Refrigeration apparatus which injects an intermediate-gas liquid refrigerant from multi-stage expansion cycle into the compressor

A refrigeration apparatus comprising:

• a refrigerant circuit configured to perform a two-stage expansion refrigeration cycle, the refrigerant circuit including:
• a compression mechanism configured to discharge compressed refrigerant,
• a utilization-side heat exchanger configured to condense the compressed refrigerant discharged by the compression mechanism, and discharge the condensed refrigerant,
• a first expansion valve configured to depressurize the condensed refrigerant discharged by the utilization-side heat exchanger,
• a gas-liquid separator configured to separate liquid refrigerant from gas refrigerant within the refrigerant depressurized by the first expansion valve, the gas-liquid separator including a first outlet to discharge the liquid refrigerant,
• a second expansion valve configured to further depressurize the liquid refrigerant discharged from the first outlet of the gas-liquid separator, and
• a heat-source-side heat exchanger configured to evaporate the liquid refrigerant further depressurized by the second expansion valve to obtain gas refrigerant, the heat-source-side heat exchanger discharging the gas refrigerant toward a first portion of the compression mechanism, wherein
• the refrigerant circuit further includes:
• a gas injection pipe connecting a second outlet of the gas-liquid separator and an inlet of the compression mechanism such that the gas refrigerant flows out of the gas-liquid separator through said gas injection pipe into a second portion of the compression mechanism configured to compress refrigerant,
• a liquid-gas heat exchanger configured to exchange heat between:
• the gas refrigerant discharged by the heat-source-side heat exchanger and travelling toward the first portion of compression mechanism, and
• the liquid refrigerant discharged by the gas-liquid separator and travelling toward the second expansion valve, and
• a passage for conveying the liquid refrigerant through the liquid-gas heat exchanger, and
• the first expansion valve and the second expansion valve respectively disposed upstream and downstream of the liquid-gas heat exchanger in the passage that conveys the liquid refrigerant through the liquid-gas heat exchanger.