| 摘要 |
PROBLEM TO BE SOLVED: To provide a CO<SB>2</SB>refrigerating cycle of a cascade two-stage compression type using CO<SB>2</SB>as refrigerant for cooling and heating operation at the same time, allowing efficient utilization of energy by using lubricating oil for a compressor separately to be non-compatible and compatible. SOLUTION: The cascade two-stage compression CO<SB>2</SB>refrigerating cycle according to the first invention comprises a low-stage CO<SB>2</SB>refrigerating cycle 18 consisting of a low-stage evaporator 10, a low-stage compressor 11, a cascade condenser 12, and a (low-stage) expansion valve 13, to be operated by CO<SB>2</SB>refrigerant in a region including a low temperature saturated region, and a high-stage compressor 14, a gas cooler 15, a (high-stage) expansion valve 16 and a high-stage evaporator 17. COPYRIGHT: (C)2005,JPO&NCIPI
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