An air conditioner and a method of controlling an air conditioner are provided. The air conditioner may include a compressor, an accumulator that recovers a liquid refrigerant contained in a refrigerant flowing into the compressor, an outdoor heat exchanger that performs heat exchange of air using the refrigerant, an outdoor unit fan that supplies outside air to the outdoor heat exchanger and discharges heat-exchanged air, a refrigerant charging pipe connected to a refrigerant pipe and allowing the refrigerant to the additionally introduced from the outside, a refrigerant charging valve installed in the refrigerant charging pipe to open and close the refrigerant charging pipe, and a controller that sets an operation mode so as to operate in a cooling operation or a heating operation upon setting of a refrigerant charging mode, sets an operation frequency of the compressor in accordance with a load of an indoor unit upon the setting of the refrigerant charging mode to allow the compressor to operate at the set operation frequency during the refrigerant charging, and calculates an amount of refrigerant in order to stop the refrigerant charging when a predetermined reference value is reached.

To reduce the possibility that temperature of refrigerant discharged from a compressor of a refrigeration apparatus becomes excessively high by controlling torque of a motor built into the compressor, the compressor includes the motor having rotation thereof controlled by inverter control. An inverter controller controls torque of the motor using inverter control when operation frequency of the compressor is at least one value within a range of from 10 Hz to 40 Hz. When at least the operation frequency is within the range of from 10 Hz to 40 Hz, torque of the motor is controlled, and under a predetermined condition in which temperature of refrigerant discharged from the compressor easily becomes excessively high, a device controller controls devices provided in a refrigerant circuit such that refrigerant sucked into the compressor is placed in a wet vapor state.

The present disclosure relates to a heat exchanger and an air conditioner improving heat exchange ability by optimizing the number of high protrusions of a heat transfer tube and a height difference between the high protrusion and a low protrusion to increase the heat transfer performance of the heat transfer tube or reduce the pressure loss in the tube. An air conditioner includes the heat exchanger including a heat transfer tube configured to allow the refrigerant to flow, fins installed on the heat transfer tube, and fin collars forming an insertion hole through which the heat transfer tube is inserted and passes, and the fin collars is in contact with the heat transfer tube by tube expansion of the heat transfer tube. The heat transfer tube includes high protrusions disposed in a spiral shape with respect to a tube axis direction of the heat transfer tube, twenty one to twenty seven of the high protrusions being formed along a circumferential direction of the heat transfer tube, and low protrusions disposed between two of the adjacent high protrusions along the circumferential direction of the heat transfer tube and having a height lower by 0.03 mm to 0.05 mm than the high protrusions.

A heat pump apparatus includes an outdoor heat exchanger, a fan configured to introduce outdoor air into the outdoor heat exchanger, and a control device configured to control a defrosting operation of the outdoor heat exchanger. The fan rotates at a first rotational speed within a first period, after the defrosting operation is finished and the fan starts rotating. The fan rotates at the first rotational speed within a second period, after a non-defrosting operation is finished and the fan starts rotating. The first period is shorter than the second period.

An air conditioning system and a method of operating the same to improve system performance is provided. The air conditioning system includes an outdoor heat exchanger, an indoor heat exchanger, and a reheat heat exchanger. A reheat temperature sensor positioned proximate an upstream end of the reheat heat exchanger in a cooling mode for measuring a reheat coil saturation temperature. A controller adjusts at least one operating parameter, such as a compressor or fan speed, in response to the reheat coil saturation temperature and/or one of an outdoor coil vapor temperature, an indoor coil vapor temperature, an outdoor coil saturation temperature, and an indoor coil saturation temperature.

A heat exchanger includes: a plurality of first heat transfer tubes, a plurality of second heat transfer tubes located on leeward side relative to the plurality of first heat transfer tubes, a first distribution unit connecting the first ends of the plurality of first heat transfer tubes and the third ends of the plurality of second heat transfer tubes. The first distribution unit includes a flow rate control unit configured to be capable of switching between a first state and a second state. In the first state, refrigerant flows in the plurality of first heat transfer tubes and the plurality of second heat transfer tubes. In the second state, in only the plurality of first heat transfer tubes, a flow rate of the refrigerant is smaller than a flow rate of the refrigerant in the first state.

A method of defrosting an indoor coil in a refrigeration system including, while the system is operating in the refrigeration mode, with a controller of the refrigeration system, determining a defrost commencement time at which the refrigeration system is to commence operating in the defrost mode. With the controller, one or more defrost energy conservation processes are initiated prior to the defrost commencement time, to decrease a rate at which thermal energy is transferred from the refrigerant in the outdoor coil to ambient air around the outdoor coil. The defrost energy conservation process continues until a defrost energy conservation termination criterion is satisfied, at which time the defrost energy conservation process is terminated. Upon termination of the defrost energy conservation process, operation of the refrigeration system in the defrost mode is commenced.

Described is a vector control system for a vapor compression circuit. The vector control system may monitor the vapor compression circuit and adjust the speed of one or more motors to increase efficiency by taking into account the torque forces placed on a compressor motor.

A refrigeration cycle apparatus includes a refrigerant circuit that is formed by connecting a compressor, a flow passage switching device, an outdoor heat exchanger, an expansion unit, and an indoor heat exchanger via pipes, and through which refrigerant flows, an outdoor air-sending device configured to blow outdoor air to the outdoor heat exchanger, an outdoor air temperature detector configured to detect a temperature of the outdoor air, and a controller configured to control an operation of the outdoor air-sending device.

A controller in a refrigeration cycle apparatus performs a refrigerant recovery operation when switching an operation mode from a defrosting mode to a heating mode. During the refrigerant recovery operation, by rotating a fan of a blower while monitoring a pressure at a discharge side of the compressor, the controller is configured to perform feedback control to cause a high-pressure side pressure to be close to a high-pressure side target pressure value. During the refrigerant recovery operation, by controlling a driving frequency of the compressor while monitoring a pressure at a suction side of the compressor, the controller is configured to perform feedback control to cause a low-pressure side pressure to be close to a low-pressure side target pressure value.