An economized refrigeration system includes a main refrigerant circuit having a condenser, an evaporator, an economizer, an expansion device intermediate the condenser and the economizer, and a main compressor fluidly connected by a main refrigerant line. The system also includes an economized refrigerant circuit including an auxiliary compressor system and an auxiliary refrigerant line fluidly connecting the economizer to the auxiliary compressor system and fluidly connecting the main refrigerant line to the auxiliary compressor at a location intermediate the main compressor system and the condenser. The auxiliary compressor system is independently controllable with respect to the main compressor system.

A refrigerant circuit includes a first compression stage for compressing a mixed refrigerant gas, the first compression stage including at least a first compressor body and a second parallel compressor body, each compressor body including a suction inlet and an outlet, a first distribution means for splitting the flow of refrigerant gas to the first stage of compression across the at least two parallel compressor bodies, such that a first stream of refrigerant gas is fed to the suction inlet of the first compressor body and a second stream of refrigerant gas is fed to the suction inlet of the second compressor body, a second compression stage for compressing the mixed refrigerant gas, and a first merging means for recombining the first stream of refrigerant gas with the second stream of refrigerant gas downstream of the first compression stage for delivery to the second compression stage.

A system includes an error module configured to integrate a difference between a superheat signal and a superheat setpoint to generate an error signal, wherein the superheat signal indicates suction superheat values of a compressor. A comparison module is configured to compare the error signal to a first predetermined threshold to generate a first comparison signal based on the comparison. A zero-crossing module is configured to compare a first count value to a second predetermined threshold to generate a second comparison signal. The first count value is generated based on at least one comparison between the superheat signal and the superheat setpoint. A setpoint module is configured to adjust the superheat setpoint based on the first comparison signal and the second comparison signal.

An air conditioner and a method of controlling the same are provided. The air conditioner includes first and second compressors capable of performing multi-stage compression, a condenser for condensing a refrigerant compressed in the first and second compressors, a refrigerant separation device for separating the refrigerant to be injected to the first or second compressor of the refrigerant condensed in the condenser, injection tubes extending from the refrigerant separation device to the first and second compressors to guide injection of the refrigerant, a main expansion device disposed at an outlet-side of the refrigerant separation device to decompress the refrigerant, an evaporator for evaporating the refrigerant decompressed in the main expansion device, a valve device disposed at an outlet-side of the first compressor to guide the refrigerant compressed in the first compressor to the condenser or the second compressor, and a bypass tube extending from the valve device to an suction-side of the second compressor.

A refrigeration system includes a subcooler configured to provide subcooling for a liquid refrigerant flowing through a first side of the subcooler by transferring heat from the liquid refrigerant to a gas refrigerant flowing through a second side of the subcooler. An expansion valve is located at an inlet of the second side of the subcooler and configured to control a flow of the gas refrigerant through the second side of the subcooler. A gas temperature sensor and a gas pressure sensor are configured to measure a temperature and pressure of the gas refrigerant. A liquid temperature sensor is configured to measure a temperature of the subcooled liquid refrigerant. A controller is configured to calculate a superheat of the gas refrigerant based on the measured temperature and measured pressure of the gas refrigerant and may compare the calculated superheat to a superheat threshold. If the calculated superheat is less than the superheat threshold, the controller may close the expansion valve. If the calculated superheat is equal to or greater than the superheat threshold, the controller may operate the expansion valve using a feedback control technique to drive the temperature of the subcooled liquid refrigerant to a subcooled liquid temperature setpoint.

A method for controlling a vapour compression system (1) including a compressor unit (2) including at least two compressors (3, 12), a heat rejecting heat exchanger (4), a receiver (6), an expansion device (7) and an evaporator (8) arranged in a refrigerant path is disclosed. At least one of the compressors is a main compressor (3) being fluidly connected to an outlet of the evaporator (8) and at least one of the compressors is a receiver compressor (12) being fluidly connected to a gaseous outlet (10) of the receiver (6). A flow of vapour entering the receiver (6), such as a mass flow of vapour entering the receiver (6) is estimated and compared to a first threshold value. In the case that the estimated flow is above the first threshold value, a pressure prevailing inside the receiver (6) is controlled by operating the receiver compressor (12).

A method for controlling a vapour compression system (1) including a compressor unit (2) including one or more compressors (3, 12), a heat rejecting heat exchanger (4), a receiver (6), an expansion device (7) and an evaporator (8) arranged in a refrigerant path. A pressure value indicating a pressure prevailing inside the receiver (6) is obtained, and the obtained pressure value is compared to a first threshold pressure value. In the case that the obtained pressure value is below the first threshold pressure value, the compressor(s) (3, 12) of the compressor unit (2) are controlled in order to reduce a suction pressure of the vapour compression system (1).

An apparatus includes a first expander, a first load, a first work recovery compressor, a valve, and a first compressor. The first expander expands a refrigerant. The first load uses the refrigerant to cool a space proximate the first load. The work recovery compressor compresses the refrigerant from the first load and is driven by the first expander. The valve reduces the pressure of the refrigerant from the work recovery compressor. The first compressor compresses the refrigerant from the valve.

Methods and systems for energy storage and management are provided. In various embodiments, heat pumps, heat engines and pumped heat energy storage systems and methods of operating the same are provided. In some embodiments, methods include controlling thermal properties of a working fluid by virtue of the timing of the operation of cylinder valves. Methods and systems for controlling mass flow rates and charging and discharging power independent of working fluid temperature and system state-of-charge are also provided.

A stepped approach to cooling capacity control and the HGRH status logic to achieve the requisite control of humidity and temperature provided to an interior area or building space receiving conditioned air. The system includes at least two independent circuits, each circuit having at least one compressor. At least one of the independent circuits includes hot gas reheat hardware thereby providing HGRH capability. The logic provides an efficient method for maintaining both humidity and temperature in the interior area comfortable for occupants within limits as determined by psychrometrics. The system and method match the sensible capacity and latent capacity of the system match to the sensible and latent loads of the conditioned space.