Methods and systems for detecting and correcting improper operation of a compressor in a refrigeration system and/or an HVAC system include a component level detection and prevention and a system level detection and prevention. The system level detection and prevention can be a backup or a confirmation of the component level detection and prevention. The component level detection and prevention can detect and prevent improper compressor operation within a predetermined time so that the compressor's operation period in an improper direction can be minimized, thereby minimizing wear and damage to the 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.

A refrigeration system and a control method of the refrigeration system are provided. The refrigeration system includes a cooling circuit and a compressor, an evaporator assembly, and a condenser assembly sequentially arranged on the cooling circuit, and the refrigeration system further includes: a liquid pump cooling assembly, arranged on the cooling circuit and located between the condenser assembly and the evaporator assembly, the liquid pump cooling assembly includes a housing and a liquid pump arranged in the housing, the housing defines a cavity having a liquid reserving function, a refrigerant inlet, a first outlet connected to the cavity and a second outlet connected to the liquid pump, an outlet of the condenser assembly is in connected with the refrigerant inlet, and both the first and second outlets are connected with an inlet of the evaporator assembly; a control assembly, connected with the compressor and the liquid pump.

Methods and systems for providing control of a heat pump of a motor vehicle are presented. In one operating mode, speed of a heat pump compressor is controlled responsive to an outlet pressure of the heat pump compressor. In a second operating mode, speed of the heat pump compressor is controlled responsive to a pressure ratio between an inlet and an outlet of the heat pump compressor.

A sensor supply tube assembly is provided for disposition within a compressor outlet through which a main flowpath is defined and a sensor port transversely coupled to the compressor outlet. The sensor supply tube assembly includes first and second tubes. The first tube is formed to direct main flowpath fluid from the compressor outlet and through a portion of the sensor port and includes first and second ends disposed within the sensor port and the compressor outlet, respectively, and a curved section interposed between the first and second ends. The second tube includes a sleeve tightly fittable between the first end and the sensor port and a base. The base has an exterior surface from which the sleeve extends and which is disposed and configured to non-rotatably abut with an interior surface of the compressor outlet.

A method of operating an air conditioning system including: operating a refrigerant compression device at a demand speed to circulate refrigerant through a refrigeration circuit; monitoring, using a temperature sensor, a temperature of external ambient air; monitoring, using a pressure sensor, a pressure of the refrigerant within the refrigerant circuit; detecting, using a controller, when the temperature of external ambient air is greater than a selected temperature; detecting, using the controller, when the pressure of the refrigerant is greater than a selected pressure; and reducing the speed of the refrigerant compression device to a selected speed for a first duration of time when the temperature of external ambient air is greater than the selected temperature and the pressure of the refrigerant is greater than the selected pressure.

A method for operating a cryocooler includes: connecting a second compressor in series with a first compressor on a high pressure line or a low pressure line; connecting a buffer volume to the low pressure line via a supply valve; executing initial cooling for cooling an expander from an initial temperature to a cryogenic temperature in a state where the second compressor and the buffer volume are connected to the cryocooler; and executing a steady operation of maintaining the expander at the cryogenic temperature after the initial cooling. The execution of the initial cooling includes supplying a working gas to the expander by using the first compressor and the second compressor, and controlling the supply valve to keep a pressure of the high pressure line within a preset appropriate pressure range based on the measured pressure of the high pressure line.

In a method for operating a compressor (22) having an inlet (26) and an outlet (28), the method includes: running the compressor to compress a fluid; shutting down (422) the compressor; determining (420) a condition-dependent threshold restart pressure difference (threshold) across the compressor; relieving the pressure-difference to reach the threshold; and, after the threshold is reached, restarting (434) the compressor.

A method for controlling a vapour compression system (1) is disclosed. Malfunctioning of a gas bypass valve (8) is registered. An actual opening degree of the gas bypass valve (8) is derived, and a target opening degree of the gas bypass valve (8) is derived, based on one or more control parameters of the vapour compression system (1). The actual opening degree is compared to the target opening degree, and the vapour compression system (1) is controlled based on the comparison, and in order to match a mass flow of gaseous refrigerant through the gas bypass valve (8) to the actual opening degree of the gas bypass valve (8).

A method for controlling a vapour compression system (1) is disclosed, the vapour compression system (1) comprising at least one compressor (2, 16), a heat rejecting heat exchanger (3), a high pressure expansion device (4, 15, 17), a receiver (5), an evaporator expansion device (6), an evaporator (7) and a gas bypass valve (8), arranged in a refrigerant path. It is registered that the gas bypass valve (8) is malfunctioning or saturated, and a pressure value for a pressure prevailing inside the receiver (5) is obtained. Finally, the vapour compression system (1) is controlled in order to control a gaseous refrigerant supply to the receiver (5) to adjust the pressure prevailing inside the receiver (5) to reach a target pressure level.