Air-conditioning apparatus

Abstract

In a case where frost is deposited a heat-source-side heat exchanger during a heating operation mode, an air-conditioning apparatus executes either a “heat recovery defrosting operation mode” using a heat capacity held in a heat medium or a “bypass defrosting operation mode” not using the heat capacity held in the heat medium.

1 . An air-conditioning apparatus comprising:
 a refrigerant circulation circuit to circulate therein a heat-source-side refrigerant, the refrigerant circulation circuit connecting, by refrigerant pipes, a compressor, a heat-source-side heat exchanger, a plurality of expansion devices, refrigerant-side flow passages of a plurality of intermediate heat exchangers, and a plurality of refrigerant flow switching devices to switch a refrigerant circulation passage;   a heat medium circulation circuit to circulate therein a heat medium, the heat medium circuit connecting, by heat medium conveyance pipes, a plurality of heat medium conveyance devices provided in association with the plurality of intermediate heat exchangers, a plurality of use-side heat exchangers, and heat-medium-side flow passages for the plurality of intermediate heat exchangers; and   a bypass pipe installed so as to return the heat-source-side refrigerant to the compressor by bypassing at least the intermediate heat exchangers,   the plurality of intermediate heat exchangers exchanging heat between the heat-source-side refrigerant and the heat medium,   the air-conditioning apparatus being configured to execute   a heating operation mode switching the refrigerant flow switching devices to a side of heating operation, heating the heat medium by at least one of the intermediate heat exchangers, operating at least one of the heat medium conveyance devices, and supplying the heated heat medium to at least one of the use-side heat exchangers,   a heat recovery defrosting operation mode melting frost formed around the heat-source-side heat exchanger by switching, during the heating operation mode, the refrigerant flow switching devices to a side of cooling operation, operating at least one of the heat medium conveyance devices, and causing the heat-source-side refrigerant to receive heat of the heat medium by at least one of the intermediate heat exchangers, and   a bypass defrosting operation mode melting frost formed around the heat-source-side heat exchanger by switching, during the heating operation mode, the refrigerant flow switching devices to the side of cooling operation and causing part or whole of the heat-source-side refrigerant to flow to the bypass pipe, wherein the heating operation mode includes   a heating main operation mode switching the refrigerant flow switching devices to the side of heating operation, heating the heat medium by at least one of the intermediate heat exchangers, and cooling the heat medium by rest of intermediate heat exchangers, and   the bypass defrosting operation mode includes   a second bypass defrosting operation mode for melting frost formed around the heat-source-side heat exchanger by switching the refrigerant flow switching devices to the side of cooling operation, causing the cold heat medium to flow to at least one of the intermediate heat exchangers, and causing part of the heat medium to flow to the bypass pipe while causing the intermediate heat exchanger having executed cooling during the heating main operation mode to continue cooling.   
     
     
         2 . The air-conditioning apparatus of  claim 1 ,
 wherein in the heat recovery defrosting operation mode,   at least one of the intermediate heat exchangers to cause the heat-source-side refrigerant to receive the heat of the heat medium is   same as the at least one of the intermediate heat exchangers having heated the heat medium before execution of the heat recovery defrosting operation mode.   
     
     
         3 . The air-conditioning apparatus of  claim 1 , further comprising:
 a heat medium temperature sensor provided at any position of a flow passage on an outlet side of the heat medium of the intermediate heat exchangers,   wherein the heat recovery defrosting operation mode is executed when a temperature of the heat medium detected by the heat medium temperature sensor is higher than a setting temperature, and   wherein the bypass defrosting operation mode is executed when the temperature of the heat medium detected by the heat medium temperature sensor is lower than the setting temperature.   
     
     
         4 . The air-conditioning apparatus of  claim 3 , further comprising:
 a use-side air temperature sensor detecting a temperature of air flowing through the use-side heat exchangers,   wherein the setting temperature is   equal to or higher than the temperature detected by the use-side air temperature sensor.   
     
     
         5 - 6 . (canceled) 
     
     
         7 . The air-conditioning apparatus of  claim 1 ,
 wherein the heat recovery defrosting operation mode includes   a second heat recovery defrosting operation mode melting frost formed around the heat-source-side heat exchanger by switching the refrigerant flow switching devices to the side of cooling operation, causing the cold heat medium to flow to all of the intermediate heat exchangers, and causing the heat-source-side refrigerant to receive heat held in the heat medium by the at least one of the intermediate heat exchangers having executed heating during the heating main operation mode while causing the at least one of the intermediate heat exchangers having executed cooling during the heating main operation mode to continue cooling, and   wherein when the air-conditioning apparatus is switched from the heating main operation mode to the second heat recovery defrosting operation mode to perform defrosting, each of the expansion devices corresponding to the at least one of the intermediate heat exchangers having executed heating during the heating main operation mode is fully opened in the second heat recovery defrosting operation mode, and defrosting is performed by switching to the second bypass defrosting mode from the second heat recovery operation mode.   
     
     
         8 . (canceled) 
     
     
         9 . The air-conditioning apparatus of  claim 1 ,
 wherein in the heat recovery defrosting operation mode,   a blower device blowing air to at least one of the use-side heat exchangers having executed a heating operation before starting a defrosting operation is stopped, and   a blower device blowing air to at least one of the use-side heat exchangers having executed a cooling operation before starting the defrosting operation is operated.   
     
     
         10 . The air-conditioning apparatus of  claim 1 , further comprising:
 a plurality of indoor units accommodating each of the plurality of use-side heat exchangers;   at least one outdoor unit accommodating the compressor and the heat-source-side heat exchanger; and   at least one relay unit accommodating the plurality of intermediate heat exchangers, the plurality of expansion devices, the plurality of heat medium conveyance devices, and the plurality of refrigerant flow switching devices,   wherein the indoor units, the outdoor unit, and the relay unit are configured to be formed independently of one another and installed at positions separated from one another.   
     
     
         11 . The air-conditioning apparatus of  claim 1 ,
 wherein in the bypass defrosting operation mode,   the heating operation continues to be performed by using a heat capacity of the heat medium having been used for the heating operation.   
     
     
         12 . The air-conditioning apparatus of  claim 11 ,
 wherein in continuing the heating operation,   an amount of air blown to one of the use-side heat exchangers that continues to perform the heating operation is reduced to be less than a setting air volume.   
     
     
         13 . The air-conditioning apparatus of  claim 12 ,
 wherein even when air is blown by using outdoor air taken in for a purpose of ventilation, hot air is suppliable by performing a heating operation using the heat medium.