A heat pump system includes a refrigerant circuit, at least one compressor, an evaporator, and a controller programmed to defrost the evaporator in a defrost mode, wherein in the defrost mode the controller is programmed to monitor the evaporator to detect frost creation thereon, and reduce the speed of the at least one compressor and/or reduce the number of some, but not all operating compressors of the at least one compressor, if frost creation is detected on the evaporator. In some embodiments, the controller is programmed to defrost the evaporator in a second defrost mode. In the second defrost mode the controller is programmed to monitor the evaporator to detect frost creation thereon, turn off the at least one compressor when frost is detected on the evaporator, and operate a fan to force ambient air over the evaporator to defrost the evaporator.

A refrigeration system includes a compressor having a first stage and a second stage; a heat rejecting heat exchanger including an inter-cooler and a gas cooler, the intercooler coupled to an outlet of the first stage and the gas cooler coupled to an outlet of the second stage; an unload valve coupled to an outlet of the intercooler and a suction port of the first stage; a flash tank coupled to an outlet of the gas cooler; a primary expansion device coupled to an outlet of the flash tank; a heat absorbing heat exchanger coupled to an outlet of the primary expansion device, an outlet of the heat absorbing heat exchanger coupled to the suction port of the first stage; and a controller for executing a startup process including controlling the unload valve to direct refrigerant from the intercooler to the suction port of the first stage.

A method of controlling a refrigerator including a cold air generator and a cold air transmission unit includes, when a temperature of the storage compartment becomes equal to or greater than a first reference temperature, operating the cold air generator with predetermined cooling power and turning on and operating the cold air transmitter with predetermined output, upon determining that the temperature of the storage compartment becomes equal to or less than a second reference temperature lower than the first reference temperature, turning off the cold air transmitter, and, upon determining that the temperature of the storage compartment becomes equal to or greater than the first reference temperature, turning on the cold air transmitter again, wherein a controller determines operation output of the cold air transmitter based on the cooling power of the cold air generator.

A thermal management system that include an electronic circuit boards having at least two circuit boards with a space in between and further includes one or more air tubes or conduits. The electronic circuit board and air tubes are configured for drawing air into the space to facilitate cooling of the electronic circuit board concurrent with cooling of a heat sink of a heat pump connected with the electronic circuit board. The system can further include a partition to isolate airflow from the heat sink from airflow through the electronics circuit board, and can further include one or more interface components for maintaining isolation and control of air flow, improving air intake and/or supporting auxiliary components.

A cooling control method for a refrigerator includes steps of measuring an actual temperature of freezer compartments, and setting a freezing parameter; if the actual temperature of at least one of the freezer compartments is higher than a freezing startup temperature, measuring an actual temperature of a refrigerator compartment, setting a refrigeration parameter, and if the actual temperature of the refrigerator compartment is higher than a refrigeration startup temperature and a difference between the actual temperature of at least one of the freezer compartments and the freezing startup temperature is higher than a preset value, re-setting the refrigeration parameter and the freezing parameter; and, according to the refrigeration parameter and the freezing parameter, causing a compressor, a fan, a refrigeration air door and a branch air supply device to operate in a preset state.

A refrigerator and a method for controlling a refrigerator are provided. The refrigerator may include a pair of evaporators. When a switching valve operates, one blower fan may be maintained in operation for a predetermined period of time to more quickly collect a refrigerant, thereby realizing an efficient cycle operation.

Air conditioner units and methods for operating air conditioner units are provided. A method includes determining an operational state of each heater bank of a plurality of heater banks of the air conditioner unit, and determining a speed of a blower fan of the air conditioner unit when the operational state of every heater bank is active. The method further includes comparing a blower fan motor rotational frequency to a rotational frequency threshold value when the speed is a low speed, and deactivating one of the plurality of heater banks when the blower fan motor rotational frequency is greater than the rotational frequency threshold value.

In various implementations, a request for operation of an air conditioner may be received. The air conditioner may include a cooling mode and/or a dehumidifying mode. In some implementations, a compressor speed for a compressor of the air conditioner may be determined, and which mode(s) of the air conditioner to allow may be determined based at least partially on the determined compressor speed.

A method of refrigeration control through a refrigeration system of a refrigerated transport container includes performing a defrost cycle on the refrigeration system by activating a heat source; and restarting the refrigeration system after the defrost cycle has completed, wherein restarting the refrigeration system includes performing a liquid slugging avoidance process including: initiating a compressor of the refrigeration system at a speed; opening a pressure equalization valve in parallel with the compressor in response to the initiating; opening a liquid valve in series between a condenser and an evaporator after opening of the pressure equalization valve; and closing the pressure equalization valve after a period of time.

A controller for controlling a refrigeration unit, a method, and a refrigeration system are disclosed. In an illustrative embodiment, a controller stores instructions for a first refrigeration setting and a second refrigeration setting, tracks a cumulative average temperature in a refrigeration element, and activates either the first refrigeration setting or the second refrigeration setting. The first refrigeration setting has a lower average power consumption and a higher range of temperature variation than the second refrigeration setting. The controller activates the first refrigeration setting until the cumulative average temperature goes outside a selected temperature range; then the controller activates the second refrigeration setting until the cumulative average temperature is within a target temperature range that has a lower threshold that is greater than the lower threshold of the selected temperature range and an upper threshold that is less than the upper threshold of the selected temperature range.