A method for operating a heat pump (20; 300) includes operating in a cooling mode wherein heat is absorbed by refrigerant in the indoor heat exchanger (26) and rejected by refrigerant in the outdoor heat exchanger (24). The heat pump switches to operation in a heating mode wherein heat is rejected by refrigerant in the indoor heat exchanger, heat is absorbed by refrigerant in the outdoor heat exchanger, and there is an ejector (60) motive flow and ejector secondary flow. In the heating mode a refrigerant pressure (P.sub.H) or temperature (T.sub.L) is measured and, responsive to the measured refrigerant pressure or temperature, at least one of a fan speed is changed and a needle (132) of the ejector is actuated.

A system (170) has a compressor (22). A heat rejection heat exchanger (30) is coupled to the compressor to receive refrigerant compressed by the compressor. A non-controlled ejector (38) has a primary inlet coupled to the heat rejection exchanger to receive refrigerant, a secondary inlet, and an outlet. The system includes means (172, e.g., a nozzle) for causing a supercritical-to-subcritical transition upstream of the ejector.

An ejector has a primary inlet, a secondary inlet, and an outlet. A primary flowpath extends from the primary inlet to the outlet and a secondary flowpath extends from the secondary inlet to the outlet, merging with the primary flowpath. A motive nozzle surrounds the primary flowpath upstream of a junction with the secondary flowpath. The motive nozzle has a throat and an exit. In one group of embodiments, an effective area of the exit is variable. In others, the needle may extend downstream from a flow control portion or may have an upstream convergent surface of a flow control portion.

A system has: a compressor having a suction port and a discharge port; an ejector having a motive flow inlet, a suction flow inlet, and an outlet; a separator having an inlet, a vapor outlet, and a liquid outlet; a first heat exchanger; an expansion device; and a second heat exchanger. Conduits and valves are positioned to provide alternative operation in: a cooling mode and a heating mode. In the cooling mode, a needle of the ejector is closed. In the heating mode refrigerant passes sequentially from a first section of the second heat exchanger to a second section. In the cooling mode refrigerant passes in parallel through the first section and the second section.

An ejector has: a motive flow inlet (40); a secondary flow inlet (42); an outlet (44); a motive flow nozzle (242) having an outlet (110); a primary flowpath from the motive flow inlet through the motive flow nozzle to the ejector outlet; a secondary flowpath from the secondary flow inlet to the ejector outlet, merging with the primary flowpath at the motive nozzle outlet; a control needle (200; 300; 400) shiftable along a range of motion between a first condition and a second condition and seated against the motive nozzle in the second condition. The needle comprises: a main shaft (210); a tip (204); a first portion (220; 320) converging toward the tip; and a shoulder portion (214; 314; 422) between the first portion and the main shaft and seated against the motive nozzle in the second condition and converging toward the tip at a greater angle (?1; ?1 2) than an angle (?2; ?2 2) of the first portion.

A system for detection and correction of reverse flow in an ejector refrigeration circuit, includes ejectors, first sensors for measuring an ejector suction superheat of a refrigerant at a secondary low pressure input port of each of the ejectors, and a second sensor for measuring a superheat of the refrigerant upstream relative to the secondary low pressure input port. A controller receives the ejector suction superheats and the refrigerant superheat and determines whether a superheat difference between each of the ejector suction superheats and the refrigerant superheat falls below a threshold superheat difference. The controller identifies a first ejector as a reverse flow affected ejector based on the determined superheat difference. The controller compares opening percentages of the ejectors to determine a second ejector having the largest opening percentage and controls the first ejector and the second ejector to increase a refrigerant flow rate of the first ejector.

Systems and methods for natural gas liquefaction capacity augmentation using supplemental cooling systems and methods to improve the efficiency of a liquefaction cycle for producing liquefied natural gas (LNG).

A system for map-interpolation based control of ejectors in an ejector refrigeration circuit includes a controller coupled to each of the ejectors and adapted to generate maps based on predefined conditions. The controller identifies a first map associated with a first temperature of a heat rejecting heat exchanger and a second map associated with a second temperature of the heat rejecting heat exchanger. The controller predicts an opening percentage of the first ejector from at least one of opening percentages indicated in the first map and opening percentages indicated in the second map. Finally, the controller adjusts the opening percentage of the first ejector based on the predicted opening percentage.

This application provides an ejector refrigeration system including: a compressor having a suction port and a discharge port; a first heat exchanger connected to the discharge port of the compressor to receive a fluid working medium flowing out from the discharge port of the compressor; and an ejector including a primary flow inlet connected to the first heat exchanger to receive a fluid working medium from the first heat exchanger, a secondary flow inlet, and an ejector outlet connected to the suction port of the compressor to return a fluid working medium entering the ejector to the suction port of the compressor; and a phase adjustment mechanism configured to adjust a phase state of the fluid working medium entering the primary flow inlet of the ejector or adjust a gas-liquid ratio of the fluid working medium at the primary flow inlet, thereby enabling the ejector to generate sufficient pressure lift.

An ejector (1; 100), e.g. for a refrigerant circuit, with a primary inlet (2), a secondary inlet (7), an outlet (12), a nozzle (5), and a mixing portion (6, 10) includes an actuating mechanism (30) moving a needle (20) between an opened position and a closed position. The actuation mechanism (30) includes a piston (31) in a cylinder (35), wherein a first cylinder chamber (37) is in fluid communication with the primary inlet (2) and a second cylinder chamber (38) is in fluid communication with the first cylinder chamber (37). The second cylinder chamber (38) is in fluid communication with the secondary inlet (7) and/or the outlet (12) via a drain passage (39, 53, 54, 55, 56, 57) when a pilot valve (50) arranged in the drain passage (39, 53, 54, 55, 56, 57) is in an open state. For ensuring smooth opening and closing, the fluid communication of the second cylinder chamber (38) with the first cylinder chamber (37) is provided by an equalization passage (32), wherein a flow cross-section of the equalization passage (32) is larger than a flow cross-section of the drain passage (39, 53, 54, 55, 56, 57).