Heat exchanger, device provided with heat pump, and temperature control device

Abstract

This heat exchanger (1A) is provided with: a heat transfer tube (4A) having a plurality of flow paths (41-47) which extends in the vertical direction and through which a first fluid, in which a liquid phase and a gas phase are mixed, is caused to flow, the heat transfer tube (4A) exchanging heat between the first fluid and a second fluid flowing outside and extending in the vertical direction; and a header (3A) having an outer tube (31A into a first peripheral wall portion of which a lower end portion of the heat transfer tube (4A) is inserted and which has an internal space communicating with the plurality of flow paths (41-47), and an inner tube (33A) which is disposed in the internal space below the lower end portion of the heat transfer tube (4A) and which supplies the first fluid to the internal space, the header (3A) causing the first fluid to flow to the lower end portion of the heat transfer tube (4A). The inner tube (33A) is disposed at a position closer to an upstream flow path, which is located upstream of the flow of the second fluid, than to the tube axis (A3) of the heat transfer tube (4A), among the plurality of flow paths (41-47) that are open to the lower end of the heat transfer tube (4A).

Description

Heat exchanger, device with heat pump, and temperature control device

[0001] The present disclosure relates to a heat exchanger, a device including a heat pump, and a temperature control device.

[0002] Some heat exchangers are equipped with a header with a double-pipe structure to distribute and collect the refrigerant fluid evenly among the heat transfer tubes. That is, some heat exchangers are equipped with a header that houses an inner tube inside an outer tube that supplies the fluid to the inner space of the outer tube.

[0003] For example, Patent Document 1 discloses that in a header to which the ends of multiple heat transfer tubes extending horizontally are connected, an inner tube is placed inside an outer tube into which the ends of each heat transfer tube are inserted.

[0004] In the header described in Patent Document 1, outlet holes for allowing fluid to flow out are formed in the peripheral wall of the inner tube, and the openings of the outlet holes face the ends of the heat transfer tubes. This makes it easier for the liquid phase fluid to enter the heat transfer tubes and evaporate when the fluid is in a mixed liquid and gas phase.

[0005] JP 2019-74287 A

[0006] In the header described in Patent Document 1, the heat transfer tubes extend horizontally. However, even in a heat exchanger in which the heat transfer tubes extend vertically, when the heat exchanger functions as an evaporator, it is desirable to facilitate evaporation of the liquid phase component of a fluid that contains a mixture of liquid and gas phases, thereby increasing the heat exchange efficiency.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a heat exchanger, an apparatus equipped with a heat pump, and a temperature control device that facilitate evaporation of the liquid phase component of a fluid that has a mixture of liquid and gas phases and has high heat exchange efficiency.

[0008] To achieve the above object, a heat exchanger according to the present disclosure has a plurality of flow paths extending vertically through which a first fluid having a mixture of liquid and gas phases flows, and exchanges heat between the first fluid and a second fluid flowing outside, and includes: heat transfer tubes extending vertically; an outer tube whose lower ends are inserted into a first peripheral wall portion and whose internal space is connected to the plurality of flow paths; and an inner tube disposed in the internal space below the lower ends of the heat transfer tubes and supplying the first fluid to the internal space, the header through which the first fluid flows to the lower ends of the heat transfer tubes. The inner tube is disposed at a position closer to an upstream flow path that is upstream of the flow of the second fluid than the axis of the heat transfer tubes, among the plurality of flow paths that open at the lower ends of the heat transfer tubes.

[0009] According to the configuration of the present disclosure, the inner tube is disposed closer to an upstream flow path, which is located upstream of the flow of the second fluid, than the axis of the heat transfer tube, among a plurality of flow paths opening at the lower end of the heat transfer tube. Therefore, the distance to the inner tube is shorter in the upstream flow path than in the other flow paths among the plurality of flow paths, and the flow resistance of the first fluid is smaller in the upstream flow path. This allows more of the liquid phase component of the first fluid to flow into the upstream flow path than in the other flow paths. As a result, in the heat exchanger, the liquid phase component of the first fluid is more likely to evaporate, resulting in high heat exchange efficiency.

[0010] A perspective view of a heat exchanger according to a first embodiment of the present disclosure. A cross-sectional view taken along the II-II cutting line shown in FIG. 1. A cross-sectional view of a header according to the first embodiment of the present disclosure. A plan view of a partition plate provided in the header according to the first embodiment of the present disclosure. A cross-sectional view of a modified example of the header according to the first embodiment of the present disclosure. A cross-sectional view of a header provided in a heat exchanger according to a second embodiment of the present disclosure. A cross-sectional view of a header provided in a heat exchanger according to a third embodiment of the present disclosure. A cross-sectional view of a header provided in a heat exchanger according to a fourth embodiment of the present disclosure. A refrigerant circuit diagram of an air conditioner incorporating a heat exchanger according to the third embodiment of the present disclosure. A cross-sectional view of a modified example of an inner tube provided in a header provided in a heat exchanger according to the first embodiment of the present disclosure.

[0011] A heat exchanger, a heat pump-equipped device, and a temperature control device according to embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical or equivalent parts are designated by the same reference numerals. In the illustrated Cartesian coordinate system XYZ, the extension direction of the cylindrical portion of the header of the heat exchanger is the left-right direction, and the extension direction of the heat transfer tubes connected to the header is the up-down direction. The left-right direction is the X-axis, the up-down direction is the Z-axis, and the direction perpendicular to the X-axis and Z-axis is the Y-axis. This coordinate system will be referenced as appropriate below.

[0012] (Embodiment 1) A heat exchanger according to Embodiment 1 includes heat transfer tubes each having a plurality of flow paths extending vertically, an upper header connected to the upper ends of the heat transfer tubes, and a lower header connected to the lower ends of the heat transfer tubes. In this heat exchanger, the upper and lower headers are formed in a so-called double-tube structure, which includes an outer tube connected to the upper or lower ends of the heat transfer tubes and an inner tube disposed within the outer tube. In order to improve heat exchange efficiency when the heat exchanger functions as an evaporator, the inner tube is disposed in the lower header at a position offset from directly below the lower ends of the heat transfer tubes inserted into the outer tube.

[0013] First, the overall configuration of this heat exchanger will be described with reference to Figures 1 and 2. Below, the configuration of the heat exchanger will be described using as an example a case in which the internal fluid flowing inside the heat transfer tube is a refrigerant and the external fluid flowing outside the heat transfer tube and exchanging heat with the internal fluid is air.

[0014] Fig. 1 is a perspective view of a heat exchanger 1A according to embodiment 1. Fig. 2 is a cross-sectional view taken along the line II-II shown in Fig. 1. For ease of understanding, Fig. 1 shows only the heat transfer tubes 4A and fins 5 in a portion of the heat exchanger 1A, and omits the heat transfer tubes 4A and fins 5 in other portions.

[0015] As shown in FIG. 1, the heat exchanger 1A includes headers 2A and 3A for distributing and collecting the refrigerant, a plurality of heat transfer tubes 4A connected to the headers 2A and 3A and through which the refrigerant flows, and a plurality of fins 5 attached to the heat transfer tubes 4A.

[0016] The headers 2A, 3A have outer pipes 21A, 31A formed in the shape of a square tube with rounded corners. Furthermore, although not shown in Fig. 1, the headers 2A, 3A have, in the interior spaces of the outer pipes 21A, 31A, inner pipes whose pipe axes are oriented in the same direction as the pipe axes of the outer pipes 21A, 31A and whose outer diameters are smaller than the inner diameters of the outer pipes 21A, 31A. By including such inner pipes and outer pipes 21A, 31A in the headers 2A, 3A, the space between the inner pipes and the outer pipes 21A, 31A and the interior spaces of the inner pipes form flow paths for the refrigerant to flow.

[0017] 1, cylindrical connectors 6 and 7 are provided at the ends of the headers 2A and 3A to allow the refrigerant to flow through the flow paths. Of these connectors 6 and 7, connector 7 is connected to a connecting pipe of an external device (not shown) that supplies the refrigerant. Connector 6 is connected to another connecting pipe of the external device (not shown) that discharges the refrigerant. By connecting such external devices to the headers 2A and 3A, the headers 2A and 3A allow the refrigerant to flow through the flow paths formed by the inner and outer tubes 21A and 31A.

[0018] 1, the headers 2A and 3A are arranged spaced apart from each other in the vertical direction with their tube axes A1 and A2 aligned horizontally and parallel to each other. A plurality of heat transfer tubes 4A are connected to the headers 2A and 3A to circulate the refrigerant therebetween.

[0019] Each heat transfer tube 4A is formed in a tubular shape to allow the refrigerant to flow through it. The heat transfer tubes 4A extend vertically. Furthermore, the upper and lower ends of the heat transfer tubes 4A are inserted into through-holes (not shown in FIG. 1 ) in the peripheral wall portions 22A and 32A of the outer tubes 21A and 31A of the headers 2A and 3A, respectively. In this way, the heat transfer tubes 4A are connected to the headers 2A and 3A. As a result, the refrigerant flows through the heat transfer tubes 4A when it flows through the headers 2A and 3A.

[0020] Each heat transfer tube 4A is formed of a metal with high thermal conductivity, such as pure aluminum or an aluminum alloy, to facilitate the transfer of heat from the refrigerant flowing therethrough. Furthermore, each heat transfer tube 4A is formed flat in cross-sectional view to facilitate the transfer of heat from the refrigerant. That is, the heat transfer tube 4A is a flat tube. As shown in FIG. 2, each heat transfer tube 4A has multiple flow paths 41-47 arranged in the longitudinal direction of the cross-sectional view. This allows the heat transfer of the refrigerant to the heat transfer tube 4A more easily. Although FIG. 2 shows seven flow paths 41-47 formed in the heat transfer tube 4A, the heat transfer tube 4A may have multiple flow paths 41-47, i.e., two or more.

[0021] Furthermore, the heat transfer tubes 4A are arranged with the short side direction of the flattened cross section of the tube 4A facing the tube axes A1, A2 of the headers 2A, 3A. The heat transfer tubes 4A are arranged at a constant pitch along the tube axes A1, A2 of the headers 2A, 3A, as shown in FIG. 1 . This arrangement of the heat transfer tubes 4A creates gaps between the heat transfer tubes 4A. Fins 5 are provided in the gaps to release heat transferred to the heat transfer tubes 4A into the surrounding air.

[0022] The fins 5 are formed of a metal with high thermal conductivity, for example, the same metal material as the heat transfer tubes 4A, to facilitate heat transfer from the heat transfer tubes 4A. Furthermore, the fins 5 are formed in a plate shape (not shown) to facilitate heat release into the surrounding air. The plate is folded into a corrugated shape. The fins 5 are sandwiched between adjacent heat transfer tubes 4A with the peaks and valleys of the corrugations facing the flat surfaces of the heat transfer tubes 4A. The peaks and valleys of the corrugations of the fins 5 are then joined to the heat transfer tubes 4A, respectively. Thus, the fins 5 are attached to the heat transfer tubes 4A. As a result, the fins 5 release heat transferred from the heat transfer tubes 4A into the air from the surface of the corrugated plate.

[0023] A heat exchanger 1A having such a configuration is incorporated into a heat pump-equipped device, such as an indoor or outdoor unit of an air conditioner. To improve heat exchange efficiency, the heat exchanger 1A may have a fan (described later) blowing air from the front to the back of the heat exchanger 1A, as shown in FIG. 1 . When the heat exchanger 1A is used as an evaporator and a refrigerant containing both liquid and gas phases flows from the lower header 3A to the upper header 2A, the air temperature may decrease due to heat exchange in the downstream portion of the heat transfer tube 4A, downstream of the blown air flow F. As a result, the liquid phase of the refrigerant may not evaporate sufficiently, resulting in insufficient heat exchange efficiency. Therefore, to improve heat exchange efficiency by flowing a refrigerant containing a large amount of liquid phase into the upstream portion of the heat transfer tube 4A, where relatively high-temperature air flows, an inner tube of the lower header 3A that supplies the refrigerant to the heat transfer tube 4A is positioned below and faces the lower end of the heat transfer tube 4A. Furthermore, the inner pipe is disposed so as to be shifted to the upstream side of the air flow F. Next, the detailed position of the inner pipe will be described with reference to Figs.

[0024] Fig. 3 is a cross-sectional view of the header 3A included in the heat exchanger 1A. Fig. 4 is a plan view of the partition plate 37 included in the header 3A. Note that Fig. 3 shows the lower ends of the heat transfer tubes 4A in addition to the header 3A to illustrate the connection relationship. Also, in Fig. 3, hatching of the heat transfer tubes 4A is omitted to facilitate understanding of the internal structure, and the shapes of the flow paths 41-47 are indicated by dotted lines. Furthermore, in Fig. 4, hatching is applied to the plate surface portion of the partition plate 37 to make the position of the through-hole 38 easier to understand.

[0025] As shown in FIG. 3, the header 3A has the outer pipe 31A and an inner pipe 33A disposed in the internal space of the outer pipe 31A.

[0026] The outer pipe 31A is formed in a rectangular shape with rounded corners in a cross-sectional view. The outer pipe 31A is arranged with the short sides of the rectangle oriented vertically. A through-hole 35 is formed in the upper surface of the peripheral wall portion 32A of the outer pipe 31A to connect the heat transfer pipe 4A and allow refrigerant to circulate between the outer pipe 31A and the heat transfer pipe 4A.

[0027] Although not shown, a plurality of through holes 35 are formed in the peripheral wall portion 32A of the outer tube 31A. Specifically, the tube axis A2 of the outer tube 31A extends in the left-right direction of the heat exchanger 1A, i.e., in the X direction in Fig. 3. The through holes 35 are formed in the peripheral wall portion 32A of the outer tube 31A extending in this manner, at a constant pitch in the X direction, and the number of through holes 35 is the same as the number of heat transfer tubes 4A.

[0028] The through holes 35 have the same shape and size. Below, only the through hole 35 shown in Fig. 3 will be described, and descriptions of the other through holes 35 will be omitted.

[0029] The through-hole 35 shown in Fig. 3 is formed in a flat shape. The flat shape is larger than the cross-sectional flatness of the heat transfer tube 4A, to the extent that the heat transfer tube 4A can be inserted. Furthermore, the through-hole 35 penetrates the upper surface portion of the peripheral wall portion 32A in the vertical direction. The lower end of the heat transfer tube 4A is inserted into the through-hole 35. The lower end of the heat transfer tube 4A is joined to the inner wall of the through-hole 35 by brazing, and as a result, the lower end of the heat transfer tube 4A is fixed to the outer tube 31A.

[0030] Furthermore, the center line C1 of the through hole 35 is located at the same position in the front-rear direction D of the heat exchanger 1A as the tube axis A2 of the outer tube 31A. Specifically, the tube axis A2 of the outer tube 31A extends in the left-right direction of the heat exchanger 1A, i.e., in the X direction. The center line C1 of the through hole 35 extends in the vertical direction, i.e., in the Z direction, at the same position in the front-rear direction D, i.e., in the Y direction, as the tube axis A2 of the outer tube 31A. The through hole 35 is located on the +Z side of the tube axis A2 of the outer tube 31A. Due to this positional relationship, the lower end of the heat transfer tube 4A is located directly above the tube axis A2 of the outer tube 31A. In other words, the tube axis A2 of the outer tube 31A and the tube axis A3 of the heat transfer tube 4A are aligned in the front-rear direction D.

[0031] Furthermore, although not shown, the longitudinal direction of the flattened shape of the through-holes 35 faces the front-to-rear direction D of the heat exchanger 1A, i.e., the Y direction. As a result, the through-holes 35 orient the longitudinal direction of the flattened cross section of the inserted heat transfer tube 4A in the Y direction. When used with a fan (not shown), the heat exchanger 1A blows air in the front-to-rear direction D of the heat exchanger 1A, i.e., from the +Y direction to the −Y direction. The through-holes 35 orient the longitudinal direction of the flattened cross section of the heat transfer tube 4A in the Y direction, thereby extending the flat surface of the heat transfer tube 4A in the Y direction. As a result, the blown air is less likely to be disturbed by the heat transfer tube 4A. By realizing this arrangement of the heat transfer tubes 4A, the through-holes 35 improve the heat exchange efficiency between the refrigerant flowing through the heat transfer tube 4A and the blown air.

[0032] As shown in FIG. 3, the outer tube 31A having the through-hole 35 accommodates the inner tube 33A so that the inner space thereof is filled with the refrigerant and the refrigerant is supplied from the lower end of the heat transfer tube 4A to the flow paths 41-47 of the heat transfer tube 4A.

[0033] The inner pipe 33A has a circular cross-sectional shape. That is, the inner pipe 33A is a circular pipe. The pipe axis A4 of the inner pipe 33A is arranged parallel to the pipe axis A2 of the outer pipe 31A, and as a result, the inner pipe 33A extends in the X direction. The connection portion 7 shown in FIG. 1 is connected to the +X end of the inner pipe 33A to introduce a refrigerant. This allows the refrigerant to be supplied to the inner pipe 33A from the connection portion 7. To supply the refrigerant evenly to each heat transfer tube 4A, the inner pipe 33A has outflow holes 36 shown in FIG. 3 formed at a regular pitch in the X direction. To allow the refrigerant to be easily received by the heat transfer tubes 4A located above the inner pipe 22, the inner pipe 33A has an outer diameter smaller than the longitudinal length L1 of the flattened cross-sectional shape of the heat transfer tube 4A.

[0034] The outflow hole 36 is formed in a portion of the peripheral wall 34A of the inner pipe 33A that does not face the lower end of the heat transfer pipe 4A and that directly faces the inner wall surface of the outer pipe 31A. In other words, the outflow hole 36 is formed in a portion of the peripheral wall 34A of the inner pipe 33A where the lower end of the heat transfer pipe 4A is not positioned in the direction D1 in which the refrigerant flows out from the outflow hole 36 itself.

[0035] Specifically, the outflow hole 36 is formed in the bottom portion of the peripheral wall 34A of the inner pipe 33A. As a result, the refrigerant outflow direction D1 from the outflow hole 36 faces downward, and the direction D1 is directed toward the bottom of the peripheral wall 34A of the outer pipe 31A. The reason for forming the outflow hole 36 in this position is that if the outflow hole 36 is provided in a portion of the inner pipe 33A facing the lower end of the heat transfer tube 4A and the refrigerant outflow direction D1 faces upward, when a refrigerant containing a mixture of gas and liquid phases flows through the inner pipe 33A, the refrigerant containing a larger amount of gas phase will tend to flow into the heat transfer tube 4A, which will likely reduce heat exchange efficiency.

[0036] As described above, a mixture of gas and liquid phase refrigerant may flow through the inner tube 33A having such outflow holes 36. In this case, for example, if the inner tube 33A is located directly below the lower end of the heat transfer tube 4A and a large amount of refrigerant flows into flow path 44 of the heat transfer tube 4A and the nearby flow paths 43, 45, etc., evaporation of the liquid phase refrigerant may be reduced compared to when a large amount of refrigerant flows into flow paths 41-43, and the heat exchange efficiency of the heat exchanger 1A may not be improved.

[0037] Specifically, because the heat transfer tube 4A is cooled by the air flow F, the flow paths 41-47 located more upstream of the air flow F are more easily cooled. As a result, in the heat transfer tube 4A, the most upstream flow path 41 is more easily cooled, and the most downstream flow path 47 is less easily cooled. In this context, if a large amount of refrigerant flows into the central flow path 43 in the upstream-downstream direction D1 of the air flow F because the inner tube 33A is located directly below the lower end of the heat transfer tube 4A, evaporation of the liquid refrigerant is likely to be reduced. As a result, the heat exchange efficiency of the heat exchanger 1A may not be improved.

[0038] Therefore, the inner pipe 33A is disposed upstream of the pipe axis A2 of the outer pipe 31A in the flow of air F toward the heat transfer pipe 4A. As a result, the inner pipe 33A is disposed below the upstream portion of the lower end of the heat transfer pipe 4A.

[0039] Specifically, the tube axis A2 of the outer tube 31A and the tube axis A3 of the heat transfer tube 4A are located at the same position in the front-to-rear direction D. In contrast, the tube axis A4 of the inner tube 33A is located forward of the tube axis A3 of the heat transfer tube 4A. In other words, the tube axis A4 of the inner tube 33A is located upstream of the tube axis A3 of the heat transfer tube 4A. As a result, in the inner tube 33A, the distance D11 to the flow path 41, which opens at the lower end of the heat transfer tube 4A and is located most upstream, is shorter than the distance D12 to the center of the lower end of the heat transfer tube 4A, through which the tube axis A3 passes. As a result, the distance D11 is shorter than the distance to the flow path 44, which opens at the center of the lower end of the heat transfer tube 4A. Or, it is shorter than the distance to the flow paths 45-47, which are located downstream of the flow path 44.

[0040] In other words, the inner tube 33A is located closer to the flow paths 41-43, which is located upstream of the tube axis A3 of the heat transfer tube 4A, among the flow paths 41-47. As a result, the refrigerant flow resistance is smaller than that of the downstream flow paths 44-47, and liquid refrigerant flows more easily into the flow paths 41-43. As a result, refrigerant containing a larger amount of liquid flows into the upstream flow paths 41-43, and refrigerant containing a relatively smaller amount of liquid flows into the downstream flow paths 44-47. In other words, the refrigerant containing a larger amount of liquid flows more easily into the upstream flow paths 41-43. In the heat transfer tube 4A, the more upstream the flow paths 41-43, the more easily it is cooled by air, so the refrigerant containing a larger amount of liquid is more easily cooled in the upstream flow paths 41-43. As a result, the refrigerant evaporates easily in the heat exchanger 1A, and heat exchange efficiency is high.

[0041] Such an arrangement of the inner tube 33A is achieved by a partition plate 37 shown in Fig. 4. More specifically, a partition plate 37 shown in Fig. 4 is fitted into each of both ends of the outer tube 31A in the extension direction, i.e., in the X direction. A through hole 38 is formed in the partition plate 37, and the inner tube 33A is fitted into the through hole 38, thereby fixing the inner tube 33A and determining its position.

[0042] In the heat exchanger 1A, the through-hole 38 is shifted forward, i.e., toward the +Y side, from the center C2 of the partition plate 37. As a result, when the inner pipe 33A is fitted into the through-hole 38 and the partition plate 37 is fitted around the outer pipe 31A, the inner pipe 33A is positioned on the +Y side of the pipe axis A2 of the outer pipe 31A, as shown in FIG. 3 . As a result, the inner pipe 33A is positioned on the +Y side of the pipe axis A3 of the heat transfer pipe 4A, and therefore the inner pipe 33A is positioned upstream of the pipe axis A3 of the heat transfer pipe 4A in the air flow F. With this configuration, the heat exchanger 1A positions the inner pipe 33A upstream of the center C2 of the partition plate 37, thereby improving the heat exchange efficiency when a fluid containing a mixture of liquid and gas phases flows through the header 3A.

[0043] The refrigerant flowing inside the heat transfer tube 4A and the air blown to the heat transfer tube 4A are examples of the first fluid and the second fluid as defined in the present disclosure. The circumferential wall portion 32A of the outer tube 31A and the circumferential wall portion 34A of the inner tube 33A are examples of the first circumferential wall portion and the second circumferential wall portion as defined in the present disclosure. Furthermore, the flow paths 41-43 are an example of an upstream flow path, among the multiple flow paths 41-47, that is located upstream of the tube axis A3 of the heat transfer tube 4A.

[0044] As described above, in the heat exchanger 1A according to the first embodiment, the inner tube 33A of the header 3A is disposed near the flow paths 41-43, which are located upstream of the air flow F toward the heat transfer tube 4A, among the flow paths 41-47 that open at the lower ends of the heat transfer tubes 4A. The inner tube 33A is also disposed far from the tube axis A3 of the heat transfer tube 4A. In other words, the inner tube 33A is disposed near the flow paths 41-43, which are located upstream of the tube axis A3 of the heat transfer tube 4A. Therefore, the distance from the inner tube 33A to the flow paths 41-43 is shorter than that of the flow paths 44-47, which are located upstream or downstream of the tube axis A3 of the heat transfer tube 4A, and the flow resistance of the refrigerant from the inner tube 33A to the flow paths 41-43 is smaller. As a result, when the heat exchanger 1A is used as an evaporator and a refrigerant containing both liquid and gas phases flows, a refrigerant containing a larger amount of liquid flows into the flow paths 41-43 than into the flow paths 44-47. In the heat exchanger 1A, the liquid phase refrigerant evaporates more easily in the flow paths 41-47 located closer to the upstream side, and as a result, the heat exchange efficiency of the heat exchanger 1A is higher.

[0045] In the heat exchanger 1A, in order to dispose the inner tube 33A at the above position, the tube axis A4 of the inner tube 33A is shifted upstream of the tube axis A3 of the heat transfer tube 4A in the air flow F toward the heat transfer tube 4A. As a result, in the heat exchanger 1A, as described above, the liquid phase refrigerant easily evaporates, and the heat exchange efficiency is high.

[0046] (Variation 1) In the first embodiment, the tube axis A3 of the heat transfer tube 4A and the tube axis A2 of the outer tube 31A are disposed at the same position in the front-to-rear direction D. The tube axis A4 of the inner tube 33A is located forward of the tube axis A2 of the outer tube 31A. That is, the tube axis A4 is located upstream of the air flow F. However, the position of the inner tube 33A is not limited to this. The inner tube 33A may be disposed in any position as long as it is closer to an upstream flow path, such as flow paths 41-43, that is located upstream of the tube axis A3 of the heat transfer tube 4A in the air flow F, among the multiple flow paths 41-47 that open at the lower end of the heat transfer tube 4A. Therefore, the position of the inner tube 33A is arbitrary as long as this condition is satisfied.

[0047] FIG. 5 is a cross-sectional view of a modified example of the header 3A included in the heat exchanger 1A.

[0048] As shown in FIG. 5 , the tube axis A4 of the inner tube 33A may be located at the same position in the front-to-rear direction D as the tube axis A2 of the outer tube 31A. For example, the inner tube 33A and the outer tube 31A may be coaxial. In this case, the tube axis A3 of the heat transfer tube 4A may be located rearward of the tube axis A4 of the inner tube 33A and the tube axis A2 of the outer tube 31A, i.e., in the −Y direction. In other words, the tube axis A3 of the heat transfer tube 4A may be located downstream of the tube axis A4 of the inner tube 33A and the tube axis A2 of the outer tube 31A in the air flow F. The inner tube 33A may be located below the lower end of the heat transfer tube 4A. For example, the inner tube 33A may be located directly below flow path 41 of the multiple flow paths 41-47 that open at the lower end of the heat transfer tube 4A.

[0049] With this arrangement, the distance D11 from the inner tube 33A to the flow path 41 of the heat transfer tube 4A can be made shorter than the distance D12 from the inner tube 33A to the center of the lower end of the heat transfer tube 4A, through which the tube axis A3 passes, and a refrigerant containing a larger amount of liquid phase can flow into the flow path 41 than the refrigerant flowing into the central flow path 44 or the downstream flow paths 45-47. Also, a refrigerant containing a larger amount of liquid phase can flow not only through the flow path 41 but also through the flow paths 42 and 43. As a result, the heat exchange efficiency of the heat exchanger 1A can be improved.

[0050] In the first embodiment and the first modification, the inner pipe 33A may be a twisted pipe instead of a circular pipe. In this case, the inner pipe 33A only needs to be disposed at a position closer to an upstream flow path that is located upstream of the axis of the circular pipe or the twisted pipe in the air flow F, among the multiple flow paths that open at the bottom end.

[0051] (Embodiment 2) In the heat exchanger 1A according to Embodiment 1, the inner tube 33A is located below the lower end of the heat transfer tube 4A, and the tube axis A4 of the inner tube 33A is located upstream of the tube axis A3 of the heat transfer tube 4A in the air flow F. However, the inner tube 33A is not limited to this. As described in Modification 1, the inner tube 33A may be located near an upstream flow path, such as flow paths 41-43, that is located upstream of the tube axis A3 of the heat transfer tube 4A in the air flow F, among the multiple flow paths 41-47 that open at the lower end of the heat transfer tube 4A. The position and shape of the inner tube 33A are arbitrary as long as they satisfy this condition. Similarly, the position and shape of the heat transfer tube 4A are arbitrary as long as they satisfy this condition.

[0052] In a heat exchanger 1B according to the second embodiment, an inner tube 33B is located below the lower end of a heat transfer tube 4B, and the lower end of the heat transfer tube 4B has an inclined surface. The configuration of the heat exchanger 1B will be described below with reference to Fig. 6. The configuration of the second embodiment that differs from the first embodiment will be mainly described.

[0053] FIG. 6 is a cross-sectional view of a header 3B provided in the heat exchanger 1B.

[0054] As shown in Figure 6, in the header 3B, a through-hole 35 is formed in the peripheral wall portion 32B of the outer tube 31B at the same position as in the first embodiment. The lower ends of the heat transfer tubes 4B are inserted into the through-hole 35. As a result, the tube axis A3 of the heat transfer tube 4B is aligned with the tube axis A2 of the outer tube 31B in the front-to-rear direction D of the heat exchanger 1B. That is, the tube axis A3 of the heat transfer tube 4B is aligned with the tube axis A2 of the outer tube 31B in the upstream-downstream direction of the air flow F. An inner tube 33B is disposed below the lower ends of the heat transfer tube 4B, and the tube axis A4 of the inner tube 33B is aligned with the tube axis A3 of the heat transfer tube 4B in the upstream-downstream direction of the air flow F.

[0055] In this positional relationship, when a refrigerant containing a mixture of liquid and gas phases flows through the header 3B, the upstream flow paths 41-43 of the heat transfer tubes 4B are designed to have a refrigerant containing a larger amount of liquid than the central flow path 44 or the downstream flow paths 45-47. Therefore, the lower ends of the heat transfer tubes 4B are inclined so that the front side is lower. That is, the +Y side of the lower ends of the heat transfer tubes 4B is inclined toward the -Z side. This causes the lower ends of the heat transfer tubes 4B to be inclined so that the upstream side of the air flow F blown to the heat transfer tubes 4B is lower. As a result, the lower ends of the heat transfer tubes 4B are shaped to approach the inner tube 33B as they move upstream.

[0056] The inner tube 33B has a circular tube shape, as in the first embodiment. Furthermore, since the lower end of the heat transfer tube 4B has the above-described shape in the inner tube 33B, the distance D11 from the opening at the lower end of the heat transfer tube 4B to the upstream flow path 41 is shorter than the distance D12 to the center of the lower end of the heat transfer tube 4B, through which the tube axis A3 passes. As a result, when a refrigerant containing a mixture of liquid and gas phases flows through the inner tube 33B, a refrigerant containing a larger amount of liquid phase is supplied to the upstream flow paths 41-43 than to the central flow path 44 or the downstream flow paths 45-47. Thus, a refrigerant containing a larger amount of liquid phase is supplied to the upstream flow paths 41-43, which are more easily cooled by the air flow F, and a refrigerant containing a smaller amount of liquid phase is supplied to the central flow path 44 or the downstream flow paths 45-47, which are relatively less easily cooled. As a result, the refrigerant evaporates easily in the heat transfer tube 4B, resulting in high heat exchange efficiency.

[0057] In the second embodiment, the distance D11 from the inner tube 33B to the upstream flow passage 41 is smaller than the distance D12 from the inner tube 33B to the center of the lower end of the heat transfer tube 4B, through which the tube axis A3 passes. However, for example, the distance from the inner tube 33B to any one of the upstream flow passages 41-43 may be smaller than the distance to the central flow passage 44 and the downstream flow passages 45-47. This is because, even in this configuration, a refrigerant containing a larger amount of liquid phase can be flowed into any one of the upstream flow passages 41-43, making it easier for the liquid phase refrigerant to evaporate, thereby improving heat exchange efficiency.

[0058] Although not described in the second embodiment, the refrigerant outlet holes 36 formed in the peripheral wall portion 34B of the inner pipe 33B may be formed in the same position and with the same size as in the first embodiment.

[0059] As described above, in the heat exchanger 1B according to the second embodiment, the inner tube 33B is disposed below the lower ends of the heat transfer tubes 4B, and the lower ends of the heat transfer tubes 4B are inclined so that the upstream side of the air flow F is lower. Here, the air flow F refers to the flow of air blown toward the heat transfer tubes 4B. With this configuration, the heat exchanger 1B is closer to the upstream flow paths 41-43 than to the central flow path 44 or the downstream flow paths 45-47. As a result, when the heat exchanger 1B is used as an evaporator and a refrigerant containing both liquid and gas phases flows through it, the inner tube 33B directs the refrigerant with a smaller liquid phase content to the upstream flow path 41, which is more likely to be cooled by the air flow F, thereby facilitating evaporation of the refrigerant. This results in high heat exchange efficiency for the heat transfer tubes 4B in the heat exchanger 1B.

[0060] In the second embodiment, the lower end of the heat transfer tube 4B has a flat inclined surface, but the lower end of the heat transfer tube 4B may have an inclined curved surface that is convex downward or convex upward.

[0061] (Embodiment 3) In embodiment 2, the lower end of the heat transfer tube 4B is inclined, but the inner tube 33B may have a shape having a longitudinal direction and a lateral direction in a cross-sectional view, and the longitudinal direction may be inclined with respect to the horizontal plane.

[0062] In a heat exchanger 1C according to the third embodiment, an inner tube 33C has a non-circular shape having a major axis and a minor axis in a cross-sectional view, and the major axis is inclined. The configuration of the heat exchanger 1C will be described below with reference to Fig. 7. The configuration of the third embodiment that is different from the first and second embodiments will be mainly described.

[0063] FIG. 7 is a cross-sectional view of a header 3C provided in a heat exchanger 1C.

[0064] As shown in FIG. 7 , in the header 3C, a through-hole 35 is formed in the peripheral wall portion 32C of the outer tube 31C at the same position as in the headers 3A and 3B of the first and second embodiments. The lower ends of the heat transfer tubes 4C are inserted into the through-hole 35. As a result, as in the first and second embodiments, the tube axis A3 of the heat transfer tube 4C is aligned with the tube axis A2 of the outer tube 31C in the front-to-rear direction D of the heat exchanger 1C. That is, the tube axis A3 of the heat transfer tube 4C is aligned with the tube axis A2 of the outer tube 31C in the upstream-downstream direction of the air flow F. Furthermore, as in the second embodiment, an inner tube 33C is disposed below the lower ends of the heat transfer tubes 4C, and the tube axis A4 of the inner tube 33C is aligned with the tube axis A3 of the heat transfer tube 4C in the upstream-downstream direction of the air flow F.

[0065] With this positional relationship, when a refrigerant containing both liquid and gas phases flows through the header 3C, the inner tube 33C has an elliptical or elongated cross-sectional shape so that the refrigerant containing a larger amount of liquid flows through the upstream flow path 41 of the heat transfer tube 4C than through the downstream flow path 47. Here, the elongated cross-sectional shape refers to a rectangular shape with semicircular ends. The major axis 39 of the inner tube 33C is inclined in cross-sectional view. Specifically, the major axis 39 of the inner tube 33C is inclined so that the front side is lower. That is, the +Y side of the major axis 39 is inclined toward the +Z side. The air flow F is perpendicular to the tube axis A3 of the heat transfer tube 4C and the tube axis A4 of the inner tube 33C. With this configuration, the inner tube 33C has a shape that rises upstream of the air flow F in a cross-sectional view perpendicular to the tube axis A4. As a result, the inner tube 33C has a shape that approaches the lower end of the heat transfer tube 4C as it moves upstream. Note that, because the inner tube 33C passes the refrigerant through the heat transfer tube 4C above it, the length L2 of the inner tube 33C in the Y direction when the major axis 39 is tilted is shorter than the length L1 of the heat transfer tube 4C in the longitudinal direction when viewed in a flat cross section.

[0066] As a result of this shape of the inner tube 33C, the distance D11 to the upstream flow passage 41, which opens at the lower end of the heat transfer tube 4C, is shorter than the distance D12 to the center of the lower end of the heat transfer tube 4C, through which the tube axis A3 passes. As a result, when a refrigerant containing a mixture of liquid and gas phases flows through the inner tube 33C, the inner tube 33C supplies a refrigerant containing a larger amount of liquid phase to the upstream flow passage 41 than to the central flow passage 44 or the downstream flow passages 45-47. As a result, a refrigerant containing a larger amount of liquid phase is supplied to the upstream flow passage 41, which is more easily cooled by the air flow F, while a refrigerant containing a smaller amount of liquid phase is supplied to the central flow passage 44 or the downstream flow passages 45-47, which are relatively less easily cooled. Similarly, a refrigerant containing a larger amount of liquid phase is also supplied to the upstream flow passages 42 and 43. Due to this effect, the refrigerant evaporates easily in the heat transfer tube 4C, resulting in high heat exchange efficiency.

[0067] Although the refrigerant outlet holes 36 formed in the peripheral wall portion 34C of the inner tube 33C are not shown in Figure 7, the outlet holes 36 should be located in a position where the refrigerant flowing out from the outlet holes 36 does not directly hit the lower end of the heat transfer tube 4C. For example, the outlet holes 36 should be formed in a curved portion of the peripheral wall portion 34C of the inner tube 33C facing downward.

[0068] As described above, in the heat exchanger 1C according to the third embodiment, the inner tube 33C is disposed below the lower end of the heat transfer tube 4C. The inner tube 33C has an elliptical or elongated cross-sectional shape, with the major axis of the elliptical or elongated cross-sectional shape tilted downward toward the upstream side of the air flow F. The air flow F is perpendicular to the tube axis A3 of the heat transfer tube 4C and the tube axis A4 of the inner tube 33C. With this configuration, the inner tube 33C is closer to the upstream flow paths 41-43 than the central flow path 44 or the downstream flow paths 45-47. As a result, the inner tube 33C allows refrigerant containing less liquid phase to flow through the upstream flow paths 41-43, which are more likely to be cooled by the air flow F, thereby facilitating evaporation of the liquid phase refrigerant. In the heat exchanger 1C, the heat transfer tube 4C has high heat exchange efficiency.

[0069] (Variation 2) In the third embodiment, the inner tube 33C has an elliptical or elongated hole shape in cross section, but the shape of the inner tube 33C is not limited to this. The inner tube 33C may have, for example, a semicircular, or D-shaped, cross section. In this case, it is preferable that the straight portion of the D-shaped cross section of the inner tube 33C faces the lower end of the heat transfer tube 4C. The inner tube 33C may also have a flattened cross section. Alternatively, the inner tube 33C may have a quadrangular, for example, rectangular, cross section.

[0070] (Variation 3) In addition, in the third embodiment, the lower end of the heat transfer tube 4C is a horizontal surface, but the lower end of the heat transfer tube 4C may be an inclined surface as described in the second embodiment. In this case, the direction of the inclination may be as described in the second embodiment. This is because even in this embodiment, the liquid phase refrigerant can be easily evaporated, thereby increasing the heat exchange efficiency of the heat transfer tube 4C.

[0071] (Embodiment 4) In Embodiments 1-3, the outer tubes 31A-31C are formed in a rectangular shape with rounded corners when viewed in cross section along the tube axis A2, and the longitudinal direction of the rectangular cross section is oriented in the vertical direction. As a result, the longitudinal direction of the rectangular cross section of the outer tubes 31A-31C is aligned with the extension direction of the tube axes A3 of the heat transfer tubes 4A-4C. However, the outer tubes 31A-31C are not limited to this. The outer tubes 31A-31C may be configured such that the lower ends of the heat transfer tubes 4A-4C are inserted into the peripheral wall portion 32A of the outer tube 31A, and the internal space of the outer tubes 31A-31C is connected to the multiple flow paths 41-47 of the heat transfer tubes 4A-4C. The longitudinal direction of the rectangular cross section of the outer tubes 31A-31C may be any direction as long as this condition is satisfied.

[0072] In the fourth embodiment, the outer tube 31D is oriented such that the longitudinal direction of the rectangular cross section is inclined. The configuration of the heat exchanger 1D will be described below with reference to Fig. 8. The fourth embodiment will be described focusing on the configuration different from the first to third embodiments.

[0073] FIG. 8 is a cross-sectional view of a header 3D provided in a heat exchanger 1D.

[0074] As shown in Fig. 8, the outer tube 31D is formed in a rectangular shape with rounded corners when viewed in cross section along the tube axis A2. The length of the rectangular cross section of the outer tube 31D in the short direction is smaller than the length of the rectangular cross section of the outer tubes 31A-31C of Embodiments 1-3, and the length of the rectangular cross section of the tube 31D in the long direction is greater than the length of the rectangular cross section of the outer tubes 31A-31C of Embodiments 1-3. As a result, the rectangular cross section of the outer tube 31D is longer and thinner than the rectangular cross section of the outer tubes 31A-31C of Embodiments 1-3.

[0075] To connect a heat transfer tube 4D to the longitudinal direction of the rectangular cross section of such an outer tube 31D as described in Embodiments 1-3, the distance D13 between the opposing inner walls W1 and W2 of the peripheral wall portion 32D in the short direction of the rectangular cross section of the outer tube 31D must be greater than the longitudinal length L1 of the flat cross section of the heat transfer tube 4D by at least a tolerance. However, as described above, if the rectangular cross section of the outer tube 31D is elongated, the distance D13 of the outer tube 31D becomes shorter than the length L1 of the heat transfer tube 4D, and the heat transfer tube 4D cannot be connected to the longitudinal direction of the rectangular cross section of the outer tube 31D.

[0076] Furthermore, when the positional relationship described in the first embodiment is applied to the inner tube 33D and the heat transfer tube 4D, as shown in Fig. 3 , the inner tube 33A is located upstream of the heat transfer tube 4A in the air flow F, which may result in the heat transfer tube 4D not being able to be connected to the outer tube 31D in the longitudinal direction of the rectangular cross section. Specifically, if the length L3 obtained by adding the distance D16 from the heat transfer tube 4D to the upstream end of the peripheral wall portion 34D of the inner tube 33D shown in Fig. 8 (i.e., the distance D16 to the +Y end) and the length L1 of the heat transfer tube 4D is greater than the distance D13 of the outer tube 31D, the heat transfer tube 4D cannot be connected to the outer tube 31D in the longitudinal direction of the rectangular cross section.

[0077] Therefore, in the outer tube 31D according to the fourth embodiment, the longitudinal direction of the rectangular cross section is inclined with respect to the vertical direction. That is, the extending direction of the two inner walls W1, W2 of the rectangular cross section of the outer tube 31D is inclined with respect to the vertical direction in which the heat transfer tube 4D extends. The inclination direction is a direction that progresses upward toward the downstream direction of the air flow F. As a result, in the outer tube 31D, the direction D2 in which the two inner walls W1, W2 of the peripheral wall portion 32D face each other is inclined with respect to the longitudinal direction of the flattened cross section of the heat transfer tube 4D. As a result, in the outer tube 31D, the horizontal distance D14 between the two inner walls W1, W2 of the peripheral wall portion 32D is greater than the distance D13. As a result, the horizontal distance D14 between the two inner walls W1, W2 of the outer tube 31D is greater than the longitudinal length L1 of the heat transfer tube 4D in the flat cross-sectional view described above, i.e., the horizontal length L1 of the heat transfer tube 4D. This arrangement of the outer tube 31D makes it possible to connect the heat transfer tube 4D extending vertically from the upper part of the outer tube 31D.

[0078] Furthermore, by inclining the above-mentioned direction D2 of the outer tube 31D relative to the longitudinal direction of the flat cross-sectional shape of the heat transfer tube 4D, the positional relationship described in embodiment 1 is applied to the inner tube 33D and the heat transfer tube 4D, and further, even if the above-mentioned length L3 is greater than the above-mentioned distance D13 of the outer tube 31D, the heat transfer tube 4D extending vertically from the top of the outer tube 31D can be connected.

[0079] Furthermore, the outer tube 31D has through holes 35 extending in the vertical direction formed at its upper end portion in the above-described arrangement. Although not shown in Fig. 8, as described in embodiment 1, the same number of through holes 35 as the heat transfer tubes 4D to be connected are formed, and the shape of each through hole 35 is the same as in embodiment 1. In other words, the through holes 35 formed in the outer tube 31D of embodiment 4 are the same as those in embodiment 1, except for the positions at which they are formed on the outer tube 31D. For this reason, a detailed description of the through holes 35 will be omitted.

[0080] The lower end portions of the heat transfer tubes 4D are inserted into the respective through holes 35. The heat transfer tubes 4D are brazed to the inner walls of the through holes 35. In this way, the lower end portions of the heat transfer tubes 4D are fixed to the outer tube 31D.

[0081] In this way, the longitudinal direction of the outer pipe 31D in a rectangular cross section is inclined relative to the vertical direction. As a result, even though the rectangular cross section is elongated, the outer pipe 31D can be connected to a heat transfer pipe 4D that is thicker than the short side of the rectangular cross section of the outer pipe 31D. This allows the header 3D to use an outer pipe 31D with a small volume relative to the outer diameter of the heat transfer pipe 4D. As a result, the heat exchanger 1D can use less refrigerant.

[0082] Furthermore, a distance D15 from the lower end of the heat transfer tube 4D to the inner wall W1 of the peripheral wall 32D of the outer tube 31D is smaller than a distance D16 from the heat transfer tube 4D to the upstream end of the peripheral wall 34D of the inner tube 33D, i.e., the +Y end. In the first embodiment, the distance D15 must be larger than the distance D16, but in the header 3D of the fourth embodiment, the longitudinal direction of the outer tube 31D, which is a rectangle in cross section, is inclined with respect to the vertical direction, and therefore the header 3D can be assembled without such a restriction.

[0083] As described above, in the heat exchanger 1D according to the fourth embodiment, the outer tube 31D of the header 3D has two parallel inner walls W1, W2 that face each other and are spaced a certain distance D13 apart in a cross section along the tube axis. The extending direction of the two inner walls W1, W2 is inclined with respect to the extending direction of the heat transfer tube 4D. As a result, even if the distance D13 between the two inner walls W1, W2 is smaller than the outer diameter of the heat transfer tube 4D, the heat transfer tube 4D can be attached to the outer tube 31D.

[0084] The inclination direction of the outer tube 31D described above is a direction toward the downstream direction of the air flow F as it goes upward, but it may also be inclined in the opposite direction. This is because, although it is not desirable when the positional relationship described in the first embodiment is applied to the inner tube 33D and the heat transfer tube 4D, when the positional relationship described in the second and third embodiments is applied to the inner tube 33D and the heat transfer tube 4D, the heat transfer tube 4D can be connected to the outer tube 31D.

[0085] In addition, in the third embodiment, the rectangular cross section of the outer tube 31D is longer and thinner than the rectangular cross section of the outer tubes 31A-31C of the first to third embodiments, but the rectangular cross section of the outer tube 31D may be the same shape and size as the rectangular cross section of the outer tubes 31A-31C of the first to third embodiments, or may be thicker than the rectangular cross section of the outer tubes 31A-31C of the first to third embodiments. The inner walls W1 and W2 of the outer tube 31D described above are examples of side walls in the present disclosure.

[0086] The heat exchangers 1A-1D, the device including a heat pump, and the temperature adjustment device according to the embodiments of the present disclosure have been described above, but the heat exchangers 1A-1D, the device including a heat pump, and the temperature adjustment device are not limited to these.

[0087] For example, in the first embodiment, the indoor or outdoor unit of an air conditioner is exemplified as the device into which the heat exchanger 1A is incorporated. However, the heat exchangers 1A-1D are not limited to this. In the second to fourth embodiments, the heat exchangers 1B-1D may also be incorporated into the indoor or outdoor unit of an air conditioner.

[0088] FIG. 9 is a refrigerant circuit diagram of an air conditioner 100 incorporating a heat exchanger 1C according to the third embodiment.

[0089] As shown in FIG. 9 , the air conditioner 100 includes an outdoor unit 110 having a compressor 111 for compressing a refrigerant, a switching valve 112 for switching the refrigerant flow direction, a fan 113, and an expansion valve 114 for expanding the refrigerant, and an indoor unit 120 having a fan 121. A heat exchanger 1C according to the third embodiment may be incorporated into each of the outdoor unit 110 and the indoor unit 120 of the air conditioner 100 configured as described above, and may exchange heat between the air blown by the fan 113 or 121 and the refrigerant flowing therethrough. The heat exchanger 1C may function as an evaporator for evaporating the refrigerant. The heat exchanger 1C may also function as a condenser for condensing the refrigerant by switching the switching valve 112. The heat exchanger 1C may be incorporated into either or both of the outdoor unit 110 and the indoor unit 120. The fans 113 and 121 may also be referred to as fluid transfer devices for transferring fluid.

[0090] Similarly, the heat exchanger 1B according to the second and fourth embodiments may be incorporated into either or both of the outdoor unit 110 and the indoor unit 120 of the air conditioner 100.

[0091] Furthermore, the device in which the heat exchanger 1A-1D is incorporated is not limited to the air conditioner 100. The heat exchanger 1A-1D is applicable to all devices equipped with a heat pump, such as an air conditioner water heater. The heat exchanger 1A-1D may also be incorporated into a temperature control device. For example, the heat exchanger 1A-1D may be incorporated into a chiller.

[0092] In the first and second embodiments, the refrigerant outlet holes 36 of the inner pipes 33A and 33B are formed in the bottom portions of the peripheral walls 34A and 34B. In the third embodiment, it is described that the outlet hole 36 of the inner pipe 33C is preferably formed in the curved portion facing downward of the peripheral wall 34C. However, the position of the outlet hole 36 is not limited to this.

[0093] FIG. 10 is a cross-sectional view of a modified example of the inner tube 33A included in the header 3A provided in the heat exchanger 1A according to the first embodiment.

[0094] 10 , the inner pipe 33A may have an outflow hole 36 formed below and forward of the peripheral wall 34A, i.e., below and upstream of the air flow F. The outflow hole 36 is preferably located at a position on the peripheral wall 34A of the inner pipe 33A such that the lower end of the heat transfer tube 4A is not located at the extension of a line L connecting the center of the opening of the outflow hole 36 to the pipe axis A4 of the inner pipe 33A, and the inner wall surface of the peripheral wall 32A of the outer pipe 31A is located there. If the outflow hole 36 is located at such a position, the refrigerant can flow to the lower end of the heat transfer tube 4A in an appropriately mixed state of liquid and gas phases.

[0095] Here, the line L connecting the opening center of the outflow hole 36 and the pipe axis A4 of the inner pipe 33A may extend within an angle range of 200° centered on the pipe axis A4 of the inner pipe 33A. With such a line L, when the refrigerant is caused to flow out from the outflow hole 36, the refrigerant will not flow to the lower end of the heat transfer pipe 4A, but to the inner wall surface portion of the peripheral wall portion 32A of the outer pipe 31A, and as a result, the refrigerant can flow to the lower end of the heat transfer pipe 4A in a state where the liquid phase and the gas phase are appropriately mixed.

[0096] For example, when the angle θ is set to 0° directly below the tube axis A4 of the inner tube 33A and the angle θ increases clockwise around the tube axis A4 in FIG. 10, that is, when the header 3A is viewed from the +X side and the tube axis A4 is rotated clockwise, the outflow holes 36 may be formed in a location of the peripheral wall portion 34A of the inner tube 33A where the angle θ is 70 to 110°.

[0097] 1, the circumferential wall of the inner pipe (not shown) of the header 2A may also have refrigerant outlet holes formed at the same locations as those of the circumferential wall 34A of the inner pipe 33A of the header 3A. That is, the refrigerant may flow in the same direction from the inner pipe (not shown) of the header 2A and the inner pipe 33A of the header 3A. In addition, although the first embodiment describes that the header 2A has an inner pipe (not shown) inside the outer pipe 21A, the header 2A may have a single-pipe structure with only the outer pipe 21A without having an inner pipe.

[0098] In embodiments 1-4, the heat transfer tubes 4A-4D are so-called flat tubes that are flat in cross section. However, the heat transfer tubes 4A-4D are not limited to this. The heat transfer tubes 4A-4D may have a plurality of flow paths 41-47 extending vertically and through which a first fluid, such as a refrigerant, having a mixture of liquid and gas phases, flows. In this case, the heat transfer tubes 4A-4D may exchange heat between a second fluid, such as air, flowing outside and the first fluid. Here, the plurality of flow paths 41-47 may be at least two or more. The cross-sectional shape of the heat transfer tubes 4A-4D may be any shape as long as it satisfies this condition.

[0099] For example, the heat transfer tubes 4A-4D may be circular tubes having a plurality of flow paths 41-47 extending in the axial direction and oriented vertically. In this case, the plurality of flow paths 41-47 may have a honeycomb structure in which regular hexagonal flow paths 41-47 are arranged.

[0100] In embodiments 1-4, the outer tubes 31A-31D have a rectangular cylindrical shape with rounded corners. However, the outer tubes 31A-31D are not limited to this. The outer tubes 31A-31D may have any shape as long as the lower ends of the heat transfer tubes 4A-4D are inserted into the peripheral wall portions 32A-32D and the internal space is connected to the multiple flow paths 41-47 of the heat transfer tubes 4A-4D. Therefore, the shape of the outer tubes 31A-31D is arbitrary as long as this condition is satisfied. For example, the outer tubes 31A-31D may be circular or rectangular. Furthermore, the outer tubes 31A-31D may have an elliptical or elongated cross-sectional shape.

[0101] In embodiments 1-4, the heat transfer tubes 4A-4D extend in the vertical direction. This is the extension direction of the heat transfer tubes 4A-4D when the heat exchanger 1A-1D is incorporated into the air conditioner 100 and the air conditioner 100 is installed at a location where the heat exchanger 1A-1D is used. The positional relationship described above is the positional relationship when the heat exchanger 1A-1D is incorporated into a device equipped with a heat pump, such as the air conditioner 100, or a temperature control device. The heat exchanger 1A-1D only needs to satisfy the positional relationship described above when these devices are installed in the usage environment. Note that the vertical direction may be a direction vertical enough to allow a fluid, such as a refrigerant, that contains a mixture of liquid and gas phases inside the heat transfer tubes 4A-4D to move vertically.

[0102] The present disclosure allows various embodiments and modifications without departing from the broad spirit and scope of the present disclosure. Furthermore, the above-described embodiments are intended to explain the present disclosure and do not limit the scope of the present disclosure. That is, the scope of the present disclosure is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and within the meaning of the disclosure equivalent thereto are considered to be within the scope of the present disclosure.

[0103] This application is based on Japanese Patent Application No. 2024-124297, filed on July 31, 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-124297 are incorporated herein by reference.

[0104] 1A-1D heat exchanger, 2A, 3A-3D header, 4A-4D heat transfer tube, 5 fin, 6, 7 connection portion, 21A outer tube, 22A peripheral wall portion, 31A-31D outer tube, 32A-32D peripheral wall portion, 33A-33D inner tube, 34A-34D peripheral wall portion, 35 through hole, 36 outflow hole, 37 partition plate, 38 through hole, 39 long axis, 41-47 flow path, 100 air conditioner, 110 outdoor unit, 111 compressor, 112 switching valve, 113 fan, 114 expansion valve, 120 indoor unit, 121 fan, 200 angle range, A1-A4 tube axis, C1 center line, C2 center, D front-rear direction, D1, D2 direction, D11-D16 Distance, L line, L1-L3 length, W1, W2 inner wall, θ angle.

Claims

1. A heat exchanger comprising: heat transfer tubes extending in the vertical direction, having a plurality of flow paths through which a first fluid, which is a mixture of liquid and gas phases, flows, and which exchange heat between the first fluid and a second fluid flowing outside; an outer tube whose lower end portion of the heat transfer tube is inserted into a first peripheral wall portion and whose internal space is connected to the plurality of flow paths; and a header having an inner tube located in the internal space below the lower end portion of the heat transfer tube and which supplies the first fluid to the internal space, and which flows the first fluid to the lower end portion of the heat transfer tube; wherein the inner tube is located at a position closer to an upstream flow path that is located upstream of the flow of the second fluid than the axis of the heat transfer tube, among the plurality of flow paths opening at the lower end portion of the heat transfer tube.

2. A heat exchanger according to claim 1, wherein the axis of the inner tube is disposed upstream of the axis of the heat transfer tube in the flow of the second fluid.

3. A heat exchanger as described in claim 2, wherein the pipe axis of the heat transfer pipe and the pipe axis of the outer pipe are located at the same position in the upstream / downstream direction of the second fluid, and the pipe axis of the inner pipe is located upstream of the pipe axis of the outer pipe in the flow of the second fluid.

4. A heat exchanger as described in claim 2, wherein the pipe axis of the heat transfer pipe is located downstream of the pipe axis of the outer pipe in the flow of the second fluid, and the pipe axis of the inner pipe and the pipe axis of the outer pipe are located at the same position in the upstream and downstream directions of the second fluid.

5. A heat exchanger according to any one of claims 1 to 4, wherein the lower end of the heat transfer tube is inclined in a direction in which the upstream side of the flow of the second fluid is lower.

6. A heat exchanger according to any one of claims 1 to 5, wherein the outer tube and the inner tube extend in the same horizontal direction, the second fluid flows in a direction perpendicular to the extension direction of the heat transfer tubes and to the outer tube and the inner tube, and the inner tube has an elliptical or elongated hole shape with its major axis tilted in a direction that is lower on the upstream side of the flow of the second fluid in a cross-sectional view of the tube.

7. A heat exchanger according to any one of claims 1 to 6, wherein the inner tube has an outlet hole in a second peripheral wall portion through which the first fluid flowing inside the inner tube flows out into the internal space of the outer tube.

8. A heat exchanger as described in claim 7, wherein the outlet hole is located at a position on the second peripheral wall portion where the lower end of the heat transfer tube is not located on the extension of a line connecting the center of the opening of the outlet hole and the axis of the inner tube, and where the inner wall surface of the first peripheral wall portion of the outer tube is located.

9. The heat exchanger according to any one of claims 1 to 8, further comprising a fan for causing the second fluid to flow from the upstream side to the downstream side.

10. A heat exchanger according to any one of claims 1 to 9, wherein the heat transfer tubes are flat tubes that are flat in cross-sectional view, the plurality of flow paths are arranged in the longitudinal direction of the flat tubes in cross-sectional view, and the second fluid is caused to flow in the longitudinal direction.

11. A heat exchanger according to any one of claims 1 to 10, wherein the outer tube has two side walls that are parallel to each other and face each other at a fixed distance apart when viewed in cross section along the tube axis, and the extending direction of the two side walls is inclined with respect to the extending direction of the heat transfer tube.

12. An apparatus comprising a heat pump, comprising: a heat exchanger according to any one of claims 1 to 11; a compressor that compresses the first fluid; a condenser that condenses the first fluid compressed by the compressor; and an expansion valve that expands the first fluid condensed by the condenser, wherein the heat exchanger is an evaporator that evaporates the first fluid expanded by the expansion valve.

13. A temperature control device comprising a heat exchanger according to any one of claims 1 to 11.

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