An illustrative example refrigerant system includes a compressor configured to pressurize a refrigerant fluid. The compressor includes a sump portion. A heater is situated to heat at least the sump portion. A controller is configured to selectively operate the heater to apply heat to at least the sump portion while the compressor is off and continue operating the heater when the compressor turns on until a temperature of the compressor or a temperature of fluid discharged from the compressor satisfies at least one criterion.

A method for controlling a refrigeration system having a compressor, heat rejecting heat exchanger, expansion valve and heat absorbing heat exchanger circulating a refrigerant in series flow, the heat absorbing heat exchanger in thermal communication with working fluid, the method includes obtaining an expansion valve position set point; using a feedback control loop to generate a controlled expansion valve position; obtaining a rate of change of an operating parameter of the system; using the rate of change of the operating parameter to generate an adjustment; modifying the controlled expansion valve position using the adjustment; and controlling the expansion valve using the modified controlled expansion valve position.

A device to protect a compressor against liquid flooding, oil heater malfunction, low refrigerant charge, high superheat. The system includes a device that measures two temperatures separated by a heat source (the electric compressor or the suction heat exchanger or both). The temperature difference can detect a liquid return to the compressor, a high superheat, a low refrigerant charge or a crankcase heater malfunction and the temperature difference can control the electronic expansion valve.

A predictive HVAC control apparatus and method, the predictive HVAC control apparatus having an input/output interface connected to a gain amplifier and a thermocouple amplifier, the gain amplifier connected to a first plurality of sensors disposed on an HVAC system, the HVAC system having HVAC system controls, and the temperature amplifier connected to a second plurality of sensors disposed on an HVAC system, a central processing unit connected to the input/output interface, and an HVAC control relay, connected to the input/output interface and the HVAC system controls.

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 may include a compressor, a first passageway, a valve and a control module. The compressor includes a compression mechanism operable to compress a working fluid. The first passageway is in fluid communication with an oil sump of the compressor and the compression mechanism. The valve is disposed along the first passageway and movable between an open position allowing lubricant from the oil sump to flow to the compression mechanism and a closed position restricting lubricant from the oil sump from flowing to the compression mechanism. The control module is in communication with the valve and configured to move the valve between the closed position and the open position based on an operating parameter indicative of a temperature of the compression mechanism.

A system for monitoring and reporting internal refrigeration unit temperatures includes a temperature measuring device for placement within the refrigeration unit. The temperature measuring device has a first temperature sensors situated in a buffer solution for measuring an average temperature within the refrigeration unit and/or has a second temperature sensors exposed to ambient air within the refrigeration unit for measuring an instantaneous temperature within the refrigeration unit. A circuit periodically transmits the average temperature and/or the instantaneous temperature from the temperature measuring device to a server where the average temperature and the instantaneous temperature are analyzed to determine and/or predict a fault with the refrigeration unit. Upon determination and/or prediction of the fault, an alert is sent to at least one staff member indicating the refrigeration unit and fault.

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 refrigeration cycle device includes a refrigeration cycle formed by connecting a compressor, a condenser, an expansion valve and an evaporator to each other. As a refrigerant in the refrigeration cycle, a working fluid containing 1,1,2-trifluoroethylene (R1123) and difluoromethane (R32) is used. A degree of opening of the expansion valve is controlled such that the refrigerant has two phases at a suction portion of the compressor.

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.