Flat tube for heat exchanger

Abstract

The object of the invention is a flat tube (1), in particular for a heat exchanger (100), in which a fluid flows, the tube (1) being formed by a plate-shaped metal strip (2) bent along its length, the metal strip (2) comprising longitudinal edges (2A, 2B), the flat tube (1) further comprising a first wall (3) and a second wall (4) parallel to the first wall (3), said walls (3, 4) being substantially flat, two complementary side wall portions (6) join together said first and second walls (3, 4) wherein the first wall (3) comprises a seam (5) extending along the longitudinal axis of the flat tube (1) such that the side-by-side longitudinal edges (2A, 2B) of the metal strip (2) join together in a parallel manner towards the second wall (4) to form a closed contour of the tube (1), and the second wall (4) comprises a seam (5) extending along the longitudinal axis of the flat tube (1). The seam (5) comprises a first segment section (5A) and a second segment section (5B) arranged in series with respect to a first portion of the seam (5), the segment sections (5A, 5B) being spaced apart from the second wall (4) and extending along the seam (5) along the longitudinal axis of the flat tube (1), characterized in that the second wall (4) comprises at least one deflection (9) projecting towards the seam (5) such that the first segment section (5A) is in contact with the second wall (4), and the second section (5B) is kept at a distance from the second wall (4).

Description

Technical Field

[0001] The present invention relates to a flat tube, and in particular to a flat tube for a heat exchanger. Background Art

[0002] In general, a heat exchanger usually comprises a core tube bundle and two headers (eg manifolds) through which the ends of the tubes of the core tube bundle pass and which are covered by a fluid distribution box cover. In order to improve heat exchange, inserts may be placed between the tubes of the core.

[0003] There are two main technologies used in the manufacture of these tubes. Either extrusion, which results in high costs (specific moulds for each tube type), or bending, which offers different advantages. In the case of bending, the tube used is manufactured by bending a metal strip onto itself.

[0004] The heat exchanger tubes may be subjected to many stresses, such as high-speed impacts with objects (such as stone chips) from the external environment. Therefore, the heat exchanger tubes are subject to external stresses.

[0005] They are also subject to stresses from the inside due to the fluid flow. Specifically, during operation, the tubes are subject to thermal stresses, pressure stresses and expansion stresses.

[0006] Sufficient material strength at the tube level must be ensured.

[0007] One known solution is to allow the tube to withstand such impacts by locally increasing the thickness of the tube wall, in the case of extruded tubes, in order to avoid any leakage of the fluid, or to withstand the internal stresses.

[0008] However, in the case of bent tubes, the tube cannot be strengthened by simply increasing the thickness of the material as is the case with extruded tubes.

[0009] In the case of bent tubes, for example, there is a known solution in which the open end of the tube receives an insert to increase the thickness of the material at the end of the tube. The disadvantages are that the inserts may affect the flow through the tube, they are actually additional parts that require precise brazing, they increase the overall cost of the heat exchanger, and they do not guarantee robustness against internal stresses.

[0010] Another known solution may be to provide a gap between the tube legs and the bottom of the tube. After the tube has been brazed, the tube legs may be mechanically separated from the bottom of the tube. This requires special tools, such as a knife, which may become blunt after repeating the process many times. Furthermore, the process itself requires great precision so that the tube is not damaged.

[0011] It would therefore be desirable to provide a solution that overcomes the latter disadvantages, or to provide an alternative solution to known tube flexibility improvements. It would also be desirable to provide a tube that can withstand internal stresses, preferably without increasing the overall cost of the heat exchanger. Summary of the invention

[0012] The object of the invention is in particular a flat tube for a heat exchanger, for a fluid to flow therein, the tube being formed by bending a sheet metal strip along its length, the metal strip comprising longitudinal edges, the flat tube further comprising: a first wall, a second wall parallel to the first wall, the walls being substantially flat, two complementary side wall portions joining the first and second walls together, wherein the first wall comprises a seam extending along the longitudinal axis of the flat tube, so that the juxtaposed longitudinal edges of the metal strip are joined together in a parallel manner towards the second wall to form a closed profile of the tube, the seam comprising a first section and a second section arranged in series relative to the first portion of the seam, the sections being spaced apart from the second wall and extending along the longitudinal axis of the seam of the flat tube, characterised in that the second wall comprises at least one deflection protruding towards the seam, so that the first section is in contact with the second wall, while the second section remains spaced apart from the second wall.

[0013] Advantageously, the longitudinal edges are at the same level relative to the surface of the second wall.

[0014] Advantageously, the flat tube comprises a first open end and a second open end, wherein the second section is located adjacent to at least one of the open ends.

[0015] Advantageously, the deflection is in the form of a groove which extends continuously along the seam, along the longitudinal axis of the flat tube, so that the end of the groove which is farthest from the surface of the second wall is aligned at least with the first section.

[0016] Advantageously, the deflection portion is in the form of at least two projections which are arranged in series along the longitudinal axis of the flat tube such that the end of each projection which is farthest from the surface of the second wall is aligned with at least the first section.

[0017] Advantageously, the longitudinal edge extends to at least half the distance between the first wall and the second wall, wherein said distance is measured between the inner faces of the walls.

[0018] Advantageously, the longitudinal edge extends substantially two thirds of the distance between the first wall and the second wall.

[0019] Advantageously, the deflection portion extends to at least one quarter of the distance between the first wall and the second wall, wherein the distance is measured between the inner faces of the walls.

[0020] A method for providing a flat tube may include the following steps:

[0021] - Provide metal strips

[0022] - Forming a deflection portion on the metal strip

[0023] - Roll-forming the metal strip to form a closed profile

[0024] - Brazing of rolled metal strips.

[0025] A heat exchanger comprising at least one flat tube, comprising:

[0026] - a first manifold,

[0027] - A second manifold, wherein the flat tubes are configured to provide fluid communication between the manifolds.

[0028] Advantageously, the heat exchanger further comprises at least one secondary tube, wherein the secondary tube comprises only a first section extending between its open ends.

[0029] Advantageously, the manifold comprises a slot for receiving at least the flat tube, wherein the second section extends through and beyond the contour of the slot on both sides thereof.

[0030] Advantageously, the heat exchanger comprises at least one fin interleaved between any of the flat tubes or the secondary tubes, wherein the second section extends from the slot at least to a contour defined by the distal end of the fin.

[0031] The flat tube allows to reduce mechanical stresses at desired locations of the tube. The second section significantly increases the flexibility of the flat tube, which allows it to withstand high pressures and temperatures. Furthermore, no tool such as a knife is required to mechanically separate the legs from the wall. Furthermore, the flow within the flat tube can be adjusted by setting the ratio between the deflection and the end portion of the metal strip. A heat exchanger comprising such a flat tube is advantageous relative to prior art solutions, since its flat tubes are easy to manufacture, they do not require the use of additional components, and therefore their manufacturing costs are also low. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Examples of the present invention will become apparent and described in detail with reference to the accompanying drawings, in which:

[0033] FIG. 1 shows a perspective view of a prior art flat tube.

[0034] FIG. 2 shows a cross section of the flat tube in FIG. 1 .

[0035] Figure 3 A perspective view of a flat tube comprising at least one deflection portion is shown.

[0036] Figure 4 Shows Figure 3 A cross section of a flat tube in a view perpendicular to the axis of extension of the flat tube.

[0037] Figure 5 A perspective view of a flat tube comprising at least one protrusion is shown.

[0038] Figure 6 A perspective view of a flat tube comprising at least one projection is shown in a view perpendicular to the axis of extension of the flat tube.

[0039] Figure 7 A cross section of a flat tube with L-shaped longitudinal edges is shown.

[0040] Figure 8 A cross section of a flat tube with stamped longitudinal edges is shown.

[0041] Fig. 9 A perspective view of a heat exchanger comprising at least one flat tube is shown.

[0042] Fig.10 A cross section of a flat tube-manifold assembly is shown. DETAILED DESCRIPTION

[0043] The present invention relates to a flat tube 1. The flat tube 1 may be adapted to operate in a heat exchanger 100 for a fluid to flow therein. For example, the heat exchanger 100 may be a radiator, and the fluid flowing therein may be a coolant. Other heat exchangers to which the flat tube 1 may be applied are also conceivable.

[0044] Figures 1 and 2 show a flat tube 1 of the prior art. The flat tube 1 can be formed by bending a sheet metal strip 2 along its length. The term "metal strip" refers to a metal sheet comprising two longer sides and two substantially shorter sides, the longer sides may further be referred to as "longitudinal edges", the shorter sides being substantially parallel to the longer sides. The metal strip may be made of, for example, aluminum, but other materials are also conceivable. The metal strip 2 may be bent along its longitudinal edges 2A, 2B to form a closed profile. Thus, the flat tube 1 may extend along its longitudinal axis. In other words, the flat tube 1 may include its axis of elongation.

[0045] The flat tube 1 may further comprise a first wall 3 and a second wall 4 parallel to the first wall 3, wherein the walls 3, 4 are formed after bending the metal strip 2. The walls 3, 4 may be substantially flat. In order to form a closed profile, the flat tube 1 may further comprise two complementary side wall portions 6 that join the first wall 3 and the second wall 4 together.

[0046] In order to provide a proper sealing of the flat tube 1, the first wall 3 may comprise a seam 5. The seam 5 may extend along the longitudinal axis of the flat tube 1, so that the juxtaposed longitudinal edges 2A, 2B of the metal strip 2 are joined together in a parallel manner towards the second wall 4 to form a closed profile of the tube 1. In other words, during the bending of the metal strip 2 to form the flat tube 1, the longitudinal edges 2A, 2B are bent inwards in a substantially right angle form so that they protrude towards the second wall 4 and they substantially contact each other from the first wall 3 to the second wall 4. The ends of the longitudinal edges 2A, 2B are fixed to the second wall 4, for example by brazing. The metal strip 2 may also be brazed along a portion extending between the first wall 3 and the second wall 4, wherein the longitudinal edges 2A and 2B are substantially parallel and in contact with each other. Thus, the seam 5 may comprise a first section 5A, which is fixed to the second wall 4 and extends along a first portion of the seam 5 along the longitudinal axis of the flat tube 1.

[0047] The seam 5 may include a first section 5A fixed to the second wall 4 and extending along a first portion of the seam 5 along the longitudinal axis of the flat tube 1, allowing the coolant to circulate within the heat exchanger 100 while providing an efficient heat exchange between the coolant and a different medium (e.g., air). However, known tubes tend to crack, which may cause coolant leakage, especially near their ends. The cracking may be caused by the lack of flexibility of the flat tube 1. The lack of flexibility coupled with the high pressure and temperature of the coolant can significantly reduce the robustness of the flat tube 1.

[0048] Figure 3-9 An exemplary solution is shown which may avoid or mitigate the negative aspects of prior art flat tubes 1 .

[0049] In order to increase the overall robustness of the flat tube 1 and its fluid tightness, the seam 5 may comprise a second section 5B.

[0050] The second section 5B may increase the flexibility of the flat tube 1 where needed. The second section 5B may extend along a second portion of the seam 5 arranged in series with respect to the first portion of the seam 5 and along the longitudinal axis of the flat tube 1. The term "arranged in series" means that the second section 5B is directly and continuously located after the first section 5A, or the second section 5B is located near the first section 5A, and there may be another optional section between them, which allows a smooth transition between the first section 5A and the second section 5B.

[0051] Unlike the first section 5A, the second section 5B may be spaced apart from the second wall 4. More precisely, the second section 5B protrudes from the first wall 3 substantially toward the second wall 4, however it does contact the second wall 4, whereas at least a portion of the first section 5A may contact the second wall 4. It should be understood that even though the first section 5A and the second section 5B are substantially one element, the first section 5A may contact any device protruding from, extending from or attached to the second wall 4. This allows the flat tube 1 to be more flexible during its operating mode. It allows compensating for differences between pressure and temperature so that the flat tube 1 always maintains its structural integrity and fluid tightness.

[0052] It should be noted that the first section 5A and the second section 5B are arranged in series relative to the first part of the seam 5, the sections 5A, 5B are initially spaced apart from the second wall 4 and extend along the seam 5 along the longitudinal axis of the flat tube 1. The first section 5A then comes into contact with the second wall 4 through the deformation 9 on the surface forming the second wall 4.

[0053] Exemplary ways of providing the flat tube 1 including the second section 5B will be discussed in subsequent paragraphs.

[0054] In order to provide a sealed connection between the first wall 3 and the second wall 4, the second wall 4 comprises at least one deflection 9 protruding towards the seam 5, so that the first section 5A is in contact with the second wall 4, while the second section 5B remains spaced apart from the second wall 4. More precisely, it is the deflection 9 that allows the longitudinal edges 2A, 2B of the second section to be connected to the second wall 4, so that the seam 5 establishes at least two separate channels for the fluid. The deflection 9 can be formed by stamping the already formed flat tube 1, so that the longitudinal ends 2A, 2B are in contact with the second wall 4. Alternatively, the deflection 9 can be formed immediately on the unfolded metal strip, i.e. before the flat tube 1 is formed. This way of providing the deflection 9 is preferred because it reduces the risk of damaging the flat tube 1, in particular the risk of damaging the longitudinal ends 2A, 2B during stamping.

[0055] The deflection 9 is in fact any structural deformation on the second wall 4 that allows at least a portion of the second wall 4 to be connected to the first wall 3. In one example, the deflection 9 can be in the form of a groove 9A extending continuously along the longitudinal axis of the flat tube 1 along the seam 5, so that the end of the groove 9A farthest from the surface of the second wall 4 is aligned with at least the first section 5A. The groove 9A can be understood as any depression on the outer face of the second wall 4, which comprises a substantially uniform depth along its elongation axis.

[0056] The deflection 9 can also be provided in the form of at least two projections 9B arranged in series along the longitudinal axis of the flat tube 1, so that the end of each projection 9B farthest from the surface of the second wall 4 is aligned with at least the first section 5A. The term "projection" refers to a deflection 9 which, unlike the groove 9A, does not extend continuously along the seam 5, along the longitudinal axis of the flat tube 1. This means that there can be at least one bypass for the fluid between subsequent projections 9B. This allows the flow pattern of the fluid to be changed to improve the overall performance of the heat exchanger 100. It should be noted that between subsequent projections 9B, the second wall 4 remains flat.

[0057] like Figure 7 As shown, the deflection portion 9 can also be provided in the form of at least one ridge 9C. The ridge 9C can include at least two protrusions 9B connected via a hill 9D. The hill 9D is actually a groove 9A that does not contact the longitudinal edges 2A, 2B of the seam 5. In other words, in the same process as the groove 9A, the hill 9D is formed by stamping the material, but its function is to partially reduce or control the fluid flow through the bypass portion between the protrusions 9B, rather than completely closing it. In addition, the hill 9D can be parallel to the surface of the second wall 4, or can be inclined in one direction. In addition, the hill 9D can include two sections, each section being located at a different height relative to the surface of the second wall 4. This type of exemplary configuration is Figure 7 This allows further manipulation of the flow in the bypass region between the protrusions 9B.

[0058] The flat tube 1 may also include at least one dimple (not shown). For the sake of clarity of the drawings, the dimple is not shown. The dimple may be in the form of a dimple configured to change the flow pattern within the flat tube 1. The dimple may be formed on the first wall 3, the second wall 4 or on both walls 3, 4. Typically, the dimple is positioned along the first section 5A. However, it is also conceivable that the dimple is formed along the second section 5B.

[0059] In the above arrangement, the second section 5B may be located at the end of the flat tube 1. In other words, the flat tube may include a first open end 6A and a second open end 6B located on the opposite side of the first open end 6A relative to the longitudinal axis of the flat tube 1. Therefore, the second section 5B may be located near the first open end 6A, the second open end 6A, or at least one of the two open ends 6A, 6B.

[0060] Alternatively, the second section 5B may be located, for example, in the middle of the flat tube 1, in other words, at least one second section 5B is located between at least two first sections 5A along the longitudinal axis of the flat tube 1. However, this configuration is only suitable for special cases where it is necessary to increase the flexibility of the flat tube 1 at a desired portion. Typically, it is necessary to increase the flexibility near the open ends 6A, 6B of the flat tube 1.

[0061] The distance ratio of the first section 5A to the distance occupied by the deflection 9 is not limited. This ratio can be measured as the distance measured between the inner faces of the walls 3, 4. The reference point for measuring the ratio can be the position of the connection point between the longitudinal edges 2A, 2B and the deflection 9.

[0062] It goes without saying, therefore, that other components occupy the remaining distance between the walls 3 , 4 .

[0063] In one example, the longitudinal edges 2A, 2B extend to at least half of the distance between the first wall 3 and the second wall 4 , wherein said distance is measured between the inner faces of the walls 3 , 4 .

[0064] In other examples, the longitudinal edges 2A, 2B may extend substantially two thirds of the distance between the first wall 3 and the second wall 4 .

[0065] In other examples, the deflector 9 may extend to at least a quarter of the distance between the first wall 3 and the second wall 4 , wherein the distance is measured between the inner faces of the walls 3 , 4 .

[0066] The longitudinal edges 2A, 2B may be directed towards the second wall 4 so that they may be located at the same level relative to the surface of the second wall 4. In other words, the second section 5B may include two parts, both of which are at the same distance from the second wall 4. This configuration may be further described as an I-shape. Figure 3-6 shown.

[0067] Alternatively, the longitudinal edges 2A, 2B may be curved so that they point toward the corresponding side wall 6. This configuration may be further described as L-shaped. It should be understood that the curved portion is still part of the longitudinal edge 2A, 2B. This configuration is as shown in FIG. Figure 8 shown.

[0068] Alternatively, the longitudinal edges 2A, 2B may be bent twice so that they are curled to point toward the first wall 3. This configuration may be further described as stamping. It should be understood that the bent portion is still part of the longitudinal edges 2A, 2B. This configuration is as follows Fig. 9 shown.

[0069] The method for providing a flat tube 1 may include several steps. A metal strip needs to be provided before the manufacturing process. Due to the relatively low cost and light weight, the preferred material may be aluminum or an aluminum alloy, however other metal materials are also conceivable.

[0070] The next step is to form the deflection portion 9 on the metal strip. The deflection portion 9 can be produced by so-called punching of the metal strip with a suitable tool. Any other means providing a similar effect (ie producing a deflection) can also be envisaged.

[0071] As mentioned previously, punching the metal strip to produce the deformation allows minimizing the risk of damaging the shape of the flat tube 1. The deformation 9 can be formed after the flat tube 1 is formed, however there is a risk of damaging the longitudinal walls 2A, 2B in the process.

[0072] The metal strip can then be rolled to form the flat tube 1. The edges of the flat metal strip are folded in the same direction to produce the longitudinal edges 2A, 2B. Next, the side walls 6 are formed which allow the closed contour of the flat tube 1 to be formed.

[0073] Finally, the flat tubes 1 are brazed together. The deflectors 9 are fixed to the longitudinal edges 2A, 2B protruding from the first wall 3 .

[0074] The flat tube 1 may be applicable to a heat exchanger 100. In other words, the heat exchanger 100 may include at least one flat tube 1 having at least one second section 5B. Fig.10 and 11 Shown in.

[0075] Reference Fig.10 The heat exchanger 100 may in particular include a first manifold 101 and a second manifold 102 , wherein the flat tube 1 is configured to provide fluid communication between the manifolds 101 , 102 .

[0076] The heat exchanger 100 may further comprise at least one secondary tube 103, wherein the secondary tube 103 comprises only a first section 5A extending between its open ends. In other words, the secondary tube 103 is a known standard tube.

[0077] The heat exchanger 100 may include only the flat tubes 1 stacked between the manifolds 101 , 102 .

[0078] Alternatively, the heat exchanger may include at least one flat tube 1 and at least one secondary tube 103. Both the flat tube 1 and the secondary tube 103 may form at least one first group and at least one second group, respectively. The first group and the second group may be arranged in a tube stack. In one of the examples, the first group is at least located at the end of the tube stack. Alternatively, at least one first group may be located between two adjacent second tube stacks.

[0079] refer to Fig.11 , the manifolds 101, 102 may include slots 104 for receiving the tubes 1, 103. In the case where the slots 104 receive the flat tubes 1, the second section 5B extends through and beyond the contour of the slots 104 on both sides thereof. In other words, the second section 5B may extend from the open ends 6A, 6B of the flat tubes along the longitudinal axis of the flat tubes 1 to the first section 5A, which does not overlap with the slots 104 in any case.

[0080] The heat exchanger 100 may also include fins 105 interlaced between either the flat tubes 1 or the secondary tubes 103, depending on the presence of the latter. For the sake of clarity of the drawing, the outline of the fins 105 is depicted by dashed lines in FIG. 12. In any case, it is preferred that the second section 5B extends from the open ends 6A, 6B of the flat tubes 1 at least to the outline defined by the ends of the fins 105 at their adjacent ends.

[0081] If the fins 105 are not present or if they cannot be considered as reference points, it is preferred that the second section 5B extends from the open ends 6A, 6B along the longitudinal axis of the flat tube 1 by 5 mm to 25 mm.

[0082] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, by studying the drawings, the disclosure, and the appended claims. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A flat tube (1) for a heat exchanger (100) for a fluid to flow therein, the tube (1) being formed by a sheet metal strip (2) bent along its length, the strip (2) comprising longitudinal edges (2A, 2B), the flat tube (1) also include: A first wall (3), a second wall (4) parallel to the first wall (3), the walls (3, 4) being substantially flat, two complementary side wall portions (6) joining the first and second walls (3, 4) together, wherein the first wall (3) comprises a seam (5) extending along the longitudinal axis of the flat tube (1), so that the juxtaposed longitudinal edges (2A, 2B) of the metal strip (2) are joined together in a parallel manner towards the second wall (4) to form a closed profile of the tube (1), the seam (5) comprising The invention comprises a first section (5A) and a second section (5B) which are arranged in series relative to a first part of the seam (5), wherein the sections (5A, 5B) are spaced apart from the second wall (4) and extend along the seam (5) and along the longitudinal axis of the flat tube (1), and is characterized in that the second wall (4) comprises at least one deflection portion (9) protruding toward the seam (5), so that the first section (5A) is in contact with the second wall (4), while the second section (5B) is spaced apart from the second wall (4).

2. The flat tube (1) according to claim 1, in, The longitudinal edges (2A, 2B) are at the same level relative to the surface of the second wall (4).

3. The flat tube (1) according to any one of the preceding claims, in, The flat tube (1) comprises a first open end (6A) and a second open end (6B), wherein the second section (5B) is located near at least one of the open ends (6A, 6B).

4. The flat tube (1) according to any one of the preceding claims, in, The deflection portion (9) is in the form of a groove (9A) extending continuously along the seam (5) and along the longitudinal axis of the flat tube (1), so that the end of the groove (9A) farthest from the surface of the second wall (4) is aligned with at least the first section (5A).

5. The flat tube (1) according to any one of claims 1 to 3, in, The deflection portion (9) is in the form of at least two protrusions (9B), which are arranged in series along the longitudinal axis of the flat tube (1) so that the end of each protrusion (9B) farthest from the surface of the second wall (4) is aligned with at least the first section (5A).

6. The flat tube (1) according to any one of the preceding claims, in, The longitudinal edges (2A, 2B) extend to at least half of the distance between the first wall (3) and the second wall (4), wherein the distance is measured between the inner faces of the walls (3, 4).

7. Flat tube (1) according to the preceding claim, in, The longitudinal edges (2A, 2B) extend substantially two thirds of the distance between the first wall (3) and the second wall (4).

8. The flat tube (1) according to any one of the preceding claims, in, The deflection portion (9) extends to at least one quarter of the distance between the first wall (3) and the second wall (4), wherein the distance is measured between the inner faces of the walls (3, 4).

9. A method for providing a flat tube as claimed in claim 1, The following steps are involved: - Provide metal strips - forming the deflection portion on the metal strip - Roll-forming the metal strip to form a closed profile - Brazing of rolled metal strips.

10. A heat exchanger (100) comprising at least one flat tube (1) according to any one of the preceding claims, wherein the heat exchanger (100) further comprises: include: - a first manifold (101), - a second manifold (102), wherein the flat tubes (1) are configured to provide fluid communication between the manifolds (101, 102).

11. The heat exchanger (100) according to claim 10, in, The heat exchanger (100) further comprises at least one secondary tube (103), wherein the secondary tube (103) comprises only the first section (5A) extending between its open ends.

12. The heat exchanger (100) according to any one of claims 10 to 11, in, The manifold (101, 102) comprises a slot (104) for receiving at least the flat tube (1), wherein the second section (5B) extends through and beyond the contour of the slot (104) on both sides thereof.

13. The heat exchanger (100) according to claims 10-12, in, The heat exchanger (100) comprises at least one fin (105) interlaced between any of the flat tubes (1) or the secondary tubes (103), wherein the second section (5B) extends from the slot (104) at least to a contour defined by the end of the fin (105).

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