| 摘要 |
PROBLEM TO BE SOLVED: To prevent inflow of liquid refrigerant from a gas-liquid separator to a high stage-side compressor in a defrosting operation of inverse cycle. SOLUTION: An option unit 30 having the high stage-side compressor 31 and the gas-liquid separator 33, is disposed between an outdoor unit 20 having a low stage-side compressor 21 and an indoor unit 40. In the defrosting operation, an outdoor heat exchanger 22 is defrosted by a discharged refrigerant of the low stage-side compressor 21, and a refrigerant of the gas-liquid separator 33 is sucked to the high stage-side compressor 31 and discharged to a suction side of the low stage side compressor 21. The option unit 30 is provided with an injection pipe 36 for returning a part of the discharged refrigerant of the high stage-side compressor 31 to the suction side of the high stage-side compressor 31 in the defrosting operation. Thus the refrigerant flowing from the gas-liquid separator 33 to the high stage-side compressor 31 is gasified by the discharged refrigerant of high temperature. COPYRIGHT: (C)2007,JPO&INPIT
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