The present disclosure relates to a heating, ventilation, and air conditioning (HVAC) unit having a vapor compression circuit including a compressor and a heat exchanger. The HVAC unit includes a controller configured to provide a first signal to control the compressor, and provide a second signal to control a variable speed fan associated with the heat exchanger based on a target speed. The HVAC unit further includes a pressure activated device coupled between the controller and the compressor, wherein the pressure activated device is configured to temporarily block the first signal from the controller while a refrigerant pressure within the vapor compression circuit is greater than a threshold value. In response to determining that the pressure activated device has blocked the first signal for at least a threshold time period, the controller is configured to both deactivate the first signal and provide the second signal for an equilibration time.

An air conditioning apparatus is equipped with an indoor fan, an indoor heat exchanger, and a control unit. The indoor heat exchanger generates conditioned air by exchanging heat between refrigerant and room air. The control unit sets operating modes. The control unit controls the rotational speed of the indoor fan. More specifically, in a case where the operating mode has been switched from one to the other of a normal heating mode and a hot air mode in which the conditioned air higher in temperature than in the normal heating mode is generated, the control unit lowers the rotational speed at a second rate that is slower than a first rate which is a rate of decrease in the rotational speed in a case where the operating mode is set to the normal heating mode.

Provided is a refrigeration apparatus capable of, even in occurrence of a refrigerant leak, suppressing the extent of the refrigerant leak in continuously operating a usage unit other than a usage unit at which the refrigerant leak occurs. When one of a first usage unit and a second usage unit connected in parallel via a liquid-refrigerant connection pipe and a gas-refrigerant connection pipe is in a refrigerant leak situation satisfying a predetermined condition, a controller closes an on-off valve of a leak unit, the on-off valve being disposed on the side of the liquid-refrigerant connection pipe with respect to a usage-side heat exchanger, continues to open an on-off valve of a non-leak unit, the on-off valve being disposed on the side of the liquid-refrigerant connection pipe with respect to a usage-side heat exchanger, and reduces a refrigerant pressure at a portion on the side of the liquid-refrigerant connection pipe with respect to each on-off valve below a refrigerant pressure at the portion at a time when the refrigerant leak situation satisfies the predetermined condition.

Embodiments of the disclosure provide a controller for a compressor and a control method, a compressor assembly, and a refrigeration system, which improve control efficiency and reliability. The controller includes an obtaining module configured to obtain at least one operation state parameter of the compressor, and a controlling module configured to shut off a liquid injection valve if one of the at least one operation state parameter of the compressor meets a protection action condition, wherein the liquid injection valve is configured to regulate flow of fluid injected into the compressor.

A rotation speed control method and system, a device, and a storage medium is provided, which is applied to a heat pump system. The heat pump system includes a throttling short tube and a compressor, both sides of the throttling short tube are provided with a temperature sensor and a pressure sensor. The rotation speed control method includes: collecting actual data of the temperature sensors and the pressure sensors, processing to obtain temperature ratio data and pressure ratio data, and obtaining a corresponding oil content prediction model through matching; obtaining predicted oil content data according to the temperature ratio data and the pressure ratio data; and controlling a rotation speed of the compressor according to the predicted oil content data.

There is provided a starting method for a cryocooler, the cryocooler including a compressor, a cold head, a high pressure line, and a low pressure line, the method including increasing a volume of the high pressure line when the cold head is at a room temperature, cooling the cold head from the room temperature to a cryogenic temperature while controlling an operation frequency of the compressor based on a pressure of the high pressure line or a differential pressure between the high pressure line and the low pressure line, after the volume of the high pressure line has been increased, decreasing the volume of the high pressure line after the cold head has been cooled to the cryogenic temperature, and maintaining the cold head at the cryogenic temperature after the volume of the high pressure line has been decreased.

A system and method are provided including a system controller for a refrigeration or HVAC system having a compressor rack with a compressor and a condensing unit with a condenser fan. The system controller monitors and controls operation of the refrigeration or HVAC system. A rack controller monitors and controls operation of the compressor rack and determines compressor rack power consumption data. A condensing unit controller monitors and controls operation of the condensing unit and determines condensing unit power consumption data. The system controller receives the compressor rack power consumption data and the condensing unit power consumption data, determines a total power consumption of the refrigeration or HVAC system, determines a predicted power consumption or a benchmark power consumption for the refrigeration system, compares the total power consumption with the predicted power consumption or the benchmark power consumption, and generates an alert based on the comparison.

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.

An expander generates cold by expanding a refrigerant gas in a cryogenic refrigerator. A compressor compresses the refrigerant gas returning from the expander. Pipes are connected to the expander and the compressor and circulate the refrigerant gas between the expander and the compressor. A determiner determines whether or not a change cycle of the pressure of the refrigerant gas flowing in the pipes is in a predetermined range. The determiner may determine whether or not the change cycle of the pressure of a low-pressure pipe in which a low-pressure refrigerant gas flows toward the compressor from the expander is in a predetermined range.

This chiller control device (74) is provided with: a storage unit (18) which stores operation data detected at each site in a turbo chiller; a compression unit (34) which, when the size of the operation data accumulated over time in the storage unit (18) becomes too large, converts the operation data each time a condition depending on the type of operation data is met, thereby compressing the data size; and a diagnostic unit (36) which evaluates the state of the turbo chiller on the basis of the operation data converted by the compression unit (34). By this means, the state of the chiller can be diagnosed without increasing the storage capacity of the storage medium that stores operation data of the turbo chiller.