Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus includes a first refrigerant circuit and a second refrigerant circuit so as to improve the efficiency of operations. A first refrigerant circuit using a first refrigerant having a pressure of 1.2 MPa or less at 30° C. and a second refrigerant circuit using a second refrigerant having a pressure of 1.5 MPa or more at 30° C. are provided, and a dual cycle operation in which the first refrigerant circuit and the second refrigerant circuit are simultaneously operated to exchange heat between the first refrigerant and the second refrigerant and a single cycle operation in which the first refrigerant circuit is operated without operating the second refrigerant circuit to perform a cooling operation or heating operation are enabled in a switchable manner.

1 . A refrigeration cycle apparatus comprising:
 a first refrigerant circuit using a first refrigerant having a pressure of 1.2 MPa or less at 30° C.; and   a second refrigerant circuit using a second refrigerant having a pressure of 1.5 MPa or more at 30° C., wherein   the refrigeration cycle apparatus enables, in a switchable manner,
 a dual cycle operation in which the first refrigerant circuit and the second refrigerant circuit are simultaneously operated to exchange heat between the first refrigerant and the second refrigerant, and 
 a single cycle operation in which the first refrigerant circuit is operated without operating the second refrigerant circuit to perform a cooling operation or heating operation. 
   
     
     
         2 . The refrigeration cycle apparatus according to  claim 1 , wherein, during the dual cycle operation, the second refrigerant flowing through the second refrigerant circuit heats the first refrigerant flowing through the first refrigerant circuit to perform the heating operation. 
     
     
         3 . The refrigeration cycle apparatus according to  claim 1 , wherein the single cycle operation is performed when a predetermined low-load condition is satisfied. 
     
     
         4 . The refrigeration cycle apparatus according to  claim 1 , comprising
 a cascade heat exchanger that exchanges heat between the first refrigerant and the second refrigerant during the dual cycle operation wherein   the cascade heat exchanger includes a first cascade channel through which the first refrigerant flows, and a second cascade channel which is independent of the first cascade channel and through which the second refrigerant flows.   
     
     
         5 . The refrigeration cycle apparatus according to  claim 4 , wherein the first refrigerant circuit includes a first compressor, a first heat exchanger, a first expansion valve, and the first cascade channel. 
     
     
         6 . The refrigeration cycle apparatus according to  claim 5 , wherein the second refrigerant circuit includes a second compressor, the second cascade channel, a second expansion valve, and a second heat exchanger. 
     
     
         7 . The refrigeration cycle apparatus according to  claim 6 , wherein, during the dual cycle operation, the first cascade channel functions as an evaporator of the first refrigerant, the first heat exchanger functions as a radiator of the first refrigerant, the second cascade channel functions as a radiator of the second refrigerant, and the second heat exchanger functions as an evaporator of the second refrigerant. 
     
     
         8 . The refrigeration cycle apparatus according to  claim 7 , wherein
 the first refrigerant circuit further includes a third heat exchanger, and   the cooling operation is enabled in which the third heat exchanger functions as a radiator of the first refrigerant and the first heat exchanger functions as an evaporator of the first refrigerant.   
     
     
         9 . The refrigeration cycle apparatus according to  claim 7 , wherein
 the first refrigerant circuit further includes a third heat exchanger, and   the heating operation is enabled, in which the third heat exchanger functions as an evaporator of the first refrigerant and the first heat exchanger functions as a radiator of the first refrigerant.   
     
     
         10 . The refrigeration cycle apparatus according to  claim 7 , wherein
 the first refrigerant circuit further includes a third heat exchanger and a switching unit that switches a channel of the first refrigerant, and   the switching unit is switched to enable the cooling operation in which the third heat exchanger functions as a radiator of the first refrigerant and the first heat exchanger functions as an evaporator of the first refrigerant and the heating operation in which the third heat exchanger functions as an evaporator of the first refrigerant and the first heat exchanger functions as a radiator of the first refrigerant.   
     
     
         11 . The refrigeration cycle apparatus according to  claim 8 , wherein
 the second heat exchanger exchanges heat between air flowing outside and the second refrigerant flowing inside,   the third heat exchanger exchanges heat between air flowing outside and the first refrigerant flowing inside, and   the refrigeration cycle apparatus further comprises a first blowing unit that forms an air flow passing through the second heat exchanger and an air flow passing through the third heat exchanger.   
     
     
         12 . The refrigeration cycle apparatus according to  claim 11 , wherein the second heat exchanger is located at a position other than leeward of the third heat exchanger in the air flow. 
     
     
         13 . The refrigeration cycle apparatus according to  claim 11 , wherein the second heat exchanger and the third heat exchanger are located away from each other in a direction of the air flow. 
     
     
         14 . The refrigeration cycle apparatus according to  claim 6 , wherein the second refrigerant circuit further includes a fourth heat exchanger provided between a discharge side of the second compressor and the second cascade channel. 
     
     
         15 . The refrigeration cycle apparatus according to  claim 14 , wherein
 the first heat exchanger exchanges heat between air flowing outside and the first refrigerant flowing inside,   the fourth heat exchanger exchanges heat between air flowing outside and the second refrigerant flowing inside, and   the refrigeration cycle apparatus further comprises a second blowing unit that forms an air flow passing through both the first heat exchanger and the fourth heat exchanger.   
     
     
         16 . The refrigeration cycle apparatus according to  claim 1 , wherein the first refrigerant includes at least any of R1234yf, R1234ze, and R290. 
     
     
         17 . The refrigeration cycle apparatus according to  claim 1 , wherein the second refrigerant includes carbon dioxide. 
     
     
         18 . The refrigeration cycle apparatus according to  claim 2 , wherein the single cycle operation is performed when a predetermined low-load condition is satisfied. 
     
     
         19 . The refrigeration cycle apparatus according to  claim 2 , comprising
 a cascade heat exchanger that exchanges heat between the first refrigerant and the second refrigerant during the dual cycle operation wherein   the cascade heat exchanger includes a first cascade channel through which the first refrigerant flows, and a second cascade channel which is independent of the first cascade channel and through which the second refrigerant flows.   
     
     
         20 . The refrigeration cycle apparatus according to  claim 3 , comprising
 a cascade heat exchanger that exchanges heat between the first refrigerant and the second refrigerant during the dual cycle operation wherein   the cascade heat exchanger includes a first cascade channel through which the first refrigerant flows, and a second cascade channel which is independent of the first cascade channel and through which the second refrigerant flows.