Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus includes a refrigerant circuit and a non-azeotropic refrigerant that flows through a refrigerant pipe. When the non-azeotropic refrigerant passes through an outdoor heat exchanger, a temperature difference occurs between an inlet and an outlet of the outdoor heat exchanger. The outdoor heat exchanger includes: a group of fins that are stacked at intervals; and a heat transfer tube that extends through the group of fins in a stacking direction of the group of fins and allows the non-azeotropic refrigerant to flow inside the heat transfer tube. The group of fins includes: a first fin part to which frost can adhere in a humid environment; and a second fin part to which no frost adheres to ensure ventilation.

1 . A refrigeration cycle apparatus comprising:
 a refrigerant circuit in which a compressor, a condenser, a first expansion valve, and an evaporator are connected by a refrigerant pipe; and   a non-azeotropic refrigerant that flows through the refrigerant pipe, wherein   when the non-azeotropic refrigerant passes through the evaporator, a temperature difference occurs between an inlet and an outlet of the evaporator,   the evaporator comprises:
 a group of fins that are stacked at intervals; and 
 a heat transfer tube that extends through the group of fins in a stacking direction of the group of fins and allows the non-azeotropic refrigerant to flow inside the heat transfer tube, and 
   the group of fins comprises:
 a first fin part to which frost can adhere in a humid environment; and 
 a second fin part to which no frost adheres to ensure ventilation; 
 the first fin part is disposed in a predetermined frost region in the evaporator, and 
 the second fin part is disposed in a predetermined non-frost region in the evaporator, 
   the refrigeration cycle apparatus further comprises a temperature sensor disposed at a boundary between the frost region and the non-frost region in the evaporator.   
     
     
         2 . The refrigeration cycle apparatus according to  claim 1 , further comprising a controller configured to control the refrigerant circuit, wherein
 the controller is configured to control the refrigerant circuit such that, when air exchanging heat with the evaporator has a temperature of 0° C. or higher, the non-azeotropic refrigerant flowing in the heat transfer tube extending through the first fin part has a temperature of 0° C. or lower and the non-azeotropic refrigerant flowing in the heat transfer tube in the second fin part has a temperature of 0° C. or higher and lower than or equal to the temperature of the air.   
     
     
         3 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the controller is configured to control a degree of opening of the first expansion valve based on an output of the temperature sensor such that a temperature of the boundary is 0° C.   
     
     
         4 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the refrigerant circuit further comprises:
 a bypass flow path that branches at a branching point from the refrigerant pipe connecting the condenser to the first expansion valve, to return refrigerant to the compressor, 
 a second expansion valve disposed in the bypass flow path, and 
   an internal heat exchanger configured to exchange heat between refrigerant flowing from the condenser toward the branching point and refrigerant having passed through the second expansion valve.   
     
     
         5 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the controller is configured to control a degree of opening of the second expansion valve based on an output of the temperature sensor such that a temperature of the boundary is 0° C.   
     
     
         6 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the refrigerant circuit further comprises
 a bypass flow path that branches from the refrigerant pipe between a discharge outlet of the compressor and the condenser and merges into the refrigerant pipe between the first expansion valve and the evaporator, and 
 a flow rate adjustment valve disposed in the bypass flow path. 
   
     
     
         7 . The refrigeration cycle apparatus according to  claim 6 , wherein
 the controller is configured to control a degree of opening of the flow rate adjustment valve based on an output of the temperature sensor such that a temperature of the boundary is 0° C.   
     
     
         8 . The refrigeration cycle apparatus according to  claim 2 , wherein the refrigerant circuit further comprises a heater configured to heat refrigerant flowing in the refrigerant pipe connecting the first expansion valve to the evaporator. 
     
     
         9 . The refrigeration cycle apparatus according to  claim 8 , wherein
 the controller is configured to control an amount of heat generated by the heater based on an output of the temperature sensor such that a temperature of the boundary is 0° C.   
     
     
         10 . The refrigeration cycle apparatus according to  claim 2 , wherein
 a part of the refrigerant pipe connecting a discharge outlet of the compressor to the condenser comprises:
 a first flow path; and 
 a second flow path disposed in parallel with the first flow path, and 
   the refrigerant circuit further comprises:
 an internal heat exchanger configured to exchange heat between refrigerant flowing from the first expansion valve toward the evaporator, and refrigerant flowing in the second flow path, and 
 a flow path switching device configured to switch to allow refrigerant discharged from the compressor to flow in the first flow path or flow in the second flow path. 
   
     
     
         11 . The refrigeration cycle apparatus according to  claim 10 , wherein
 the controller is configured to control the flow path switching device based on an output of the temperature sensor such that a temperature of the boundary is 0° C.   
     
     
         12 . The refrigeration cycle apparatus according to  claim 1 , further comprising a four-way valve configured to interchange a discharge outlet and a suction inlet of the compressor to connect the discharge outlet and the suction inlet to the refrigerant circuit, wherein
 the four-way valve is configured to switch to allow refrigerant to flow through the refrigerant circuit in a first direction or a second direction, the refrigerant flowing in order of the compressor, the condenser, the first expansion valve, and the evaporator in the first direction, the refrigerant flowing in order of the compressor, the evaporator, the first expansion valve, and the condenser in the second direction.