A method and system for improving energy efficiency of a refrigeration system include system components such as a condenser, one or more expansion valves, an evaporator, one or more compressors, and a system controller electrically coupled to the one or more of the system components, according to one embodiment. The system controller is configured to selectively actuate, directly or indirectly, the one or more expansion valves, the condenser, and/or the one or more compressors, at least partially based on temperatures and/or pressures of the system fluid at various points of the system, to control a temperature of a refrigerated area.

An integrated system floods an air conditioning low side heat exchanger such that the air conditioning low side heat exchanger does not evaporate all the liquid refrigerant entering the air conditioning low side heat exchanger. As a result, both liquid and vapor refrigerant leave the air conditioning low side heat exchanger. The system includes an additional receiver that stores the refrigerant leaving the air conditioning low side heat exchanger. To prevent the liquid refrigerant in the receiver from overflowing, the liquid refrigerant in the receiver is used in a refrigeration system when the level of liquid refrigerant in the receiver exceeds a threshold (e.g., as detected by a sensor in the receiver).

A control system for controlling an output for a plurality of compressors includes a control unit receiving a first value from a first sensor and generating a first output based on the first value. The control unit receives a second value from a second sensor and derives a final output from the first output and the second value. A plurality of compressors receives the control commands from the control unit based on the final output.

A method for controlling a vapour compression system in an energy efficient and stable manner, the vapour compression system (1) including at least two evaporator groups (5a, 5b, 5c), each evaporator group (5a, 5b, 5c) including an ejector unit (7a, 7b, 7c), at least one evaporator (9a, 9b, 9c) and a flow control device (8a, 8b, 8c) controlling a flow of refrigerant to the at least one evaporator (9a, 9b, 9c). For each evaporator group (5a, 5b, 5c) the outlet of the evaporator (9a, 9b, 9c) is connected to a secondary inlet (12a, 12b, 12c) of the corresponding ejector unit (7a, 7b, 7c).

A system includes a high side heat exchanger, a first load, a second load, a third load, a first compressor, a second compressor, a third compressor, and a fourth compressor. The high side heat exchanger removes heat from a refrigerant. The first load uses the refrigerant to remove heat from a first space proximate the first load. The second load uses the refrigerant to remove heat from a second space proximate the second load. The third load uses the refrigerant to remove heat from a third space proximate the third load. The first compressor compresses the refrigerant from the first load. The second compressor compresses the refrigerant from the second load. The third compressor compresses the refrigerant from the third load and the refrigerant from the second compressor. The fourth compressor compresses the refrigerant from the first compressor.

A method of operating a multiple-compressor refrigeration system is provided. This method includes the steps of supplying, via a common supply line, refrigerant gas and oil to a plurality of compressors coupled in series, and attaching an oil flow conduit between adjacent compressors of the plurality of compressors. The oil flow conduit is configured to move oil from a compressor with a relatively higher pressure to a compressor with a relatively lower pressure. The method further includes controlling the pressure for each of the plurality of compressors by regulating a speed at which each of the plurality of compressors operates in order to maintain a pressure differential between the adjacent compressors to facilitate the flow of oil from the compressor with the relatively higher pressure to the compressor with the relatively lower pressure.

A method and system for improving energy efficiency of a refrigeration system include system components such as a condenser, one or more expansion valves, an evaporator, one or more compressors, and a system controller electrically coupled to the one or more of the system components, according to one embodiment. The system controller is configured to selectively actuate, directly or indirectly, the one or more expansion valves, the condenser, and/or the one or more compressors, at least partially based on temperatures and/or pressures of the system fluid at various points of the system, to control a temperature of a refrigerated area.

A control system for controlling an output for at least one compressor includes a control unit that receives an indoor set point and an outdoor ambient temperature. The control unit determines a load request based on the indoor set point and the outdoor ambient temperature without considering an indoor room temperature. The at least one compressor receives control commands from the control unit based on the load request.

The compressor system includes a first compressor, a second compressor, and a third compressor. A common equalization line fluidly couples the first compressor, the second compressor, and the third compressor. The common equalization line provides a single path for passage of fluids between the first compressor, the second compressor, and the third compressor. An obstruction device is disposed in the common equalization line between the first compressor and the second compressor. When the first compressor is deactivated, the second compressor is activated, and the third compressor is activated, the obstruction device is in a closed configuration. Prevention of fluid flow between the first compressor and the second compressor causes at least minimum prescribed fluid levels to be maintained in the first compressor, the second compressor, and the third compressor.

A refrigeration system is of the type that includes a refrigerant compressor unit which compresses normal refrigerating mass flow and a parallel compressor. The parallel compressor in a parallel compression mode of operation of the refrigerant circuit, sucks in refrigerant from the intermediate pressure accumulator and compresses it to high pressure. It is proposed that, in order to increase efficiency, the power of the parallel compressor is controlled by a control system. The control system determines at least one reference variable representing a load state of the refrigerant circuit, that determines a set intermediate pressure value on the basis of the at least one reference variable at least in a parallel compression mode of operation, and that regulates the intermediate pressure in accordance with the set intermediate pressure value at least in the parallel compression mode of operation.