The present invention provides a system and method for an improved multistage, cascade refrigeration system using hot gas defrost to rid the evaporator of ice build-up which accumulates over time, while the air in the evaporator enclosure remains below the freezing point of water. The present invention thus provides greater defrost flexibility with increased ease of design and implementation than current refrigeration systems, which allows for more robust hot gas defrost function for multistage refrigeration systems, such that it is unaffected by temperature changes of the condensing fluid (ambient air temperature for air cooled condensers, water temperature for water cooled condensers), and can be readily adapted to any refrigerant suitable for a selected temperature range.

An air conditioning system including one or more supercooling heat exchangers, a supercooling expansion device, a temperature sensor, and a pressure sensor so as to measure and control a current supercooling degree value of a fluid coolant flowing between a fluid pipe and a plurality of indoor devices.

A refrigeration cycle device includes a refrigeration cycle formed by connecting a compressor, a condenser, an expansion valve and an evaporator to each other. As a refrigerant in the refrigeration cycle, a working fluid containing 1,1,2-trifluoroethylene (R1123) and difluoromethane (R32) is used. A degree of opening of the expansion valve is controlled such that the refrigerant has two phases at a suction portion of the compressor.

A refrigeration system includes a variable capacity compressor system configured to pressurize refrigerant within a refrigerant circuit and a controller configured to receive data indicative of an operating capacity of the variable capacity compressor system and configured to adjust a superheat target setpoint of the refrigerant within the refrigerant circuit based on the data.

An air conditioner includes a refrigerant circuit and refrigerant. The refrigerant circuit has a compressor, a condenser, a pressure-regulating valve, and an evaporator. The refrigerant is R32. The pressure-regulating valve includes a flow path causing the refrigerant flowing from the condenser to flow to the evaporator, a pressure reference chamber partitioned from the flow path and filled with inert gas, and a valve portion. The pressure-regulating valve is configured to adjust a degree of opening of the valve portion to adjust a flow rate of the refrigerant flowing through the flow path. The valve portion is configured to increase the degree of opening when a pressure in the flow path is higher than a pressure in the pressure reference chamber, and reduce the degree of opening when the pressure in the flow path is lower than the pressure in the pressure reference chamber.

A method of controlling injection into a compressor in a refrigeration cycle is described. A refrigeration cycle may comprise at least an economizer heat exchanger, a heat rejection heat exchanger, a first expansion device, and a compressor. A discharge port of the compressor is connected to the heat rejection heat exchanger via a discharge line and an injection port of the compressor is connected to the means for compressing. The economizer heat exchanger comprises a first path having an input connected to the heat rejection heat exchanger and an output connected to the first expansion device, and a second path having an input connected to the heat rejection heat exchanger via an economizer valve and an output connected to the injection port of the compressor via an injection line. The economizer valve is regulated based on a superheat level of the refrigerant in the economizer heat exchanger.

A refrigeration system comprises a variable speed compressor and a first evaporator. A second evaporator is operably coupled in series with the first evaporator. A first valve is coupled to the variable speed compressor and the first evaporator. A second valve is fluidly coupled to the second evaporator, and a pressure regulator is coupled to the second valve.

A refrigeration system comprises a variable speed compressor and a first evaporator. A second evaporator is operably coupled in series with the first evaporator. A first valve is coupled to the variable speed compressor and the first evaporator. A second valve is fluidly coupled to the second evaporator, and a pressure regulator is coupled to the second valve.

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 and a thermal management assembly. The electronic expansion valve has a valve port and a valve core. A valve body includes a first flow portion, a second flow portion, a first cavity and a second cavity. The first flow portion comprises a first connection section and a first subsection, and the first subsection is directly in communication with the first cavity. The second flow portion comprises a second connection section and a second subsection, and the second subsection is directly in communication with the second cavity. In a clockwise direction, an angle formed between at least one of the center line of the first subsection and the center line of the second subsection and the center line of the valve core is an acute angle.