| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a wet operation by surely detecting a wet state. Ž<P>SOLUTION: A controller 20 of a refrigerant circuit 3 constituted by connecting a two-stage compressor 31, a condenser 32, an economizer heat exchanger 33, an evaporator 35 and an intermediate injection circuit 4, controls a second expansion valve 41 in such a state that a high-pressure discharge gas superheat degree in intermediate saturation which is a superheat degree of a high-pressure discharge gas when a refrigerant of an intermediate injection section becomes a saturated gas, calculated on the basis of a pressure of the high-pressure discharge gas discharged from the compressor 31, measured by a high-pressure pressure sensor 21, a pressure of an intermediate-pressure discharge gas discharged from the economizer heat exchanger 33 to the intermediate injection circuit 4, measured by the intermediate-pressure pressure sensor 22, and a temperature of the intermediate injection section detected by the intermediate injection section temperature sensor 23, is a lower limit of the superheat degree of the high-pressure discharge gas. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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