A heat pump unit and methods for operating the heat pump unit are provided. The heat pump unit includes a compressor (101), a throttling device (107), a first heat exchanger (104), a second heat exchanger (102), a third heat exchanger (103) and a mid-pressure tank (110). The heat pump unit operates in multiple run modes and switches between the run modes without shutdown. The first heat exchanger or the second heat exchanger is capable of acting as a condenser in the multiple run modes. When switching from a pre-switching run mode to a post-switching run mode, a control device determines whether to perform a pressure release operation to the first heat exchanger or the second heat exchanger.

A method for directing thermal energy to an evaporator of a transport climate control circuit of a transport climate control system is provided. The method includes a controller determining whether the climate control circuit is operating in a start-stop cooling mode. Also, the method includes the controller determining a thermal energy charge of the thermal storage reservoir when the climate control circuit is operating in the start-stop cooling mode. The method also includes determining whether the thermal energy charge is greater than a charge threshold. Further, the method includes determining whether the climate control circuit is operating in a stop portion of the start-stop cooling mode when the thermal energy charge is greater than the charge threshold. The method further includes transferring thermal energy from the thermal storage reservoir to an evaporator when the climate control circuit is operating in the stop portion of the start-stop cooling mode.

A refrigerator cooling system, comprising a pipe forming a loop and, sequentially provided on the pipe, a compressor, a condenser, a refrigerant amount regulating apparatus, a capillary tube, and an evaporator. The refrigerant amount regulating apparatus comprises a storage device and a regulating mechanism provided within the storage device. The storage device is provided therein with a storage cavity for holding a refrigerant. The storage device is provided with an opening for the storage cavity to be in communication with the pipe. The regulating mechanism comprises a sealing part used for opening or closing the opening.

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.

Provided is an air-conditioning apparatus configured so that a decrease in a refrigeration capacity can be suppressed without increasing the amount of refrigerant with which a refrigerant circuit is filled and that refrigerant can be suitably stored during a pump down operation. The air-conditioning apparatus includes a first on-off valve provided at a pipe between an expansion valve and a use side heat exchanger, a bypass branching from a pipe between the expansion valve and the first on-off valve and connected to a pipe at a suction-side of a compressor, and a refrigerant storage unit configured to store the refrigerant having passed through the bypass. In a pump down operation in which the compressor operates with the first on-off valve being in a closed state, the refrigerant having flowed out from the heat source side heat exchanger flows into the bypass, and then, is stored in the refrigerant storage unit.

A refrigeration system is described that includes a compression device configured to increase a pressure of a refrigerant. The refrigeration system further includes a first heat exchanger configured to reject heat from the refrigerant and reduce a temperature of the refrigerant. The refrigeration system further includes a storage device configured to store the refrigerant at a supercritical state. The refrigeration system further includes an expansion device configured to reduce the pressure of the refrigerant. The refrigeration system further includes a second heat exchanger configured to absorb heat into the refrigerant and increase the temperature of the refrigerant. The refrigeration system further includes a controller configured to release the refrigerant from the storage device to the expansion device to provide cooling capacity to the refrigeration system.

A heat exchanger, such as for example, a condenser coil constructed as a fin and microchannel tube is fluidly connected with a volume constructed and configured to store refrigerant in certain operations, such as for example during a pump down operation. The volume is fluidly connected to a fluid port of the heat exchanger, where the fluid port is an inlet (in the cooling mode) to the heat exchanger, such as the high side condensing section of the heat exchanger. The volume receives refrigerant exiting the heat exchanger from the fluid port in a mode other than a cooling mode, e.g., a pump down operation.

An apparatus for optimizing an efficiency of a refrigeration system, comprising means for measuring a refrigeration efficiency of an operating refrigeration system; means for altering a process variable of the refrigeration system during efficiency measurement; and a processor for calculating a process variable level which achieves an optimum efficiency. The process variables may include refrigerant charge and refrigerant oil concentration in evaporator.

In a refrigeration cycle apparatus, a controller is configured to, when a defrost mode is started, control a first pressure reducing device is controlled to adjust a flow rate of refrigerant to bring a degree of superheat of the refrigerant at a suction side of a compressor close to a target value, control a flow path switching device to form a first flow path through which the refrigerant released from the compressor flows to a first heat exchanger; perform a refrigerant release operation of opening one of a second pressure reducing device and a valve and closing the other of the second pressure reducing device and the valve, and perform a refrigerant collection operation of opening the second pressure reducing device and the valve, with the flow path switching device retained to form the first flow path, after the refrigerant release operation.

The present invention provides a pressure relief and recovery loop, a carbon dioxide refrigeration system and a control method thereof. The pressure relief and recovery loop includes: a gas storage reservoir (110), which is used for storing gas-phase carbon dioxide; a pressure relief flow passage (120), which is used for connecting the gas storage reservoir and an associated carbon dioxide refrigeration system, and is used for discharging the gas-phase carbon dioxide in the carbon dioxide refrigeration system into the gas storage reservoir; and a recovery flow passage (130), which is used for connecting the gas storage reservoir and the associated carbon dioxide refrigeration system, and on which a driving apparatus (131) is arranged, the recovery flow passage being used for recovering the gas-phase carbon dioxide in the gas storage reservoir into the carbon dioxide refrigeration system under the drive of the driving apparatus.