A method for controlling a supply of refrigerant to an evaporator (2) of a vapour compression system (1) is disclosed. During a system identification phase an opening degree (12) of the expansion valve (3) is alternatingly increased and decreased, and a maximum temperature difference, (S.sub.4−S.sub.2).sub.max, between temperature, S.sub.4, of air flowing away from the evaporator (2) and temperature, S.sub.2, of refrigerant leaving the evaporator (2) is determined. During normal operation, the supply of refrigerant to the evaporator (2) is controlled by calculating a reference temperature, S.sub.2,ref, based on the monitored temperature, S.sub.4, and the maximum temperature difference, (S.sub.4−S.sub.2).sub.max, determined during the system identification phase. The supply of refrigerant to the evaporator (2) is controlled in order to obtain a temperature, S.sub.2, of refrigerant leaving the evaporator (2) which is substantially equal to the calculated reference temperature, S.sub.2,ref.

A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

Methods and systems provided for determining a phase state and/or for determining a degree of subcooling in a fluid. An exemplary method for operating a refrigeration cycle includes flowing a refrigerant through a metering device and calculating a pressure differential of the refrigerant across the metering device. Further, the method includes determining whether the refrigerant is a saturated liquid based on the pressure differential. The method includes, when the refrigerant is not a saturated liquid, cooling the refrigerant upstream of the metering device.

An electronic expansion valve includes: a valve seat, the valve seat has a valve cavity and is provided with a valve port; a valve needle, matching the valve port and used to perform flow adjustment of the electronic expansion valve; a lead screw, forming a floating connection to the valve needle via a barrel portion; and a nut, wherein a threaded fit is formed between the nut and the lead screw, and a lower portion of the nut is provided with a nut guiding portion. A guide component is fixedly connected to the valve seat. The guide component guides both the barrel portion and the valve needle. The electronic expansion valve of the invention is provided with the guide component, and the guide component can guide both the valve needle and the barrel portion, effectively preventing abnormal wear caused by radial deviation of the valve needle and the barrel portion.

An air conditioner unit and method of operating the same includes performing an operating cycle in a feedback control mode, including adjusting the an electronic expansion valve (EEV) to minimize an error between a measured superheat and a target superheat using a PI controller, determining that a target compressor speed has changed by greater than a predetermined speed threshold, and initiating a linear control mode of the operating cycle, including adjusting the EEV using a valve position equation that is a function of the target compressor speed, an indoor temperature, and an outdoor temperature. The controller may also start a transition timer upon initiation of the linear control mode, transition back into a feedback control mode upon expiration of the transition timer, and initialize the integral term of the PI controller based on the EEV position from the linear control mode.

An air conditioner unit includes a refrigeration loop comprising an outdoor heat exchanger, an indoor heat exchanger, a compressor for circulating refrigerant, and an electronic expansion valve. A controller performs a first operating cycle of the air conditioner unit with the compressor at a first compressor speed and the electronic expansion valve in a first valve position, receives a command to perform a second operating cycle at a target compressor speed, determines that the target compressor speed of the second operating cycle corresponds to the first compressor speed, and initiates the second operating cycle with the electronic expansion valve positioned at the first valve position. The controller is further configured to determine that the first valve position is below a predetermined position threshold at an end of the first operating cycle and open the electronic expansion valve to the predetermined position threshold after the first operating cycle.

An air conditioner unit includes a refrigeration loop including a condenser and an evaporator, a compressor for circulating refrigerant, and an electronic expansion valve. A controller monitors an operating superheat of the refrigerant across the evaporator, identifies a superheat fault condition based on at least one of the operating superheat, a target valve position of the electronic expansion valve, or a compressor speed, stops the compressor in response to identifying the superheat fault condition, and initiates a calibration process of the electronic expansion valve.

An air conditioner unit includes a refrigeration loop including an indoor heat exchanger and an outdoor heat exchanger, a compressor for circulating refrigerant, and an electronic expansion valve. A controller receives a command to perform an operating cycle at a target compressor speed, determines a starting position of the electronic expansion valve using a valve position equation that is a function of the target compressor speed, an indoor temperature, an outdoor temperature, and empirically determined constants, and initializes the operating cycle with the electronic expansion valve at the starting position.

To improve the heat exchange efficiency of a heat exchanger that includes an upstream heat exchange unit and a downstream heat exchange unit. When the heat exchanger functions as an evaporator, a gas outlet pipe is an upstream refrigerant outlet that is located adjacent to the other end of upstream flat pipes of the upstream heat exchange unit, and a gas outlet pipe is a downstream refrigerant outlet that is located adjacent to the other end of downstream flat pipes of the downstream heat exchange unit. First resistance to refrigerant flow in the upstream heat exchange unit and second resistance to refrigerant flow in the downstream heat exchange unit are adjusted in order that the degree of superheating of refrigerant at the downstream refrigerant outlet is smaller than the degree of superheating of refrigerant at the upstream refrigerant outlet.

An air conditioning system includes a refrigerant circuit including a compressor, an indoor heat exchanger, a first expansion valve, a gas-liquid separator, a second expansion valve, and an outdoor heat exchanger which are sequentially connected together to perform a two-stage expansion refrigeration cycle. The refrigerant circuit further includes: a gas injection pipe through which intermediate-pressure gas refrigerant in the gas-liquid separator flows into an intermediate port of the compressor, and a liquid-gas heat exchanger configured to exchange heat between low-pressure gas refrigerant obtained by evaporating refrigerant in the outdoor heat exchanger and travelling toward the compressor and intermediate-pressure liquid refrigerant travelling from the gas-liquid separator toward the second expansion valve.