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.

A vapor compression cycle is provided including a compressor, condenser, expansion device, and evaporator fluidly connected via one or more fluid conduits, A fluid circulating within the one of more fluid conduits has a high temperature glide. An intermediate heat exchanger has a first part including at least one pass there through and a second part including at least one pass there through. The first part is arranged downstream from the condenser and at least a portion of the fluid output from the condenser is provided to the first part of the intermediate heat exchanger. Within the first part, a temperature of the at least a portion of the fluid output from the condenser is reduced.

Thermal management systems include an open circuit refrigeration system featuring a first receiver configured to store a gas, a second receiver configured to store a liquid refrigerant fluid, an evaporator configured to extract heat from a heat load that contacts the evaporator, and an exhaust line, where the first receiver, the second receiver, the evaporator, and the exhaust line are connected to provide a refrigerant fluid flow path.

An air conditioning apparatus 1 includes a compressor (321), an indoor heat exchanger (242) that is a use-side heat exchanger that exchanges heat with first air (F1), an outdoor heat exchanger (323) that is a heat-source-side heat exchanger that exchanges heat with second air, a refrigerant, a first duct (209), and a casing (230). The refrigerant contains at least 1,2-difluoroethylene, and circulates in the compressor (321), the indoor heat exchanger (242), and the outdoor heat exchanger (323) to repeat a refrigeration cycle. The first duct (209) supplies the first air (F1) to a plurality of rooms in an interior. The casing (230) includes a use-side space (SP2) that is connected to the first duct (209) and that accommodates the indoor heat exchanger (242). The casing (230) is configured to allow the first air (F1) after heat exchange with the refrigerant at the indoor heat exchanger (242) to be sent out to the first duct (209).

Provided is a composition containing a refrigerant that has a refrigerating capacity equivalent to that of widely used R404A, and a low GWP. The composition contains a refrigerant that contains difluoromethane (R32), pentafluoroethane (R125), 1,1,1-trifluoroethane (R143a), and 1,1,1,2-tetrafluoroethane (R134a) in specific concentrations.

Disclosed techniques include enabling controlled refrigeration and liquefaction and energy management. A liquid is pumped into a closed chamber to compress a vapor. Pressure is increased in the closed chamber by pumping additional liquid into the closed chamber. The increasing pressure enables assimilation of the vapor into the liquid. The heat of compression is removed from the vapor simultaneously with compression. The liquid containing the vapor that was assimilated is withdrawn from the chamber. It is flashed to release at least a portion of the vapor that was assimilated. The flashing results in absorbing a latent heat of vaporization from surfaces in thermal contact with the liquid. A first and second heating/cooling circuit are controlled. Gas within the first heating/cooling circuit is cooled and compressed using a liquid piston. A gas is warmed within the second heating/cooling circuit, and expansion is accomplished using a liquid piston.

The present disclosure is directed to refrigerant compositions having reduced flammability profiles. The reduced flammability refrigerants comprise a refrigerant and an additive. Also disclosed are methods of increasing the minimum ignition energy of a refrigerant and methods of increasing the lower flammability limit of a refrigerant. The present disclosure is also directed to a method of scavenging radicals in a refrigerant.

A control unit (19) that controls the operation of a refrigerant circuit (10) executes pump down operation in which a non-azeotropic refrigerant mixture is collected into a portion of the refrigerant circuit (10) within an outdoor unit (2), executes compositional ratio determination in which the compositional ratio of the non-azeotropic refrigerant mixture is determined based on the pressure and temperature of the non-azeotropic refrigerant mixture collected into the outdoor unit (2) by the pump down operation, and generates an alert when the compositional ratio of the non-azeotropic refrigerant mixture determined by the compositional ratio determination is outside an acceptable proportion range of a hydrofluorocarbon having the property of undergoing a disproportionation reaction.

The present disclosure addresses the problem of providing a refrigerant composition that has a low GWP and a refrigerating capacity equivalent to that of R404A, which is currently widely used. As a solution to the problem, the present disclosure provides a composition containing carbon dioxide and a mixture of fluorinated hydrocarbons, the mixture containing difluoromethane (R32), pentafluoroethane (R125), 2,3,3,3-tetrafluoropropene (R1234yf), 1,1,1,2-tetrafluoroethane (R134a), and carbon dioxide (CO.sub.2) in specific concentrations.

Inverter for an electric compressor comprising an auxiliary voltage supply that supplies a control electronics of the inverter with a DC voltage. The auxiliary voltage supply comprises a series circuit of a linear voltage regulator and a linear pre-regulator. The linear pre-regulator comprises a transistor and is connected to the input terminal of the linear voltage regulator. The linear pre-regulator and/or the linear voltage regulator are advantageously actively cooled by a refrigerant utilized in the electric compressor.