An air-conditioning apparatus including a compressor incorporating an electric motor; a temperature sensor configured to detect indoor temperature; a drive circuit configured to drive the electric motor; a connection switching device configured to switch connection of stator windings of the electric motor between a first connection state and a second connection state higher in line-to-line voltage than the first connection state; and a controller configured to enter thermo-off when the indoor temperature reaches a target temperature or a correction temperature set based on the target temperature and cause the connection switching device to switch connection, the thermo-off being entered by stopping the compressor via the drive circuit. When a thermo-off count reaches a reference count with the electric motor being in the first connection state, the controller causes the connection switching device to switch connection from the first connection state to the second connection state.

A system includes a compressor and a controller. The controller operates the compressor in a flooded-start control mode. The flooded start control mode includes operating the compressor according to at least one cycle including a first time period during which the compressor is on, followed by a second time period during which the compressor is off. The controller determines at least one of the first time period, the second time period, and a number of cycles for the flooded-start control mode. At least one of the first time period, the second time period, and the number of cycles is based on received asset data corresponding to at least one of a type and a characteristic of at least one component of the refrigeration system. The controller operates the compressor in the flooded-start control mode after determining the first time period, the second time period, and the number of cycles.

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.

The disclosure describes a compressor housing of a centrifugal compressor. The compressor housing includes a main housing portion and an end housing portion separate from the main housing portion. The main housing portion and the end housing portion are configured to interface at a mating surface of the respective housing portions. The mating surface of the respective housing portions is configured to provide a hermetically sealable surface between the main housing portion and the end housing portion. The main housing portion includes an outlet port configured to discharge compressed vapor refrigerant. The outlet port is configured to receive an adaptor from outside the compressor housing.

A mechanical device includes a working medium, a hot end, a cold end, and first and second volume regulating units. The hot and cold ends are in thermal contact with the working medium during circulation thereof. The first and second volume regulating units are disposed between the hot and cold ends, and are configured to allow passage of the working medium therethrough to perform compression and expansion of the working medium. The volume of the working medium exiting the first volume regulating unit differs from that of the working medium entering the second volume regulating unit. The volume of the working medium entering the first volume regulating unit differs from that of the working medium exiting the second volume regulating unit.

Provided is a gas-liquid separator, including a connection pipe connected to a refrigerant pipe in the evaporator, the refrigerant pipe in which a two-phase refrigerant flows, a header connected to the connection pipe, wherein a gas refrigerant separated from the two-phase refrigerant flows inside the header, a bypass pipe connected to the header to guide a flow of the gas refrigerant to a compressor, a flow rate control valve installed at the bypass pipe, and a controller configured to control opening and closing of the flow rate control valve based on whether a preset condition is satisfied.

A compressor includes a compressor housing, a fastening device arranged on the compressor housing, and a support device, connected to the fastening device, for a temperature sensor, the support device being designed to hold, by pressing, the temperature sensor against a wall of the compressor housing. The support device has, for multiple connection to the fastening device, at least two sections, located on different sides of the temperature sensor, wherein, when the compressor is used as intended, the temperature sensor is designed to brace against the compressor housing from below.

A compressor frequency regulation method includes acquiring a first exhaust temperature of a compressor operating at a first operating frequency; determining that the first exhaust temperature is greater than or equal to a first preset temperature; controlling the compressor to perform frequency reduction processing, the frequency reduction processing reducing the first operating frequency to a second operating frequency, such that a second exhaust temperature of the compressor operating at the second operating frequency is less than the first preset temperature; and controlling the compressor to operate at the second operating frequency.

Techniques are disclosed for systems and methods to reduce mechanical vibrations within a cryocooler/refrigeration system configured to provide cryogenic and/or general cooling of a device or sensor system. A cryocooler includes a motor driver controller configured to receive operational parameters and generate motor driver control signals and/or balancer system control signals based, at least in part, on the received operational parameters, and a motor driver configured to receive the control signals and generate drive signals to drive a motor and/or a balancer system of the cryocooler. The cryocooler includes a motorized and/or actively balanced expander configured to drive and/or balance motion of a displacer of the expander. The expander includes a magnet ring fixed to the displacer and a motor coil disposed within a cylinder head of the motorized and/or actively balanced expander.

An economizer control system includes a compressor including a compression area, a piston chamber, and an economizer inlet configured to receive economizer vapor into the compression area via a flow path that extends between the economizer inlet and the compression area. At least a portion of the flow path traverses the piston chamber. The economizer control system also includes a piston disposed within the piston chamber and configured to contact the economizer vapor. The piston is moveable between an open position that opens the flow path and a closed position that closes the flow path. Additionally, the economizer control system includes a biasing system configured to apply force to the piston to bias the piston toward the closed position.