The supercritical refrigerating apparatus has refrigerant bypass means for bypassing a heat exchanger according to a physical value of the refrigerant. Therefore, the temperature of refrigerant on a suction side of the compressor becomes lower than that of refrigerant sucked into the compressor via the heat exchanger. As a result, the refrigerant temperature in a refrigerant passage extending from a suction side to a discharge side of the compressor is decreased, thereby preventing breakage of the compressor.

A heat pump equipped with an extraction heat exchanger includes a compressor sucking low-temperature-and-low-pressure liquid refrigerant, and compressing and discharging the low-temperature-and-low-pressure liquid refrigerant into high-temperature-and-high-pressure liquid refrigerant, a condenser in which air passing therethrough absorbs heat from the liquid refrigerant to liquefy the liquid refrigerant, an evaporator in which refrigerant absorbs heat from indoor air and is evaporated to cool indoor air, a main electronic expansion valve connected between the condenser and the evaporator to decompress the liquid refrigerant liquefied in the condenser such that the decompressed refrigerant is easily evaporated in the evaporator and flows at a predetermined flow rate; and the extraction heat exchanger branching a part of the high-temperature-and-high-pressure liquid refrigerant, and performing and bypassing heat exchange between high-temperature-and-high-pressure super-cooled liquid refrigerant and high-temperature-and-high-pressure refrigerant passing through a heat exchanging refrigerant tube between the condenser and the main electronic expansion valve to an accumulator.

A refrigerant circulation apparatus utilizing two evaporators operating at respectively different evaporating temperatures which is capable of efficient refrigerant circulation by performing a heat exchange by contact between a refrigerant pipe guiding refrigerant discharged from a condenser to an evaporator and a refrigerant pipe guiding refrigerant discharged from the evaporator to a compressor in order to enhance the refrigerating ability when an evaporator is operated at a high evaporating temperature and pressure, includes a compressor, a condenser, a plurality of evaporators operating at different respective evaporating temperatures, a first plurality of refrigerant pipes for guiding the refrigerant discharged from the condenser to the plurality of evaporators, and a second plurality of refrigerant pipes predetermined portions of which are in heat exchanging contact with the first plurality of refrigerant pipes.