A refrigeration system includes a receiver, a gas bypass valve, a parallel compressor, and a controller. The gas bypass valve and the parallel compressor are fluidly coupled to an outlet of the receiver in parallel and configured to control a pressure of a gas refrigerant in the receiver. The controller is configured to switch from operating the gas bypass valve to operating the parallel compressor to control the pressure of the gas refrigerant in the receiver in response to a value of a process variable crossing a switchover setpoint. The value of the process variable depends on an amount of the gas refrigerant produced by the refrigeration system. The controller is configured to automatically adjust the switchover setpoint in response to the amount of the gas refrigerant produced by the refrigeration system being insufficient to sustain operation of the parallel compressor.

A technique that allows a plurality of series-connected compressors in a refrigerant circuit to have equal amounts of oil in a more versatile manner is provided. A compression apparatus according to an embodiment in the disclosure includes series-connected compressors 10, 20 in a refrigerant circuit 1 that is to circulate a refrigerant; an oil separator 30 is provided in a discharge passage 50 of the compressor 10 of the compressors 10, 20, and separates oil from the refrigerant discharged from the compressor 10 and causes the refrigerant separated from the oil to flow downstream (intake passage 80); an oil return passage 70 returns the oil separated by the oil separator 30 to the compressor 10 neighboring upstream; an oil discharge outlet 10A is provided in the compressor 10; and an oil discharge passage 60 connects the oil discharge outlet 10A to an inlet of the oil separator 30.

Operation of a transcritical refrigerant vapor compression system is controlled, when operating in a high capacity mode, through control of the refrigerant pressure in the refrigerant heat rejection heat exchanger (40) or the compressor (30) discharge pressure, also referred to herein as the high side pressure, so as to optimize energy efficiency. When operating in unloaded low capacity mode, such as for chilling perishable product during temperature maintenance operation, the high side pressure is controlled so that the system can operate in a continuous running mode.

Provided are an air conditioner and a method of controlling the same. The air conditioner includes an indoor unit including an indoor heat exchanger, a first outdoor unit connected to the indoor unit, the first outdoor unit including a first compressor compressing a refrigerant and a first outdoor heat exchanger, a second outdoor unit including an engine generating a power by using combustion gas, a generator supplying electricity into the first compressor by using the power generated in the engine, a second compressor compressing the refrigerant by using the power of the engine, and a second outdoor heat exchanger, and a controller determining an additional operation of the second compressor on the basis of required cooling or heating load while the first compressor operates.

A compressor control apparatus for a vehicle includes: a compressor configured to compress coolant of an air conditioner; a coolant temperature measurement unit configured to measure a coolant temperature; a data detector configured to detect state data for controlling the compressor; and a controller configured to determine an operation rate of the compressor based on the coolant temperature and the state data, and operate the compressor based on the operation rate of the compressor.

A refrigeration system includes a receiver, a gas bypass valve, a medium temperature subsystem, a first valve system, a second valve system, and a controller. The gas bypass valve is operable to control a pressure of the refrigerant in the receiver. The medium temperature subsystem includes one or more expansion valves, one or more medium temperature evaporators, and a suction group including two or more transcritical compressors operable to compress gas refrigerant and discharge the compressed gas refrigerant into a discharge line. The first valve system is fluidly coupled to a first one of the transcritical compressors. The second valve system is fluidly coupled to a second one of the transcritical compressors. The controller is configured to activate each of the first and second transcritical compressors to operate as a parallel compressor by modulating its valve system to switch a suction input of the transcritical compressor from an evaporator outlet of the one or more medium temperature evaporators to the outlet of the receiver.

A climate-control system includes a variable-capacity compressor. An outdoor ambient temperature sensor indicates a temperature of the outdoor ambient air. A return air temperature sensor indicates a temperature of the return air in the system. A controller commands a startup compressor stage based on the temperature from the outdoor ambient temperature sensor and commands a running compressor stage based on a time-based slope of the temperature from the return air temperature sensor and the startup compressor stage.

A system includes a dynamic compressor and a controller having a processor and a memory. The compressor includes a first compressor stage having a first variable inlet guide vane (VIGV) and a second compressor stage having a second VIGV. The memory stores instructions that program the processor to operate the compressor at a current speed, a first position of the first VIGV, and a second position of the second VIGV to compress the working fluid, and to determine if a condition is satisfied. If the condition is not satisfied, the processor is programmed to continue to operate the compressor at the current speed, the first position of the first VIGV, and the second position of the second VIGV. If the condition is satisfied, the processor is programmed to change the second position of the second VIGV to a third position and maintain the first position of the first VIGV.

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 refrigerating machine which is equipped with: a turbocompressor 2 that compresses a refrigerant; a condenser 3 that condenses the refrigerant compressed by the turbocompressor 2; an intermediate cooler 4 that is a plate heat exchanger which performs heat exchange between the liquid refrigerant introduced from the condenser 3 and the two-phase refrigerant obtained by expanding, with a sub-expansion valve 13, part of the liquid refrigerant introduced from the condenser 3; a main expansion valve 5 that expands the liquid refrigerant introduced from the intermediate cooler 4; and an evaporator 7 that evaporates the refrigerant introduced from the main expansion valve 5. The plate heat exchanger includes 80 or more laminated plates, the width of which is 100-400 mm and the height of which is 300-1000 mm.