Heat exchanger microtube and microtube heat exchanger made of microtube

Abstract

The utility model discloses a heat exchanger microtube and a microtube heat exchanger made of the heat exchanger microtube. The heat exchanger microtube comprises a tube body. The pipe body comprises a base layer pipe body, and a welding flux layer or a welding layer formed by mixing welding flux and welding flux is compounded on the outer side wall of the base layer pipe body. The inner side wall of the base layer pipe body is compounded with an anti-corrosion layer or not compounded with other materials. A welding layer or a welding flux layer is compounded on the outer side wall of the tube body, meanwhile, a welding flux layer or a welding flux layer is compounded on the surface of the heat exchange fin, the tube body and the heat exchange fin can be directly connected and fixed through brazing after being assembled, welding is firm, the effect is good, the manual labor amount is greatly reduced, the outer diameter of the tube body is small, and the service life is long. By means of the structure, it can be guaranteed that refrigerants flowing inside and the inner wall face of the pipe body fully exchange heat, the heat exchange effect is good, the distance between the heat exchange fins is kept through the bent side plate parts, the normal air circulation amount is guaranteed, and the heat exchanger can be suitable for being used in most environments and is wide in application range.

Description

Technical field:

[0001] The utility model relates to the technical field of heat exchanger related equipment, and more specifically to a heat exchange tube of a heat exchanger and a micro-tube heat exchanger made of the micro-tube. Background technology:

[0002] In the existing refrigeration system, the heat exchanger is an important heat exchange component;

[0003] Existing heat exchangers generally include conventional fin-tube heat exchangers formed by winding fins on heat exchange tubes, and microchannel heat exchangers made of microchannel flat tubes;

[0004] The finned tube heat exchanger has the characteristics of large gaps between the tubes, which facilitates the flow of wind and ensures normal wind circulation. However, since the tubes are processed by extrusion, the inner diameter of the tubes is relatively large, so that the refrigerant flowing inside only exchanges heat with the part in contact with the inner wall. The refrigerant in the center of the tube cannot contact the tube wall, so that good heat exchange cannot be achieved, resulting in a general heat exchange effect.

[0005] The microchannel heat exchanger is characterized by its small size. Compared with the fin-tube heat exchanger, its volume can be four to five times smaller than that of the fin-tube heat exchanger under the same heat exchange rate, which greatly reduces the space occupied. However, due to its small size, the gap between the heat exchange fins between the microchannel flat tubes will be very small. The problem is that this gap is easily blocked by the surrounding dust, etc., which affects the air circulation. It is not suitable for use in some environments containing a lot of dust or dust.

[0006] In addition, the existing fins and the outer wall of the heat exchange tube body are fixed by pressing to achieve heat conduction and heat exchange, or it is necessary to apply solder and flux to the joints after the fins and the heat exchange tubes are assembled, and then weld them by brazing. In this process, it is necessary to manually apply solder and flux to the joints, and each joint needs to be coated twice. There are many joints, and the manual coating is labor-intensive, and the effect is not ideal. Utility model content:

[0007] The purpose of the utility model is to overcome the deficiencies of the prior art and to provide a heat exchanger heat exchange tube and a micro-tube heat exchanger made of the micro-tube. The outer wall of the tube body is already compounded with a welding layer or a solder layer. At the same time, the surface of the heat exchange fin is compounded with a solder layer or a welding layer. After the two are assembled, they can be directly connected and fixed by brazing. The welding is firm and the effect is good, which greatly reduces the amount of manual labor. In addition, the outer diameter of the tube body is small, which can ensure that the refrigerant flowing inside can fully exchange heat with the inner wall of the tube body, and the heat exchange effect is good.

[0008] The solution of the utility model to solve the technical problem is:

[0009] A heat exchanger microtube comprises a tube body; the tube body comprises a base tube body, and a solder layer or a welding layer made of a mixture of solder and flux is compounded on the outer wall of the base tube body;

[0010] The inner side wall of the base pipe body is compounded with an anti-corrosion layer or is not compounded with other materials.

[0011] An anti-corrosion layer is compounded on the outer wall of the base tube body, and a solder layer or a welding layer made of a mixture of solder and flux is compounded on the outer wall surface of the anti-corrosion layer.

[0012] A micro-tube heat exchanger made of the above heat exchanger micro-tube, comprising a heat exchange tube made of a tube body and a plurality of heat exchange fins;

[0013] The heat exchange fin is formed with a connecting through hole, and a plurality of bent side plates bent backward are formed on the side wall of the connecting through hole. The straight tube portion of the heat exchange tube is inserted into the corresponding connecting through hole, and the inner side wall of the bent side plate portion is tightly attached to the outer side wall of the corresponding straight tube portion and fixed by welding.

[0014] The surface of the heat exchange fin is compounded with a solder layer or a welding layer made of a mixture of solder and flux.

[0015] A bending portion is formed at the rear end of the bent side plate portion, and the bending portion is pressed against the front wall surface of the adjacent rear heat exchange fin and fixed by welding.

[0016] The heat exchange tube is formed by welding and fixing a plurality of long U-shaped connecting tubes and short U-shaped connecting tubes;

[0017] The ends of the two straight tube parts of the long U-shaped connecting tube are connected to the corresponding ends of the two short U-shaped connecting tubes by adopting an expansion hole structure.

[0018] The ends of the two straight tube portions of the long U-shaped connecting tube are close to the corresponding ends of the two corresponding short U-shaped connecting tubes and are welded and fixed in the same welding ring sleeve, or the ends of the two straight tube portions of the long U-shaped connecting tube are inserted into the corresponding ends of the two corresponding short U-shaped connecting tubes and are welded and fixed.

[0019] The heat exchange tube is formed by welding a plurality of special-shaped connecting tubes to each other;

[0020] The special-shaped connecting pipe comprises a U-shaped connecting portion, one end of which is formed with a straight pipe portion extending straight outward;

[0021] The end of the straight tube portion of the special-shaped connecting pipe is connected to one end of the U-shaped connecting portion of the adjacent special-shaped connecting pipe on one side, and one end of the U-shaped connecting portion of the special-shaped connecting pipe is connected to the end of the straight tube portion of the adjacent special-shaped connecting pipe on the other side.

[0022] A hole expansion section is formed at one end of the U-shaped connecting portion, and the end of the straight pipe portion of the adjacent special-shaped connecting pipe is inserted into the corresponding hole expansion section and fixed by welding;

[0023] Alternatively, one end of the U-shaped connecting portion is fixed to the end of the straight pipe portion of the adjacent special-shaped connecting pipe through the same first welding ring.

[0024] The heat exchange tube is formed by welding and fixing a plurality of long tubes and a plurality of short U-shaped connecting tubes.

[0025] The outstanding effects of the utility model are:

[0026] Compared with the prior art, the outer wall of its tube body is already compounded with a welding layer or a solder layer, and at the same time, the surface of the heat exchange fin is compounded with a solder layer or a welding layer. After the two are assembled, they can be directly connected and fixed by brazing (when the surfaces of both are solder layers, it is necessary to apply flux on the outer wall of the heat exchange fin or the heat exchange tube before assembly, and only one application is required). The welding is firm and effective, which greatly reduces the amount of manual labor. In addition, the outer diameter of the tube body is small, which can ensure that the refrigerant flowing inside can fully exchange heat with the inner wall of the tube body, and the heat exchange effect is good. In addition, the spacing between the heat exchange fins is maintained by bending the side plate to ensure normal wind circulation, so that it can be used in most environments and has a wide range of applications. Description of the drawings:

[0027] Figure 1 It is a partial structural schematic diagram of the pipe body of the utility model;

[0028] Figure 2 This is a schematic diagram of a second partial structure of the pipe body of the utility model;

[0029] Figure 3 It is a simplified schematic diagram of a heat exchanger using a tube body connected in a hole expansion manner according to the present invention;

[0030] Figure 4 It is a schematic diagram of the local structure between the tube body and the corresponding heat exchange fins when the tube body is compounded with a solder layer or a welding layer;

[0031] Figure 5 It is a schematic diagram of the local structure between the tube body and the heat exchange fins when no other materials are compounded on the tube body;

[0032] Figure 6 This is a structural schematic diagram of the long U-shaped connecting pipe and the short U-shaped connecting pipe of the utility model;

[0033] Figure 7 This is a second structural schematic diagram of the long U-shaped connecting pipe and the short U-shaped connecting pipe of the utility model;

[0034] Figure 8 It is a schematic diagram of a third partial structure in which the straight pipe portion of the long U-shaped connecting pipe and one end of the short U-shaped connecting pipe of the utility model are connected;

[0035] Fig. 9 This is a schematic diagram of a fourth structure in which the straight pipe portion of the long U-shaped connecting pipe and one end of the short U-shaped connecting pipe of the utility model are connected;

[0036] Fig.10 This is a schematic diagram of the structure of the utility model using a special-shaped connecting pipe;

[0037] Fig.11 This is a schematic diagram of the second structure of the utility model using a special-shaped connecting pipe;

[0038] Fig.12 This is a schematic diagram of the third structure of the utility model using a special-shaped connecting pipe;

[0039] Fig.13 This is a schematic diagram of a partial structure of the utility model using a long tube connected with a short U-shaped connecting tube;

[0040] Fig.14 It is a partial structural schematic diagram of another connection between the long tube and the short U-shaped connecting tube of the utility model;

[0041] Fig.15 It is a partial structural schematic diagram of another connection between the long tube and the short U-shaped connecting tube of the utility model;

[0042] Fig.16 This is a fourth structural schematic diagram of the utility model using a long tube and a short U-shaped connecting tube. Specific implementation method:

[0043] For example, see Figure 1 to Figure 2 As shown, a heat exchanger microtube includes a tube body 10; the tube body 10 includes a base tube body 1, and the outer wall of the base tube body 1 is compounded with a solder layer 3 or a welding layer 4 made of a mixture of solder and flux (all welding layers 4 in this embodiment are made of a mixture of solder and flux); the base tube body 1 is made of 3003 series aluminum plate, which is a common product of the aluminum-manganese alloy series. Due to the manganese alloy element, this product has excellent anti-rust properties and is also called anti-rust aluminum plate.

[0044] The anti-corrosion layer 2 uses 7072 aluminum alloy, which is a cold-treated forged alloy with high strength, far superior to mild steel. The chemical composition of 7072 aluminum alloy: silicon Si: 0.40; iron Fe: 0.50; copper Cu: 1.2-2.0; manganese Mn: 0.30; magnesium Mg: 2.1-2.9; chromium Cr: 0.18-0.28; zinc Zn: 5.1-6.1; titanium Ti: 0.20; aluminum Al: balance. Its anti-corrosion effect is higher than that of the base pipe body 1.

[0045] The solder layer 3 uses 4343 aluminum-based solder, 4045 aluminum-based solder, and 4047 aluminum-based solder.

[0046] The welding layer 4 is made of a sheet made of the material used for the solder layer 3 mixed with a flux, and then compounded onto the base tube body 1 by extrusion and rolling with a roller. The method of compounding the solder layer 3 onto the base tube body 1 is the same as that of the welding layer 4, and will not be described in detail here. Figure 1 As shown, at this time, no other material is compounded on the inner wall of the base tube body 1;

[0047] Furthermore, the inner wall of the base tube body 1 is compounded with an anti-corrosion layer 2, the outer wall of the base tube body 1 is compounded with an anti-corrosion layer 2, and the outer wall of the anti-corrosion layer 2 is compounded with a solder layer 3 or a welding layer 4 made of a mixture of solder and flux. Figure 2 As shown, the composite method of the anti-corrosion layer 2, the solder layer 3 or the welding layer 4 is the same as Figure 1 The composite method of the structures shown is the same and will not be described in detail here.

[0048] The outer diameter of the tube body 10 is 2 mm to 5 mm. The inner diameter of the tube body is small, so that the refrigerant flowing inside can fully contact the tube wall of the tube body 10 to ensure the heat exchange effect.

[0049] The composite solder layer 3 or welding layer 4 can be convenient for subsequent brazing. When the composite solder layer 3 is used, there is no need to manually apply solder, only flux is needed. When the composite welding layer 4 is used, there is no need to manually apply solder and flux subsequently.

[0050] like Figure 3 to Figure 4 As shown, a micro-tube heat exchanger made of the above heat exchanger micro-tube comprises a heat exchange tube 20 coiled in an S shape made of a tube body 10 and a plurality of heat exchange fins 30;

[0051] The heat exchange fin 30 is formed with a connecting through hole 31, and a plurality of bent side plate portions 32 bent backward are formed on the side wall of the connecting through hole 31. The straight tube portion 21 of the heat exchange tube 20 is inserted into the corresponding connecting through hole 31, and the inner side wall of the bent side plate portion 32 is tightly attached to the outer side wall of the corresponding straight tube portion 21 and fixed by welding.

[0052] The surface of the heat exchange fin 30 is compounded with a solder layer 3 or a welding layer 4 made of a mixture of solder and flux.

[0053] A bent portion 33 is formed at the rear end of the bent side plate portion 32 , and the bent portion 33 is pressed against the front wall surface of the adjacent rear heat exchange fin 30 and fixed by welding.

[0054] like Figure 4 As shown, when the surface of the heat exchange fin 30 is compounded with a solder layer 3, and the outer wall of the straight tube portion 21 of the heat exchange tube 20 is compounded with a solder layer 3, a flux can be applied on the surface of the heat exchange fin 30 or the outer wall of the straight tube portion 21 of the heat exchange tube 20 before installation, and after the two are installed, they can be brazed and fixed;

[0055] When the surface of the heat exchange fin 30 is compounded with the welding layer 4 or the outer wall of the straight tube portion 21 of the heat exchange tube 20 is compounded with the welding layer 4, that is, as long as one of the outer walls of the heat exchange fin 30 and the straight tube portion 21 of the heat exchange tube 20 is compounded with the welding layer 4, after the two are assembled, there is no need to apply flux and they can be fixed by brazing, which is convenient to process and greatly reduces the amount of manual labor.

[0056] And as Figure 5 As described above, when the outer wall surface of the heat exchange tube 20 is not compounded with any material, it only needs to be compounded with the welding layer 4 on the heat exchange fin 30, and it can also be directly fixed by brazing later.

[0057] Figure 4 and Figure 5 There is no composite anti-corrosion layer 2 on the inner wall surface and the outer wall surface of the middle base pipe body 1.

[0058] Furthermore, if Figures 6 to 9 As shown, the heat exchange tube 20 is formed by welding and fixing a plurality of long U-shaped connecting tubes 22 and short U-shaped connecting tubes 23;

[0059] The ends of the two straight tube parts 21 of the long U-shaped connecting tube 22 are formed with a flared tube section 211 whose inner diameter is larger than that of the straight tube part 21, and the ends of the flared tube section 211 are formed with a tapered hole section 212 extending outward, and the two ends of the short U-shaped connecting tube 23 are respectively inserted into the flared tube section 211 of one of the straight tube parts 21 of the two corresponding long U-shaped connecting tubes 22. After the assembly of this structure is completed, the solder layer 3 (the solder layer 3 needs to be coated with flux) or the welding layer 4 of the outer wall of the end of the short U-shaped connecting tube 23 is melted, welded and fixed on the inner wall of the corresponding flared tube section 211 by brazing. This method is flared connection.

[0060] The ends of the two straight tube portions 21 of the long U-shaped connecting tube 22 are inserted into the corresponding ends of the two corresponding short U-shaped connecting tubes 23 (at this time, the inner diameter of the hole at the end of the short U-shaped connecting tube 23 needs to be larger than the outer diameter of the ends of the two straight tube portions 21 of the long U-shaped connecting tube 22), and the solder layer 3 (the solder layer 3 needs to be coated with flux) or the welding layer 4 on the outer wall of the end of the straight tube portion 21 is melted, welded and fixed on the inner wall of the corresponding end of the corresponding short U-shaped connecting tube 23, thereby realizing a welded fixed connection and communication.

[0061] A welding ring sleeve 40 can also be used for connection. The ends of the two straight tube portions 21 of the long U-shaped connecting tube 22 are close to the corresponding ends of the two corresponding short U-shaped connecting tubes 23. The outer diameter and inner diameter of the close part of the two are the same. The middle outer wall of the welding ring sleeve 40 can be extruded to form a radial annular edge. The outer wall surface of the welding ring sleeve 40 is compounded with a solder layer 3 (the solder layer 3 needs to be coated with flux) or a welding layer 4. First, the two ends of the welding ring sleeve 40 are inserted into the ends of the straight tube portion 21 and the corresponding short U-shaped connecting tube 23. At one end, the radial annular edge is clamped between the end face of the end of the straight tube portion 21 and the end face of one end of the corresponding short U-shaped connecting tube 23. By brazing, the solder layer 3 or the welding layer 4 on the outer wall surface of the welding ring sleeve 40 is melted, and the radial annular edge is welded and fixed to the end face of the end of the straight tube portion 21 and the end face of one end of the corresponding short U-shaped connecting tube 23. At the same time, the outer wall surface of the welding ring sleeve 40 is welded and fixed to the inner side wall of the end of the straight tube portion 21 and the inner side wall of one end of the corresponding short U-shaped connecting tube 23 to achieve connection.

[0062] At the same time, it can also be a sleeve-type welding ring sleeve 40, that is, an inner radial extension edge is formed on the inner wall of the middle part of the welding ring sleeve 40, and a solder layer 3 (the solder layer 3 needs to be coated with flux) or a welding layer 4 is compounded on the inner wall surface of the welding ring sleeve 40. The ends of the straight tube portion 21 and one end of the corresponding short U-shaped connecting tube 23 are inserted into the two ends of the welding ring sleeve 40, and the inner radial extension edge is clamped between the end face of the end of the straight tube portion 21 and the end face of one end of the corresponding short U-shaped connecting tube 23. By brazing, the solder layer 3 or the welding layer 4 is melted. At this time, the outer side wall of the end of the straight tube portion 21 and one end of the corresponding short U-shaped connecting tube 23 is welded and fixed to the inner side wall of the welding ring sleeve 40, and the inner radial annular edge is welded and fixed to the end face of the end of the straight tube portion 21 and the end face of one end of the corresponding short U-shaped connecting tube 23 to achieve connection and fixation.

[0063] like Figures 10 to 12 As shown, the heat exchange tube 20 is formed by welding a plurality of special-shaped connecting tubes 24 to each other;

[0064] The special-shaped connecting pipe 24 includes a U-shaped connecting portion 241, and one end of the U-shaped connecting portion 241 is formed with a straight pipe portion 21 extending straight outward;

[0065] The end of the straight tube portion 21 of the special-shaped connecting tube 24 is connected to one end of the U-shaped connecting portion 241 of the adjacent special-shaped connecting tube 24 on one side, and one end of the U-shaped connecting portion 241 of the special-shaped connecting tube 24 is connected to the end of the straight tube portion 21 of the adjacent special-shaped connecting tube 24 on the other side.

[0066] A hole expansion section is formed at one end of the U-shaped connecting portion 241, and the end of the straight tube portion 21 of the adjacent special-shaped connecting tube 24 is inserted into the corresponding hole expansion section and welded and fixed; this connection method is the same as the hole expansion connection method of the long U-shaped connecting tube 22 and the short U-shaped connecting tube 23, and will not be described in detail here.

[0067] Alternatively, one end of the U-shaped connecting portion 241 is fixed to the end of the straight tube portion 21 of the adjacent special-shaped connecting tube 24 via the same first welding ring 50 .

[0068] The connection method of the first welding ring 50 is the same as that of the welding ring sleeve 40, and the structure is also the same, which will not be described in detail here.

[0069] like Figures 13 to 16 As shown, the heat exchange tube 20 is formed by welding and fixing a plurality of long tubes 29 and a plurality of short U-shaped connecting tubes 23;

[0070] The two ends of the long tube 29 are close to the corresponding ends of the two corresponding short U-shaped connecting tubes 23 and are welded and fixed in the same welding ring sleeve 40, or the two ends of the long tube 29 are inserted into the corresponding ends of the two corresponding short U-shaped connecting tubes 23 and are welded and fixed, or the two ends of the long tube 29 are formed with a reaming tube section 211 with an inner diameter larger than that of the long tube 2), and a conical hole section 212 extending outward is formed at the end of the reaming tube section 211, and the two ends of the short U-shaped connecting tube 23 are respectively inserted into the corresponding reaming tube section 211, and the outer side wall of the end of the short U-shaped connecting tube 23 is welded and fixed on the inner side wall of the corresponding reaming tube section 211.

[0071] The specific connection structure is the same as the welding and fixing method of the long U-shaped connecting pipe 22 and the short U-shaped connecting pipe 23, and will not be described in detail here.

[0072] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The scope of patent protection of the present invention should be limited by the claims.

Claims

1. A heat exchanger microtube, comprising a tube body (10); characterized in that: The tube body (10) comprises a base tube body (1), the outer side wall of the base tube body (1) being compounded with a solder layer (3) or a welding layer (4) made of a mixture of solder and flux; The inner side wall of the base pipe body (1) is compounded with an anti-corrosion layer (2) or is not compounded with other materials.

2. A heat exchanger microtube according to claim 1, characterized in that: The outer wall of the base tube body (1) is compounded with an anti-corrosion layer (2), and the outer wall surface of the anti-corrosion layer (2) is compounded with a solder layer (3) or a welding layer (4) made of a mixture of solder and flux.

3. The heat exchanger microtube according to claim 1, characterized in that: The base tube body (1) is an aluminum tube, and the tube body (10) is a tube body with an outer diameter of 2 mm to 5 mm; the anti-corrosion layer (2) is an aluminum alloy layer.

4. A microtube heat exchanger made of a heat exchanger microtube according to any one of claims 1 to 3, characterized in that: It comprises a heat exchange tube (20) made of a tube body (10) and a plurality of heat exchange fins (30); The heat exchange fin (30) is formed with a connecting through hole (31), and a plurality of bent side plate portions (32) bent backward are formed on the side wall of the connecting through hole (31); the straight tube portion (21) of the heat exchange tube (20) is inserted into the corresponding connecting through hole (31), and the inner side wall of the bent side plate portion (32) is tightly attached to the outer side wall of the corresponding straight tube portion (21) and is fixed by welding.

5. The micro-tube heat exchanger according to claim 4, characterized in that: The surface of the heat exchange fin (30) is compounded with a solder layer (3) or a welding layer (4) made of a mixture of solder and flux.

6. The micro-tube heat exchanger according to claim 4, characterized in that: A bent portion (33) is formed at the rear end of the bent side plate portion (32), and the bent portion (33) is pressed against the front wall surface of the adjacent rear heat exchange fin (30) and fixed by welding.

7. The micro-tube heat exchanger according to claim 4, characterized in that: The heat exchange tube (20) is formed by welding a plurality of long U-shaped connecting tubes (22) and short U-shaped connecting tubes (23); The ends of the two straight tube portions (21) of the long U-shaped connecting tube (22) are formed with a flared tube section (211) having an inner diameter greater than that of the straight tube portion (21), and the ends of the flared tube section (211) are formed with a tapered hole section (212) extending outwards, and the two ends of the short U-shaped connecting tube (23) are respectively inserted into the flared tube section (211) of one of the straight tube portions (21) of the two corresponding long U-shaped connecting tubes (22), and the outer side wall of the end of the short U-shaped connecting tube (23) is welded and fixed to the inner side wall of the corresponding flared tube section (211).

8. The micro-tube heat exchanger according to claim 4, characterized in that: The heat exchange tube (20) is formed by welding a plurality of long U-shaped connecting tubes (22) and short U-shaped connecting tubes (23); The ends of the two straight tube portions (21) of the long U-shaped connecting tube (22) are close to the corresponding ends of the two corresponding short U-shaped connecting tubes (23) and are welded and fixed in the same welding ring sleeve (40), or the ends of the two straight tube portions (21) of the long U-shaped connecting tube (22) are inserted into the corresponding ends of the two corresponding short U-shaped connecting tubes (23) and are welded and fixed.

9. The micro-tube heat exchanger according to claim 4, characterized in that: The heat exchange tube (20) is formed by welding a plurality of special-shaped connecting tubes (24) connected to each other; The special-shaped connecting pipe (24) comprises a U-shaped connecting portion (241), and one end of the U-shaped connecting portion (241) is formed with a straight pipe portion (21) extending straight outwards; An end of the straight tube portion (21) of the special-shaped connecting tube (24) is connected to one end of the U-shaped connecting portion (241) of the adjacent special-shaped connecting tube (24) on one side, and one end of the U-shaped connecting portion (241) of the special-shaped connecting tube (24) is connected to an end of the straight tube portion (21) of the adjacent special-shaped connecting tube (24) on the other side; A hole expansion section is formed at one end of the U-shaped connecting portion (241), and the end of the straight tube portion (21) of the adjacent special-shaped connecting tube (24) is inserted into the corresponding hole expansion section and fixed by welding; Alternatively, one end of the U-shaped connecting portion (241) is fixed to the end of the straight tube portion (21) of the adjacent special-shaped connecting tube (24) via the same first welding ring (50).

10. The micro-tube heat exchanger according to claim 4, characterized in that: The heat exchange tube (20) is formed by welding a plurality of long tubes (29) and a plurality of short U-shaped connecting tubes (23); The two ends of the long tube (29) are close to the corresponding ends of the two corresponding short U-shaped connecting tubes (23) and are welded and fixed in the same welding ring sleeve (40); or the two ends of the long tube (29) are inserted into the corresponding ends of the two corresponding short U-shaped connecting tubes (23) and are welded and fixed; or the two ends of the long tube (29) are formed with a reaming tube section (211) having an inner diameter greater than that of the long tube (29); a conical hole section (212) extending outward is formed at the end of the reaming tube section (211); the two ends of the short U-shaped connecting tube (23) are respectively inserted into the corresponding reaming tube section (211); and the outer side wall of the end of the short U-shaped connecting tube (23) is welded and fixed to the inner side wall of the corresponding reaming tube section (211).

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