A heat source-side unit (10) includes a heat source-side circuit (11). The heat source-side circuit (11) includes a compression unit (20) including a lower-stage compression element (23) and a higher-stage compression element (21), an intermediate heat exchanger (17) disposed on a refrigerant path between the lower-stage compression element (23) and the higher-stage compression element (21), and a bypass passage (23c) connected to a suction pipe (23a) and a discharge pipe (23b) each connected to the lower-stage compression element (23). At startup of the compression unit (20), a first action is performed for stopping the lower-stage compression element (23) and operating the higher-stage compression element (21). This configuration thus suppresses occurrence of liquid compression at startup of a compressor.

A thermal management system includes an open-circuit refrigeration system including a cooling system configured to supply a cooling medium. The open-circuit refrigeration system includes a receiver having a receiver outlet, the receiver configurable to store a refrigerant fluid, the receiver configured to receive the cooling medium from the cooling system, an evaporator coupled to the receiver outlet, the evaporator configurable to receive liquid refrigerant fluid from the receiver outlet and to extract heat from a heat load when the heat load contacts or is proximate to the evaporator a control device configurable to control a temperature of the heat load and an exhaust line, with the receiver, the evaporator, and the exhaust line coupled to form an open-circuit refrigerant fluid flow path.

Provided is a heat pump system having a liquid-side on-off valve, a gas-side on-off valve, an ambient temperature detector configured to detect temperature of fluid which passes through a heatsource-side heat exchanger, and a controller. The controller is configured to perform a refrigerant recovery operation for recovering refrigerant from a utilization-side piping section to a heatsource-side piping section by operating a compressor while the liquid-side on-off valve is closed and the gas-side on-off valve is open, and control the compressor such that, when the ambient temperature is higher than or equal to a predetermined value, increase rate of compressor rotation speed is low compared with that of when the ambient temperature is lower than the predetermined value.

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.

A heat pump system and a control method therefor. The heat pump system includes a compressor; an indoor heal exchanger; an outdoor heat exchanger, including a first heat exchange portion and a second heat exchange portion, wherein a flow path switching device is provided between the first heat exchange portion and the second heat exchange portion to disconnect or communicate the first heat exchange portion and the second heat exchange portion; a first four-way valve; and a second four-way valve, configured to enable a high-temperature refrigerant to be input into the first heat exchange portion in a heating mode, so as to enable the heat pump system to operate in a heating and deicing mode.

An economizer control system includes a compressor including a compression area, a piston chamber, and an economizer inlet configured to receive economizer vapor into the compression area via a flow path that extends between the economizer inlet and the compression area. At least a portion of the flow path traverses the piston chamber. The economizer control system also includes a piston disposed within the piston chamber and configured to contact the economizer vapor. The piston is moveable between an open position that opens the flow path and a closed position that closes the flow path. Additionally, the economizer control system includes a biasing system configured to apply force to the piston to bias the piston toward the closed position.

A combined heat exchanger, a heat exchange system, and an optimization method thereof are provided. The heat exchange system includes: an enhanced vapor injection compressor, a condenser, an expansion valve and an evaporator, which are located in a main circuit; wherein the heat exchange system further includes a first branch branched from the main circuit to an vapor injection port of the compressor at a branch point P downstream of the condenser, and a first heat exchange unit and a second heat exchange unit are further provided in the main circuit between the branch point P and the expansion valve; and wherein a refrigerant leaving the condenser is divided at the branch point P into a first portion passing through the first heat exchange unit and the second heat exchange unit from the main circuit, and a second portion passing through the first branch to the vapor injection port.

A refrigeration system operable in cooling mode and defrosting mode is provided. The refrigeration system includes a defrost line connecting a first reservoir to an evaporation stage for conveying at least part of the flash gas from the first reservoir to the evaporation stage when the refrigeration system is operating in defrosting mode. The flash gas thereby releases heat in the evaporation stage for defrosting the evaporation stage. The refrigeration system can also include a discharge line connecting the evaporation stage to a second reservoir.

A heat pump includes a refrigerant loop. The refrigerant loop includes a first heat exchanger, a first region of a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a compressor, a vapor generator, a first check valve, and a second check valve. The compressor includes a low-pressure inlet, a mid-pressure inlet, and an outlet. The vapor generator is positioned downstream of the outlet of the compressor and upstream of both the low-pressure inlet and the mid-pressure inlet. The first check valve is positioned immediately downstream of the third heat exchanger. The second check valve is positioned immediately downstream of the fourth heat exchanger.

A heat pump includes a refrigerant loop. The refrigerant loop includes a first heat exchanger, a first region of a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a compressor, a vapor generator, and a four-way valve. The compressor includes a low-pressure inlet, a mid-pressure inlet, and an outlet. The vapor generator is positioned downstream of the outlet of the compressor and upstream of both the low-pressure inlet and the mid-pressure inlet. The four-way valve is positioned immediately upstream of the first heat exchanger. At least one component chosen from the first heat exchanger, the second heat exchanger, and the vapor generator is free from compressor-driven flow of the first heat exchange fluid during a first predetermined set of heating modes of operation of the heat pump and a first predetermined set of cooling modes of operation of the heat pump.