| 摘要 |
PROBLEM TO BE SOLVED: To prevent wasteful heat dissipation and further prevent a liquid-back trouble upon returning to an ordinary operation in a defrosting operation of a heat pump that absorbs heat from fresh air. SOLUTION: A heat absorption heat exchanger 3 for forcing fresh air OA to serve to absorb heat is divided to an air upstream side section 3A and an air downstream side section 3B, and changeover is ensured between an ordinary operation where a refrigerant R is circulated in the order of a compressor 1-a heat dissipation heat exchanger 2-an expansion mechanism 5-a parallel connection circuit or a series connection circuit of the air upstream side section 3A and the air downstream side section 3B-the compressor 1, and a defrosting operation for circulating the refrigerant R in the order of the compressor 1-the air upstream side section 3A of the heat absorption heat exchanger 3-the expansion mechanism 5-heat dissipation heat exchanger 2-the compressor 1 in the state that refrigerant passing through the air downstream side section 3B of the heat absorption heat exchanger 3 is interrupted.
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