| 摘要 |
PROBLEM TO BE SOLVED: To obtain a control valve for heat pump, in which a refrigerant circuit and a solenoid valve, etc., are eliminated for a defrosting operation. SOLUTION: In a supercritical heat pump, since the refrigerant pressure and density of the circulating refrigerant are high in the high-pressure side, a large mass flow rate can be obtained, even if the volumetric flow rate is small. As a result, not only in a heat-pump operation but also in defrosting operation, a necessary heat amount (mass flow rate) can be obtained at a smaller volumetric flow rate, as compared with a subcritical heat pump which employs fluorocarbon or the like as refrigerant. Accordingly, the difference between the volumetric flow rate required for the defrosting operation and the flow rate required for the heat pump operation becomes small. As a result, if the highest flow rate of a control valve 300 is made greater than conventionally (when a refrigerant circuit for defrosting operation and a solenoid valve, etc., are provided), volumetric flow rate necessary for defrosting operation can be secured, by making the stroke of the valve element 314 longer than the length of the second tapered part 314b, without having to install a bypass circuit and a solenoid valve for the defrosting operation.
|
