A refrigerant leakage determination system capable of detecting leakage of refrigerant without requiring complicated processing is provided. A refrigerant leakage determination system is a refrigerant leakage determination system of a refrigeration cycle apparatus that includes a refrigerant circuit including a heat-source-side heat exchanger and has, as operating modes, a normal mode in which the heat-source-side heat exchanger is caused to function as an evaporator and a defrosting mode in which the heat-source-side heat exchanger frosted during a normal operation is defrosted. The refrigerant leakage determination system includes a processor configured to acquire defrosting information regarding a relationship between a normal operation period and the number of defrosting operations, and memory that stores the defrosting information. The processor is further configured to determine, based on the acquired defrosting information, leakage of refrigerant in the refrigerant circuit.

A hybrid multi-air conditioning system with no receiver is provided for optimal valve control. The hybrid multi-air conditioning system includes: a hot-water unit for exchanging heat between refrigerant and water; at least one indoor unit installed indoors and comprising an indoor heat exchanger and an indoor unit expansion valve; and an outdoor unit connected to the indoor unit and the hot-water unit via a refrigerant pipeline and comprising an outdoor heat exchanger, a compressor, and an outdoor unit expansion valve, wherein, when an abnormal refrigerant enters either the at least one indoor unit or the outdoor unit according to an operation mode, the abnormal refrigerant is shut off from the hot-water unit and the at least one indoor unit or the outdoor unit which operates as a condenser. Accordingly, the hybrid multi-air conditioning system improves heat exchange efficiency via direct heat transfer between refrigerant and water by having a coil wound on the water tank to transfer heat between refrigerant and water.

An air conditioning apparatus includes an outdoor device that is configured to circulate refrigerant and that includes a compressor and an outdoor heat exchanger, a plurality of indoor devices configured to circulate water, and a heat exchange device connecting the outdoor device with the indoor device. The heat exchange device includes a heat exchanger configured to exchange heat between the refrigerant and the water, and a switch device configured to control flow of refrigerant between the indoor devices and the heat exchanger.

An air conditioning apparatus is provided that may include an outdoor unit including a compressor and an outdoor heat exchanger and through which a refrigerant is circulated, an indoor unit through which a fluid, such as water is circulated, and at least one heat exchange device including a heat exchanger in which the refrigerant and the fluid are heat-exchanged with each other. The at least one heat exchange device may include a high-pressure guide tube that extends from a high-pressure gas tube of the outdoor unit so as to be connected to a first side of the heat exchanger, a low-pressure guide tube that extends from a low-pressure gas tube of the outdoor unit so as to be combined with the high-pressure guide tube, a liquid guide tube that extends from a liquid tube of the outdoor unit so as to be connected to a second side of the heat exchanger, and a solenoid valve installed in the high-pressure guide tube or the low-pressure guide tube to perform an opening and closing operation so as to allow the refrigerant to flow in a first direction. The high-pressure gas tube and the low-pressure gas tube may be connected to each other by a single gas tube, and when the indoor unit performs a cooling operation or a heating operation, flow of refrigerant in the first direction may be blocked in a state in which power is applied to the solenoid valve.

A heat exchanger includes: a plurality of flat tubes; a fin in which a plurality of notches are arranged side by side in a vertical direction, the fin having a plurality of intermediate portions and a connecting portion connecting the intermediate portions to each other; and a first bulging portion having an upper end edge and a lower end edge provided between a first notch and a second notch, the upper end edge being positioned in the intermediate portion and the lower end edge being positioned in the connecting portion. The upper end edge has a first upper end positioned on an intermediate portion side, and a second upper end positioned on a connecting portion side, the first upper end being positioned to be higher than the second upper end, or the first upper end being positioned at the same height as the second upper end.

The invention provides a refrigeration apparatus configured to cool the interior of a casing of a heat source unit by a refrigerant. An air conditioner includes a heat source unit, a utilization unit having a utilization heat exchanger and constituting a refrigerant circuit along with the heat source unit, and a controller. The heat source unit causes heat exchange between a refrigerant and a heat source, and cools the interior of the casing, and causes a valve to switch to supply or not to supply the cooling heat exchanger with the refrigerant. The controller assesses, before the refrigerant is supplied to the cooling heat exchanger, whether or not the refrigerant flowing from the cooling heat exchanger toward the compressor comes into a wet state when the refrigerant is supplied, and determines whether or not to open the valve in accordance with an assessment result.

An outdoor unit control unit includes a degree-of-dryness calculating unit that calculates the degree of dryness of a refrigerant flowing into an heat exchanger (an indoor heat exchanger at the time of a cooling operation, and an outdoor heat exchanger at the time of a heating operation) disposed on the downstream side of a liquid pipe, and performs an inhibition mode of inhibiting, when the degree of dryness exceeds a threshold A, control that is performed in the direction of decreasing the degree of opening of the expansion valve (an indoor expansion valve at the time of the cooling operation, and an outdoor expansion valve at the time of the heating operation) disposed on the upstream side of the liquid pipe.

An air treatment system controls airflow volume in accordance with momentarily varying airflow volume to be demanded. A supply fan unit is disposed separately from an air treatment unit, and sends outdoor air from an outdoor space to the air treatment unit and sends outdoor air treated by the air treatment unit to an indoor space. An exhaust fan unit is disposed separately from the air treatment unit, and sends indoor air from the indoor space to the air treatment unit and sends indoor air treated by the air treatment unit to the outdoor space. A controller controls a rotation speed of a first fan in accordance with a first detection value of a first airflow volume detection unit, and controls a rotation speed of a second fan in accordance with a second detection value of a second airflow volume detection unit.

Air recirculation systems for heat pumps are disclosed. The air recirculation systems include a heat pump subsystem and a recirculation subsystem. The recirculation subsystem can include one or more arms that direct cool, dehumidified air flowing from the heat pump subsystems back to air inlets. The recirculation subsystems can transition from open to closed configurations either manually or via motors. The air recirculation systems can include a controller that outputs a control signal to the motors to open or close the recirculation subsystems. The control signals can be based on temperature data, current data, and the like.

The air-conditioning apparatus includes: a refrigerant circuit in which a compressor, an outdoor heat exchanger, the expansion valve, and an indoor heat exchanger are connected by pipes; and a controller. The controller includes a valve opening-degree adjusting module, a flow-rate determination module, and a clogging determination module.