An apparatus includes a flash tank that stores a refrigerant, a first load that uses the refrigerant to cool a first space, second and third loads, first and second compressors, and a high side heat exchanger configured to remove heat from the refrigerant. During a first mode of operation: the second load uses the refrigerant to cool a second space, the third load uses the refrigerant to cool a third space, the second compressor compresses the refrigerant from the second and third loads, and the first compressor compresses the refrigerant from the first load and the second compressor. During a second mode of operation, the second compressor compresses the refrigerant from the second load and directs the compressed refrigerant to the third load to defrost the third load.

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.

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.

Provided is a heat pump system having a compressor, a liquid-side on-off valve, a gas-side on-off valve, 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 the compressor while the liquid-side on-off valve is closed and the gas-side on-off valve is open, and control the system such that the gas-side on-off valve starts closing when a predetermined valve-close condition is satisfied during the compressor is operating for recovering refrigerant, and such that the operation of the compressor for recovering refrigerant stops after the closing of the gas-side on-off valve started.

A thermal management system includes a receiver configured to store a refrigerant fluid; a refrigeration system having a refrigerant fluid path that includes the receiver, and at least one evaporator disposed in the refrigerant fluid path. The refrigeration system is configured to receive the refrigerant fluid from the receiver through the refrigerant fluid path. The at least one evaporator is configured to receive the refrigerant fluid and to extract heat from at least one heat load having a specified thermal inertia that is in at least one of thermal conductive or convective contact with the at least one evaporator.

A method for defrosting an evaporator, includes: (i) closing an outlet part that serves as a refrigerant outlet of the evaporator; (ii) closing an inlet part that serves as a refrigerant inlet of the evaporator; (iii) connecting the outlet part and the inlet part to one another; (iv) heating the evaporator. An evaporator, includes: an inlet part that serves as a refrigerant inlet; a first switching valve that is placed in the inlet part; an outlet part that serves as a refrigerant outlet; a second switching valve that is placed in the outlet part; a bypass pathway that connected the inlet part and the outlet part to one another; a horizontal pipe that is communicated with the inlet part; and a vertical pipe that connects the horizontal pipe and the outlet part to one another. A cooling apparatus can include the evaporator.

A refrigeration system comprising a main refrigeration circuit including a compression stage, a condensing stage, and an evaporation stage, a refrigerant circulating between the compression stage, the condensing stage and the evaporation stage in a refrigeration cycle. An integrated transfer system is in closeable and openable fluid communication with the main refrigeration circuit, the transfer system including a receiver. Valves are operable to selectively open the fluid communication between the main refrigeration circuit and the transfer system. A motive force source displaces refrigerant from the main refrigeration circuit to the transfer system.

A dynamic receiver is included in parallel to an expander of a heating, ventilation, air conditioning, and refrigeration (HVACR) system. The dynamic receiver allows control of the refrigerant charge of the HVACR system to respond to different operating conditions. The dynamic receiver can be filled or emptied in response to the subcooling observed in the HVACR system compared to desired subcooling for various operating modes. The HVACR system can include a line directly conveying working fluid from compressor discharge to the dynamic receiver to allow emptying of the dynamic receiver to be assisted by injection of the compressor discharge.

A refrigeration apparatus includes a heat source-side unit and a utilization-side unit that are connected to each other, and performs a refrigeration cycle in which a high pressure of a refrigerant reaches or exceeds a critical pressure. The refrigeration apparatus also includes a control unit configured to perform a first action of returning the refrigerant to the heat source-side unit when a stop condition of the utilization-side unit is satisfied, and a second action of prohibiting the first action when a pressure at the heat source-side unit is equal to or more than the critical pressure of the refrigerant. This configuration suppresses damage to a refrigerant storage reservoir and the like in returning the refrigerant to the heat source-side unit.

A vehicular thermal management system includes: a refrigerant circulation line including a compressor, a high-pressure heat exchanger, an outdoor heat exchanger, a plurality of expansion valves and a low-pressure heat exchanger; an air conditioning mode branch line configured to allow a refrigerant passing through the compressor and the high-pressure heat exchanger to circulate in the order of the outdoor heat exchanger and the low-pressure heat exchanger in an air conditioning mode; a heat pump mode branch line configured to allow the refrigerant passing through the compressor and the high-pressure heat exchanger to circulate by bypassing the outdoor heat exchanger and the low-pressure heat exchanger in a heat pump mode; and a refrigerant/oil recovery part configured to, when one of the branch lines is used, recover the refrigerant and oil in the other unused branch line to the compressor.