An outdoor unit control unit 200 has a defrosting operation condition table 300a that defines an activation rotational speed Cr in accordance with a total sum of flow rate coefficients Cva that is a total sum of flow rate coefficients Cv representing capacities of indoor expansion valves 52a to 52c. The outdoor unit control unit 200 calculates the total sum of the flow rate coefficients Cva by adding the flow rate coefficient Cv of each of the indoor expansion valves 52a to 52c, and refers to the defrosting operation condition table 300a, so as to determine the activation rotational speed Cr. Then, the outdoor unit control unit 200 activates a compressor 21 at the determined activation rotational speed Cr when starting a defrosting operation, maintains this activation rotational speed Cr for a predetermined time from the start of the defrosting operation, and drives the compressor 21.

An air conditioner, having an outdoor unit and an indoor unit, to perform a heating operation and a defrosting operation, the air conditioner including a detection unit to detect a state of at least one selected between the outdoor unit and the indoor unit and to output the detected value, a controller to determine whether the air conditioner is in a stable state when the defrosting operation is completed and, upon determining that the air conditioner is in the stable state, to control the detected value output from the detection unit to determine entry time of the next defrosting operation, and a storage unit to store a value detected in the stable state. The entry time of the defrosting operation is accurately determined, thereby minimizing the number of times of the defrosting operation during the heating operation.

Disclosed is a chiller including a pull-down procedure or pull-down mode, a sustain procedure or sustain mode and, additionally, a heat-up procedure or heat-up mode or temper mode. This allows the chiller to deliberately and determined heat up content if the starting temperature of the content is below the target temperature for serving the content.

A heating, ventilation, and/or air conditioning (HVAC) system includes a compressor, a fan, an inverter configured to drive operation of the compressor, and a controller communicatively coupled to the fan and the inverter. The controller includes a tangible, non-transitory, computer-readable medium with computer-executable instructions that, when executed by processor circuitry, are configured to cause the processor circuitry to determine an operating parameter of the fan in response to an interruption in receiving communication signals from the inverter and operate the fan based on the operating parameter during the interruption.

An outdoor heat exchanger includes a fan configured to adjust a heat transfer coefficient ao of the outside of a heat transfer tube through which a refrigerant flows, a bypass passage and flow rate control valve configured to adjust a heat transfer coefficient i of the inside of the heat transfer tube through which the refrigerant flows, and an on-off valve configured to adjust a heat transfer area A where the refrigerant exchanges heat with a heat medium. A controller controls the heat transfer coefficient o of the outside of the heat transfer tube, the heat transfer coefficient i of the inside thereof, and the heat transfer area A to control a heat exchange amount of the outdoor heat exchanger.

A refrigeration cycle apparatus includes a compressor, a water-refrigerant heat exchanger, pressure reducing devices which reduce the pressure of a refrigerant, an air-side heat exchanger, an outdoor fan which delivers air to the air-side heat exchanger, a geothermal-side heat exchanger, a switching device which switches a flow passage so that the air-side heat exchanger or the geothermal-side heat exchanger functions as an evaporator, and a controller. The controller controls the switching device so that, when the geothermal-side heat exchanger functions as an evaporator, the air-side heat exchanger and the water-refrigerant heat exchanger are connected in parallel, and stops the outdoor fan.

A refrigeration cycle apparatus includes a refrigerant circuit including a compressor, a condenser (outdoor heat exchanger), an expansion valve, and an evaporator (indoor heat exchanger), a fan configured to blow air to the condenser, a fan configured to blow air to the evaporator, and a controller configured to control at least one of a frequency of the compressor, an opening degree of the expansion valve, a rotation speed of the fan, and a rotation speed of the fan, such that the refrigerant sucked into the compressor has a quality of 1.0 or greater. The refrigerant circuit is configured for use with a refrigerant mixture inclusive of 30 wt % to 50% wt ethylene-based hydrofluorocarbon refrigerant.

A refrigeration cycle apparatus includes: a refrigeration cycle circuit including a compressor, a four-way valve, a heat source side heat exchanger, a heat source side pressure-reducing mechanism, an indoor side pressure-reducing mechanism, and an indoor side heat exchanger, and a hot water supply refrigerant circuit branching off from between the compressor and the four-way valve, including a hot water supply side heat exchanger and a hot water supply side pressure-reducing mechanism in order, and connected between the heat source side pressure-reducing mechanism and the indoor side pressure-reducing mechanism, wherein when a refrigerant state value on at least one of a low pressure side of the refrigeration cycle circuit and a discharge side of the compressor becomes a refrigerant collection start state value, a refrigerant collecting operation that collects refrigerant accumulated in the hot water supply refrigerant circuit into the refrigeration cycle circuit is started.

In various implementations, frost in a vapor compression system may be controlled. A property of a fan may be determined. A determination may be made whether a frost event and/or a nonfrost event has occurred based at least partially on the determined fan property.

A controller of an inverter control apparatus includes an A/D conversion unit that performs digital conversion of an input signal when a signal for either an A/D converter start trigger or an A/D converter start trigger is input thereinto; a first inverter control unit that generates the A/D converter start trigger which starts the A/D conversion unit, based on A/D converter start timing information and a first carrier signal; a second inverter control unit that generates the A/D converter start trigger which starts the A/D conversion unit, based on A/D converter start timing information and a second carrier signal; and an A/D start factor selection unit that receives either the A/D converter start trigger or the A/D converter start trigger and selects an A/D start factor at a predetermined period timing of an operation period of the first carrier signal and the second carrier signal.