Provided is an air conditioner capable of improving heating performance in a cold region by reducing a refrigerant pressure loss in an outdoor heat exchanger in a heating operation. The air conditioner includes a compressor, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger. The outdoor heat exchanger may include a plurality of unit channels into which a refrigerant channel is partitioned, and a separating device installed in each of the plurality of unit channels and configured to separate a liquid refrigerant component and a vapor refrigerant component in each of the plurality of unit channels in a heating operation. The air conditioner may further include a compressor suction channel connecting a heating-operation outlet of the outdoor heat exchanger and an inlet of the compressor, and a bypass pipe connecting the separating device and the compressor suction channel.

A heat exchanger has first and second heat exchange units disposed one above the other. In a case where the heat exchanger functions as a condenser, refrigerant flows through the second heat exchange unit after having flowed through the first heat exchange unit. An intermediate header unit through which the first heat exchange unit and the second heat exchange unit communicate with each other causes at least a portion of refrigerant having flowed through a first heat transfer pipe group on the windward side of the first heat exchange unit to flow to a fourth heat transfer pipe group. Further, the intermediate header unit causes at least a portion of refrigerant having flowed through a second heat transfer pipe group on the leeward side of the first heat exchange unit to flow into a third heat transfer pipe group or the fourth heat transfer pipe group.

A heat exchanger has first and second heat exchange units disposed one above the other. In a case where the heat exchanger functions as a condenser, refrigerant flows through the second heat exchange unit after having flowed through the first heat exchange unit. An intermediate header unit through which the first heat exchange unit and the second heat exchange unit communicate with each other causes at least a portion of refrigerant having flowed through a first heat transfer pipe group on the windward side of the first heat exchange unit to flow to a fourth heat transfer pipe group. Further, the intermediate header unit causes at least a portion of refrigerant having flowed through a second heat transfer pipe group on the leeward side of the first heat exchange unit to flow into a third heat transfer pipe group or the fourth heat transfer pipe group.

An air conditioner indoor unit is provided. The air conditioner indoor unit includes: a base module, having a base part which is arranged with a fan motor; a heat exchange module having a heat exchanger and a connection pipeline for connecting the heat exchanger to an air conditioner outdoor unit; the heat exchanger and the connection pipeline are arranged in such a way that in a mounted state, the heat exchanger and the connection pipeline are entirely located at a front side of the base module; an air and water duct module having an air duct assembly; the air duct assembly is suitable to be entirely disassembled from the base part without disassembling the fan motor in the base part. During mounting, pre-assembly is first performed and then general assembly is performed; in such manner, the time needed to assemble the whole unit may be reduced.

An indoor unit, being configured to constitute a refrigeration apparatus including a refrigerant circuit, includes: a heat exchanger; and a plurality of refrigerant pipes. R32 refrigerant is enclosed in the refrigerant circuit. At least one of the plurality of refrigerant pipes that circulates the R32 refrigerant has an outer diameter of (Do-1)/8 inches while another of the plurality of refrigerant pipes that circulates R410A refrigerant has an outer diameter of Do/8.

An air conditioner may include a case through which outdoor air flows into an indoor space is formed; a first heat exchanger that exchanges heat between the air and refrigerant; a second heat exchanger disposed downstream of the first heat exchanger, through which the refrigerant selectively flows, and that exchanges heat between the air and the refrigerant; a liquid pipe connected to each of the first and second heat exchangers; a high-pressure gas pipe connected to each of the first and second heat exchangers; a low-pressure gas pipe through which the gaseous refrigerant discharged from the first and second heat exchangers flows; a high-pressure gas pipe valve; a low-pressure gas pipe valve; an expansion valve installed in the liquid pipe; and a controller configured to control an opening degree of the low-pressure gas pipe valve, based on a temperature of the refrigerant flowing through the first heat exchanger.

An air conditioner may include a case through which outdoor air flows into an indoor space is formed; a first heat exchanger that exchanges heat between the air and refrigerant; a second heat exchanger disposed downstream of the first heat exchanger, through which the refrigerant selectively flows, and that exchanges heat between the air and the refrigerant; a liquid pipe connected to each of the first and second heat exchangers; a high-pressure gas pipe connected to each of the first and second heat exchangers; a low-pressure gas pipe through which the gaseous refrigerant discharged from the first and second heat exchangers flows; a high-pressure gas pipe valve; a low-pressure gas pipe valve; an expansion valve installed in the liquid pipe; and a controller configured to control an opening degree of the low-pressure gas pipe valve, based on a temperature of the refrigerant flowing through the first heat exchanger.

An air conditioner includes a compressor and a heat exchanger. The heat exchanger includes a first heat exchanger, a second heat exchanger, a plurality of connectors, at least one first header, a second header, and a main air pipe assembly. A plurality of flat pipes in the second heat exchanger correspond to a plurality of flat pipes in the first heat exchanger. The plurality of connectors are arranged corresponding to the plurality of flat pipes in the first heat exchanger. The at least one first header is connected to first ends of the plurality of flat pipes in the first heat exchanger. The second header is connected to first ends of the plurality of flat pipes in the second heat exchanger. The main air pipe assembly makes the second header communicated with the compressor.

An air conditioner includes a compressor and a heat exchanger. The heat exchanger includes a first heat exchanger, a second heat exchanger, a plurality of connectors, at least one first header, a second header, and a main air pipe assembly. A plurality of flat pipes in the second heat exchanger correspond to a plurality of flat pipes in the first heat exchanger. The plurality of connectors are arranged corresponding to the plurality of flat pipes in the first heat exchanger. The at least one first header is connected to first ends of the plurality of flat pipes in the first heat exchanger. The second header is connected to first ends of the plurality of flat pipes in the second heat exchanger. The main air pipe assembly makes the second header communicated with the compressor.

A pipe joint structure includes: a union; a flare nut that includes a female thread formed at one of axially opposite ends of the flare nut, and a first annular surface formed at the other of the axially opposite ends of the flare nut; a cylindrical sleeve that houses the flare nut such that the flare nut can be rotate and moved forward and backward; a rotary ring that has a second annular surface located to face the first annular surface, and is attached to the sleeve such that the rotary ring can be rotated for the union; and a pressing member that presses the flare nut toward the rotary ring. At the second annular surface, a claw is formed in such a manner as to protrude towards the flare nut. The first annular surface includes an engagement surface that is formed in such a manner to face one side in a circumferential direction and a helically inclined surface that is adjacent to the engagement surface in the circumferential direction and formed helically in such a way as to incline and face the opposite side of the one side in the circumferential direction.