Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus efficiently performs a cooling operation and a heating operation using a low-pressure refrigerant and a high-pressure refrigerant. A refrigeration cycle apparatus using a first refrigerant having 1 MPa or less at 30° C. and a second refrigerant having 1.5 MPa or more at 30° C. performs a heating operation by performing a two-stage refrigeration cycle including a use-side refrigeration cycle using the first refrigerant and a heat-source-side refrigeration cycle using the second refrigerant, and performs a cooling operation by performing a single-stage refrigeration cycle using the first refrigerant.

1 . A refrigeration cycle apparatus, wherein the refrigeration cycle apparatus
 performs a heating operation by performing a two-stage refrigeration cycle, the two-stage refrigeration cycle including a use-side refrigeration cycle using a first refrigerant having 1 MPa or less at 30° C. and a heat-source-side refrigeration cycle using a second refrigerant having 1.5 MPa or more at 30° C., and   performs a cooling operation by performing a single-stage refrigeration cycle using the first refrigerant.   
     
     
         2 . The refrigeration cycle apparatus according to  claim 1 , comprising
 an outdoor heat exchanger that functions as an evaporator of the second refrigerant during the heating operation and functions as a radiator of the first refrigerant during the cooling operation.   
     
     
         3 . The refrigeration cycle apparatus according to  claim 2 , comprising
 a cascade heat exchanger including a first cascade flow path through which the first refrigerant flows during the heating operation and a second cascade flow path that is independent of the first cascade flow path and through which the second refrigerant flows during the heating operation, the cascade heat exchanger being configured to exchange heat between the first refrigerant and the second refrigerant.   
     
     
         4 . The refrigeration cycle apparatus according to  claim 3 , comprising
 a use heat exchanger in which the first refrigerant radiates heat during the heating operation, wherein   during the heating operation, the first refrigerant evaporates when passing through the first cascade flow path, and the second refrigerant radiates heat when passing through the second cascade flow path.   
     
     
         5 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the first refrigerant evaporates in the use heat exchanger during the cooling operation.   
     
     
         6 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the first refrigerant is collectable in a first region other than the outdoor heat exchanger, and the second refrigerant is collectable in a second region other than the outdoor heat exchanger and other than the first region.   
     
     
         7 . A refrigeration cycle apparatus, wherein the refrigeration cycle apparatus
 performs a heating operation by performing a two-stage refrigeration cycle, the two-stage refrigeration cycle including a use-side refrigeration cycle using a first refrigerant having 1 MPa or less at 30° C. and a heat-source-side refrigeration cycle using a second refrigerant having 1.5 MPa or more at 30° C., and   performs a cooling operation by performing a two-stage refrigeration cycle, the two-stage refrigeration cycle including a use-side refrigeration cycle using the second refrigerant and a heat-source-side refrigeration cycle using the first refrigerant.   
     
     
         8 . The refrigeration cycle apparatus according to  claim 7 , wherein
 a refrigerant to be used in the heat-source-side refrigeration cycle and a refrigerant to be used in the use-side refrigeration cycle are interchanged between the heating operation and the cooling operation.   
     
     
         9 . The refrigeration cycle apparatus according to  claim 8 , comprising
 a refrigerant tank that temporarily stores either the first refrigerant or the second refrigerant when the refrigerants are interchanged.   
     
     
         10 . The refrigeration cycle apparatus according to  claim 7 , comprising
 a cascade heat exchanger including a first cascade flow path in which the first refrigerant evaporates during the heating operation and a second cascade flow path that is independent of the first cascade flow path and in which the second refrigerant radiates heat during the heating operation, the cascade heat exchanger being configured to exchange heat between the first refrigerant and the second refrigerant.   
     
     
         11 . The refrigeration cycle apparatus according to  claim 7 , comprising
 a use heat exchanger that functions as a radiator of the first refrigerant during the heating operation and functions as an evaporator of the second refrigerant during the cooling operation.   
     
     
         12 . The refrigeration cycle apparatus according to  claim 7 , comprising
 an outdoor heat exchanger that functions as an evaporator of the second refrigerant during the heating operation and functions as a condenser of the first refrigerant during the cooling operation.   
     
     
         13 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the refrigeration cycle apparatus detects a state of mixing of the first refrigerant and the second refrigerant.   
     
     
         14 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the refrigeration cycle apparatus separates the first refrigerant and the second refrigerant from each other.   
     
     
         15 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the first refrigerant includes at least one of R1234yf or R1234ze.   
     
     
         16 . The refrigeration cycle apparatus according to  claim 1 , wherein
 The second refrigerant includes carbon dioxide.   
     
     
         17 . The refrigeration cycle apparatus according to  claim 3 , wherein
 the first refrigerant is collectable in a first region other than the outdoor heat exchanger, and the second refrigerant is collectable in a second region other than the outdoor heat exchanger and other than the first region.   
     
     
         18 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the first refrigerant is collectable in a first region other than the outdoor heat exchanger, and the second refrigerant is collectable in a second region other than the outdoor heat exchanger and other than the first region.   
     
     
         19 . The refrigeration cycle apparatus according to  claim 5 , wherein
 the first refrigerant is collectable in a first region other than the outdoor heat exchanger, and the second refrigerant is collectable in a second region other than the outdoor heat exchanger and other than the first region.   
     
     
         20 . The refrigeration cycle apparatus according to  claim 8 , comprising
 a cascade heat exchanger including a first cascade flow path in which the first refrigerant evaporates during the heating operation and a second cascade flow path that is independent of the first cascade flow path and in which the second refrigerant radiates heat during the heating operation, the cascade heat exchanger being configured to exchange heat between the first refrigerant and the second refrigerant.