Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus suppresses a phenomenon that a condensed refrigerant accumulates in a heat source-side heat exchanger during a low-load operation. A refrigeration cycle apparatus performs air conditioning of a target space. The refrigeration cycle apparatus includes a refrigerant circuit and a controller. The refrigerant circuit includes a compressor, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, and a flow direction switching mechanism. The controller controls the compressor and the flow direction switching mechanism. The controller executes first control of temporarily increasing the pressure of the refrigerant flowing through the heat source-side heat exchanger in a low-load operation in which the refrigerant circuit is in a low-load state with a low air conditioning load and the compressor operates at a predetermined number of rotations or less.

1 . A refrigeration cycle apparatus that performs air conditioning of a target space, the refrigeration cycle apparatus comprising:
 a refrigerant circuit including a compressor, a heat source-side heat exchanger, an expansion mechanism, a usage-side heat exchanger, and a flow direction switching mechanism; and   a controller that controls the compressor and the flow direction switching mechanism, wherein   the controller executes first control of temporarily increasing a pressure of a refrigerant flowing through the heat source-side heat exchanger in a low-load operation in which the refrigerant circuit is in a low-load state with a low air conditioning load and the compressor operates at a predetermined number of rotations or less.   
     
     
         2 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller increases a pressure of the refrigerant flowing through the heat source-side heat exchanger by increasing a number of rotations of the compressor in the first control.   
     
     
         3 . The refrigeration cycle apparatus according to  claim 1 , further comprising a heat source-side fan that blows air to the heat source-side heat exchanger, wherein
 the controller, in the first control, increases a pressure of the refrigerant flowing through the heat source-side heat exchanger by stopping the heat source-side fan.   
     
     
         4 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller, in the low-load operation, further executes second control of increasing an opening degree of the expansion mechanism during execution of the first control.   
     
     
         5 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller executes the first control over a predetermined first time period, and   the first time period is 10 seconds or more and 5 minutes or less.   
     
     
         6 . The refrigeration cycle apparatus according to  claim 5 , wherein
 the controller executes the first control at an interval of a second time period or more longer than the first time period.   
     
     
         7 . The refrigeration cycle apparatus according to  claim 6 , wherein
 the controller determines the first time period or the second time period based on a number of rotations of the compressor.   
     
     
         8 . The refrigeration cycle apparatus according to  claim 6 , wherein
 the controller determines the first time period or the second time period based on a first temperature that is a temperature of heat source air for heat exchange with a refrigerant in the heat source-side heat exchanger.   
     
     
         9 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller determines that the refrigerant circuit is in the low-load state when a difference between a first temperature that is a temperature of heat source air for heat exchange with a refrigerant in the heat source-side heat exchanger and a second temperature that is a temperature of the refrigerant flowing through the heat source-side heat exchanger is less than or equal to a predetermined first temperature difference.   
     
     
         10 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller determines that the refrigerant circuit is in the low-load state when a difference between a first estimated temperature of a refrigerant flowing through the usage-side heat exchanger calculated based on a first temperature that is a temperature of heat source air for heat exchange with the refrigerant in the heat source-side heat exchanger, or a third temperature that is a temperature of the refrigerant flowing through the usage-side heat exchanger, and the second temperature is less than or equal to a predetermined second temperature difference.   
     
     
         11 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller determines that the refrigerant circuit is in the low-load state when a difference between a third temperature that is a temperature of the refrigerant flowing through the usage-side heat exchanger, or a second estimated temperature of the refrigerant flowing through the usage-side heat exchanger calculated based on a number of rotations of the compressor, and a first temperature that is a temperature of heat source air for heat exchange with the refrigerant in the heat source-side heat exchanger is less than or equal to a predetermined third temperature difference.   
     
     
         12 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller determines that the refrigerant circuit is in the low-load state when a difference between a first temperature that is a temperature of heat source air for heat exchange with a refrigerant in the heat source-side heat exchanger and a sixth temperature that is a temperature in the target space is less than or equal to a predetermined fourth temperature difference.   
     
     
         13 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the controller determines that the refrigerant circuit is in the low-load state when a number of rotations of the compressor is less than or equal to a predetermined number of rotations.   
     
     
         14 . The refrigeration cycle apparatus according to  claim 2 , further comprising a heat source-side fan that blows air to the heat source-side heat exchanger, wherein
 the controller, in the first control, increases a pressure of the refrigerant flowing through the heat source-side heat exchanger by stopping the heat source-side fan.   
     
     
         15 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the controller, in the low-load operation, further executes second control of increasing an opening degree of the expansion mechanism during execution of the first control.   
     
     
         16 . The refrigeration cycle apparatus according to  claim 3 , wherein
 the controller, in the low-load operation, further executes second control of increasing an opening degree of the expansion mechanism during execution of the first control.   
     
     
         17 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the controller executes the first control over a predetermined first time period, and the first time period is 10 seconds or more and 5 minutes or less.   
     
     
         18 . The refrigeration cycle apparatus according to  claim 3 , wherein
 the controller executes the first control over a predetermined first time period, and   the first time period is 10 seconds or more and 5 minutes or less.   
     
     
         19 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the controller executes the first control over a predetermined first time period, and   the first time period is 10 seconds or more and 5 minutes or less.   
     
     
         20 . The refrigeration cycle apparatus according to  claim 7 , wherein
 the controller determines the first time period or the second time period based on a first temperature that is a temperature of heat source air for heat exchange with a refrigerant in the heat source-side heat exchanger.