Heat Exchanger and Refrigeration Cycle Apparatus

This application is a U.S. national stage application of PCT/JP2022/031523 filed on Aug. 22, 2022, the contents of which are incorporated herein by reference.

The present disclosure relates to a heat exchanger and a refrigeration cycle apparatus that have a plurality of flat tubes.

Among refrigeration cycle apparatuses that each have a plurality of heat exchangers, some refrigeration cycle apparatus includes a plurality of groups of heat exchangers, with one or more heat exchangers defined as one group. Such a refrigeration cycle apparatus is referable to, for example, Patent Literature 1. The heat exchanger in each of the plurality of groups is an air heat exchanger and has an upper header tube, a lower header tube, heat transfer tubes, and fins.

In cooling operation, groups are connected in series to each other and a series refrigerant flow passage is thus formed through which refrigerant is caused to flow in series between groups. All the heat exchangers in the series refrigerant flow passage each have heat transfer tubes through which refrigerant is caused to flow from above to below.

In heating operation, groups are connected in parallel to each other and a parallel refrigerant flow passage is thus formed through which refrigerant is caused to flow in parallel to respective groups. All the heat exchangers in the parallel refrigerant flow passage each have heat transfer tubes through which refrigerant is caused to flow from below to above.

Also, in some heat exchanger, a refrigerant distributor structured with a double tube provided with an inner tube and an outer tube is used as a lower header, for example. A plurality of outer tubes are provided. Between outer tubes adjacent to each other among the plurality of outer tubes, a gap is defined. A single inner tube is provided and sequentially connected to the plurality of outer tubes. To the outer tubes, a plurality of heat transfer tubes are connected in a tubular-axial direction of the outer tubes. Refrigerant that has flowed between the inner tube and the outer tubes is distributed to the plurality of heat transfer tubes.

Patent Literature 1: International Publication No. 2019/008664

Usually, a case in which a heat exchanger serves as an evaporator, refrigerant in a two-phase gas-liquid state in which gas refrigerant and liquid refrigerant is mixed to each other flows into the heat exchanger. In this case, as a refrigerant distributor located on an inflow side of the heat exchanger, a refrigerant distributor structured with a double tube provided with an inner tube and an outer tube may be used. In the refrigerant distributor structured with a double tube, a large number of refrigerant outflow holes are arranged in parallel to each other in the inner tube. The refrigerant distributor structured with a double tube is formed such that refrigerant is evenly distributed to a plurality of heat transfer tubes included in a heat exchanger and the refrigerant distributor is reduced in capacity.

On an outflow side of a heat exchanger that serves as an evaporator, a refrigerant distributor structured with a single tube is provided. In a case in which the heat exchanger serves as a condenser, the refrigerant distributor has the function of distributing refrigerant to a plurality of heat transfer tubes included in the heat exchanger.

However, as in Patent Literature 1 described above, in a case in which a plurality of heat exchangers are mounted on one outdoor unit, connection states between the plurality of heat exchangers are distinguished between a case in which the series refrigerant flow passage is formed and a case in which the parallel refrigerant flow passage is formed. In a case in which, to perform cooling operation, the plurality of heat exchangers mounted on the outdoor unit each serve as a condenser and the plurality of heat exchangers form with each other the series refrigerant flow passage, a heat exchanger located upstream in a flow passage and a heat exchanger located downstream are different in a state of refrigerant that flows in. That is, into the heat exchanger located upstream, gas refrigerant, which is in a single phase, flows. On the other hand, into the heat exchanger located downstream, refrigerant in a two-phase gas-liquid state in which gas refrigerant and liquid refrigerant is mixed to each other flows, because a portion of the gas refrigerant exchanges heat and thus condenses in the heat exchanger located upstream. The refrigerant distributor on an inflow side of the heat exchanger located downstream in this case, however, is a refrigerant distributor structured with a single tube. In the heat exchanger located downstream, refrigerant caused to flow in is thus not evenly distributed to the plurality of flat tubes included in the heat exchanger. In the heat exchanger located downstream, the amounts of the distributed refrigerant vary at different locations of flat tubes. The heat exchange amount is insufficient around the flat tubes into which a large amount of refrigerant is distributed. The heat exchange amount is excessive around the flat tubes into which a small amount of refrigerant is distributed. Such an uneven distribution causes a problem in that efficiency of heat exchange is reduced.

The present disclosure is made to solve such a problem, and an object of the present disclosure is to provide a refrigeration cycle apparatus and a heat exchanger that is one heat exchanger among a plurality of heat exchangers that each serve as a condenser in cooling operation and is provided with a refrigerant distributor that evenly distributes refrigerant to a plurality of flat tubes also in a case in which, when the plurality of heat exchangers are connected in series to each other and a series refrigerant flow passage is thus formed, the heat exchanger is located downstream in a direction through refrigerant flows.

A heat exchanger according to one embodiment of the present disclosure includes a first heat exchange body that has a plurality of first flat tubes arranged and spaced from each other in a first direction and each of which tube axis extends in a second direction that intersects the first direction; a first refrigerant distributor into which one end portion of each of the plurality of first flat tubes is inserted; and a second refrigerant distributor into which the other end portion of each of the plurality of first flat tubes is inserted, the first refrigerant distributor having a first outer tube that extends in the first direction and into which the one end portion of each of the plurality of first flat tubes is inserted, a first inner tube that extends in the first direction, is located inside the first outer tube, and has a plurality of first refrigerant outflow holes arranged and spaced from each other in the first direction, and a first partition plate joined to an internal wall of the first outer tube in a state in which the first inner tube passes through a plate thickness, the second refrigerant distributor having a second outer tube that extends in the first direction and into which the other end portion of each of the plurality of first flat tubes is inserted, a second inner tube that extends in the first direction, is located inside the second outer tube, and has a plurality of second refrigerant outflow holes arranged and spaced from each other in the first direction, and a second partition plate joined to an internal wall of the second outer tube in a state in which the second inner tube passes through a plate thickness.

A refrigeration cycle apparatus according to another embodiment of the present disclosure is provided with an outdoor unit, in which the outdoor unit is provided with the heat exchanger described above, a second heat exchanger, a refrigerant pipe through which the heat exchanger and the second heat exchanger are connected to each other, a housing that is box-shaped and houses the heat exchanger and the second heat exchanger inside, and an air-sending device located at a upper portion of the housing and configured to form a flow of air by being driven to rotate and blow out the air that passes through the heat exchanger and the second heat exchanger upward from an upper face of the housing, and the heat exchanger and the second heat exchanger are located along a part or all of four side faces of the housing.

The heat exchanger and the refrigeration cycle apparatus according to an embodiment of the present disclosure have a refrigerant distributor structured with a double tube and a plurality of refrigerant outflow holes arranged in parallel to each other in an inner tube of the refrigerant distributor. Also in a case, for example, in which refrigerant in a two-phase gas-liquid state is caused to flow into the heat exchanger, the refrigerant distributor is thus provided, such an uneven situation is therefore addressed in which refrigerant is unevenly distributed to a plurality of flat tubes. Also, refrigerant is thus evenly distributed to the plurality of flat tubes, which ensures that the required heat exchange amount is uniform across all faces of the heat exchange body and that a reduction in heat exchange efficiency is thus prevented.

Embodiments of a heat exchanger and a refrigeration cycle apparatus according to the present disclosure are described below with reference to drawings. The present disclosure is not limited to embodiments described below and may be variously changed without departing from the spirit of the present disclosure. The present disclosure also includes any combination of combinable configurations among configurations described in the embodiments and their modifications described below. Also, the same or equivalent elements are denoted by the same reference signs in the drawings. Their descriptions are omitted or simplified as long as resultant descriptions are suited. Furthermore, among a plurality of components or elements of the same kind that are, for example, differentiated by suffixes such as uppercase alphabetic characters postfixed to the reference signs, components or elements not required to be to distinguished or specified in particular may be described without such suffixes. In addition, relative relationships in dimension between components, shapes of components, and other details of components illustrated in the drawings may differ from those of actual components. Shapes, sizes, locations and other details of components illustrated in the drawings may be changed without departing from the scope of the present disclosure as long as resultant configurations are suited.

Also, in the drawings, each outdoor heat exchanger has a width direction referred to as an X direction, a height direction referred to as a Z direction, and a front-rear direction referred to as a Y direction. The X direction and the Y direction are, for example, horizontal directions. The Z direction is, for example, an up-down direction and may be a vertical direction in some cases. The X direction is a direction in which a plurality of flat tubes are arranged. The Z direction is an axial direction of the flat tube and a direction through which refrigerant flows. The Y direction is a direction through which air flows. The X direction may be referred to as a first direction or a third direction. The Z direction may be referred to as a second direction.

is a refrigerant circuit diagram that illustrates a configuration of a refrigeration cycle apparatusaccording to Embodiment 1. The refrigeration cycle apparatushas an outdoor unitand an indoor unitand forms a refrigeration cycle such that the outdoor unitand the indoor unitare connected to each other by a refrigerant pipe. In addition, the refrigerant pipeincludes a plurality of refrigerant pipesto. These refrigerant pipestodescribed herein may be collectively referred to as the refrigerant pipe. The outdoor unitand the indoor unitare connected to each other at connection ports Pand P. The connection port Pand the connection port Pare each included in the refrigerant pipe. The connection port Pis an inflow connection port through which refrigerant flows into the outdoor unitwhen the refrigeration cycle apparatusis in a cooling operation state and is also an outflow connection port through which refrigerant flows out from the outdoor unitwhen the refrigeration cycle apparatusis in a heating operation state. The connection port Pis an outflow connection port through which refrigerant flows out from the outdoor unitwhen the refrigeration cycle apparatusis in a cooling operation state and is also an inflow connection port through which refrigerant flows into the outdoor unitwhen the refrigeration cycle apparatusis in a heating operation state. In addition, Embodiment 1 describes that one outdoor unitand one indoor unitare provided; however, each of the number of the outdoor unitsand the number of the indoor unitsis not limited to one and may also be two or more.

A refrigerant circuit included in the refrigeration cycle apparatusis filled with a refrigerant such as a fluorocarbon refrigerant and an HFO refrigerant.

Examples of a fluorocarbon refrigerant include an HFC refrigerant, which stands for fluorinated hydrocarbon or hydrofluorocarbon. Examples of an HFC refrigerant include difluoromethane, which is also referred to as HFC-32 and R32, pentafluoroethane, which is also referred to as HFC-125 and R125, 1,1,1-trifluoroethane, which is also referred to as HFC-143a and R143a, 1,1,1,2-tetrafluoroethane, which is also referred to as HFC-134a and R134a. Furthermore, other examples of a fluorocarbon refrigerant also include a refrigerant mixture in which HFC refrigerants described above are mixed with each other. Examples of a refrigerant mixture include a refrigerant mixture R410A in which R32 and R125 are mixed with each other, a refrigerant mixture R407C in which R32, R125, and R134a are mixed with each other, and a refrigerant mixture R404A in which R125, R143a, and R134a are mixed with each other.

Examples of a HFO refrigerant, which stands for a hydrofluoroolefin refrigerant, include HFO-1234yf, HFO-1234ze(E), and HFO-1234ze(Z).

A refrigerant with which the refrigerant circuit included in the refrigeration cycle apparatusis filled is not limited to the examples described above and any refrigerants used in a vapor-compression heat pump is also usable. Specific examples of usable refrigerants include a CO2 refrigerant, an HC refrigerant, such as a propane refrigerant and an isobutane refrigerant, and an ammonia refrigerant. Furthermore, a refrigerant mixture in which a fluorocarbon refrigerant and an HFO refrigerant are mixed with each other, such as a refrigerant mixture in which R32 and HFO-1234yf are mixed with each other, is also usable as a refrigerant.

The outdoor unithas a compressor, a four-way valve, an outdoor heat exchanger, an outdoor heat exchanger, an expansion valve, an expansion valve, a solenoid valve, a solenoid valve, two outdoor air-sending devices, an accumulator, and the refrigerant pipestothrough which these components are connected to each other.

The compressoris a fluid machine configured to compress sucked low-pressure refrigerant and discharge the refrigerant as high-pressure refrigerant. The compressoris, for example, a rotary compressor or a scroll compressor. In addition, the compressormay also be, for example, a compressor of which rotational frequency is constant or a compressor of which rotational frequency is controllable with an inverter mounted.

The four-way valveis a flow switching device provided at a discharge side of the compressorand configured to switch between a circulation direction of refrigerant in the cooling operation state and a circulation direction of refrigerant in the heating operation state. Four connection portstoincluded in the four-way valveare each connected to its corresponding one of the compressor, the outdoor heat exchanger, the accumulator, and the connection port Pat which the outdoor unitand the indoor unitare connected to each other. Among the four connection portstoof the four-way valve, the connection portlocated toward the compressoris selected to be connected to either the connection portlocated toward the outdoor heat exchangeror the connection portlocated toward the connection port Pof the outdoor unit. Also, between the connection portsand, an unselected connection port is connected to the connection port, which is connected to the accumulator. Specifically, in the cooling operation state, the connection portis connected to the connection portand the connection portis connected to the connection port. In the heating operation state, the connection portis connected to the connection portand the connection portis connected to the connection port

The outdoor heat exchangeris a heat exchanger that allows refrigerant that flows inside and air to exchange heat with each other. The outdoor heat exchangerserves as a condenser in the cooling operation state and serves as an evaporator in the heating operation state. The outdoor heat exchangeris connected to the four-way valvethrough the refrigerant pipe. The refrigerant pipeis branched from between the outdoor heat exchangerand the four-way valveto the refrigerant pipe. The refrigerant pipeis connected to the solenoid valve. The outdoor heat exchangerhas connection portsand, which are connected to the refrigerant pipes. The connection portis connected to the four-way valve. The connection portlocated across inside from the opposite connection portis connected to the expansion valvethrough the refrigerant pipe. The refrigerant pipeis branched from between the outdoor heat exchangerand the expansion valveto the refrigerant pipe. The refrigerant pipeis connected to the solenoid valve. When wind generated by the outdoor air-sending devicespasses through the outdoor heat exchanger, the outdoor heat exchangerallows air that passes through and refrigerant that flows inside to exchange heat with each other. The outdoor air-sending devicesare, for example, centrifugal fans, such as sirocco fans and turbo fans, cross-flow fans, diagonal-flow fans, or propeller fans. In addition, the outdoor heat exchangerdescribed in the embodiments corresponds to a second heat exchanger.

The outdoor heat exchangeris a heat exchanger that allows refrigerant that flows inside and air to exchange heat with each other. The outdoor heat exchangerserves as a condenser in the cooling operation state and serves as an evaporator in the heating operation state. The outdoor heat exchangeris connected to the solenoid valvethrough the refrigerant pipe. The refrigerant pipeis branched from between the outdoor heat exchangerand the solenoid valveto the refrigerant pipedescribed above. The outdoor heat exchangerhas connection portsand, which are connected to the refrigerant pipes. The connection portis connected to the four-way valvethrough the solenoid valve. The connection portlocated across inside from the opposite connection portis connected to the expansion valvethrough the refrigerant pipe. When wind generated by the outdoor air-sending devicespasses through the outdoor heat exchanger, the outdoor heat exchangerallows air that passes through and refrigerant that flows inside to exchange heat with each other. In addition, the outdoor heat exchangerdescribed in the embodiments corresponds to a heat exchanger. The refrigerant pipeprovided with the expansion valveis joined to the refrigerant pipeprovided with expansion valve. A junction at which the refrigerant pipeand the refrigerant pipeare joined to each other is connected to the connection port P. The connection port Pis an outflow connection port through which refrigerant flows out from the outdoor unitin the cooling operation state and is also an inflow connection port through which refrigerant flows into the outdoor unitin the heating operation state.

The expansion valveand the expansion valveare each configured to serve as a pressure reducing valve or an expansion valve and reduce the pressure of refrigerant and thus expand the refrigerant. The expansion valveand the expansion valveare each, for example, a pressure reducing device such as a linear electronic expansion valve of which opening degree is multi-stepwise or serially adjustable.

The solenoid valveand the solenoid valveare each configured to open and close a flow passage depending on whether voltage is applied. The solenoid valveand the solenoid valveare configured block and open respective flows of refrigerant and thus switch flow passages of refrigerant.

The accumulatoris provided such that an outflow side of the accumulatoris connected to a suction side of the compressor. The accumulatorhas the function of separating liquid refrigerant and gas refrigerant from each other and storing surplus refrigerant. An inflow side of the accumulatoris connected to the connection portof the four-way valvethrough the refrigerant pipe.

To the outdoor unit, a controlleris provided. The controllercontrols acts of the compressor, the four-way valve, the expansion valve, the expansion valve, the solenoid valve, the solenoid valve, and the two outdoor air-sending devices.

A hardware configuration of the controlleris described below. The controlleris formed by a processor circuit. The processor circuit is formed by dedicated hardware or a processor. r. Examples of the dedicated hardware include an application specific integrated circuit, which is also referred to as an ASIC, and a field programmable gate array, which is also referred to as an FPGA. The processor executes a program stored in a memory. The controllerhas unillustrated memory circuitry. The memory circuitry is formed by a memory. The memory is non-volatile or volatile semiconductor memory such as a random access memory, which is also referred to as a RAM, a read only memory, which is also referred to as a ROM, a flash memory, and an erasable programmable ROM, which is also referred to as an EPROM, or a disk such as a magnetic disk, a flexible disk, and an optical disk.

The indoor unitis formed by an indoor heat exchanger, an indoor air-sending device, an expansion valve, and the refrigerant pipesandthrough which these components are connected to each other. The indoor unitforms, together with the outdoor unit, a refrigeration cycle. The indoor unitsupplies cooling energy or heating energy from the outdoor unitto a cooling load or a heating load. In addition, the cooling load and the heating load correspond to, for example, an indoor space in which the indoor unitis located.

The indoor heat exchangeris a heat exchanger that allows refrigerant that flows inside and air to exchange heat with each other. The indoor heat exchangerserves as an evaporator in the cooling operation state and serves as a condenser in the heating operation state. The indoor heat exchangerhas connection portsand, which are connected to the refrigerant pipes. The connection portis connected to the expansion valvethrough the refrigerant pipe. The connection portlocated across inside from the opposite connection portis connected to the connection port Pthrough the refrigerant pipe. When wind generated by the indoor air-sending devicepasses through the indoor heat exchanger, the indoor heat exchangerallows air that passes through and refrigerant that flows inside to exchange heat with each other. The indoor air-sending deviceis, for example, a centrifugal fan, such as a sirocco fan and a turbo fan, a cross-flow fan, a diagonal-flow fan, or a propeller fan.

The expansion valveis configured to serve as a pressure reducing valve or an expansion valve and reduce the pressure of refrigerant and thus expand the refrigerant. The expansion valveis, for example, a pressure reducing device such as a linear electronic expansion valve of which opening degree is multi-stepwise or serially adjustable.

When the refrigeration cycle apparatusis in a cooling operation state, the controllerexercises control such that the expansion valveis in a fully closed state, the solenoid valveis in an open state, the solenoid valveis in a closed state, and the expansion valveis in a fully open state. The compressorsucks in refrigerant from the accumulatorand then compresses the refrigerant. The compressed refrigerant turns into gas refrigerant, is then discharged from the compressor, and flows into the outdoor heat exchangerthrough the four-way valve. In the outdoor heat exchanger, a portion of the gas refrigerant condenses and the gas refrigerant then turns into a two-phase gas-liquid state of gas refrigerant and liquid refrigerant. The refrigerant in a two-phase gas-liquid state passes through the solenoid valveand then flows into the outdoor heat exchanger. The refrigerant compressed in the outdoor heat exchangerturns into refrigerant in a liquid state. The refrigerant in a liquid state passes through the expansion valve, then flows out from the outdoor unit, and flows into the indoor unit. In the indoor unit, the refrigerant is reduced in pressure in the expansion valve, then evaporates in the indoor heat exchanger, and supplies cooling energy to air. The refrigerant flows out from the indoor unit, then flows into the outdoor unit, passes through the refrigerant pipe, and flows into the four-way valve. Subsequently, the refrigerant flows out from the four-way valve, passes through the refrigerant pipe, and flows into the accumulator. The refrigerant is then sucked from the accumulatorinto the compressoragain and circulates in the refrigerant circuit. This operation establishes a refrigerant circuit that has a refrigerant flow passage through which the outdoor heat exchangerand the outdoor heat exchangerare connected in series to each other.

When the refrigeration cycle apparatusis in a heating operation state, a direction in which refrigerant flows is opposite to a direction in which refrigerant flows in a cooling operation state. Similarly to the states in a cooling operation state, the controllerexercises control such that the expansion valveis in a fully closed state, the solenoid valveis in an open state, the solenoid valveis in a closed state, and the expansion valveis in a fully open state. The compressorsucks in refrigerant from the accumulatorand then compresses the refrigerant. The compressed refrigerant turns into gas refrigerant, is then discharged from the compressor, and flows out through the four-way valvefrom the outdoor unitinto the indoor unit. In the indoor unit, heat is exchanged at the indoor heat exchangerand the refrigerant thus condenses. The refrigerant flows into the expansion valveand is then reduced in pressure in the expansion valve. Subsequently, the refrigerant flows out from the indoor unitand then flows into the outdoor unit. In the outdoor unit, the refrigerant flows into the outdoor heat exchangerthrough the expansion valveand then evaporates by heat exchange. Subsequently, the refrigerant passes through the solenoid valveand then flows into the outdoor heat exchanger. The refrigerant of which heat is further exchanged at the outdoor heat exchangerturns into refrigerant in a gas state. The refrigerant in a gas state flows into the four-way valve. Subsequently, the refrigerant flows out from the four-way valve, passes through the refrigerant pipe, and flows into the accumulator. The refrigerant is then sucked from the accumulatorinto the compressoragain and circulates in the refrigerant circuit. This operation establishes a refrigerant circuit that has a refrigerant flow passage through which the outdoor heat exchangerand the outdoor heat exchangerare connected in series to each other.

A case is described in “Heating Operation State in Case of Series Refrigerant Flow Passage” in which a series refrigerant flow passage is formed in which the outdoor heat exchangerand the outdoor heat exchangerare connected in series to each other. A state of connection, however, is not limited to such a case. That is, a configuration may also be established such that, depending on an operation state of the refrigeration cycle apparatus, connection between the outdoor heat exchangerand the outdoor heat exchangermay also be switched to connection by use of a series refrigerant flow passage or connection by use of a parallel refrigerant flow passage. Furthermore, in a heating operation state, a parallel refrigerant flow passage may also be formed in which the outdoor heat exchangerand the outdoor heat exchangerare connected in parallel to each other. This case is described later with reference toand.

is a perspective view that illustrates a connection state in which the outdoor heat exchangerand the outdoor heat exchangerare connected to each other in the refrigeration cycle apparatusaccording to Embodiment 1.illustrates a case in which the refrigeration cycle apparatusis in a cooling operation state.illustrates a refrigerant flow passage through which the outdoor heat exchangerand the outdoor heat exchangerare connected in series to each other, which is expressed by simple connection of refrigerant pipes. Solid arrows illustrated ineach represent a direction in which refrigerant flows and outlined arrows illustrated ineach represent a direction of wind generated by its corresponding one of the outdoor air-sending devices, that is, a direction of airflow.is a cross-sectional view that illustrates a configuration of the outdoor heat exchangerillustrated in.is a cross-sectional view that illustrates a configuration of the outdoor heat exchangerillustrated in.

First, the configuration of the outdoor heat exchangeris described below. As illustrated inand, the outdoor heat exchangeris formed by a refrigerant distributor, a refrigerant distributor, a plurality of heat exchange bodies, and a reverse header. As illustrated in, a refrigerant pipeis connected to the refrigerant distributorand a refrigerant pipeis connected to the refrigerant distributor.

The plurality of heat exchange bodiesincludes, as illustrated in, a heat exchange bodyA and a heat exchange bodyB. The heat exchange bodyA and the heat exchange bodyB are arranged in a direction of airflow and face each other. In other words, the heat exchange bodyA and the heat exchange bodyB are located such that the two heat exchange bodies form layers in a direction along a direction of wind generated by its corresponding one of the outdoor air-sending devices. In following description, a heat exchange bodylocated windward is referred to as the heat exchange bodyB and a heat exchange bodylocated leeward is referred to as the heat exchange bodyA. The heat exchange bodyA and the heat exchange bodyB are basically the same in configuration and are thus collectively described below as the heat exchange body.

The heat exchange bodyis formed by a plurality of flat tubesand a plurality of fins. The plurality of flat tubesare spaced from each other and arranged in a horizontal direction, that is, the X direction. This configuration causes wind generated by its corresponding one of the outdoor air-sending devicesto flow between the flat tubes, which are adjacent to each other, in a direction represented by its corresponding one of outlined arrows illustrated in. The axial direction of the plurality of flat tubesis the Z direction. Refrigerant flows inside the flat tubesin the Z direction. Refrigerant flows inside the flat tubesand the refrigerant and air thus exchange heat with each other.

The finsare arranged between the flat tubes, which are adjacent to each other in the X direction. The finsare each joined to a side face portion of the flat tubethat is adjacent to the finand each transfer heat to the flat tube. In addition, the fin, such as a corrugated fin, is used to improve efficiency of heat exchange between air and refrigerant. The finis, however, not limited to a corrugated fin and may also be, for example, a flat-plate fin. Also, air and refrigerant exchange heat with each other even at a surface of the flat tube, and the finsthus do not necessarily have to be provided. In a case in which the plurality of heat exchange bodieshave fins, the same finsmay also be shared among the plurality of heat exchange bodies.

is a cross-sectional view that illustrates a configuration of the refrigerant distributorprovided in the outdoor heat exchangerillustrated in.is a cross-sectional view that illustrates a configuration of the refrigerant distributorprovided in the outdoor heat exchangerillustrated in.

As illustrated in, the plurality of flat tubesincluded in the heat exchange bodyA each have tube end portionsandat both respective ends in the axial direction. The refrigerant distributoris provided under, between the tube end portionsand, the tube end portion, which is lower than the tube end portion. The refrigerant distributoris, as illustrated in, formed by an outer tubeand a connection tube. The refrigerant distributorhas a single-tube structure. The outer tubeis a circular tube and its axial direction is the X direction. In an upper face portion of the outer tube, a plurality of flat-tube insertion holesare provided. The plurality of flat-tube insertion holesare spaced from each other and arranged in the X direction. The plurality of flat-tube insertion holesare through holes that pass through the upper face portion of the outer tube. The tube end portionof each of the flat tubesis directly inserted into a flat-tube insertion holeof the outer tube. The outer tubehas tube end portionsandat both respective ends in the X direction. Between the tube end portionsand, at the tube end portion, a closure plateis provided and, at the tube end portion, a closure plateis provided. The tube end portionand the tube end portionare each in a closed state by the closure plateand the closure plate, respectively, and are not open.

The connection tubeis, as illustrated in, connected to the outer tube. An axial direction of the connection tubeis the Z direction. A lower end portionof the connection tubeis inserted into the outer tube. An internal space in the connection tubeand an internal space in the outer tubecommunicate with each other. As described above, the refrigerant distributoris, as illustrated in, connected to the refrigerant pipe. Specifically, the outer tubeof the refrigerant distributoris connected to the refrigerant pipethrough the connection tube. An inside of the refrigerant distributoris, as illustrated in, one space formed by the internal space in the connection tubeand the internal space in the outer tube. Refrigerant having flowed from the refrigerant pipeinto the space inside the refrigerant distributoris directly distributed to the plurality of flat tubesincluded in the heat exchange bodyA.

In addition, the outer tubeis herein illustrated as a shape of one circular cylinder with both ends closed by lids, which are the closure platesand; however, a cross-sectional shape of the outer tubedoes not necessarily have to be circular and may also be rectangular or elliptical. Also, the outer tubedoes not necessarily have to be formed by one cylindrical part. The outer tubemay also be divided into two portions such as an upper half into which the flat tubesare inserted and the other half, that is, a lower half, and may also be formed by joining the upper half and the lower half to each other. The same also applies to an outer tube, an outer tube, and an outer tube, which are described later.

On top of the tube end portionsof the flat tubesin the heat exchange bodyA and on top of the tube end portionsof the flat tubesin the heat exchange bodyB, the reverse headeris provided. The heat exchange bodyA is thus connected to the heat exchange bodyB through the reverse header. The reverse headerhas the function of reversing an upward flow of refrigerant into a downward flow by causing refrigerant having flowed in from the plurality of flat tubesincluded in the heat exchange bodyA to flow out into the plurality of flat tubesincluded in the heat exchange bodyB. Specifically, in the plurality of flat tubesincluded in the heat exchange bodyA, refrigerant flows from a lower position toward a higher position in the Z direction. On the other hand, in the plurality of flat tubesincluded in the heat exchange bodyB, refrigerant flows from a higher position toward a lower position in the Z direction. The reverse headerthus allows directions in which refrigerant flows to be switched. An example is herein provided in which the flat tubeslocated leeward and the flat tubeslocated windward are connected through the reverse header; however, the configuration is not limited to such a case. The flat tubesmay also not be divided into windward ones and leeward ones and may also be formed by one flat tube. The case in which the flat tubeis formed by one flat tube is described later in Embodiment 2 with reference to.

As illustrated in, the refrigerant distributoris provided under the tube end portions, which are lower portions of the plurality of flat tubesincluded in the heat exchange bodyB. The refrigerant distributoris, as illustrated in, formed by the outer tube, an inner tube, and a connection tube. The refrigerant distributorhas a double-tube structure. The outer tubeis a circular tube and its axial direction is the X direction. In an upper face portion of the outer tube, a plurality of flat-tube insertion holesare provided. The plurality of flat-tube insertion holesare spaced from each other and arranged in the X direction. The plurality of flat-tube insertion holesare through holes that pass through the upper face portion of the outer tube. The tube end portionof each of the flat tubesis directly inserted into a flat-tube insertion holeof the outer tube. Between the tube end portionsandof the outer tube, at the tube end portion, a closure plateis provided and, at the tube end portion, a closure plateis provided. The tube end portionand the tube end portionare each in a closed state by the closure plateand the closure plate, respectively, and are not open.

The connection tubeis, as illustrated in, connected to the outer tube. An axial direction of the connection tubeis the Z direction. A lower end portionof the connection tubeis inserted into the outer tube. An internal space in the connection tubeand a first internal space, which is an internal space that faces the tube end portionof the outer tube, communicate with each other. A cross-sectional shape of the first internal spaceis circular. As described above, the refrigerant distributoris, as illustrated in, connected to the refrigerant pipe. Specifically, the outer tubeof the refrigerant distributoris connected to the refrigerant pipethrough the connection tube.

Also, the refrigerant distributorhas a double-tube structure such that, inside the outer tube, the inner tubeis located. Between an internal wallof the outer tubeand an external wallof the inner tube, a gap is defined as a second internal spacein the outer tube. A cross-sectional shape of the second internal spaceis doughnut-shaped, that is, ring-shaped. The inner tubeis provided with a plurality of refrigerant outflow holesarranged in parallel to each other in a side face portion of the inner tube. The inner tubeis joined to the outer tubewith a partition platein between. The partition plateis located between the first internal spaceand the closure plateof the outer tube. The partition platepartitions an area into the first internal spaceand the second internal space. In the central portion of the partition plate, a through holeis formed. Between the tube end portionsandof the inner tube, the tube end portionis fitted into the through hole. The tube end portionopens toward the first internal space. The first internal spaceand an internal space in the inner tubethus communicate with each other. Also, the tube end portionof the inner tubeis joined to the closure plateand is in a closed state. An outer circumference portion of the partition plateis joined to the internal wallof the outer tube. The partition plateis, as described above, joined to the internal wallof the outer tubeand the external wallof the inner tube. The refrigerant that flows inside the refrigerant distributoris thus allowed to pass through between the first internal spaceat the tube end portionto which the connection tubeis connected and the closure plateat the opposite tube end portiononly through the internal space in the inner tube.