Air conditioning apparatus

Abstract

An air conditioning apparatus includes an outdoor unit, indoor units, a branch unit, and a heat medium circuit through which a heat medium having a global warming potential (GWP) lower than that of the refrigerant circulates. The heat medium circuit has a first pump, a second pump, a first heat exchanger, a second heat exchanger, a first branch header, a second branch header, a first merge header, a second merge header, first on-off valves, second on-off valves, third on-off valves, fourth on-off valves, a fifth on-off valve, a sixth on-off valve, a seventh on-off valve, an eighth on-off valve, a ninth on-off valve, and a tenth on-off valve disposed in the branch unit, a supply main pipe and a return main pipe connecting the branch unit to the outdoor unit, and supply branch pipes and return branch pipes connecting the branch unit to the respective indoor units.

1 . An air conditioning apparatus comprising:
 an outdoor unit, a plurality of indoor units, and a branch unit;   a refrigerant circuit through which refrigerant circulates; and   a heat medium circuit through which a heat medium having a global warming potential (GWP) lower than that of the refrigerant circulates, wherein   the refrigerant circuit is disposed in the branch unit, has a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger, and is provided such that the refrigerant circulates through the compressor, the first heat exchanger, the expansion valve, and the second heat exchanger in order,   the heat medium circuit has
 a first pump, a second pump, the first heat exchanger, the second heat exchanger, a first branch header, a second branch header, a first merge header, a second merge header, a plurality of first on-off valves, a plurality of second on-off valves, a plurality of third on-off valves, a plurality of fourth on-off valves, a fifth on-off valve, a sixth on-off valve, a seventh on-off valve, an eighth on-off valve, a ninth on-off valve, and a tenth on-off valve disposed in the branch unit, 
 an outdoor heat exchanger disposed in the outdoor unit, 
 an indoor heat exchanger disposed in each of the plurality of indoor units, 
 a supply main pipe and a return main pipe connecting the branch unit to the outdoor unit, and 
 a plurality of supply branch pipes and a plurality of return branch pipes connecting the branch unit to respective ones of the plurality of indoor units, 
   a first end of each of the plurality of supply branch pipes is connected to the first branch header via a corresponding one of the plurality of first on-off valves and is connected to the second branch header via a corresponding one of the plurality of second on-off valves,   a second end of each of the plurality of supply branch pipes is connected to a first end of the indoor heat exchanger of a corresponding one of the plurality of indoor units,   a first end of each of the plurality of return branch pipes is connected to the first merge header via a corresponding one of the plurality of third on-off valves and is connected to the second merge header via a corresponding one of the plurality of fourth on-off valves,   a second end of each of the plurality of return branch pipes is connected to a second end of the indoor heat exchanger of a corresponding one of the plurality of indoor units,   the first branch header is connected to the first merge header via the fifth on-off valve,   the second branch header is connected to the second merge header via the sixth on-off valve,   the first merge header, the first pump, the first heat exchanger, and the first branch header are connected in order,   the second merge header, the second pump, the second heat exchanger, and the second branch header are connected in order,   a first end of the supply main pipe is connected to the first merge header via the seventh on-off valve and is connected to the second merge header via the eighth on-off valve,   a second end of the supply main pipe is connected to a first end of the outdoor heat exchanger of the outdoor unit,   a first end of the return main pipe is connected to the first pump via the ninth on-off valve and is connected to the second pump via the tenth on-off valve, and   a second end of the return main pipe is connected to a second end of the outdoor heat exchanger of the outdoor unit.   
     
     
         2 . The air conditioning apparatus according to  claim 1 , wherein
 the heat medium circuit further has an eleventh on-off valve and a twelfth on-off valve, and   a point of connection between the supply main pipe and the first merge header is connected to a point of connection between the return main pipe and the first pump via the eleventh on-off valve, and   a point of connection between the supply main pipe and the second merge header is connected to a point of connection between the return main pipe and the second pump via the twelfth on-off valve.   
     
     
         3 . The air conditioning apparatus according to  claim 2 , wherein in the heat medium circuit, the eleventh on-off valve is disposed downstream of the first merge header as viewed from the first pump, and the twelfth on-off valve is disposed downstream of the second merge header as viewed from the second pump. 
     
     
         4 . The air conditioning apparatus according to  claim 2 , wherein when each of the plurality of indoor units performs a cooling operation in a low outside temperature state in which a temperature outside where the outdoor unit is disposed is lower than a temperature of a room in which each of the plurality of indoor units is placed,
 the compressor stops,   the plurality of third on-off valves, the plurality of fourth on-off valves, the eighth on-off valve, and the tenth on-off valve are opened, and the plurality of first on-off valves, the plurality of second on-off valves, the fifth on-off valve, the sixth on-off valve, the seventh on-off valve, the ninth on-off valve, the eleventh on-off valve, and the twelfth on-off valve are closed, and   the second pump, the second heat exchanger, the second branch header, each of the plurality of third on-off valves, each of the plurality of supply branch pipes, the indoor heat exchanger, each of the plurality of return branch pipes, each of the plurality of fourth on-off valves, the second merge header, the eighth on-off valve, the supply main pipe, the outdoor heat exchanger, the return main pipe, and the tenth on-off valve are connected in order in the heat medium circuit.   
     
     
         5 . The air conditioning apparatus according to  claim 1 , wherein a minimum value of a flow path sectional area of each of the supply main pipe and the return main pipe is greater than a maximum value of a flow path sectional area of each of the plurality of supply branch pipes and the plurality of return branch pipes. 
     
     
         6 . The air conditioning apparatus according to  claim 1 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         7 . The air conditioning apparatus according to  claim 1 , wherein the GWP of the heat medium is smaller than that of carbon dioxide. 
     
     
         8 . The air conditioning apparatus according to  claim 3 , wherein when each of the plurality of indoor units performs a cooling operation in a low outside temperature state in which a temperature outside where the outdoor unit is disposed is lower than a temperature of a room in which each of the plurality of indoor units is placed,
 the compressor stops,   the plurality of third on-off valves, the plurality of fourth on-off valves, the eighth on-off valve, and the tenth on-off valve are opened, and the plurality of first on-off valves, the plurality of second on-off valves, the fifth on-off valve, the sixth on-off valve, the seventh on-off valve, the ninth on-off valve, the eleventh on-off valve, and the twelfth on-off valve are closed, and   the second pump, the second heat exchanger, the second branch header, each of the plurality of third on-off valves, each of the plurality of supply branch pipes, the indoor heat exchanger, each of the plurality of return branch pipes, each of the plurality of fourth on-off valves, the second merge header, the eighth on-off valve, the supply main pipe, the outdoor heat exchanger, the return main pipe, and the tenth on-off valve are connected in order in the heat medium circuit.   
     
     
         9 . The air conditioning apparatus according to  claim 2 , wherein a minimum value of a flow path sectional area of each of the supply main pipe and the return main pipe is greater than a maximum value of a flow path sectional area of each of the plurality of supply branch pipes and the plurality of return branch pipes. 
     
     
         10 . The air conditioning apparatus according to  claim 3 , wherein a minimum value of a flow path sectional area of each of the supply main pipe and the return main pipe is greater than a maximum value of a flow path sectional area of each of the plurality of supply branch pipes and the plurality of return branch pipes. 
     
     
         11 . The air conditioning apparatus according to  claim 4 , wherein a minimum value of a flow path sectional area of each of the supply main pipe and the return main pipe is greater than a maximum value of a flow path sectional area of each of the plurality of supply branch pipes and the plurality of return branch pipes. 
     
     
         12 . The air conditioning apparatus according to  claim 8 , wherein a minimum value of a flow path sectional area of each of the supply main pipe and the return main pipe is greater than a maximum value of a flow path sectional area of each of the plurality of supply branch pipes and the plurality of return branch pipes. 
     
     
         13 . The air conditioning apparatus according to  claim 2 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         14 . The air conditioning apparatus according to  claim 3 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         15 . The air conditioning apparatus according to  claim 4 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         16 . The air conditioning apparatus according to  claim 5 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         17 . The air conditioning apparatus according to  claim 8 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         18 . The air conditioning apparatus according to  claim 9 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         19 . The air conditioning apparatus according to  claim 10 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.   
     
     
         20 . The air conditioning apparatus according to  claim 11 , wherein
 the outdoor heat exchanger has a plurality of heat exchange units connected in parallel to each other with respect to the supply main pipe and the return main pipe,   the plurality of heat exchange units have a first heat exchange unit, and a second heat exchange unit having an internal volume smaller than that of the first heat exchange unit, and   when a value obtained by dividing an area of an outer surface of the outdoor heat exchanger by an area of an internal surface of the outdoor heat exchanger is defined as an area expansion ratio, the area expansion ratio of the second heat exchange unit is smaller than the area expansion ratio of the first heat exchange unit, the outer surface coming into contact with outdoor air, the inner surface coming into contact with the heat medium.