An ejector refrigeration cycle includes a bypass passage that guides a refrigerant on an outlet side of an evaporator drawn from a refrigerant suction port of an ejector to a suction port side of a compressor while bypassing a diffuser passage of the ejector. A differential pressure regulating valve is disposed as a bypass flow-rate adjustment device that adjusts a bypass flow rate of the refrigerant circulating though the bypass passage. An enlarged portion for gradually enlarging the passage area is formed at a most downstream part of the refrigerant flow in the bypass passage. During a low-load operation, the differential pressure regulating valve increases the bypass flow rate, thereby allowing the refrigerant to flow into the evaporator connected to the upstream side of a refrigerant suction port using the suction effect of the compressor.

A system has a first compressor and a second compressor. A heat rejection heat exchanger is coupled to the first and second compressors to receive refrigerant compressed by the compressors. The system includes an economizer for receiving refrigerant from the heat rejection heat exchanger and reducing an enthalpy of a first portion of the received refrigerant while increasing an enthalpy of a second portion. The second portion is returned to the compressor. The ejector has a primary inlet coupled to the means to receive a first flow of the reduced enthalpy refrigerant. The ejector has a secondary inlet and an outlet. The outlet is coupled to the first compressor to return refrigerant to the first compressor. A first heat absorption heat exchanger is coupled to the economizer to receive a second flow of the reduced enthalpy refrigerant and is upstream of the secondary inlet of the ejector. A second heat absorption heat exchanger is between the outlet of the ejector and the first compressor.

An internal heat exchanger and a first flow control valve are connected in series between a condenser and a refrigerant inlet of an ejector. A gas refrigerant outlet of a gas-liquid separator is connected to a suction port of a compressor. A first bypass circuit connects a refrigerant outlet of the condenser to an intermediate pressure portion of the compressor via a second flow control valve and the internal heat exchanger. A second bypass circuit connects a refrigerant outlet of the internal heat exchanger to the liquid refrigerant outlet of the gas-liquid separator via a third flow control valve. While the second flow control valve is opened such that the refrigerant flows through the first bypass circuit, the fourth flow control valve is switched to be opened or closed, and the third flow control valve is switched to be closed or opened.