Heat exchanger and outdoor unit of air conditioner

Abstract

To improve an amount of heat exchange between a refrigerant and air.SOLUTION: An outdoor heat exchanger includes a plurality of heat transfer tubes disposed in a ventilation space through which air flows, and an expansion valve side header 21 to which the plurality of heat transfer tubes are joined. A plurality of flow paths arranged in a ventilation direction 20 in which air flows are formed inside each of the plurality of heat transfer tubes. A circulation flow path 45 into which a low-pressure gas-liquid two phase refrigerant flows, a plurality of insertion spaces 46 into which one end of each of the plurality of heat transfer tubes is respectively inserted, and a plurality of introduction holes 62 that cause the circulation flow path 45 to communicate with the plurality of insertion spaces 46 are formed inside the expansion valve side header 21. The plurality of introduction holes 62 are formed on the leeward side so that the low-pressure gas-liquid two phase refrigerant flowing into each of the plurality of insertion spaces 46 flows from the leeward side to the windward side in the ventilation direction 20.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a heat exchanger and an outdoor unit of an air conditioner. [Background technology]

[0002] A heat exchanger is known that includes a plurality of heat transfer tubes arranged in a ventilation space through which air flows, and a header that divides a gas-liquid two-phase refrigerant into the plurality of heat transfer tubes (Patent Document 1). In such a heat exchanger, by dividing the gas-liquid two-phase refrigerant circulating in a circulation flow path formed inside the header into the plurality of heat transfer tubes, it is possible to prevent the gas-liquid two-phase refrigerant from flowing unevenly into some of the plurality of heat transfer tubes, and to prevent a decrease in the amount of heat exchanged between the gas-liquid two-phase refrigerant and air. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-8974 Summary of the Invention [Problem to be solved by the invention]

[0004] Inside the heat transfer tube, multiple refrigerant flow paths are formed, aligned in the direction of air flow through the ventilation space. The air flowing through the ventilation space exchanges heat with the refrigerant flowing through the multiple refrigerant flow paths, and its temperature changes as it flows from the upwind side to the downwind side. At this time, the temperature difference between the refrigerant flowing through the downwind flow path and the downwind air is smaller than the temperature difference between the refrigerant flowing through the upwind flow path and the upwind air. When the heat exchanger functions as an evaporator, the amount of heat exchange is increased by flowing more of the liquid refrigerant to be evaporated to the upwind side, where the temperature difference with the air is greater.

[0005] In the header of Patent Document 1, the refrigerant is introduced from the circulation flow path to the upwind side of the insertion space into which each heat transfer tube is inserted. In the insertion space, the refrigerant flows from the upwind side to the downwind side and is divided into each refrigerant flow path, but at this time, liquid refrigerant, which has a higher specific gravity than gas refrigerant, is biased to the downwind side, and more liquid refrigerant flows in the downwind refrigerant flow path, resulting in a problem of a decrease in the amount of heat exchanged between the refrigerant and air.

[0006] The disclosed technology has been made in consideration of the above points, and aims to provide a heat exchanger and an outdoor unit of an air conditioner that improve the amount of heat exchange between a refrigerant and air. [Means for solving the problem]

[0007] A heat exchanger according to one aspect of the present disclosure comprises a plurality of heat transfer tubes arranged in a ventilation space through which air flows, and a header to which the plurality of heat transfer tubes are joined, wherein a plurality of flow paths are formed inside each of the plurality of heat transfer tubes and aligned in the ventilation direction through which the air flows, and wherein the header is formed with a branch space into which refrigerant flows, a plurality of insertion spaces into which one ends of the plurality of heat transfer tubes are respectively inserted, and a plurality of introduction flow paths that connect the branch space to each of the plurality of insertion spaces, and the plurality of introduction flow paths are formed so that refrigerant flowing into each insertion space of the plurality of insertion spaces flows from the downwind side to the upwind side in the ventilation direction. [Effects of the Invention]

[0008] The disclosed heat exchanger and outdoor unit of an air conditioner can improve the amount of heat exchange between a refrigerant and air. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a refrigerant circuit diagram of an air conditioner provided with a heat exchanger according to an embodiment. [Figure 2] FIG. 2 is a front view showing the heat exchanger of the embodiment. [Figure 3] FIG. 3 is a top view showing the heat exchanger of the embodiment. [Figure 4]FIG. 4 is a cross-sectional view showing a heat transfer tube of a heat exchanger according to an embodiment. [Figure 5] FIG. 5 is an exploded perspective view showing the internal structure of the expansion valve side header of the heat exchanger of the embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing one of the plurality of insertion spaces. [Figure 7] FIG. 7 is a front view of the plate-shaped member for introduction holes as seen from the heat transfer tube side plate-shaped member side. [Figure 8] FIG. 8 is a perspective view showing a plurality of insertion space plate-shaped members. [Figure 9] FIG. 9 is a perspective view showing other plural insertion space plate-shaped members. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a heat exchanger according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the following description does not limit the technology of the present disclosure. In addition, in the following description, the same components are given the same reference numerals, and duplicated descriptions will be omitted. [Example]

[0011] The heat exchanger of the embodiment is an outdoor heat exchanger 1 provided in an air conditioner 10, as shown in Fig. 1. Fig. 1 is a refrigerant circuit diagram of the air conditioner 10 provided with the outdoor heat exchanger 1 of the embodiment. The air conditioner 10 includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 is installed outdoors. The indoor unit 3 is installed inside an indoor room.

[0012] The air conditioner 10 includes a refrigerant circuit 4. The refrigerant circuit 4 includes a compressor 5, a four-way valve 6, an indoor heat exchanger 7, an expansion valve 8, and an outdoor heat exchanger 1. The compressor 5 is disposed inside the outdoor unit 2. A suction pipe 11 and a discharge pipe 12 are connected to the compressor 5. The compressor 5 compresses the refrigerant sucked through the suction pipe 11 and discharges the compressed refrigerant to the discharge pipe 12.

[0013] The four-way valve 6 is disposed inside the outdoor unit 2. The four-way valve 6 is connected to a suction pipe 11 and a discharge pipe 12, is connected to the outdoor heat exchanger 1 via a refrigerant pipe 14, and is connected to the indoor heat exchanger 7 via a refrigerant pipe 15. The four-way valve 6 switches the refrigerant circuit 4 between a heating cycle and a cooling cycle. When the refrigerant circuit 4 is switched to the heating cycle, the discharge pipe 12 is connected to the indoor heat exchanger 7 via the four-way valve 6, and the suction pipe 11 is connected to the outdoor heat exchanger 1 via the four-way valve 6. When the refrigerant circuit 4 is switched to the cooling cycle, the discharge pipe 12 is connected to the outdoor heat exchanger 1 via the four-way valve 6, and the suction pipe 11 is connected to the indoor heat exchanger 7 via the four-way valve 6.

[0014] The indoor heat exchanger 7 is disposed inside the indoor unit 3. One refrigerant inlet and outlet of the indoor heat exchanger 7 is connected to the expansion valve 8 via refrigerant piping 16, and the other refrigerant inlet and outlet is connected to the four-way valve 6 via refrigerant piping 15 as described above. By rotating a fan (not shown), the indoor unit 3 passes air from the room in which the indoor unit 3 is installed through the indoor heat exchanger 7 to exchange heat with the refrigerant, and blows the air that has exchanged heat with the refrigerant into the room. The expansion valve 8 is disposed inside the outdoor unit 2. The expansion valve 8 is connected to the outdoor heat exchanger 1 via refrigerant piping 17. The air conditioner 10 adjusts the opening of the expansion valve 8 to adjust the amount of refrigerant flowing through the indoor heat exchanger 7 according to the air-conditioning capacity required by the indoor unit 3.

[0015] The outdoor unit 2 is equipped with an outdoor fan 18 (blower section). The outdoor fan 18 is disposed inside the outdoor unit 2. The outdoor fan 18 blows outdoor air so that the air flows into a ventilation space 19 inside the outdoor unit 2. A ventilation direction 20 in which the air flows due to the outdoor fan 18 is approximately horizontal when the outdoor unit 2 is properly installed. The outdoor heat exchanger 1 is disposed inside the outdoor unit 2 and fixed to the outdoor unit 2 so that the air flowing through the ventilation space 19 passes through the outdoor heat exchanger 1. The outdoor heat exchanger 1 exchanges heat between the refrigerant flowing through the outdoor heat exchanger 1 and the air flowing through the ventilation space 19.

[0016] 2 is a front view showing the outdoor heat exchanger 1 of the embodiment. The outdoor heat exchanger 1 includes an expansion valve side header 21 (header), a compressor side header 22, a plurality of heat transfer tubes 23, and a plurality of fins 24. The expansion valve side header 21 is formed in a cylindrical shape, and is disposed so that a header longitudinal direction 25 (longitudinal direction) which is the extension direction of the expansion valve side header 21 is perpendicular to the bottom surface of the outdoor unit 2 (not shown), and is fixed to the outdoor unit 2. A refrigerant pipe 17 is connected to the expansion valve side header 21, and an expansion valve 8 is connected via the refrigerant pipe 17.

[0017] The compressor side header 22 is formed in a columnar shape, is arranged so that the extension direction of the compressor side header 22 is parallel to the header longitudinal direction 25, and is fixed to the outdoor unit 2. A flow dividing space is formed inside the compressor side header 22. The refrigerant piping 14 is connected to the compressor side header 22 so that the four-way valve 6 is connected to the flow dividing space via the refrigerant piping 14.

[0018] 2 and 3 , the plurality of heat transfer tubes 23 are arranged so that a heat transfer tube longitudinal direction 26, which is the extension direction of the heat transfer tubes, is perpendicular to the header longitudinal direction 25, and are lined up at equal intervals in the header longitudinal direction 25. One end of each of the plurality of heat transfer tubes 23 is connected to the expansion valve side header 21. The other end of each of the plurality of heat transfer tubes 23 is connected to the compressor side header 22. The plurality of heat transfer tubes 23 are fixed to the expansion valve side header 21 and the compressor side header 22 by connecting both ends of the plurality of heat transfer tubes 23 to the expansion valve side header 21 and the compressor side header 22, respectively, and the outdoor heat exchanger 1 is fixed to the outdoor unit 2 by the expansion valve side header 21 and the compressor side header 22.

[0019] Each of the fins 24 is formed in a flat plate shape. Fig. 3 is a top view showing the outdoor heat exchanger 1 of the embodiment. The fins 24 are arranged perpendicular to the heat transfer tube longitudinal direction 26 (parallel to the ventilation direction 20) and are aligned at equal intervals in the heat transfer tube longitudinal direction 26. The fins 24 are fixed to the heat transfer tubes 23 so as to be thermally connected to them.

[0020] As shown in Fig. 4, each of the multiple heat transfer tubes 23 is formed in a flat shape. Fig. 4 is a cross-sectional view of the heat transfer tube 23 of the outdoor heat exchanger 1 of the embodiment. A multiple number of flow paths 33 are formed inside the heat transfer tube 23 and are aligned in the ventilation direction 20. The multiple flow paths 33 include a multiple number of upwind-side flow paths 34 and a multiple number of downwind-side flow paths 35. The multiple upwind-side flow paths 34 are arranged upwind of a center 36 of the heat transfer tube 23 in the ventilation direction 20. The multiple downwind-side flow paths 35 are arranged downwind of the center 36 in the ventilation direction 20 and downwind of the multiple upwind-side flow paths 34 in the ventilation direction 20. The multiple flow paths 33 are connected to the flow division space of the compressor-side header 22 by connecting the other ends of the multiple heat transfer tubes 23 to the compressor-side header 22.

[0021] 5 is an exploded perspective view showing the internal structure of the expansion valve side header 21 of the outdoor heat exchanger 1 of the embodiment. The expansion valve side header 21 includes a plurality of plate-like members 71 to 76 that are all rectangular in shape. The plurality of plate-like members 71 to 76 are stacked and joined to one another, with the stacking direction being approximately parallel to the heat transfer tube longitudinal direction 26. The plurality of plate-like members 71 to 76 include a refrigerant piping side plate-like member 71, a heat transfer tube side plate-like member 72, a plurality of circulation flow path plate-like members 73, a plurality of return flow path plate-like members 74, a plurality of insertion space plate-like members 75, and an introduction hole plate-like member 76. 5, the plate-like members are stacked in the following order from upstream to downstream in the introduction direction 48 (the direction in which refrigerant flows in the outdoor heat exchanger 1 when the outdoor heat exchanger 1 functions as an evaporator): refrigerant piping side plate-like member 71, multiple return flow path plate-like members 74, multiple circulation flow path plate-like members 73, introduction hole plate-like member 76, multiple insertion space plate-like members 75, and heat transfer tube side plate-like member 72. In the following description, when referring to the multiple return flow path plate-like members 74, the multiple circulation flow path plate-like members 73, and the multiple insertion space plate-like members 75 formed by the multiple plate-like members 71 to 76, the word "multiple" may be omitted when referring to a combination of the multiple plate-like members 71 to 76 joined together.

[0022] The circulation flow path plate-shaped members 73 are formed to have the same shape (in this embodiment, the two circulation flow path plate-shaped members 73 shown in FIG. 5 have the same shape). The return flow path plate-shaped member 74 is disposed between the circulation flow path plate-shaped member 73 and the refrigerant pipe side plate-shaped member 71. The insertion space plate-shaped members 75 are formed to have the same shape (in this embodiment, the three insertion space plate-shaped members 75 shown in FIG. 5 have the same shape). The insertion space plate-shaped member 75 is disposed between the introduction hole plate-shaped member 76 and the heat transfer tube side plate-shaped member 72. The introduction hole plate-shaped member 76 is disposed between the circulation flow path plate-shaped member 73 and the insertion space plate-shaped member 75.

[0023] In the following description, the end face of the lower end of the expansion valve side header 21 in the header longitudinal direction 25 will be referred to as one end 41, and the end face of the upper end of the expansion valve side header 21 opposite the one end 41 will be referred to as the other end 42.

[0024] The expansion valve-side header 21 is formed by stacking the above-described plate-like members in the order of refrigerant pipe-side plate-like member 71, return flow path plate-like member 74, circulation flow path plate-like member 73, introduction hole plate-like member 76, insertion space plate-like member 75, and heat transfer tube-side plate-like member 72 from upstream to downstream in the introduction direction 48, thereby forming an inflow space 43, a refrigerant pipe through-hole 44, a circulation flow path 45 (division space), an inlet 61, a plurality of insertion spaces 46, a plurality of heat transfer tube through-holes 47, and a plurality of introduction holes 62 (a plurality of introduction flow paths) inside the expansion valve-side header 21. The inflow space 43 is located in a region close to the one end 41 inside the expansion valve-side header 21. The inflow space 43 is formed from inflow space holes 83 formed in each circulation flow path plate-like member 73.

[0025] The refrigerant piping through-hole 44 is formed by a refrigerant piping hole 77 formed in the refrigerant piping side plate-like member 71 and a refrigerant piping hole 78 formed in the return flow path plate-like member 74. Therefore, the refrigerant piping through-hole 44 is disposed on the upstream side of the inflow space 43 in the introducing direction 48. The refrigerant piping 17 passes through the refrigerant piping through-hole 44, and the inflow space 43 is connected to the expansion valve 8 via the refrigerant piping 17.

[0026] The circulation flow path 45 is formed by a circulation flow path plate-shaped member 73 and a turn-back flow path plate-shaped member 74, and includes a first flow path 57, a second flow path 58, a first turn-back flow path 51, and a second turn-back flow path 52. The first flow path 57 is formed from first flow path holes 84 formed in a plurality of circulation flow path plate-shaped members 73. The second flow path 58 is formed from second flow path holes 85 formed in a plurality of circulation flow path plate-shaped members 73. Therefore, the first flow path 57 and the second flow path 58 are aligned with the inflow space 43 in the header longitudinal direction 25 and are located above the inflow space 43. The first flow path 57 is formed along a straight line parallel to the header longitudinal direction 25. The second flow path 58 is located upwind of the first flow path 57 in the ventilation direction 20 and is formed along another straight line parallel to the header longitudinal direction 25.

[0027] The first turn flow path 51 is formed by first turn flow path holes 81 formed in the plurality of turn flow path plate-shaped members 74, and turns the refrigerant flowing through the first flow path 57 back to the second flow path 58. That is, the direction in which the refrigerant flows through the first turn flow path 51 is perpendicular to the introduction direction 48 and parallel to the ventilation direction 20. The second turn flow path 52 is formed by second turn flow path holes 82 formed in the plurality of turn flow path plate-shaped members 74, and turns the refrigerant flowing through the second flow path 58 back to the first flow path 57. That is, the direction in which the refrigerant flows through the second turn flow path 52 is perpendicular to the introduction direction 48 and parallel to the ventilation direction 20. Therefore, the first turn flow path 51 and the second turn flow path 52 are aligned in the header longitudinal direction 25 and are disposed upstream of the first flow path 57 and the second flow path 58 in the introduction direction 48. The first turning flow path 51 is formed in a region close to the other end 42, and is connected to the upper end of the first flow path 57 and the upper end of the second flow path 58. The second turning flow path 52 is formed in a lower region close to the one end 41, and is connected to the lower end of the first flow path 57 and the lower end of the second flow path 58.

[0028] The width dimension of the first turn flow path 51 in the airflow direction 20 is equal to the width of the second turn flow path 52 in the airflow direction 20. Furthermore, the width of the first turn flow path 51 in the introduction direction 48 is equal to the width of the second turn flow path 52 in the introduction direction 48 because the first turn flow path 51 and the second turn flow path 52 are formed in multiple turn flow path plate-shaped members 74. On the other hand, the width dimension of the first turn flow path 51 in the header longitudinal direction 25 is larger than the width of the second turn flow path 52 in the header longitudinal direction 25. Therefore, the area of ​​the first turn flow path hole 81 is larger than the area of ​​the second turn flow path hole 82 so that the flow path cross-sectional area of ​​the first turn flow path 51 is larger than the flow path cross-sectional area of ​​the second turn flow path 52. In other words, the flow path cross-sectional area of ​​the first turn flow path 51 when viewed from the introduction direction 48 is larger than the flow path cross-sectional area of ​​the second turn flow path 52 when viewed from the introduction direction 48.

[0029] The inlet 61 is formed from an inlet hole 86 formed in the plurality of circulation flow path plate-shaped members 73. Therefore, the inlet 61 is disposed between the inflow space 43 and the first flow path 57, and the refrigerant that has flowed into the inlet 61 flows into the first flow path 57 via the inlet 61.

[0030] The multiple insertion spaces 46 are formed by communicating multiple insertion space holes 87 formed in the multiple insertion space plate-shaped members 75. Therefore, the multiple insertion spaces 46 are arranged downstream in the introduction direction 48 as seen from the area where the inflow space 43 and the circulation flow path 45 are arranged, and are lined up in the header longitudinal direction 25. The multiple insertion spaces 46 have approximately the same volume.

[0031] The plurality of introduction holes 62 are formed in the introduction hole plate member 76. The plurality of introduction holes 62 are aligned in the header longitudinal direction 25 and are respectively disposed between the first flow passage 57 and the plurality of insertion spaces 46. The plurality of insertion spaces 46 and the first flow passage 57 are connected by the plurality of introduction holes 62.

[0032] The plurality of heat transfer tube through holes 47 are formed in the heat transfer tube side plate member 72. The plurality of heat transfer tube through holes 47 are arranged downstream in the introduction direction 48 as seen from the plurality of insertion spaces 46, and are aligned at equal intervals in the header longitudinal direction 25. The plurality of insertion spaces 46 are connected to each heat transfer tube 23 via the plurality of heat transfer tube through holes 47, respectively.

[0033] The expansion valve-side header 21 has a lowest-stage insertion space 53, a lowest-stage introduction hole 64, and a lowest-stage heat transfer tube through-hole 54. The lowest-stage insertion space 53 is formed below the multiple insertion spaces 46 in the header longitudinal direction 25, and is arranged downstream of the inflow space 43 in the introduction direction 48. The lowest-stage introduction hole 64 is formed below the multiple introduction holes 62 in the header longitudinal direction 25, and is arranged between the inflow space 43 and the lowest-stage insertion space 53 in the introduction direction 48. The lowest-stage insertion space 53 and the inflow space 43 are in communication via the lowest-stage introduction hole 64. The lowest-stage heat transfer tube through-hole 54 is formed below the multiple heat transfer tube through-holes 47 in the header longitudinal direction 25, and is arranged downstream of the lowest-stage insertion space 53 in the introduction direction 48. The lowest stage insertion space 53 communicates with the heat transfer tube 23 connected to the lowest stage heat transfer tube through hole 54 .

[0034] The surfaces of each of the multiple plate-like members 71-76 are coated with brazing material, and the plate-like members are stacked and heated in a furnace, melting the brazing material and joining them together to form the expansion valve side header 21. In this case, when it is desired to change the cross-sectional area of ​​a portion of the refrigerant flow path of the expansion valve side header 21 in accordance with a change in the type of refrigerant used, this can be accommodated by simply changing the plate-like member that covers that portion. This improves the design flexibility of the outdoor heat exchanger 1, including the expansion valve side header 21, and reduces development and manufacturing costs.

[0035] The lowest heat transfer tube, which is located at the lowest position among the plurality of heat transfer tubes 23, passes through the lowest heat transfer tube through-hole 54 and is joined to the expansion valve side header 21. The remaining heat transfer tubes other than the lowest heat transfer tube among the plurality of heat transfer tubes 23 pass through the plurality of heat transfer tube through-holes 47, respectively, and are joined to the expansion valve side header 21.

[0036] FIG. 6 shows a state in which one heat transfer tube 231 of the heat transfer tubes 23 is inserted into one insertion space 461 of the multiple insertion spaces 46 via a heat transfer tube through-hole 471. As shown in FIG. 6, the end portion 231a of the heat transfer tube 231 that passes through the heat transfer tube through-hole 471 is disposed in the insertion space 461, and the multiple flow paths 33 of the heat transfer tube 231 open toward the insertion space 461. By disposing the end portion 231a in the insertion space 461 in this manner, the multiple flow paths 33 formed inside the heat transfer tube 231 communicate with the insertion space 461. The insertion space 461 includes an upwind region 462 and a downwind region 463. The upwind region 462 is on the windward side of the insertion space 461 in the ventilation direction 20, and is a portion facing the upwind flow path 34 shown in FIG. 4 among the multiple flow paths 33. The leeward region 463 is on the leeward side of the insertion space 461 in the ventilation direction 20, and is a portion of the plurality of flow paths 33 facing the leeward flow path 35 shown in FIG. 4 . The leeward region 463 is connected to the first flow path 57 via one of the plurality of introduction holes 62, an inlet hole 621. In this embodiment, the upwind region 462 and the downwind region 463 are defined with the center of the insertion space 461 in the ventilation direction 20 as a boundary. The boundary may be moved in the ventilation direction 20 depending on the degree of bias of the liquid refrigerant toward the upwind side. In this case, the heat transfer tube 231 is formed so that the upwind flow path 34 opens to the upwind region 462, and so that the downwind flow path 35 opens to the downwind region 463.

[0037] The lowest-stage insertion space 53 is formed in the same manner as the insertion space 461. That is, the end of the lowest-stage heat transfer tube that penetrates the lowest-stage heat transfer tube through-hole 54 among the multiple heat transfer tubes 23 is disposed in the lowest-stage insertion space 53, and the multiple flow paths 33 of the lowest-stage heat transfer tube open toward the lowest-stage insertion space 53. By disposing the end of the lowest-stage heat transfer tube in the lowest-stage insertion space 53 in this manner, the multiple flow paths 33 formed inside the lowest-stage heat transfer tube communicate with the lowest-stage insertion space 53. The lowest-stage insertion space 53 includes an upwind region and a downwind region. The upwind region of the lowest-stage insertion space 53 is the windward side of the lowest-stage insertion space 53 in the ventilation direction 20, and is the location where the upwind flow paths 34 of the multiple flow paths 33 of the lowest-stage heat transfer tube face. The windward region of the lowest stage insertion space 53 is the windward side of the lowest stage insertion space 53 in the ventilation direction 20, and is the location where the leeward flow passages 35 of the multiple flow passages 33 of the lowest stage heat transfer tube face. The leeward region of the lowest stage insertion space 53 communicates with the inflow space 43 via the lowest stage introduction hole 64.

[0038] 7 is a front view of an introduction hole plate member 76 that constitutes part of the expansion valve side header 21, as viewed from the heat transfer tube side plate member 72 side in the introduction direction 48. The flow path cross-sectional area of ​​each of the multiple introduction holes 62 increases as the introduction hole is located lower in the header longitudinal direction 25. For example, when the uppermost introduction hole of the multiple introduction holes 62 is designated as a first introduction hole 62a and the introduction hole located lower than the first introduction hole 62a is designated as a second introduction hole 62b, the flow path cross-sectional area of ​​the first introduction hole 62a is smaller than the flow path cross-sectional area of ​​the second introduction hole 62b.

[0039] The air conditioner 10 can perform heating and cooling operations as described below. [Cooling operation] When the user operates the air conditioner 10 to perform cooling operation, the four-way valve 6 is switched so that the refrigerant circuit 4 is in the cooling cycle. The compressor 5 compresses the low-pressure gas-phase refrigerant drawn in from the four-way valve 6 through the suction pipe 11. The low-pressure gas-phase refrigerant is compressed by the compressor 5 to become high-pressure gas-phase refrigerant, which is then discharged to the discharge pipe 12. The high-pressure gas-phase refrigerant discharged to the discharge pipe 12 flows into the outdoor heat exchanger 1 via the four-way valve 6 and the refrigerant piping 14.

[0040] The high-pressure gas-phase refrigerant that flows into the outdoor heat exchanger 1 flows into the compressor-side header 22 and is diverted to the multiple heat transfer tubes 23. The high-pressure gas-phase refrigerant diverted to the multiple heat transfer tubes 23 exchanges heat with air flowing through the ventilation space 19 due to the rotation of the outdoor fan 18, condensing and becoming a supercooled high-pressure liquid-phase refrigerant. In other words, the outdoor heat exchanger 1 functions as a condenser when the air conditioner 10 performs cooling operation. The high-pressure liquid-phase refrigerant flows out of the multiple heat transfer tubes 23 and into the multiple insertion spaces 46 and the lowest-stage insertion space 53 of the expansion valve-side header 21. The high-pressure liquid-phase refrigerant that flows into the multiple insertion spaces 46 flows into the first flow path 57 of the circulation flow path 45 through the multiple introduction holes 62 and into the inlet space 43 through the inlet 61. The high-pressure liquid-phase refrigerant that flows into the lowest-stage insertion space 53 flows into the inlet space 43 through the lowest-stage introduction hole 64. The high-pressure liquid-phase refrigerant that has flowed into the inflow space 43 flows into the refrigerant pipe 17 and then flows into the expansion valve 8 through the refrigerant pipe 17.

[0041] The high-pressure liquid-phase refrigerant that flows into the expansion valve 8 is decompressed to become a low-pressure two-phase gas-liquid refrigerant, which then flows out of the expansion valve 8, through the refrigerant pipe 16, and into the indoor heat exchanger 7. The low-pressure two-phase gas-liquid refrigerant that flows into the indoor heat exchanger 7 exchanges heat with room air drawn into the indoor unit 3 by the rotation of the indoor fan (not shown). As a result, the air passing through the indoor heat exchanger 7 is cooled by the low-pressure two-phase gas-liquid refrigerant that flows into the indoor heat exchanger 7, and the cooled air is blown into the room where the indoor unit 3 is installed, thereby cooling the room. Meanwhile, the low-pressure two-phase gas-liquid refrigerant that flows into the indoor heat exchanger 7 is heated and evaporated in the indoor heat exchanger 7 to become a low-pressure gas-phase refrigerant. In other words, the indoor heat exchanger 7 functions as an evaporator when the air conditioner 10 performs cooling operation. The low-pressure gas-phase refrigerant that flows out of the indoor heat exchanger 7 flows sequentially through the refrigerant pipe 15, the four-way valve 6, and the suction pipe 11, before being drawn into the compressor 5 and compressed again.

[0042] [Heating operation] The heating operation is performed, for example, when the air conditioner 10 is operated by a user to perform the heating operation. When the air conditioner 10 performs the heating operation, the four-way valve 6 switches the refrigerant circuit 4 to the heating cycle. The compressor 5 compresses the low-pressure gas-phase refrigerant that flows from the four-way valve 6 into the suction pipe 11. The low-pressure gas-phase refrigerant is compressed by the compressor 5 to become high-pressure gas-phase refrigerant. The compressor 5 discharges the high-pressure gas-phase refrigerant into the discharge pipe 12. The high-pressure gas-phase refrigerant discharged into the discharge pipe 12 flows into the indoor heat exchanger 7 via the four-way valve 6 because the refrigerant circuit 4 has been switched to the heating cycle.

[0043] The indoor unit 3 passes air from the room in which the indoor unit 3 is installed through the indoor heat exchanger 7. The indoor heat exchanger 7 exchanges heat between the high-pressure gas-phase refrigerant that has flowed into the indoor heat exchanger 7 and the air passing through the indoor heat exchanger 7, cooling the high-pressure gas-phase refrigerant that has flowed into the indoor heat exchanger 7 and heating the air passing through the indoor heat exchanger 7. The indoor unit 3 blows the air heated by the indoor heat exchanger 7 into the room in which the indoor unit 3 is installed, heating the room. The high-pressure gas-phase refrigerant is cooled and condensed in the indoor heat exchanger 7, becoming a supercooled high-pressure liquid-phase refrigerant. In other words, the indoor heat exchanger 7 functions as a condenser when the air conditioner 10 performs heating operation. The high-pressure liquid-phase refrigerant flows out of the indoor heat exchanger 7 and flows into the expansion valve 8.

[0044] Expansion valve 8 reduces the pressure of the high-pressure liquid-phase refrigerant that has flowed into expansion valve 8. The high-pressure liquid-phase refrigerant is reduced in pressure by expansion valve 8 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant flows out of expansion valve 8 and flows into refrigerant piping 17. Outdoor fan 18 flows outdoor air into ventilation space 19.

[0045] In outdoor heat exchanger 1, the low-pressure gas-liquid two-phase refrigerant that has flowed into outdoor heat exchanger 1 exchanges heat with the air flowing through ventilation space 19 due to the rotation of outdoor fan 18, and evaporates, becoming low-pressure gas-phase refrigerant. In other words, outdoor heat exchanger 1 functions as an evaporator when air conditioner 10 performs heating operation. The low-pressure gas-phase refrigerant that has flowed out of outdoor heat exchanger 1 flows through refrigerant piping 14, four-way valve 6, and suction pipe 11 in that order, before being drawn into compressor 5 and compressed again.

[0046] In the outdoor heat exchanger 1 during heating operation, the low-pressure gas-liquid two-phase refrigerant flowing through the refrigerant pipe 17 flows into the inlet space 43 of the expansion valve-side header 21 through the refrigerant pipe through-hole 44. The low-pressure gas-liquid two-phase refrigerant that has flowed into the inlet space 43 further flows into the lower end region 59 of the first flow path 57 through the inlet 61. The low-pressure gas-liquid two-phase refrigerant that has flowed into the lower end region 59 through the inlet 61 flows toward the other end 42 in the header longitudinal direction 25 and rises along the first flow path 57. At this time, the refrigerant is diverted from the first flow path 57 to each of the introduction holes 62. The remaining gas-liquid two-phase refrigerant that has flowed through the first flow path 57 and reached the upper end region 60 of the first flow path 57 (other than the diverted refrigerant diverted to each of the introduction holes 62) flows into the second flow path 58 through the first return flow path 51. The low-pressure gas-liquid two-phase refrigerant that has flowed into the second flow path 58 descends along the second flow path 58.

[0047] The low-pressure gas-liquid two-phase refrigerant descending along the second flow path 58 flows from the second flow path 58 into the lower end region 59 of the first flow path 57 via the second turning flow path 52. The gas-liquid two-phase refrigerant that has flowed into the lower end region 59 via the second turning flow path 52 ascends along the first flow path 57 together with the low-pressure gas-liquid two-phase refrigerant that has flowed into the lower end region 59 via the inlet 61. That is, during heating operation, the low-pressure gas-liquid two-phase refrigerant that has flowed into the circulation flow path 45 circulates through the circulation flow path 45. Circulating the low-pressure gas-liquid two-phase refrigerant through the circulation flow path 45 suppresses imbalance of the liquid refrigerant of the low-pressure gas-liquid two-phase refrigerant in the circulation flow path 45.

[0048] When the low-pressure gas-liquid two-phase refrigerant rises along the first flow path 57, when the refrigerant circulation rate in the refrigerant circuit 4 is high and the amount of refrigerant flowing into the expansion valve side header 21 is large, the amount of low-pressure gas-liquid two-phase refrigerant flowing through the first flow path 57 is larger and the flow velocity is faster than when the refrigerant circulation rate is low and the amount of refrigerant flowing into the expansion valve side header 21 is small. At this time, the flow velocity of the liquid refrigerant is slower than the flow velocity of the gas refrigerant because the liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant has a higher density than the gas refrigerant. Therefore, the liquid refrigerant is pushed toward the four corners of the first flow path 57 by the flow of the gas refrigerant. The liquid refrigerant pushed toward the four corners of the first flow path 57 is pushed by the gas refrigerant, flows through the four corners of the first flow path 57, and reaches the upper end region 60. The liquid refrigerant that reaches the upper end region 60 is pushed by the flow (momentum) of the gas refrigerant and tends to stagnate in the upper end region 60. In this way, when liquid refrigerant stagnates in the upper end region 60 of the first flow path 57, the amount of liquid refrigerant flowing from the upper end region 60 of the first flow path 57 to the heat transfer tubes 23 becomes greater than the amount of liquid refrigerant flowing from below the upper end region 60 of the first flow path 57 to the heat transfer tubes 23, resulting in an imbalance in the flow rate of liquid refrigerant between the heat transfer tubes 23.

[0049] To solve the above problem, this embodiment provides a circulation flow path 45 that directs the refrigerant flowing upward along the first flow path 57 to the second flow path 58 and then returns it to the first flow path 57. By providing the circulation flow path 45, the liquid refrigerant that accumulates in the upper end region 60 of the first flow path 57 is returned to the first flow path 57 via the second flow path 58, so that the liquid refrigerant does not accumulate in the upper end region 60 of the first flow path 57 and unevenness in the amount of liquid refrigerant that is diverted to each insertion space 46 can be suppressed. In other words, unevenness in the amount of liquid refrigerant flowing through each heat transfer tube 23 can be suppressed.

[0050] Furthermore, the refrigerant that flows into the first flow path 57 from the inlet 61 flows toward the upper end region 60 of the first flow path 57, and the flow velocity of the refrigerant as it flows through the first flow path 57 decreases toward the upper end region 60. As the flow velocity of the refrigerant through the first flow path 57 decreases, the velocity of the refrigerant flowing into the upper insertion spaces 46 decreases. At this time, as the flow velocity of the refrigerant through the first flow path 57 decreases, the velocity of the refrigerant flowing into the upper insertion spaces 46 also decreases. When the velocity of the refrigerant flowing into the insertion space 461 decreases, the liquid refrigerant is less likely to reach the windward flow path 34 in the ventilation direction 20 of the heat transfer tube 231 inserted in the insertion space 461. This reduces the amount of heat exchange between the refrigerant and the air in each heat transfer tube 23, and ultimately reduces the heat exchange amount of the outdoor heat exchanger 1.

[0051] 7, in this embodiment, the flow path cross-sectional areas of the multiple introduction holes 62 of the expansion valve-side header 21 are made smaller toward the upper side in the header longitudinal direction 25. When the flow path cross-sectional area of ​​the introduction hole 621 is small, the flow velocity of the refrigerant flowing into the insertion space 461 is faster than when the flow path cross-sectional area is large. Therefore, even if the flow velocity decreases as the refrigerant flows upward through the first flow path 57, the flow velocity of the refrigerant flowing into the insertion space 461 can be increased. As a result, the liquid refrigerant that flows into the insertion space 461 reaches the upwind-side flow path 34 of the heat transfer tube 231 in the ventilation direction 20, and a decrease in the heat exchange amount in the outdoor heat exchanger 1 can be suppressed.

[0052] As described above, by providing the circulation flow path 45 to prevent liquid refrigerant from accumulating in the upper end region 60 of the first flow path 57 and by decreasing the flow path cross-sectional areas of the multiple introduction holes 62 upward in the header longitudinal direction 25, it is possible to ensure the flow rate of the refrigerant flowing into the upper insertion space 461. By ensuring the flow rate of the liquid refrigerant flowing into the insertion space 461, the liquid refrigerant of the gas-liquid two-phase refrigerant that has flowed into the insertion space 461 from the introduction hole 621 as shown by arrow A in Fig. 6 flows through the insertion space 461 from the downwind side to the upwind side in the ventilation direction 20 as shown by arrow B in Fig. 6 and reaches the upwind region 462 of the insertion space 461. By ensuring the flow rate of the gas-liquid two-phase refrigerant flowing into the insertion space 461, the liquid refrigerant in the gas-liquid two-phase refrigerant reaches the upwind region 462 of the insertion space 461, so that the amount of liquid refrigerant in the upwind region 462 becomes greater than the amount of liquid refrigerant in the downwind region 463, and the amount of liquid refrigerant in the multiple upwind flow paths 34 becomes greater than the amount of liquid refrigerant in the multiple downwind flow paths 35.

[0053] When air flowing in the ventilation direction 20 through the ventilation space 19 exchanges heat with the refrigerant in the outdoor heat exchanger 1, the air whose temperature has decreased after flowing through the upwind region of the ventilation space 19 and exchanging heat with the refrigerant flows into the downwind region of the ventilation space 19. Therefore, the amount of heat exchanged between the air and the low-pressure gas-liquid two-phase liquid refrigerant flowing through the downwind-side flow passage 35 is less than the amount of heat exchanged between the air and the liquid refrigerant flowing through the upwind-side flow passage 34. Therefore, if a large amount of liquid refrigerant flows through the upwind-side flow passage 34 of the heat transfer tube 23 as in the above-described embodiment, the amount of heat exchanged per unit amount of liquid refrigerant in the multiple upwind-side flow passages 34 and the amount of heat exchanged per unit amount of liquid refrigerant in the multiple downwind-side flow passages 35 become closer, and a decrease in the amount of heat exchanged by the outdoor heat exchanger 1 can be suppressed.

[0054] [Heat exchanger of comparative example] The heat exchanger of the comparative example is configured in a manner generally similar to the outdoor heat exchanger 1 described above, and is configured so that the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing into the multiple upwind flow paths 34 of the heat transfer tube 231 is equal to the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing into the multiple downwind flow paths 35. In the heat exchanger of the comparative example, the heat exchange amount in the multiple downwind flow paths 35 is less than the heat exchange amount in the multiple upwind flow paths 34, so the heat exchange amount per unit amount of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing into the multiple upwind flow paths 34 differs from the heat exchange amount per unit amount of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing into the multiple downwind flow paths 35, and this may result in a decrease in the heat exchange amount throughout the heat exchanger.

[0055] Compared to the heat exchanger of the comparative example, the outdoor heat exchanger 1 of this embodiment can allow a larger amount of liquid refrigerant to flow through the upwind-side flow passages 34, and can increase the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing into the multiple upwind-side flow passages 34 compared to the multiple downwind-side flow passages 35. In the outdoor heat exchanger 1 of this embodiment, even when the heat exchange rate between the low-pressure gas-liquid two-phase liquid refrigerant flowing through the downwind-side flow passages 35 and the air is smaller than the heat exchange rate between the liquid refrigerant flowing through the upwind-side flow passages 34 and the air, the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing into the multiple upwind-side flow passages 34 is larger than the proportion of liquid refrigerant in the multiple downwind-side flow passages 35. This makes it possible to make the evaporation rate of liquid refrigerant in the multiple upwind-side flow passages 34 closer to the evaporation rate of liquid refrigerant in the multiple downwind-side flow passages 35. Therefore, the outdoor heat exchanger 1 can improve the heat exchange performance of exchanging heat between the low-pressure gas-liquid two-phase refrigerant and the air compared to the heat exchanger of the comparative example.

[0056] 8 is a perspective view showing a plurality of insertion space plate-shaped members 75. The expansion valve side header 21 is formed so that the shapes of the plurality of insertion spaces 46 are the same as one another, that is, so that the heights of the plurality of insertion spaces 46 in the header longitudinal direction 25 are equal to height T1. Therefore, when the plurality of insertion spaces 46 are used as flow paths through which low-pressure gas-liquid two-phase refrigerant flows from the downwind side to the upwind side in the ventilation direction 20, the flow path cross-sectional areas of the plurality of insertion spaces 46 are equal to one another. The expansion valve side header 21 further includes a plurality of partition portions 91. The plurality of insertion spaces 46 are separated from one another by the plurality of partition portions 91. The expansion valve side header 21 is formed so that the thicknesses of the plurality of partition portions 91 in the header longitudinal direction 25 are thickness t1.

[0057] 9 is a perspective view showing other multiple insertion space plate members 95 modified so that the flow path cross-sectional area of ​​the above-described multiple insertion spaces 46 is smaller. The multiple insertion space plate members 95 are configured as multiple insertion spaces 96 with a smaller flow path cross-sectional area than the insertion spaces 46 shown in FIG. 8, and other parts are the same as the multiple insertion space plate members 75 shown in FIG. 8. The multiple insertion space plate members 95 are formed so that the height of the multiple insertion spaces 96 in the header longitudinal direction 25 is equal to height T2, which is smaller than height T1. In other words, the flow path cross-sectional area of ​​the multiple insertion spaces 96 is different from and smaller than the flow path cross-sectional area of ​​the above-described multiple insertion spaces 46.

[0058] The multiple insertion spaces 96 are separated from one another by multiple partitions 97, similar to the multiple insertion spaces 46 described above. The multiple partitions 97 of the multiple insertion space plate members 95 are formed to have a thickness t2 in the header longitudinal direction 25 that is thicker than the thickness t1 of the multiple partitions 91 shown in FIG. 8. In other words, the insertion space plate member 95 shown in FIG. 9 has a larger flow path cross-sectional area than the insertion space plate member 75 shown in FIG. 8, by increasing the thickness of the partitions 97 without changing the number or pitch of the insertion spaces, thereby increasing the height T2 of the insertion spaces 96 in the header longitudinal direction 25. In this way, the flow path cross-sectional area of ​​the insertion spaces can be easily changed simply by changing the dimensions of the partitions in the insertion space plate member.

[0059] [Effects of the heat exchanger of the embodiment] The heat exchanger of the embodiment includes a plurality of heat transfer tubes 23 arranged in a ventilation space 19 through which air flows, and an expansion valve-side header 21 to which the plurality of heat transfer tubes 23 are joined. A plurality of flow paths 33 aligned in the ventilation direction 20 through which air flows are formed inside each of the plurality of heat transfer tubes 23. The expansion valve-side header 21 is formed inside with a circulation flow path 45 into which low-pressure gas-liquid two-phase refrigerant flows, a plurality of insertion spaces 46 into which one ends of the plurality of heat transfer tubes 23 are respectively inserted, and a plurality of introduction holes 62 that respectively connect the circulation flow path 45 to the plurality of insertion spaces 46. The plurality of introduction holes 62 are formed on the downwind side so that the low-pressure gas-liquid two-phase refrigerant flowing into each insertion space 461 of the plurality of insertion spaces 46 flows from the downwind side to the upwind side in the ventilation direction 20.

[0060] In the heat exchanger of the embodiment, the low-pressure gas-liquid two-phase refrigerant flowing into the multiple insertion spaces 46 flows from the downwind side to the upwind side in each insertion space 461, thereby forcing the liquid refrigerant of the low-pressure gas-liquid two-phase refrigerant to the upwind region 462 of the insertion space 461. Because the liquid refrigerant is forced to the upwind region 462, the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing through the multiple upwind flow paths 34 of the multiple heat transfer tubes 231 becomes higher than the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing through the multiple downwind flow paths 35. Therefore, in the heat exchanger of the embodiment, when the heat exchange amount in the multiple downwind flow paths 35 is smaller than the heat exchange amount in the multiple upwind flow paths 34, the evaporation rate of the liquid refrigerant in the multiple upwind flow paths 34 and the evaporation rate of the liquid refrigerant in the multiple downwind flow paths 35 can be made closer to each other, thereby improving the heat exchange performance of exchanging heat between the low-pressure gas-liquid two-phase refrigerant and the air.

[0061] The expansion valve-side header 21 of the heat exchanger of the embodiment further includes an inflow space 43 into which low-pressure gas-liquid two-phase refrigerant flows from outside the expansion valve-side header 21, and an inflow port 61 that connects the inflow space 43 to the circulation flow path 45. The inflow port 61 is located at the same position as the multiple introduction holes 62 in the ventilation direction 20 so that the low-pressure gas-liquid two-phase refrigerant that has flowed into the circulation flow path 45 is guided to the multiple introduction holes 62. The heat exchanger of the embodiment can reduce the resistance that the low-pressure gas-liquid two-phase refrigerant experiences when it flows into the circulation flow path 45 through the multiple introduction holes 62 and into the multiple insertion spaces 46, thereby ensuring a flow rate at which the low-pressure gas-liquid two-phase refrigerant flows into the multiple insertion spaces 46. Therefore, the heat exchanger of the embodiment can reliably push the liquid refrigerant out of the low-pressure gas-liquid two-phase refrigerant that has flowed into the multiple insertion spaces 46 to the upwind regions 462 of the insertion spaces 461.

[0062] Furthermore, in the heat exchanger of the embodiment, the multiple introduction holes 62 are formed such that the flow path cross-sectional area of ​​a first introduction hole 62a among the multiple introduction holes 62 is smaller than the flow path cross-sectional area of ​​a second introduction hole 62b, which is disposed closer to the inflow space 43 than the first introduction hole 62a among the multiple introduction holes 62. The heat exchanger of the embodiment can equalize the flow velocities of the refrigerant flowing into the multiple insertion spaces 46, even when the flow rate of the low-pressure gas-liquid two-phase refrigerant flowing through the first flow path 57 decreases toward the upper side. In the heat exchanger of the embodiment, the flow velocities of the refrigerant flowing into the multiple insertion spaces 46 are equalized, so that the liquid refrigerant can be appropriately pushed toward the windward region 462 for each of the multiple insertion spaces 46, thereby improving the heat exchange performance between the air flowing through the ventilation space 19 and the low-pressure gas-liquid two-phase refrigerant flowing through the multiple heat transfer tubes 23.

[0063] Although the multiple inlet holes 62 of the heat exchanger in the above-described embodiment are formed so that the flow path cross-sectional area decreases toward the upper side, some of the inlet holes 62 may be formed so that the flow path cross-sectional area is the same. Even in this case, the heat exchanger can improve the heat exchange amount between the refrigerant and the air because the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing through the multiple downwind-side flow paths 35 of the multiple heat transfer tubes 23 is smaller than the proportion of liquid refrigerant in the low-pressure gas-liquid two-phase refrigerant flowing through the multiple upwind-side flow paths 34.

[0064] Although the embodiments have been described above, the embodiments are not limited to the above content. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, at least one of various omissions, substitutions, and modifications of the components can be made without departing from the spirit of the embodiments. [Explanation of symbols]

[0065] 1: Outdoor heat exchanger (heat exchanger) 2:Outdoor unit 18: Outdoor fan (blower) 19: Ventilation space 20: Ventilation direction 21: Expansion valve side header (header) 23: Heat transfer tube 25: Header longitudinal direction 33: Multiple flow paths 43:Inflow space 45: Circulation flow path (separation space) 46: Multiple insertion spaces 51: First return flow path 52: Second return flow path 57: First flow path 58: Second flow path 61:Inlet 62: Multiple introduction holes (multiple introduction channels) 462: Windward area 463: Leeward area

Claims

1. a plurality of heat transfer tubes arranged in a ventilation space through which air flows; a header to which the plurality of heat transfer tubes are joined, A plurality of flow paths are formed inside each of the plurality of heat transfer tubes and are aligned in a ventilation direction in which the air flows, Inside the header: a dividing space into which the refrigerant flows; a plurality of insertion spaces into which one ends of the plurality of heat transfer tubes are inserted, respectively; a plurality of introduction flow paths are formed that connect the branch space to the plurality of insertion spaces, respectively; The plurality of introduction flow paths are formed so as to communicate the leeward side of each of the plurality of insertion spaces in the ventilation direction with the branch space. heat exchanger.

2. Inside the header: an inflow space into which a refrigerant flows from the outside of the header; an inlet that connects the inflow space to the branch space is further formed, The inlet is formed at the same position as the plurality of introduction flow paths in the airflow direction. The heat exchanger of claim 1 .

3. The shape of each insertion space is determined so that, when gas-liquid two-phase refrigerant flows into each insertion space, the proportion of liquid refrigerant in the gas-liquid two-phase refrigerant flowing to the upwind side in the ventilation direction in each insertion space is greater than the proportion of liquid refrigerant in the gas-liquid two-phase refrigerant flowing to the downwind side in the ventilation direction in each insertion space.

3. The heat exchanger of claim 2.

4. The header has a plurality of partition members that form a portion of the plurality of insertion spaces, The plurality of partition members are arranged at equal intervals in the direction in which the refrigerant flows through the flow dividing space, The thickness dimensions of the plurality of partition members are changed to make the shapes of the insertion spaces different. The heat exchanger according to claim 3.

5. When the side where the inlet is arranged is defined as one end and the opposite end is defined as the other end of the flow dividing space, a first flow path that causes the refrigerant that has flowed in from the inlet to flow toward the other end; a second flow path that causes the refrigerant that has flowed in from the first flow path to flow to the one end side and return the refrigerant to the first flow path; a first return flow path that connects the other end of the first flow path with the other end of the second flow path; a second return flow path that connects the one end of the first flow path to the one end of the second flow path, the first flow path is disposed on the downwind side of the second flow path in the airflow direction, The plurality of introduction channels respectively connect the first channel to the plurality of insertion spaces.

3. The heat exchanger of claim 2.

6. The plurality of inlet flow paths are formed such that the cross-sectional area of ​​the inlet flow path arranged on the one end side is smaller than the cross-sectional area of ​​the inlet flow path arranged on the other end side.

6. The heat exchanger according to claim 5.

7. The heat exchanger according to claim 1; A blower that blows air into the ventilation space An outdoor unit of an air conditioner comprising:

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