heat exchanger

Abstract

A heat exchanger (10) comprises a tube (300) demarcating a flow passage through which a fluid flows, and a fin (400) bonded to the tube (300) by means of a bonding agent (610). Coating layers 301, 401 for promoting covalent bonding with the bonding agent 610 are formed on a bonded surface of at least one of the tube (300) and the fin 400.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from Japanese Patent Application No. 2022-053060, filed on March 29, 2022, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a heat exchanger. [Background technology]

[0003] For example, heat exchangers used in vehicle air conditioners and the like are required to have high heat exchange performance, and therefore aluminum is often used as the material for these devices. In recent years, from the perspective of carbon neutrality and the like, studies have been underway on the production of heat exchangers using recycled aluminum.

[0004] Recycled aluminum often contains magnesium as an impurity. However, it is known that magnesium reacts with the flux used in brazing, impairing the function of the flux. For this reason, when manufacturing a heat exchanger using recycled aluminum, it is difficult to join components by brazing. For this reason, as described in Patent Document 1 below, it is possible to join components by adhesive rather than brazing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4026503 Summary of the Invention

[0006] Adhesives have significantly lower thermal conductivity than metallic materials such as brazing filler metals, so to ensure the performance of a heat exchanger, it is necessary to somehow increase the thermal conductivity of the joints, such as the joints between the tubes and fins, among the multiple joints joined with adhesive.

[0007] An object of the present disclosure is to provide a heat exchanger that has high performance even though at least some of the joining is performed by a method other than brazing.

[0008] The heat exchanger according to the present disclosure includes a flow path member (300) that defines a flow path through which a fluid flows, and fins (400) that are bonded to the flow path member with an adhesive (610). A coating layer (301, 401) is formed on the bonded surface of at least one of the flow path member and the fin to promote covalent bonding with the adhesive.

[0009] When a coating layer is formed on the bonded surface, the proportion of covalent bonds in the bond between the adhesive and the coating layer at the joint increases. This reduces the thermal resistance at the interface between the adhesive and the coating layer, ensuring sufficient thermal conductivity between the bonded flow path member and fin. In other words, even if at least a portion of the heat exchanger is joined by a method other than brazing, it is possible to suppress any resulting performance degradation of the heat exchanger. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a heat exchanger according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of tubes and fins in the heat exchanger according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing the structure of the joint between the tube and the fin. [Figure 4] FIG. 4 is a cross-sectional view showing the configuration of the joint between the tube and the header plate. [Figure 5] FIG. 5 is a diagram showing the appearance of the heat exchanger according to the second embodiment. [Figure 6] FIG. 6 is a diagram showing the internal configuration of the heat exchanger of FIG. [Figure 7] FIG. 7 is a cross-sectional view showing the configuration of a joint portion inside the heat exchanger of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0012] A first embodiment will be described. A heat exchanger 10 according to this embodiment is a heat exchanger for exchanging heat between air and a heat transfer fluid, and is configured as a so-called "heater core" provided in a vehicle air conditioner. In the heat exchanger 10, high-temperature coolant supplied from the outside is used as the heat transfer fluid, and air is heated by heat exchange with the coolant. As shown in FIG. 1, the heat exchanger 10 includes an inlet tank 100, an outlet tank 200, tubes 300, and fins 400.

[0013] The inlet tank 100 is a container that receives cooling water supplied from the outside and distributes and supplies it to each of the tubes 300. The inlet tank 100 is formed as a long, narrow container with a roughly cylindrical shape, and is arranged with its longitudinal direction aligned horizontally. The inlet tank 100 has a header plate 110, a tank plate 120, and a joint portion 130.

[0014] The header plate 110 is a generally flat, plate-like member. The header plate 110 is made of metal. A plurality of through holes are formed in the header plate 110, and the lower end of each tube 300 is inserted into each through hole from above. The edges of the through holes in the header plate 110 and the outer surfaces of the tubes 300 are joined watertight around the entire circumference.

[0015] The tank plate 120 is a member for partitioning a space for storing cooling water. The tank plate 120 is arranged so as to cover the header plate 110 from the lower side, i.e., the side opposite the tubes 300. The tank plate 120 is made of metal. The tank plate 120 and the header plate 110 are joined together watertightly, which prevents cooling water from leaking out from between them.

[0016] The joint part 130 receives cooling water supplied from the outside and guides it to the space inside the inlet tank 100. A pipe (not shown) for supplying cooling water to the heat exchanger 10 is connected to the joint part 130. The joint part 130 is provided at a position that is an end of the inlet tank 100 along its longitudinal direction. An opening 131 that is an inlet for cooling water is formed at the end of the joint part 130 along the same direction. The cooling water supplied to the joint part 130 from the outside through the opening 131 flows inside the inlet tank 100 along the longitudinal direction and is distributed to each of the tubes 300.

[0017] The outlet tank 200 is a container for receiving the cooling water that has passed through each of the tubes 300 and discharging it to the outside. The outlet tank 200 is disposed vertically above the inlet tank 100. The outlet tank 200 has a header plate 210, a tank plate 220, and a joint portion 230.

[0018] The header plate 210 is a generally flat, plate-like member. The header plate 210 is made of metal. The shape of the header plate 210 is generally the same as the shape of the header plate 110. A plurality of through holes are formed in the header plate 210, and the upper ends of the tubes 300 are inserted into each through hole from below. The edges of the through holes in the header plate 210 and the outer surfaces of the tubes 300 are joined watertight around the entire circumference.

[0019] The tank plate 220 is a member for partitioning a space for storing cooling water. The tank plate 220 is arranged so as to cover the header plate 210 from above, i.e., from the side opposite the tubes 300. The tank plate 220 is made of metal. The tank plate 220 and the header plate 210 are joined together watertightly, which prevents cooling water from leaking out from between them.

[0020] The joint part 230 is a part configured as an outlet for discharging the cooling water stored inside the outlet-side tank 200 to the outside. A pipe (not shown) for discharging the cooling water from the heat exchanger 10 is connected to the joint part 230. The joint part 230 is provided at a position that is an end of the outlet-side tank 200 along its longitudinal direction. An opening 231 that is an outlet for the cooling water is formed at the end of the joint part 230 along the same direction. The cooling water that is supplied to the inside of the outlet-side tank 200 through each tube 300 flows inside the outlet-side tank 200 along the longitudinal direction, and then is discharged to the outside from the joint part 230.

[0021] The tubes 300 are tubular members having a flow path through which the cooling water flows. In other words, the tubes 300 define the flow path. The tubes 300 correspond to the "flow path member" in this embodiment. A plurality of tubes 300 are provided in the heat exchanger 10. Each tube 300 is arranged between the inlet tank 100 and the outlet tank 200 with its longitudinal direction aligned in the up-down direction. The tubes 300 are stacked together with fins 400 (described later) and aligned along the longitudinal direction of the inlet tank 100 and the outlet tank 200. For this reason, the direction in which the stacked tubes 300 are aligned is hereinafter also referred to as the "stacking direction." The stacking direction is the left-right direction in FIG. 1.

[0022] As already described, the lower end of the tube 300 is connected to the header plate 110 of the inlet tank 100, and the upper end of the tube 300 is connected to the header plate 210 of the outlet tank 200. The internal space of the inlet tank 100 and the internal space of the outlet tank 200 are connected by a flow path formed in the tube 300.

[0023] The fins 400 are corrugated fins formed by bending a metal plate into a wave shape. A plurality of fins 400 are provided in the heat exchanger 10, and are arranged between each of the tubes 300. Each fin 400 abuts against and is joined to each of a pair of tubes 300 arranged on both sides of the fin 400.

[0024] The portion of the heat exchanger 10 where the tubes 300 and the fins 400 are alternately stacked as described above is the portion where heat exchange occurs between the cooling water passing through the inside of the tubes 300 and the air passing outside the tubes 300, and is the portion referred to as the "heat exchange core portion." Side plates 11 and 12 are arranged at the left and right end portions of the heat exchange core portion in FIG. 1 .

[0025] The side plates 11 and 12 are plate-like members formed by bending metal plates and are arranged to extend in the same direction as the longitudinal direction of the tubes 300. The side plate 11 is arranged at the end of the heat exchanger core unit closest to the joint unit 130 in the stacking direction. The side plate 12 is arranged at the end of the heat exchanger core unit closest to the joint unit 130 in the stacking direction. The side plates 11 and 12 sandwich the heat exchanger core unit from both sides in the stacking direction, thereby increasing the rigidity of the heat exchanger core unit.

[0026] When heat exchange is performed by the heat exchanger 10, high-temperature cooling water that has passed through an internal combustion engine (not shown) is supplied from the opening 131 of the joint portion 130 into the inside of the inlet-side tank 100. The cooling water flows inside the inlet-side tank 100 in the stacking direction and is supplied to each tube 300. The cooling water flows upward inside each tube 300 and is supplied to the inside of the outlet-side tank 200.

[0027] A fan (not shown) that blows air through the heat exchange core is provided near the heat exchanger 10. The direction in which the air is blown by the fan is from the front side to the back side of the paper in FIG.

[0028] The coolant is cooled by the air as it flows through the flow paths formed in the tubes 300 as described above. The air, i.e., the air sent out by the fan, is heated by the coolant as it passes around the tubes 300, increasing its temperature. This air is blown into the vehicle cabin as, for example, air conditioning for heating. The coolant that has passed through each tube 300 and is supplied to the inside of the outlet-side tank 200 is discharged to the outside through the joint portion 230, as described above.

[0029] The x-axis shown in FIG. 1 is a horizontal axis set along the direction from the front side to the back side of the page. The y-axis is a horizontal axis perpendicular to the above-mentioned axis set along the direction from the joint portion 130 toward the inside of the inlet tank 100. The z-axis is a vertical axis perpendicular to both the x-axis and y-axis set along the direction from the inlet tank 100 toward the outlet tank 200. The x-axis, y-axis, and z-axis defined above are also shown in figures other than FIG. 1 for reference.

[0030] 2 shows a perspective view of one of the multiple tubes 300 and one fin 400 joined to the tube 300. As shown in the figure, multiple louvers 410 are formed on a portion of each fin 400 that extends generally along the y-axis. The louvers 410 are formed by cutting and raising a portion of the fin 400.

[0031] Specifically, a plurality of linear cuts are formed along the y-axis in a line along the x-axis, and the strip-shaped portions separated by each cut are then rotated around an axis along the longitudinal direction to form louvers 410. The formation of louvers 410 enables more efficient heat exchange with the air passing through. Note that a conventional shape can be adopted for such louvers 410, and detailed illustrations thereof will be omitted.

[0032] Recycled aluminum is used as the material for each component of the heat exchanger 10. As is well known, recycled aluminum often contains magnesium as an impurity, making it difficult to join components by brazing. This is because magnesium reacts with the flux used in brazing and inhibits the function of the flux. Therefore, in the heat exchanger 10 according to this embodiment, adhesive is used to join the components. For example, a thermosetting epoxy adhesive is used as the adhesive, but other adhesives such as thermoplastic resins may also be used.

[0033] Among the multiple joints in the heat exchanger 10, there are some that require high thermal conductivity and some that do not. An example of a part that requires high thermal conductivity is the joint between the tube 300 and the fin 400. An example of a part that does not require high thermal conductivity is the joint between the tube 300 and the header plate 210.

[0034] The thermal conductivity of a bonded joint is lower than that of a brazed joint. Therefore, in the heat exchanger 10 according to this embodiment, the performance degradation of the heat exchanger 10 is suppressed by devising a configuration for the parts that require high thermal conductivity.

[0035] 3 shows a cross section of the joint between the tube 300 and the fin 400 as an example of the "portion requiring high thermal conductivity." As shown in the figure, the tube 300 and the fin 400 are bonded together with an adhesive 610. Note that "FP" shown in the figure is a flow path formed inside the tube 300.

[0036] As mentioned above, a thermosetting epoxy adhesive is used as the adhesive 610. The adhesive 610 may be any adhesive containing any of epoxy, silicone, urethane, and acrylic.

[0037] The adhesive 610 contains a filler (not shown). The "filler" here refers to a plurality of particles for promoting thermal conduction, and is contained in the adhesive 610 at a predetermined ratio (wt %). It is preferable to use particles made of a material with as high a thermal conductivity as possible as the filler. Furthermore, considering that the heat exchanger 10 will be recycled, it is preferable to use particles made of a material that can be easily removed when the aluminum material is melted. In view of these points, it is preferable that the filler be formed from any of the elements contained in the tubes 300 or fins 400 to be bonded, an oxide of the element, a nitride of the element, or carbon, etc.

[0038] In addition, examples of "any element contained in the tube 300 or the fin 400 to be bonded" include Al, Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti.

[0039] In this embodiment, alumina particles are used as the filler. The adhesive 610 containing the filler corresponds to the "first adhesive" in this embodiment. When carbon is used as the filler, it is preferable to use carbon nanotubes that are oriented in the thickness direction.

[0040] The adhesive 610 contains a filler as described above, and therefore has a relatively high thermal conductivity. By using such adhesive 610, the thermal conductivity at the joint between the tube 300 and the fin 400 is increased.

[0041] 3, a coating layer 301 is formed on the surface of the tube 300 in a portion bonded with adhesive 610 (i.e., the bonded surface). Similarly, a coating layer 401 is formed on the surface of the fin 400 in a portion bonded with adhesive 610 (i.e., the bonded surface). Both coating layers 301 and 401 are formed as layers for promoting covalent bonding with adhesive 610.

[0042] The coating layers 301 and 401 have OH groups, which are hydrophilic groups, on their surfaces. Examples of such coating layers 301 and 401 include layers containing aluminosilicate or aluminum hydroxide.

[0043] To form the coating layers 301, 401 containing aluminosilicate, for example, an aluminum material may be immersed in sodium silicate and then the surface may be dried. Alternatively, sodium silicate may be sprayed onto the surface of the aluminum material and then the surface may be dried. To form the coating layers 301, 401 containing aluminum hydroxide, for example, an aluminum material may be sprayed with superheated steam and then the surface may be dried.

[0044] The process of forming the coating layers 301, 401 on each aluminum material is preferably carried out after the forming (pressing, etc.) of the aluminum material is completed. Although it is possible to form the coating layers 301, 401 in advance before forming, in this case, there is a possibility that a part of the coating layers 301, 401 may be damaged or deteriorated due to impact or distortion during forming.

[0045] 3, the coating layers 301 and 401 are formed on the bonded surfaces, so that the proportion of covalent bonds (compared to anchor bonds) is higher at the bonded portions between the adhesive 610 and the coating layers 301 and 401. This reduces the thermal resistance at the interfaces between the adhesive 610 and the coating layers 301 and 401, further increasing the thermal conductivity between the tube 300 and the fin 400.

[0046] In addition, the adhesive 610 and the coating layers 301 and 401 have an advantage of increasing the bonding strength at the interface by increasing the degree of adhesion at the interface. Furthermore, the adhesive 610 and the coating layers 301 and 401 have an advantage of suppressing the permeation of a fluid (cooling water in this embodiment) along the interface.

[0047] In this way, in this embodiment, even though at least a portion of the heat exchanger 10 is joined by a method other than brazing, it is possible to suppress the resulting deterioration in performance of the heat exchanger 10.

[0048] In this embodiment, the coating layer 301 is formed on the entire surface of the tube 300, including the bonded surface. Alternatively, the coating layer 301 may be formed locally only on the bonded surface and its vicinity on the surface of the tube 300. Similarly, the coating layer 401 may be formed locally on the surface of the fin 4000, only on the bonded surface and its vicinity.

[0049] Furthermore, the coating layers 301, 401 may be formed only on the joined surfaces of either the tube 300 or the fin 400. For example, at one joint, the coating layer 301 may be formed on the surface of the tube 300, while the coating layer 401 may not be formed on the surface of the fin 400.

[0050] It should be noted that a portion of the heat exchanger 10 may be made of aluminum, which is not a recycled material, and the members may be joined by brazing.

[0051] 4 shows a cross section of a joint between a tube 300 and a header plate 210 as an example of the aforementioned "portion where high thermal conductivity is not required." As shown in the figure, a through hole 211 is formed in the header plate 210. The tube 300 is adhered to the edge of the through hole 211 with an adhesive 620, with the tip of the tube 300 inserted through the through hole 211. Note that an inner fin may be provided in the flow path FP of the tube 300.

[0052] The adhesive 620 is the same epoxy adhesive as the adhesive 610. However, the adhesive 620 does not contain the filler mentioned above. This is because there is no need to increase the thermal conductivity between the components at the joint shown in FIG. 4. The adhesive 620, which does not contain a filler, corresponds to the "second adhesive" in this embodiment. Because there is no filler in the portion bonded with the adhesive 620, the amount of resin material that serves as the matrix is ​​relatively large, ensuring sufficient adhesive strength.

[0053] The adhesive 620 may contain any of epoxy, silicone, urethane, and acrylic. The adhesive 620 may be the same adhesive as the adhesive 610 except that it does not contain a filler, or it may be a different adhesive from the adhesive 610. For example, only the adhesive 620 may contain an additive to increase the bonding strength.

[0054] In this embodiment, the coating layer 301 is formed on the entire surface of the tube 300. Therefore, the coating layer 301 is also formed on the surface of the tube 300 that is to be bonded by the adhesive 620. However, the coating layer 301 is not necessarily required at the joint in FIG.

[0055] However, if it is necessary to improve the bonding strength at the interface and reliably prevent leakage of fluid due to permeation, it is preferable that a coating layer 301 is formed on the surface of the tube 300 at the joint shown in Fig. 4. Also, a coating layer similar to the coating layer 301 may be formed on the edge of the through-hole 211 or in the vicinity thereof.

[0056] As described above, heat exchanger 10 has a plurality of bonded portions where two members are bonded to each other. The plurality of bonded portions include a first bonded portion bonded with adhesive 610 (first adhesive) and a second bonded portion bonded with adhesive 620 (second adhesive) that has a lower thermal conductivity than adhesive 610. By using different adhesives depending on the required level of thermal conductivity, it is possible to select an appropriate adhesive for each bonded portion.

[0057] In this embodiment, all of the components constituting the heat exchanger 10 are made of recycled materials, i.e., aluminum alloys containing magnesium. However, regular aluminum materials that are not recycled materials may be used in part of the heat exchanger 10. If at least one of the tubes 300 and the fins 400 is made of an aluminum alloy containing magnesium, the effect of applying the adhesive joint configuration described above is particularly significant.

[0058] The second embodiment will be described below. Differences from the first embodiment will be mainly described below, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0059] As shown in FIGS. 5 and 6, the heat exchanger 10A according to this embodiment is configured as a plate-type heat exchanger formed by stacking multiple plates 15. The heat exchanger 10A is installed, for example, in a vehicle air conditioning system and performs heat exchange between a coolant and a refrigerant. As shown in FIG. 6, the heat exchanger 10A has a first flow path FP1 through which the coolant flows and a second flow path FP2 through which the refrigerant flows, each of which is formed alternately. The plates 15 that define the first flow path FP1 and the second flow path FP2 correspond to the "flow path member" in this embodiment. Since a known configuration can be adopted for the configuration of this fin-plate type heat exchanger 10A, detailed configurations other than those shown in the drawings will not be described.

[0060] The first flow path FP1 is provided with an inner fin 310, and the second flow path FP2 is provided with an inner fin 320. Both the inner fins 310 and 320 are joined to the adjacent plate 15.

[0061] The joining method will be described with reference to Fig. 7. Fig. 7 shows a schematic cross-sectional view of a pair of plates 15 that define the second flow path FP2 and an inner fin 320 provided inside the second flow path FP2.

[0062] A coating layer 151 is formed on the surface of the plate 15 that faces the inner fin 320. Also, a coating layer 321 is formed on the entire surface of the inner fin 320 that faces the plate 15 (the entire surface in this embodiment). Both coating layers 151 and 321 are the same films as the coating layer 301 in the first embodiment, and are layers containing aluminosilicate or aluminum hydroxide, which is an OH group. The method of forming them is the same as the method described above.

[0063] The plates 15 and the inner fins 320 are bonded together with the same adhesive 610 as in the first embodiment. This makes the thermal conductivity between the plates 15 and the inner fins 320 relatively high. Furthermore, the adjacent pairs of plates 15 are bonded together with the same adhesive 620 as in the first embodiment. This ensures sufficient adhesive strength between the plates 15.

[0064] In this way, the heat exchanger 10A has a plurality of bonding portions that include first bonding portions bonded with adhesive 610 (first adhesive) and second bonding portions bonded with adhesive 620 (second adhesive) that has a lower thermal conductivity than adhesive 610. Even with this configuration, the same effects as those described in the first embodiment are achieved.

[0065] The adhesive portion between the plate 15 and the inner fin 310 can also be a first adhesive portion using adhesive 610 (first adhesive). In this case, the coating layer 151 may be formed on both the front and back surfaces of the plate 15. Also, a coating layer similar to the coating layer 321 may be formed on the entire surface of the inner fin 310.

[0066] Furthermore, the adhesive portion between the inlet pipe 16, which serves as the cooling water inlet, and the plate 15, as well as other adhesive portions that do not require high thermal conductivity, can also be second adhesive portions using the adhesive 620 (second adhesive).

[0067] [Note] Notes 1 to 13 below can be combined in any way as long as there is no technical contradiction.

[0068] [Appendix 1] a flow path member (300) that defines a flow path through which a fluid flows; a fin (400) bonded to the flow path member with an adhesive (610); A heat exchanger, wherein a coating layer (301, 401) for promoting covalent bonding with the adhesive is formed on the bonded surface of at least one of the flow path member and the fin.

[0069] [Appendix 2] 2. The heat exchanger of claim 1, wherein the coating layer contains a hydrophilic group.

[0070] [Appendix 3] 3. The heat exchanger of claim 2, wherein the coating layer comprises an aluminosilicate.

[0071] [Appendix 4] 4. The heat exchanger of claim 2 or 3, wherein the coating layer comprises aluminum hydroxide.

[0072] [Appendix 5] At the joint where two members are glued together, a first adhesive portion bonded by a first adhesive; A heat exchanger according to any one of appendices 1 to 4, further comprising a second adhesive portion bonded with a second adhesive having a lower thermal conductivity than the first adhesive.

[0073] [Appendix 6] 6. The heat exchanger according to claim 5, wherein the fins are bonded to the flow path member by the first adhesive portion.

[0074] [Appendix 7] the first adhesive contains a filler for promoting thermal conduction; 7. The heat exchanger according to claim 5, wherein the second adhesive contains less filler than the first adhesive.

[0075] [Appendix 8] the first adhesive contains a filler for promoting thermal conduction; 8. The heat exchanger of claim 7, wherein the second adhesive does not contain the filler.

[0076] [Appendix 9] 9. The heat exchanger according to claim 7, wherein the filler is formed from any one of an element contained in the flow path member or the fin to be bonded, an oxide of the element, or a nitride of the element.

[0077] [Appendix 10] 9. The heat exchanger of claim 7 or 8, wherein the filler is carbon.

[0078] [Appendix 11] 11. The heat exchanger of any one of claims 1 to 10, wherein the fluid comprises a refrigerant.

[0079] [Appendix 12] 12. The heat exchanger of claim 1, wherein the adhesive comprises any one of epoxy, silicone, urethane, and acrylic.

[0080] [Appendix 13] 13. The heat exchanger according to any one of claims 1 to 12, wherein at least one of the flow path member and the fins is formed of an aluminum alloy containing magnesium element.

[0081] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

Claims

1. A flow path member (300) that defines a flow path through which a fluid flows; and a fin (400) bonded to the flow path member with an adhesive (610), a coating layer (301, 401) for promoting covalent bonding with the adhesive is formed on the adherend surface of at least one of the flow path member and the fin; The heat exchanger, wherein the coating layer contains a hydrophilic group and includes aluminum hydroxide.

2. At the joint where two components are bonded together, a first adhesive portion bonded by a first adhesive; The heat exchanger according to claim 1 , further comprising: a second adhesive portion bonded with a second adhesive having a thermal conductivity lower than that of the first adhesive.

3. The heat exchanger according to claim 2 , wherein the fins are bonded to the flow path member by the first adhesive portion.

4. the first adhesive contains a filler for promoting thermal conduction; The heat exchanger according to claim 2 , wherein the second adhesive contains less filler than the first adhesive.

5. the first adhesive contains a filler for promoting thermal conduction; The heat exchanger according to claim 4 , wherein the second adhesive does not include the filler.

6. 5. The heat exchanger according to claim 4, wherein the filler is formed from any one of an element contained in the flow path member or the fin to be bonded, an oxide of the element, and a nitride of the element.

7. 5. The heat exchanger of claim 4, wherein the filler is carbon.

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