An air conditioner includes: a heat-source-side unit including a compressor and a heat-source-side heat exchanger; use-side units each including a use-side heat exchanger; an intermediate unit that causes the use-side heat exchanger of each of the use-side units to individually function as an evaporator or a radiator of a refrigerant; and two connection pipes that each connect the heat-source-side unit and the intermediate unit. The intermediate unit includes: an ejector that is configured to pressurize the refrigerant evaporated in the use-side heat exchanger that functions as the evaporator by using a driving flow; and a gas-liquid separator into which the refrigerant flowing out from the ejector flows.

A circulation system of an air conditioner, an air conditioner, and an air conditioner control method. The circulation system of the air conditioner includes a compressor, a first heat exchanger, a second heat exchanger, and a gas-liquid separation assembly. The gas-liquid separation assembly, together with the compressor, the first heat exchanger, and the second heat exchanger, forms a loop; the gas-liquid separation assembly includes two or more gas-liquid separators which are connected in series; the gas-liquid separation assembly is configured to perform gas-liquid separation for refrigerant. Further, two or more-staged gas-liquid separation can be performed for the refrigerant flowing back to the compressor, so that a problem that return oil containing liquid in the compressor can be effectively solved.

A refrigeration cycle apparatus (1) is capable of performing a refrigeration cycle using a small-GWP refrigerant. The refrigeration cycle apparatus (1) includes a refrigerant circuit (10) and a refrigerant enclosed in the refrigerant circuit (10). The refrigerant circuit includes a compressor (21), a condenser (23), a decompressing section (24), and an evaporator (31). The refrigerant contains is a small-GWP refrigerant.

An air conditioning unit capable of performing a refrigeration cycle using a small-GWP refrigerant is provided. A refrigeration cycle apparatus (1, 1a to 1m) includes a refrigerant circuit (10) including a compressor (21), a condenser (23, 31, 36), a decompressing section (24, 44, 45, 33, 38), and an evaporator (31, 36, 23), and a refrigerant containing at least 1,2-difluoroethylene enclosed in the refrigerant circuit (10).

A flow path switching mechanism (70) includes first to fourth flow paths (71, 72, 73, 74) and opening and closing mechanisms (V1, V2, V3, V4, 75, 76) that can each open and close a corresponding one of the flow paths (71, 72, 73, 74). A first connection point (C1) connecting an inflow portion of the first flow path (71) and an inflow portion of the second flow path (72) is connected to a discharge portion of a compression unit (30). A second connection point (C2) connecting an outflow portion of the first flow path (71) and an inflow portion of the third flow path (73) is connected to a gas-side end of a heat source heat exchanger (22). A third connection point (C3) connecting an outflow portion of the second flow path (72) and an inflow portion of the fourth flow path (74) is connected to a gas-side end of a second utilization heat exchanger (85, 93). A fourth connection point (C4) connecting an outflow portion of the third flow path (73) and an outflow portion of the fourth flow path (74), and a gas-side end of a first utilization heat exchanger (83) are connected to a suction portion of the compression unit (30).

A refrigeration cycle apparatus (1) is capable of performing a refrigeration cycle using a small-GWP refrigerant. The refrigeration cycle apparatus (1) includes a refrigerant circuit (10) and a refrigerant enclosed in the refrigerant circuit (10). The refrigerant circuit includes a compressor (21), a condenser (23), a decompressing section (24), and an evaporator (31). The refrigerant contains is a small-GWP refrigerant.

When a controller receives an instruction for a heating operation, the controller switches an operation mode of a refrigeration cycle apparatus between a heating operation mode and an oil recovery operation mode. The heating operation mode is a mode to circulate refrigerant in a refrigerant circuit such that the refrigerant flows through a gas extension pipe in a gas phase state. The oil recovery operation mode is a mode to circulate the refrigerant in the refrigerant circuit such that the refrigerant flows in the gas extension pipe in a gas-liquid two-phase state. The direction in which the refrigerant flows in the gas extension pipe in the oil recovery operation mode is opposite to that in which the refrigerant flows in the gas extension pipe in the heating operation mode.

An air conditioner including a refrigerant circuit including a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, and an indoor heat exchanger. The refrigerant circuit including an auxiliary heat exchanger provided on a refrigerant pipe between the outdoor heat exchanger and the indoor expansion valve and connected in series with the outdoor expansion valve, and a rectifier configured to allow a refrigerant flowing from the outdoor heat exchanger toward the indoor expansion valve in a cooling operation or a refrigerant flowing from the indoor expansion valve toward the outdoor heat exchanger in a heating operation to sequentially flow through the auxiliary heat exchanger and the outdoor expansion valve.

A refrigeration cycle apparatus includes an outdoor unit a plurality of indoor units a relay unit a refrigerant circuit and a controller The relay unit includes a plurality of high-pressure valves and a plurality of low-pressure valves The controller when an operation state of at least one of the indoor units is changed from a first state to a second state, judges, based on a degree of supercooling of an outlet of the outdoor heat exchanger or the indoor heat exchanger or based on a degree of superheating of a suction side of the compressor, whether an abnormality is present in the plurality of high-pressure valves or the plurality of low-pressure valves.

An air conditioner includes an outdoor unit including a compressor, an outdoor heat exchanger, and a switching device, an indoor unit including a first heat exchanger and a throttle regulator, a discharge pipe connected to a discharge side of the compressor, a low-pressure suction pipe connected to a low-pressure suction side of the compressor, a first piping connecting the discharge pipe, the outdoor heat exchanger, the throttle regulator, and the first heat exchanger in sequence, a second piping connecting the first heat exchanger and the low-pressure suction pipe, an economizer arranged at the first piping between the outdoor heat exchanger and the throttle device, and first and second refrigerant flow paths arranged in the economizer. Refrigerant flow directions in the first and second refrigerant flow paths are opposite to each other.