A refrigerator and a method of controlling a refrigerator are provided. The refrigerator may include a machine room defined in or at one side of a storage compartment, a base that defines a bottom surface of the machine room, a compressor seated on the base to compress a refrigerant, a condenser that condenses a refrigerant compressed in the compressor, the condenser being disposed on or at one side of the compressor, a drain pan disposed on the base to store condensed water generated in the condenser, and a fan assembly coupled to the base to generate an air flow within the machine room. The fan assembly may include a plurality of condensation fans.

A system and method for controlling a sound level in a heating, ventilation, and air conditioning (HVAC) system are disclosed. The system includes a refrigeration unit including a compressor, a condenser fan, a controller, and a sound controller. The sound controller is configured to maintain a sound level of the refrigeration unit within a sound level operating range. A method of controlling a refrigeration unit for a heating, ventilation, and air conditioning (HVAC) system is described. The method includes determining, by a controller, a cooling requirement of a conditioned space. The controller also determines a sound level operating range for the refrigeration unit. The method further includes the controller applying a cooling setting based on the cooling requirement and the sound level operating range.

A refrigeration system includes a receiver, a gas bypass valve, a parallel compressor, and a controller. The gas bypass valve and the parallel compressor are fluidly coupled to an outlet of the receiver in parallel and configured to control a pressure of a gas refrigerant in the receiver. The controller is configured to switch from operating the gas bypass valve to operating the parallel compressor to control the pressure of the gas refrigerant in the receiver in response to a value of a process variable crossing a switchover setpoint. The value of the process variable depends on an amount of the gas refrigerant produced by the refrigeration system. The controller is configured to automatically adjust the switchover setpoint in response to the amount of the gas refrigerant produced by the refrigeration system being insufficient to sustain operation of the parallel compressor.

A method for a refrigeration system includes receiving a temperature difference (TD) setpoint indicating a desired temperature difference between outside air and refrigerant and modifying the TD setpoint based on conditions currently being experienced by the refrigeration system. The modified TD setpoint is selected to cause a decrease in total power consumption, wherein the total power consumption comprises power consumed by a compressor to yield a discharge pressure and power consumed by a condenser fan to operate a fan speed.

A method of operating a heat pump system is provided, the heat pump system having at least a controller and configured to operate at least two defrost cycles. The method comprises receiving, at the controller, weather data for a defined geographic area proximate to an installed location of the heat pump system; and selecting, based on said weather data, one of the at least two defrost cycles.

A refrigeration system includes a receiver, a gas bypass valve, a parallel compressor, and a controller. The gas bypass valve and the parallel compressor are fluidly coupled to an outlet of the receiver in parallel and configured to control a pressure of a gas refrigerant in the receiver. The controller is configured to switch from operating the gas bypass valve to operating the parallel compressor to control the pressure of the gas refrigerant in the receiver in response to a value of a process variable crossing a switchover setpoint. The value of the process variable depends on an amount of the gas refrigerant produced by the refrigeration system. The controller is configured to automatically adjust the switchover setpoint in response to the amount of the gas refrigerant produced by the refrigeration system being insufficient to sustain operation of the parallel compressor.

The disclosure describes a system that includes an evaporator, an accumulator downstream of the evaporator, a centrifugal compressor downstream of the accumulator, a first heat exchanger stage downstream of the centrifugal compressor, and a second heat exchanger stage downstream of the first heat exchanger stage. The evaporator is configured to cool a conditioned air stream using a refrigerant. The accumulator is configured to store excess refrigerant. The centrifugal compressor is configured to compress the refrigerant. The first heat exchanger stage is configured to cool the refrigerant using environmental air. The second heat exchanger stage is configured to cool the refrigerant from the first heat exchanger stage using a portion of the excess refrigerant from the accumulator.

A refrigeration system includes a receiver, a gas bypass valve, a parallel compressor, and a controller. The gas bypass valve and the parallel compressor are fluidly coupled to an outlet of the receiver in parallel and configured to control a pressure of a gas refrigerant in the receiver. The controller is configured to switch from operating the gas bypass valve to operating the parallel compressor to control the pressure of the gas refrigerant in the receiver in response to a value of a process variable crossing a switchover setpoint. The value of the process variable depends on an amount of the gas refrigerant produced by the refrigeration system. The controller is configured to automatically adjust the switchover setpoint in response to the amount of the gas refrigerant produced by the refrigeration system being insufficient to sustain operation of the parallel compressor.

A control method and device and an air conditioner are provided. The air conditioner has an outdoor condenser, an indoor evaporator, a first electronic expansion valve, a throttle valve, and a heat dissipation coolant pipe arranged in an electric control box. By utilizing the control method and device, the air conditioner uses the heat dissipation coolant pipe to dissipate heat from the electric control box of the air conditioner. The heat generated by the electric control box can thus be timely removed. The temperature of the elements of the air conditioner can be lowered and the reliability and service life of the air conditioner can be improved.

A household refrigeration appliance has a thermally-insulated body with an interior container that delimits a coolable interior space, a refrigeration circuit for cooling the coolable interior space and at least one fan. During the proper operation of the household refrigeration appliance, the fan is operated in a closed loop speed-controlled manner according to an at least indirectly specified desired rotational speed of the fan. During an inspection mode, the fan is operated without closed loop speed control, the actual rotational speed of the fan is ascertained and the actual rotational speed is evaluated in order to detect an abnormal operating state of the fan.