Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus includes a compressor, a first heat exchanger, a second heat exchanger, a third heat exchanger, a flow path switching valve, a first expansion valve, a second expansion valve, a third expansion valve, a refrigerant container, a first check valve, and a second check valve. The flow path switching valve switches a circulation direction of a non-azeotropic refrigerant mixture between a first circulation direction and a second circulation direction. A first port of the third expansion valve communicates with the refrigerant container through the third heat exchanger. A second port of the third expansion valve communicates through the first check valve with a first flow path between the first heat exchanger and the first expansion valve, and communicates through the second check valve with a second flow path between the second heat exchanger and the second expansion valve.

1 . A refrigeration cycle apparatus through which a non-azeotropic refrigerant mixture circulates, the refrigeration cycle apparatus comprising:
 a compressor;   a first heat exchanger;   a second heat exchanger;   a third heat exchanger;   a flow path switching valve configured to switch a circulation direction of the non-azeotropic refrigerant mixture between a first circulation direction and a second circulation direction;   a first expansion valve;   a second expansion valve;   a third expansion valve having a first port and a second port;   a refrigerant container;   a first check valve;   a second check valve; and   a controller configured to control a degree of opening of the third expansion valve, wherein   in the first circulation direction, the non-azeotropic refrigerant mixture circulates in order of the compressor, the flow path switching valve, the first heat exchanger, the first expansion valve, the refrigerant container, the second expansion valve, the second heat exchanger, the flow path switching valve, and the third heat exchanger,   in the second circulation direction, the non-azeotropic refrigerant mixture circulates in order of the compressor, the flow path switching valve, the second heat exchanger, the second expansion valve, the refrigerant container, the first expansion valve, the first heat exchanger, the flow path switching valve, and the third heat exchanger,   the first port communicates with the refrigerant container through the third heat exchanger,   the second port communicates through the first check valve with a first flow path between the first heat exchanger and the first expansion valve, and communicates through the second check valve with a second flow path between the second heat exchanger and the second expansion valve, and   based on: a first temperature of the non-azeotropic refrigerant mixture inside a specific heat exchanger functioning as a condenser among the first heat exchanger and the second heat exchanger; a second temperature of the non-azeotropic refrigerant mixture that flows out of the specific heat exchanger; and pressure of the non-azeotropic refrigerant mixture inside the refrigerant container, the controller is configured to control the degree of opening of the third expansion valve such that a degree of dryness of the non-azeotropic refrigerant mixture inside the refrigerant container falls within a first reference range.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller is configured to
 increase a degree of opening of a specific expansion valve which is the first expansion valve or the second expansion valve when a discharge temperature of the non-azeotropic refrigerant mixture discharged from the compressor is higher than a maximum value of a second reference range, the specific expansion valve receiving the non-azeotropic refrigerant mixture from the refrigerant container, 
 decrease the degree of opening of the specific expansion valve when the discharge temperature is lower than a minimum value of the second reference range, and 
 control the degree of opening of the third expansion valve when the discharge temperature falls within the second reference range. 
   
     
     
         5 . A refrigeration cycle apparatus through which a non-azeotropic refrigerant mixture circulates, the refrigeration cycle apparatus comprising:
 a compressor;   a first heat exchanger;   a second heat exchanger;   a third heat exchanger;   a flow path switching valve configured to switch a circulation direction of the non-azeotropic refrigerant mixture between a first circulation direction and a second circulation direction;   a first expansion valve;   a second expansion valve;   a third expansion valve having a first port and a second port;   a refrigerant container;   a first check valve; and   a second check valve, wherein   in the first circulation direction, the non-azeotropic refrigerant mixture circulates in order of the compressor, the flow path switching valve, the first heat exchanger, the first expansion valve, the refrigerant container, the second expansion valve, the second heat exchanger, the flow path switching valve, and the third heat exchanger,   in the second circulation direction, the non-azeotropic refrigerant mixture circulates in order of the compressor, the flow path switching valve, the second heat exchanger, the second expansion valve, the refrigerant container, the first expansion valve, the first heat exchanger, the flow path switching valve, and the third heat exchanger,   the first port communicates with the refrigerant container through the third heat exchanger,   the second port communicates through the first check valve with a first flow path between the first heat exchanger and the first expansion valve, and communicates through the second check valve with a second flow path between the second heat exchanger and the second expansion valve, and   the controller is configured to
 increase a degree of opening of a specific expansion valve which is the first expansion valve or the second expansion valve when a discharge temperature of the non-azeotropic refrigerant mixture discharged from the compressor is higher than a maximum value of a second reference range, the specific expansion valve receiving the non-azeotropic refrigerant mixture from the refrigerant container, 
 decrease the degree of opening of the specific expansion valve when the discharge temperature is lower than a minimum value of the second reference range, and 
 control the degree of opening of the third expansion valve when the discharge temperature falls within the second reference range. 
   
     
     
         6 . The refrigeration cycle apparatus according to  claim 5 , further comprising a controller configured to control a degree of opening of the third expansion valve, wherein
 based on: a first temperature of the non-azeotropic refrigerant mixture that flows out of the refrigerant container into the third heat exchanger; and a second temperature of the non-azeotropic refrigerant mixture that flows out of the refrigerant container into the first expansion valve or the second expansion valve, the controller is configured to control the degree of opening of the third expansion valve such that a difference between the first temperature and the second temperature approaches a temperature gradient at pressure of the non-azeotropic refrigerant mixture inside the refrigerant container, and   the temperature gradient is a temperature difference between saturated vapor and saturated liquid of the non-azeotropic refrigerant mixture at the pressure.