| 摘要 |
The low-side pressure of a refrigeration cycle and the refrigerant temperature at the exit of a gas cooler under reference operating conditions are employed as a reference low pressure and a reference refrigerant temperature, respectively, and the high-side pressure of the refrigeration cycle at which the COP of the refrigeration cycle reaches a maximum value under the reference operating conditions is employed as a reference high pressure. In this case, the volume v2 of a first fluid chamber (72) in the expander (60) just after the closing off of fluid communication from its inlet channel and the volume v3 of a second fluid chamber (82) in the expander (60) just before the provision of fluid communication with its outlet channel are set to v2=rho1v1r/rho2 and v3=rho2v2/rho3, respectively, where rho1 is the density of saturated gas refrigerant at the reference low pressure, rho2 is the density of refrigerant at the reference high pressure and the reference refrigerant temperature, rho3 is the density of refrigerant adiabatically expanded from a condition of the reference high pressure and the reference refrigerant temperature into a condition of the reference low pressure, v1 is the volume of the fluid chamber in the compressor just after the closing off of fluid communication from its suction channel, and r is the rotational speed ratio of the compressor to the expander.
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