Method for controlling a compressor system, arranged in a heat pumping circuit, said compressor system being designed to be operated at at least two different compressor capacity stages, said compressor capacity stages being adjusted by a capacity adjustment system enabling switching from one compressor capacity stage to another compressor capacity stage, said capacity adjustment system being controlled by a capacity selection signal defining the compressor capacity stage to be selected, said method comprising determining a capacity set value, determining a decision quantity on the basis of said capacity set value, determining a calculated capacity average value on the basis of capacity selection signals generated before, comparing said calculated capacity average value with said decision quantity and changing said compressor capacity stage to the next higher stage if the calculated capacity average value is below the decision quantity or changing said compressor capacity stage to the next lower stage if the calculated capacity average value is above the decision quantity, or not changing said compressor capacity stage if the calculated capacity average value meets said decision quantity.

An air conditioner that is a refrigeration apparatus has, in a refrigerant circuit, a compressor, an outdoor heat exchanger that functions as an evaporator in a heating operation, an indoor heat exchanger that functions as a condenser in the heating operation, and a four way valve. The refrigerant circuit is configured in such a way that a high-pressure value of the refrigerant circuit in a defrost operation is lower than a high-pressure value of the refrigerant circuit in the heating operation. An end-of-defrost frequency decrease rate, which is a rate of decrease in the operating frequency of the compressor in the defrost operation, is set faster than a normal frequency decrease rate, which is a rate of decrease in the operating frequency of the compressor in the heating operation.

A heat pump cycle includes a first usage side heat exchanger that heats a target fluid via heat exchange with refrigerant discharged from a compressor. The refrigerant flowing out of the first usage side heat exchanger is reduced in pressure by a first pressure reducing unit, and then separated into gas and liquid by a gas-liquid separation unit. The separated gas-phase refrigerant flows toward an intermediate-pressure port of the compressor. The separated liquid-phase refrigerant is reduced in pressure by a second pressure reducing unit. An additional heat exchanger performs heat exchange between the refrigerant flowing from the second pressure reducing unit and a heat medium, and allows the refrigerant to flow toward an intake port of the compressor. A second usage side heat exchanger performs heat exchange between the separated liquid-phase refrigerant and a counterpart fluid, and allows the refrigerant to flow toward the second pressure reducing unit.

A multi-stage compression refrigeration cycle device includes a controller that controls rotational speeds of a low-stage side compression mechanism and a high-stage side compression mechanism, and a physical quantity sensor that detects a physical quantity correlated with a pressure of a low-pressure refrigerant. The controller is configured to increase a rotational speed ratio of the rotational speed of the low-stage side compression mechanism to the rotational speed of the high-stage side compression mechanism as the pressure of the low-pressure refrigerant becomes higher, based on the physical amount detected by the physical quantity sensor.

A cooling system and a control method thereof are provided. The cooling system may include a first compressor, a second compressor disposed downstream of the first compressor, an outdoor heat exchanger the performs heat exchange between refrigerant compressed in the first and/or second compressor and external air, an expansion device that decompresses the refrigerant condensed in the outdoor heat exchanger, a cooling evaporator evaporating the refrigerant decompressed in the expansion device, a bypass tube that guides refrigerant compressed in the first compressor to the outdoor heat exchanger, bypassing the second compressor, and a valve device controlling the flow of refrigerant discharged from the first compressor so as to selectively introduce refrigerant into the second compressor.

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.

This application provides a refrigeration heat pump unit, including a refrigerant circuit formed by a centrifugal compressor, a condenser, a throttling device, and an evaporator. The centrifugal compressor includes a housing, a first motor, a second motor, a first compression chamber, a second compression chamber, a first impeller, a second impeller, and a controller. The controller is configured to turn on the first motor and turn off the second motor in response to a first working condition, turn off the first motor and turn on the second motor in response to a second working condition, and turn on the first motor and the second motor in response to a third working condition.

A thermal management system is disclosed having an integrated thermal energy storage module that is operated in a manner that reduces noise when desired. By leveraging the integrated thermal energy storage module, the thermal management system advantageously decouples noisy operation of a compressor from heating and cooling of an environment. The thermal management system schedules noisy charging or discharging of the thermal energy storage module to be performed during times at which increased noise is determined to be acceptable. Conversely, the thermal management system also schedules quiet heating or cooling to be performed during times at which reduced noise is determined to be preferred.