A controller for a refrigeration system includes a processing circuit having one or more processors and memory. The processing circuit is configured to calculate a superheat of a gas refrigerant exiting a first side of a subcooler based on a measured temperature and a measured pressure of the gas refrigerant and compare the calculated superheat to a superheat threshold. In response to a determination that the calculated superheat is less than the superheat threshold, the processing circuit closes an expansion valve to restrict a flow of the gas refrigerant through a second side of the subcooler. In response to a determination that the calculated superheat is equal to or greater than the superheat threshold, the processing circuit operates the expansion valve to drive a temperature of a subcooled liquid refrigerant exiting the second side of the subcooler to a subcooled liquid temperature setpoint.

A chiller system includes a compressor that compress refrigerant, a condenser that exchanges heat between the refrigerant and a cooling water discharged from the compressor, and a flow adjusting device that is provided to a refrigerant outlet side of the condenser and adjusts refrigerant amount in the inside of the condenser, the flow adjusting device includes, a main body portion that is communicated with a tubing of the outlet side of the condenser, a refrigerant supply tube that extends to the main body portion from the condenser and supplies the refrigerant in the inside of the condenser to the inside of the main body portion, and a flow hole that is formed on the main body portion and is selectively opened and closed according to refrigerant pressure which is input through the refrigerant supply tube.

Described is, among other things, a method and an apparatus for control of a cooling device. The cooling device comprise a circuit in which a refrigerant fluid is circulated in a fluid path where the circuit comprises a compressor and a condenser provided down streams the compressor. A fluid expansion device is provided down streams the condenser and an evaporator is provided between the fluid expansion device and the compressor. The circuit further comprises a valve provided in the fluid path between the condenser and the fluid expansion device. The method comprises to during an on-cycle of the compressor controlling the valve opening to provide a variable fluid mass flow of the refrigerant fluid circulated in the circuit where the valve opening is controlled to decrease during the on-cycle of the compressor.

Condenser control, systems, devices, and methods are described herein. One system includes a number of pressure sensors, wherein each of the number of pressure sensors is configured to sense a pressure associated with a condenser of a refrigeration system, a temperature sensor configured to sense an outdoor air temperature, and a controller configured to activate operation of a number of condenser fans and a number of split valves associated with the condenser based, at least in part, on the sensed outdoor air temperature upon a failure of each of the number of pressure sensors.

A dual reclaim coil with a smart control application is provided that allows the refrigerant inlet to the HVAC unit switch between the two sides of the condenser is aimed to use the high temperature and pressure of the condenser/gas cooler outlet while a CO.sub.2 refrigerant system is operating above critical point. This occurs in hot ambient conditions, when the need for heating in the space is not as great as in the wintertime and the available heat at the condenser/gas cooler's outlet is sufficient to satisfy the heating load. This also mitigates space overcooling, while increasing the CO.sub.2 transcritical system's efficiency by subcooling the refrigerant for applications involving dehumidification HVAC systems which often results in a phenomenon called overcooling during the dehumidification season.

The present disclosure relates to a vapour-compression circuit for circulating a working fluid. The vapour-compression circuit comprises a compressor, a first heat exchanger, an expansion device, a second heat exchanger, a discharge line, a bypass line and a controller. The discharge line extends from an outlet of the compressor to an inlet of the first heat exchanger. The vapour-compression circuit is configured to operate in a heating mode in which the first heat exchanger operates as a condenser and the second heat exchanger operates as an evaporator. The vapour-compression circuit is also configured to operate in a defrost mode in which the working fluid is directed from the compressor to the second heat exchanger via the bypass line and the expansion device, the bypass line extending from the discharge line to bypass the first heat exchanger.

Systems and method for operating a refrigeration system include a heat exchanger configured to remove heat from a refrigerant and discharge the refrigerant into a conduit. A temperature sensor, a pressure sensor, and a pressure control valve are located along the conduit. A controller is configured to determine that the refrigerant leaving the heat exchanger is outside of a subcritical region based on the measured temperature or measured pressure of the refrigerant. A target temperature is determined based at least in part on a pseudo-subcooling temperature value and the measured temperature of the refrigerant. A supercritical pseudo-saturated pressure is determined based on the target temperature. A pressure offset is determined based on the target temperature, a maximum operating pressure of the refrigeration system, and an offset factor. The pressure control valve is operated to drive the pressure to a target pressure based on the pressure offset and the pseudo-saturated pressure.

Systems and methods for a heat pump water heater can include a heat pump water heater system having an evaporator, a condenser, a vapor injection line, a compressor, and a multi-fluid heat exchanger. The vapor injection line can include an expansion valve to transition refrigerant received from the condenser at a first pressure to a second pressure. The compressor can be configured to circulate refrigerant through the condenser, the multi-fluid heat exchanger, the vapor injection line, and the evaporator. The multi-fluid heat exchanger can be configured to receive refrigerant at a first pressure from the condenser, refrigerant at a second pressure from the vapor injection line, and water. The multi-fluid heat exchanger can further facilitate heat transfer between the refrigerants at the first and second pressures and the water to preheat the water before the water is passed through the condenser.

An air conditioner is provided that may include at least one compressor that compresses a refrigerant to a high pressure; a plurality of heat exchanger that condenses the refrigerant compressed in the at least one compressor; a plurality of outdoor valves, respectively, provided at an outlet side pipe of the plurality of heat exchangers; a gas liquid separator that separates the refrigerant into gas and liquid refrigerants and supplies the gas refrigerant to the at least one compressor; and one or more bypass devices connected to the outlet side pipe of one or more of the plurality of heat exchangers and an inlet side pipe of the gas liquid separator, the one or more bypass devices controlling a flow of the liquid refrigerant. During a cooling low load operation in which a portion of the plurality of heat exchangers is operating, a liquid refrigerant loaded into a heat exchanger of the plurality of heat exchangers, which is not operated, may flow through the one or more bypass device.

A system and method for a CO.sub.2 refrigeration system includes a compressor, a heat exchanger, a liquid receiver, a first valve, and a valve controller. The heat exchanger operates as a gas cooler when the CO.sub.2 refrigeration system is in a transcritical mode and as a condenser when the CO.sub.2 refrigeration system is in the subcritical mode. The first valve controls a flow of refrigerant from the heat exchanger to the liquid receiver. The valve controller monitors an outdoor ambient temperature and a pressure of refrigerant exiting the heat exchanger, determines whether the CO.sub.2 refrigeration system is in the subcritical mode or in the transcritical mode, determines a pressure setpoint based on the monitored outdoor ambient temperature, and controls the first valve based on a comparison of the determined pressure setpoint and the monitored pressure when the CO.sub.2 refrigeration system is in the transcritical mode.