A refrigeration system comprises: a compressor, a first heat exchanger, a reservoir, a throttling element and a second heat exchanger in the refrigeration circuit. The refrigeration system comprises a cooling mode and a hot-gas bypass heating mode. In the hot-gas bypass heating mode, the refrigerant leaving the outlet of the compressor is delivered directly to the second heat exchanger before returning to the inlet of the compressor, wherein, the refrigeration system further comprises a branch flow path with a control valve provided thereon. The control valve is capable of being opened or closed in the hot-gas bypass heating mode.

A multimode system for cooling and desalination includes a humidification-dehumidification (HDH) system, an ejector cooling cycle (ECC) system and valves. The HDH system includes a heater, a humidifier and a dehumidifier. The ECC system includes a generator, an evaporator, an ejector and a condenser. The valves are configured to connect to inlets and outlets of the heater, the generator and a heat source so that by selectively opening and closing the valves, the heat source is connected to the heater while disconnected from the generator, or connected to the generator while disconnected from the heater, or connected to both the heater and the generator, or disconnected from both the heater and the generator. The ECC system and the HDH system are connected at the condenser for heat exchange.

Heat pump systems with a gas bypass tank and that operate in both heating and cooling modes are disclosed. The systems include a first splitting valve that can route liquid refrigerant to either the indoor coil or the outdoor coil, depending on whether the heat pump system is in heating or cooling mode. An expansion valve in the system can lower the pressure of liquid refrigerant leaving a condenser, thereby creating a two-phase fluid comprising liquid refrigerant and vaporized refrigerant. The gas bypass tank can separate liquid refrigerant from vaporized refrigerant. The liquid refrigerant can be supplied to the evaporator of the system, while the vaporized refrigerant can be bypassed to a compressor. The first splitting valve can include a first plurality of switching paths that route the separated liquid refrigerant to either the outdoor coil or the indoor coil.

Methods for shortening the cycle time in each of the defrost, standby and cool modes of operation of a very low temperature refrigeration system. These methods can be used alone or in combination with one or more of each of the other techniques, including, for example, in a single very low temperature refrigeration system, to provide a fast total cycle of one, two or all three of the defrost, standby and cool modes.

An air conditioning apparatus includes an outdoor device that is configured to circulate refrigerant and that includes a compressor and an outdoor heat exchanger, a plurality of indoor devices configured to circulate water, and a heat exchange device that connects the outdoor device with the indoor device. The heat exchange device includes a heat exchanger configured to exchange heat between the refrigerant and the water, and a switch device configured to control flow of refrigerant between the indoor device and the heat exchanger.

A refrigeration circuit for a vehicle system includes a compressor, an evaporator, an accumulator, an inlet tube, an outlet tube, and a bypass valve. The inlet tube is configured to deliver refrigerant from the evaporator to the accumulator. The outlet tube is configured to deliver refrigerant from the accumulator to the compressor. The bypass valve is in fluid communication with the inlet and outlet tubes. The bypass valve has an open position and a closed position. The bypass valve is configured to direct refrigerant flow from the inlet tube to the outlet tube to bypass the accumulator when in the open position. The bypass valve is configured to restrict refrigerant from flowing from the inlet tube to the outlet tube when in the closed position.

A system is described herein for repurposing waste heat from a refrigeration cycle to improve the efficiency of the cycle and power electronic devices. The system may include a compressor, a turbine, an accumulator, a condenser, a throttle, and an evaporator. The accumulator may include a high-pressure chamber connected between the turbine and condenser, and a low-pressure chamber connected between the evaporator and the compressor. The high-pressure chamber may be segregated from the low-pressure chamber such that high-pressure refrigerant in the high-pressure chamber is prevented from mixing with low-pressure refrigerant in the low-pressure chamber. The high-pressure chamber and low-pressure chamber may be thermally coupled such that liquid refrigerant in the low-pressure chamber is vaporized by heat exchange with the high-pressure chamber. The turbine may power an electronic component of the refrigerator or may feed electricity back into a community grid power system.

In an air-conditioning, first flow passage selection device and a second flow passage selection device each are a constant-energized-type three-way valve in which a position of a main valve can be fixed in a de-energized state. When the refrigerant circuit is switched to the cooling circuit by a flow switching device, when at least one of the first flow passage selection device and the second flow passage selection device is in a de-energized state, the first flow passage selection device or the second flow passage selection device in the de-energized state is configured to output refrigerant discharged from the compressor and input therein via the flow switching device and the bypass pipe to a corresponding one of an upper-side outdoor heat exchanger and a lower-side outdoor heat exchanger.

Provided is a refrigeration apparatus with improved safety. A refrigeration apparatus includes: a compressor; a heat source-side expansion valve to be controlled to have a minimum opening degree and brought into a closed state in which the heat source-side expansion valve maximizes prevention of a flow of a refrigerant toward a usage-side refrigerant circuit; a fusible plug; a controller; and a refrigerant leak detector configured to detect a refrigerant leak at the usage-side refrigerant circuit. The fusible plug is disposed in a refrigerant circuit, and is brought into an open state to allow the refrigerant circuit to communicate with an external space. When the refrigerant leak detector detects a refrigerant leak at the usage-side refrigerant circuit, the controller performs refrigerant leak first control to bring the heat source-side expansion valve into the closed state, and performs refrigerant leak second control to bring the fusible plug into the open state.

An object is to provide a mixed refrigerant that has desired properties as an alternative refrigerant for R410A. As a solution to achieve the object, a composition containing a refrigerant that contains difluoromethane (R32), carbon dioxide (CO.sub.2), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), and 2,3,3,3-tetrafluoropropene (R1234yf) in a specific mixture ratio is provided.