The disclosed technology includes systems and methods for a heat pump water heater. The disclosed technology can include a heat pump water heater system having an evaporator, a condenser, a vapor injection line, a compressor, and a multi-fluid heat exchanger. The vapor injection line can include an expansion valve to transition refrigerant received from the condenser at a first pressure to a second pressure. The compressor can be configured to circulate refrigerant through the condenser, the multi-fluid heat exchanger, the vapor injection line, and the evaporator. The multi-fluid heat exchanger can be configured to receive refrigerant at a first pressure from the condenser, refrigerant at a second pressure from the vapor injection line, and water. The multi-fluid heat exchanger can further facilitate heat transfer between the refrigerants at the first and second pressures and the water to preheat the water before the water is passed through the condenser.

An air conditioner and a control method thereof. The air conditioner includes an indoor unit including an indoor heat exchanger and an indoor fan, an outdoor unit connected to the indoor unit and including an outdoor heat exchanger, an outdoor fan, a compressor, an expansion valve, and a four-way valve, and at least one processor configured to perform a test operation by controlling the indoor unit and the outdoor unit. Based on an outdoor temperature being less than a predetermined reference temperature, the at least one processor is configured to determine whether the indoor unit and the outdoor unit operate normally, by continuously performing a heating operation and a defrosting operation during the test operation.

A monitoring method of a cooling system and a monitoring device thereof are provided. The monitoring method includes the steps: establishing an abnormality determination model according to predetermined abnormal data and predetermined abnormal types using deep learning by a monitoring module; generating groups of temperature data respectively by a plurality of temperature sensors; and determining one or more abnormal types and an abnormal prediction of the cooling system according to the groups of temperature data and the plurality of temperature sensors using the abnormality determination model by the monitoring module.

There is disclosed a method of controlling an air-cargo transport refrigeration unit to regulate a compressor speed and a condenser fan speed. There is also disclosed a method of controlling an air-cargo transport refrigeration unit based on determining an in-flight condition of the refrigeration unit.

Disclosed are climate systems and methods for control the climate systems. A climate system includes a refrigerant circuit, a first compressor, a second compressor, a first refrigerant-to-air heat exchanger, a second refrigerant-to-air heat exchanger, and a controller communicatively coupled to the first and second compressors. Respective outlets of the first and second compressors are fluidically coupled to the first refrigerant-to-air heat exchanger, the first refrigerant-to-air heat exchanger is fluidically coupled to the second refrigerant-to-air heat exchanger, and the second refrigerant-to-air heat exchanger is fluidically coupled with respective inlets of the first and second compressors. The fluidic connection between the second refrigerant-to-air heat exchanger and the first and second compressors includes a vertical split that is configured to mitigate or reduce the amount of compressor oil that migrates to dormant components.

A defrost method for a heat pump system includes running the heat pump system in a heating mode to provide heat to an enclosed space and determining if an outdoor temperature is less than an outdoor threshold temperature. Responsive to a determination that the outdoor temperature is below the outdoor threshold temperature, determining if a calibration state has been previously run. Responsive to a determination that the calibration state has not been previously run, running the heat pump system in the calibration state. Responsive to a determination that the calibration state has been previously run, determining if a temperature difference between a temperature of an evaporator coil of the heat pump system and the outdoor temperature exceeds a temperature threshold value. Responsive to a determination that the temperature difference between the evaporator coil and the outdoor temperature is greater than the temperature threshold value, running the heat pump system in a defrost state.

An HVAC system includes a reversing valve configured to receive compressed refrigerant and direct the refrigerant based on an operating mode. One or more suction-side sensors measure suction-side properties associated with refrigerant, including a suction-side temperature and a suction-side pressure. One or more liquid-side sensors measure liquid-side properties associated with the refrigerant. A controller monitors the suction-side pressure and liquid-side pressure and determines a ratio of the liquid-side pressure to the suction-side pressure. The controller further determines whether the suction-side temperature has an increasing trend. If the suction-side temperature has the increasing trend, the reversing valve is determined to be in an equalizing configuration. The equalizing configuration corresponds to a configuration in which the refrigerant provided from the outlet of the compressor is directed to the inlet of the compressor without first being directed to other components of the HVAC system.

Disclosed herein are air conditioning systems including a refrigerant line configured to transport a refrigerant; a compressor in fluid communication with the suction line; and a controller in communication with a sensor configured to measure a characteristic of the refrigerant line. The compressor can be configured to move the refrigerant through the refrigerant line, and the refrigerant can have a first temperature at the outlet of the compressor. The controller can be configured to receive sensor data from the sensor indicating a current value associated with the characteristic of the refrigerant line; determine, based at least partially on the sensor data, that the characteristic of the refrigerant line is above a predetermined threshold; and output instructions for the compressor to perform one or more corrective actions.

The propagation of a disproportionation reaction of a refrigerant is suppressed. Disclosed is a method of using a composition as a refrigerant in a compressor, in which the composition includes one or more compounds selected from the group of ethylene-based fluoroolefins, 2,3,3,3-tetrafluoropropene, and 1,3,3,3-tetrafluoropropene, and the dimension of a gap of a predetermined portion through which the refrigerant flows around an ignition energy generation portion in the compressor is less than or equal to 2 mm.

A system has: a compressor having a suction port and a discharge port; an ejector having a motive flow inlet, a suction flow inlet, and an outlet; a separator having an inlet, a vapor outlet, and a liquid outlet; a first heat exchanger; an expansion device; and a second heat exchanger. Conduits and valves are positioned to provide alternative operation in: a cooling mode and a heating mode. In the cooling mode, a needle of the ejector is closed. In the heating mode refrigerant passes sequentially from a first section of the second heat exchanger to a second section. In the cooling mode refrigerant passes in parallel through the first section and the second section.