Provided is an air conditioning apparatus. The air conditioning apparatus includes an outdoor unit through which a refrigerant is circulated, an indoor unit through which water is circulated, and a heat exchange device including a heat exchanger in which the refrigerant and the water are heat-exchanged with each other. The heat exchanger includes a high-pressure guide tube, a low-pressure guide tube, a liquid guide tube, a bypass tube configured to connect a bypass branch point of the high-pressure gas tube of the outdoor unit to a bypass combination point of the liquid guide tube to bypass a high-pressure refrigerant existing in the high-pressure tube to the liquid guide tube, and a bypass valve installed in the bypass tube. The outdoor unit includes a first valve device configured to guide a refrigerant compressed in the compressor to the outdoor heat exchanger and a second valve device configured to guide the refrigerant compressed in the compressor to the high-pressure guide tube of the heat exchange device.

An air conditioning unit capable of performing a refrigeration cycle using a small-GWP refrigerant is provided. A refrigeration cycle apparatus (1, 1a to 1m) includes a refrigerant circuit (10) including a compressor (21), a condenser (23, 31, 36), a decompressing section (24, 44, 45, 33, 38), and an evaporator (31, 36, 23), and a refrigerant containing at least 1,2-difluoroethylene enclosed in the refrigerant circuit (10).

An air-conditioning system includes: an air conditioner including a refrigerant circuit formed by connecting an outdoor unit and a plurality of indoor units together, the air conditioner being configured to condition air in a plurality of indoor spaces; at least one countermeasure device provided in correspondence with at least one of the plurality of indoor spaces and configured to operate during leakage of a refrigerant; a plurality of detectors configured to detect a concentration of the refrigerant, at least one of the detectors being provided in each of the plurality of indoor spaces; and a control unit configured to operate all of the at least one countermeasure device if at least one of the concentrations of the refrigerant respectively detected by the plurality of detectors exceeds a predetermined value.

The refrigeration cycle apparatus includes a refrigerant circuit, a controller to control the refrigerant circuit, a bypass flow path, and a flow control valve. The bypass flow path communicates between the discharge side of the compressor and the first outdoor heat exchanger or between the discharge side of the compressor and the second outdoor heat exchanger. The flow control valve is provided to the bypass flow path. The refrigerant circuit is configured to be able to perform a heating defrosting simultaneous operation. The heating defrosting simultaneous operation is an operation of supplying part of the refrigerant discharged from the compressor to one of the first outdoor heat exchanger and the second outdoor heat exchanger via the bypass flow path, causing the other of the first outdoor heat exchanger and the second outdoor heat exchanger to serve as an evaporator, and causing the indoor heat exchanger to serve as a condenser.

A system comprising a compressor, a first valve coupled to the compressor and to a first coil, a first expansion valve coupled to the first coil, and a second expansion valve. The second expansion valve coupled to a second coil. A second valve is coupled to the second coil and the compressor. A third valve is coupled to the compressor and a third coil. In response to receiving a heating demand that is below a threshold heating demand, a controller induces an artificial heating demand.

A system comprising a compressor, a first valve coupled to the compressor and coupled to a first coil, a first expansion valve coupled to the first coil, a second coil, and a second expansion valve. The second expansion valve coupled to a third coil, a second valve coupled to the compressor and the third coil. A controller operable to operate the first valve, the first expansion valve, the second expansion valve, and the second valve. The second coil is coupled to the compressor and the refrigerant flows from the second coil to the compressor.

A multi-type air conditioner is provided including an outdoor unit and a plurality of indoor units connected to the outdoor unit by a liquid pipe and a gas pipe. The plurality of indoor units includes a first indoor unit including first and second heat exchangers and first and second heat exchanger connecting pipes, and a second indoor unit. An indoor heat exchanger connecting pipe connects the first and second indoor units, and a liquid pipe connecting tube connects the first indoor unit and the liquid pipe. Opening amounts of a first indoor expansion valve, and first and second bypass expansion valves provided in the first indoor unit are opened selectively to operate the first heat exchanger as a condenser and the second heat exchanger as an evaporator to continuously drive a dehumidification mode while maintaining a room temperature within a predefined range.

A heat exchanger includes: a heat exchange element including flat tubes spaced from each other; and a first header in which one end portion of each of the flat tubes is inserted. The first header includes: a first main header portion in which some of the flat tubes are inserted; a first sub-header portion in which others of the flat tubes are inserted such that the number of the flat tubes inserted in the first sub-header portion is smaller than that of the flat tubes inserted in the first main header portion; and a partition plate provided between the first main header portion and the first sub-header portion, and joined to the first main header portion and the first sub-header portion. The partition plate has a surface area that is larger than a sectional area of the first main header portion and a sectional area of the first sub-header portion.

An air-conditioning system includes: an air conditioner including an outdoor unit and a plurality of indoor units each provided in a corresponding one of a plurality of indoor spaces and each including a first control unit; and a second control unit capable of communicating with the first control units. Each first control unit is capable of communicating with a countermeasure device if the countermeasure device is installed in correspondence with one of the indoor spaces where the first control unit is located. The second control unit has a first function of prohibiting operation of the air conditioner if a first condition where communication between the first control unit and the countermeasure device is not established in any of the indoor units is satisfied.

A determination device includes a refrigerant circuit, an operation determination unit, and a refrigerant determination unit. The refrigerant circuit is made of a compressor, a condenser, an expansion mechanism, and an evaporator that are circularly connected. In a refrigeration cycle operation in accordance with a quantity of heat required by the condensers or the evaporators, the operation determination unit determines whether the refrigeration cycle operation can be normally carried out or not. Upon determination that the refrigeration cycle operation cannot be normally carried out, the refrigerant determination unit determines whether a refrigerant in the refrigerant circuit is regenerable or not, based on a result of the determination. Thus the determination device is provided by which an effort involved with determination as to whether the refrigerant is regenerable or not can be reduced.