MULTI-STAGE COMPRESSION TYPE HEAT PUMP SYSTEM CONTROLLING PRESSURE RANGE OF REFRIGERANT CIRCULATING

摘要

PURPOSE: A multi-stage compression type heat pump system is provided to control a pressure range of refrigerant circulating through an inside of a system by controlling the number of compressors to be driven, thereby appropriately coping with a heating load of an indoor side. CONSTITUTION: An outdoor heat exchanger(1) is installed outside for exchanging heat so that a refrigerant absorbs heat. A plurality of compressors(2,4) is connected in serial to compress the refrigerant by steps. A switch valve(3) opens and shuts a pipe to compress the refrigerant by steps by the compressors. An indoor heat exchanger(5) exchanges heat to emit heat from the discharged refrigerant. An electronic expansion valve(6) expands the refrigerant discharged from the indoor heat exchanger for discharging the refrigerant to the outdoor heat exchanger. A control unit controls operation of each compressor and the switch valve according to a heating load of an indoor side(10).