discharge side of a compressor 20 of the low-temperature-side refrigerant circuit 38 so that oil is separated from non-azeotropic mixed refrigerants to return the oil to the compressor 20, and a radiator 39 interposed between the oil separator 43 and the compressor 20.

1 . A refrigeration apparatus comprising: a high-temperature-side refrigerant circuit and a low-temperature-side refrigerant circuit each constituting an independent refrigerant closed circuit in which a refrigerant discharged from a compressor is condensed and then evaporated to exert a cooling function, the low-temperature-side refrigerant-circuit having the compressor, a condenser, an evaporator, and a plurality of intermediate heat exchangers and a plurality of pressure reducing units connected in series so that the refrigerant fed back from the evaporator circulates, wherein a plurality of types of non-azeotropic mixed refrigerants are introduced, a condensed refrigerant in the refrigerants passed through the condenser is allowed to join the intermediate heat exchanger through the pressure reducing unit, a non-condensed refrigerant in the refrigerants is cooled by the intermediate heat exchanger to successively condense the refrigerant having a lower boiling point, the refrigerant having the lowest boiling point is allowed to flow into the evaporator through the final stage of the pressure reducing unit, an evaporator of the high-temperature-side refrigerant circuit and the condenser of the low-temperature-side refrigerant circuit constitute a cascade heat exchanger, and the evaporator of the low-temperature-side refrigerant circuit is configured to obtain an extremely low temperature,
 the refrigeration apparatus further comprising: an oil separator provided on the discharge side of the compressor of the low-temperature-side refrigerant circuit so that oil is separated from the non-azeotropic mixed refrigerants to return the oil to the compressor; and a radiator interposed between the oil separator and the compressor.   
   
   
       2 . The refrigeration apparatus according to  claim 1 , wherein the non-azeotropic mixed refrigerants include a refrigerant having a satisfactory solubility in the oil and a high boiling point as compared with at least another refrigerant.