| 摘要 |
PROBLEM TO BE SOLVED: To prevent a valve element of a check valve of a thermally driven pump from becoming oscillatory, avoid vibrations and sound caused by the oscillatory behavior, and improve reliability of the check valve. SOLUTION: Main tanks (T1, T2) of a pump circuit (30) are connected to a main circuit (21). In the pump circuit (30) solenoid valve (SVH1, SVL1, etc.), are opened and closed to raise and reduce pressures in the main tanks (T1, T2). Extrusion of a liquid refrigerant from the one main tank (T1) and recovery of a liquid refrigerant to the other main tank (T2) are simultaneously achieved, and a secondary side refrigerant is circulated in the main circuit (21). A controller (60) opens and closes the solenoid valves (SVH1, SVL1, etc.). The controller (60) starts reduction of pressure in the main tanks (T1, T2) after a gas refrigerant emanated from the main tanks (T1, T2) reaches outflow side check valves (CVH1, CVH2). A refrigerant flowing upon the outflow side check valves (CVH1, CVH2) being interrupted is the gas refrigerant, so that valve element of the check valve is prevented from vibrating.
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