Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus includes a compressor, an expansion valve, a flow switching device, a heat source side heat exchanger including a first heat source side heat exchanger and a second heat source side heat exchanger connected in parallel, an opening-and-closing valve provided on downstream of the second heat source side heat exchanger through which refrigerant flows during a defrosting operation, and a controller that, when the defrosting operation is performed, controls the flow switching device so that the refrigerant discharged from the compressor flows into the heat source side heat exchanger. The controller switches the opening-and-closing valve from an open state to a closed state when the defrosting operation is started, determines a point in time when defrosting targets to be defrosted are switched, and switches the opening-and-closing valve from the closed state to the open state in accordance with the point in time determined.

1 . A refrigeration cycle apparatus comprising:
 a compressor configured to compress and discharge refrigerant;   an expansion valve configured to reduce pressure of the refrigerant to cause the refrigerant to expand;   a load side heat exchanger connected to the expansion valve;   a four-way valve connected to the compressor and the load side heat exchanger;   a heat source side heat exchanger including a first heat source side heat exchanger and a second heat source side heat exchanger connected in parallel between the four-way valve and the expansion valve;   a gas pipe configured to join a first gas pipe connected to the first heat source side heat exchanger and a second gas pipe connected to the second heat source side heat exchanger to allow the first gas pipe and the second gas pipe to communicate with the flow switching device;   a first gas header configured to split the refrigerant flowing into the first heat source side heat exchanger including a plurality of first heat-transfer tubes from the compressor via the four-way valve into streams flowing through the plurality of first heat-transfer tubes;   a second gas header configured to split the refrigerant flowing into the second heat source side heat exchanger including a plurality of second heat-transfer tubes from the compressor via the four-way valve into streams flowing through the plurality of second heat-transfer tubes;   an opening-and-closing valve provided on downstream of the second heat source side heat exchanger through which the refrigerant flows during a defrosting operation; and   a controller configured to, when the defrosting operation is performed, control the four-way valve so that the refrigerant discharged from the compressor flows into the heat source side heat exchanger,   wherein   a number of the plurality of first heat-transfer tubes is larger than a number of the plurality of second heat-transfer tubes,   the first gas pipe is connected to a middle portion in a gravity direction of the first gas header,   the second gas pipe is connected to a middle portion in the gravity direction of the second gas header, and   the controller is configured to   switch the opening-and-closing valve from an open state to a closed state when the defrosting operation is started,   determine a point in time when defrosting targets to be defrosted are switched, and   switch the opening-and-closing valve from the closed state to the open state in accordance with the point in time determined.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . The refrigeration cycle apparatus of  claim 1 , further comprising
 a temperature sensor provided on the downstream of the second heat source side heat exchanger and configured to detect a temperature of the refrigerant,   wherein the controller is configured to   determine, as the point in time, a time when a value detected by the temperature sensor reaches not less than a predetermined temperature threshold.   
     
     
         5 . The refrigeration cycle apparatus of  claim 1 , further comprising
 a flow control valve provided on downstream of the first heat source side heat exchanger through which the refrigerant flows during the defrosting operation,   wherein, when the defrosting operation is started, the controller is configured to maintain the flow control valve in an open state and switch the opening-and-closing valve from an open state to a closed state, and   wherein, in accordance with the point in time determined, the controller is configured to switch the flow control valve from the open state to a closed state and switch the opening-and-closing valve from the closed state to the open state.   
     
     
         6 . The refrigeration cycle apparatus of  claim 5 , further comprising
 a temperature sensor provided on the downstream of the first heat source side heat exchanger and configured to detect a temperature of the refrigerant,   wherein the controller is configured to   determine, as the point in time, a time when a value detected by the temperature sensor reaches not less than a predetermined temperature threshold.   
     
     
         7 . The refrigeration cycle apparatus of  claim 1 ,
 wherein the controller further includes a timer configured to measure a time period, and   wherein the controller is configured to   determine, as the point in time, a time when a time period measured from start of the defrosting operation by the timer reaches not less than a predetermined time threshold.   
     
     
         8 . The refrigeration cycle apparatus of  claim 1 , further comprising:
 a third heat source side heat exchanger connected in parallel with the first heat source side heat exchanger and the second heat source side heat exchanger between the four-way valve and the expansion valve;   a first flow control valve provided on downstream of the first heat source side heat exchanger through which the refrigerant flows during the defrosting operation; and   a second flow control valve provided on downstream of the third heat source side heat exchanger through which the refrigerant flows during the defrosting operation,   wherein, when the defrosting operation is started, the controller is configured to   maintain the first flow control valve in an open state and switch the opening-and-closing valve and the second flow control valve from an open state to a closed state,   wherein, in accordance with the point in time determined, the controller is configured to   switch the first flow control valve from the open state to a closed state and switch the opening-and-closing valve from the closed state to the open state, and   wherein, after switching the opening-and-closing valve from the closed state to the open state, in accordance with the point in time determined, the controller is configured to   switch the opening-and-closing valve from the open state to the closed state and switch the second flow control valve from the closed state to the open state.