Heat exchanger and method of manufacturing a heat exchanger

Abstract

Heat exchanger and method of manufacturing heat exchanger. The heat exchanger includes a partition wall that separates two fluids of different temperatures, and a plurality of plate-shaped fins formed on at least one surface of the partition wall and each having a pair of heat transfer surfaces. The partition wall and the plurality of plate-shaped fins are made of the same metal material to constitute an integrally molded product. The plurality of plate-shaped fins each have a curved portion and are arranged to be spaced apart from each other in a direction intersecting the pair of heat transfer surfaces. Each of the pair of heat transfer surfaces is formed with a plurality of grooves having a depth of 100 μm to 400 μm in a thickness direction of each plate-shaped fin.

Description

Technical Field

[0001] The present invention relates to a heat exchanger having a partition wall separating two fluids at different temperatures and fins formed on the partition wall, and a method for manufacturing the heat exchanger. Background Technology

[0002] Heat exchangers, employing various heat transfer methods, are widely used as devices for heat exchange between two fluids at different temperatures. In surface-type (partitioned-wall) heat exchangers, the two fluids flow in two spaces separated by partitions, and heat exchange occurs between them due to heat transfer via the partitions. In some heat exchangers, to increase the heat transfer area (and thus improve heat exchange efficiency), the partitions are formed with fins, or the heat transfer surface of the partitions is perforated.

[0003] For example, a heat exchanger is known having a heat transfer tube through which a coolant circulates and fins in contact with the heat transfer tube, wherein each fin has a fin body with grooves provided on its surface (see JP2017-150756A).

[0004] In addition, for example, a heat exchanger made of aluminum or an aluminum alloy is known, which includes metal fins, each fin having an anodized aluminum coating formed on its surface (see JP2011-252192A).

[0005] As a result of careful research into improving the heat exchange efficiency of heat exchangers, the inventors of this application have found that it is particularly effective to reduce the thermal resistance (i.e., heat transfer loss) at the interface between each fin and the partition wall and to increase the heat transfer area of ​​the fins (i.e., to make the surface structure more refined) while smoothing the fluid flow near the fin surface (to increase the flow velocity and thereby reduce the thickness of the temperature boundary layer).

[0006] Regarding these points, the conventional techniques described in JP2017-150756A and JP2011-252192A do not provide specific teachings or suggestions on reducing heat transfer losses at the interface between the individual fins and the partition wall or reducing the thickness of the temperature boundary layer formed near the fin surface. In the conventional technique described in JP2017-150756A, grooves provided on the individual fin bodies of the heat exchanger are used to form a waterproof membrane on the fin surface. Furthermore, in the conventional technique described in JP2011-252192A, an anodized aluminum coating formed on the metal fins of the heat exchanger is used to suppress uneven frost formation. Summary of the Invention

[0007] In view of the above background technology, the main object of the present invention is to provide a heat exchanger and a method for manufacturing such a heat exchanger, wherein the thermal resistance at the interface between each fin and the partition wall is reduced, the heat transfer area of ​​the fins is increased, and the fluid flow near the fin surface is smoothed.

[0008] To achieve the above objectives, one aspect of the present invention provides a heat exchanger 1, the heat exchanger comprising: a partition wall 3 separating two fluids 14, 15 at different temperatures; and a plurality of plate-shaped fins 5 formed on at least one surface 3A of the partition wall and each having a pair of heat transfer surfaces 21, 21, wherein the partition wall and the plurality of plate-shaped fins are made of the same metal material to form an integrally molded product, each of the plurality of plate-shaped fins having a curved portion 17 and arranged to be spaced apart from each other in a direction intersecting the pair of heat transfer surfaces, and each of the pair of heat transfer surfaces having a plurality of grooves 25 with a depth of 100 μm to 400 μm in the thickness direction of each plate-shaped fin.

[0009] According to this aspect, since the partition wall and multiple fins are integrally molded, the thermal resistance at the interface between each fin and the partition wall is reduced. Furthermore, forming grooves of appropriate depth on the multiple fins, each with a curved portion, increases the heat transfer area of ​​the fins while smoothing the fluid flow near the fin surface. As a result, the heat exchange efficiency of the heat exchanger can be improved.

[0010] In the foregoing, preferably, the heat exchanger further includes plate members 35, each plate member being made of another metal material with a higher emissivity than the metal material, and attached to the partition wall between adjacent plate fins of the plurality of plate fins.

[0011] According to this, even when there are limitations on the metal material used in the fins integrally molded with the partition wall, plate-shaped members with high emissivity can enhance thermal radiation (radiative heat transfer) to improve the uniformity of fluid temperature in the heat exchanger and thus improve the heat exchange efficiency of the heat exchanger.

[0012] In the above aspects, preferably, the other surface 3B of the partition wall, which is not provided with the plate-shaped fins, is formed with a plurality of holes, each hole having a diameter of 10 nm to 30 nm.

[0013] According to this aspect, fins formed on one surface of the partition wall facilitate heat transfer between one of the two fluids (e.g., gas) and the partition wall, while holes formed on the other surface of the partition wall facilitate heat transfer between the other of the two fluids (e.g., liquid) and the partition wall.

[0014] In the above aspects, preferably, the partition wall is formed as a bottom cylindrical body, and the plurality of plate-shaped fins are each connected to the bottom surface and the side circumferential surface of the bottom cylindrical body forming the outer surface of the bottom cylindrical body. In the first portion 17 of the plate-shaped fins connected to the bottom surface of the bottom cylindrical body, the plurality of grooves extend toward the bottom surface, and in the second portion 19 of the plate-shaped fins connected to the side circumferential surface of the bottom cylindrical body, the plurality of grooves extend along the side circumferential surface.

[0015] According to this aspect, fluid near the bottom surface of the bottomed cylindrical body is guided by multiple channels to flow toward the bottom surface, thereby promoting heat transfer at the bottom of the bottomed cylindrical body. Furthermore, fluid near the side circumferential surfaces of the bottomed cylindrical body is guided by multiple channels to flow along the side circumferential surfaces, thereby promoting heat transfer in the side circumferential portions of the bottomed cylindrical body.

[0016] In the foregoing, preferably, the heat exchanger further includes a housing 9, the housing being configured to cover the outer side of the plurality of plate-shaped fins, and the outer edge portions of the plurality of plate-shaped fins opposite to the partition wall are each connected to the housing.

[0017] According to this aspect, the outer shell covering the outside of multiple fins can effectively guide fluid to the fins disposed on the bottom cylindrical body.

[0018] In the above aspects, preferably, the heat exchanger further includes a plurality of pin-shaped fins 7, the plurality of pin-shaped fins being arranged to protrude outward on the area of ​​the bottom surface of the bottom cylindrical body where the plurality of plate-shaped fins are not formed.

[0019] Based on this, pin-shaped fins can effectively promote heat transfer at the bottom of the bottomed cylindrical body.

[0020] In the above aspects, preferably, the curved portion of each of the plurality of plate-shaped fins is helically curved.

[0021] Based on this, the fluid flow near the surface of multiple fins can be smoothed (increasing the fluid velocity).

[0022] In the above aspects, preferably, each plate-shaped fin has a cross-section that tapers in the direction away from the partition wall.

[0023] This method can suppress fluid retention between adjacent fins.

[0024] To achieve the above objectives, another aspect of the present invention provides a method for manufacturing a heat exchanger 1, the method comprising the steps of: integrally molding a partition wall 3 and a plurality of plate-shaped fins 5 using the same metal material by additive manufacturing, the partition wall separating two fluids 14, 15 at different temperatures, the plurality of plate-shaped fins being formed on at least one surface 3A of the partition wall and each having a pair of heat transfer surfaces 21, 21, wherein each of the plurality of plate-shaped fins has a curved portion 17 and is arranged to be spaced apart from each other in a direction intersecting the pair of heat transfer surfaces; and each of the pair of heat transfer surfaces having a plurality of grooves 25 having a depth of 100 μm to 400 μm in the thickness direction of the respective plate-shaped fin.

[0025] According to this aspect, since the partition wall and multiple fins are integrally molded based on additive manufacturing, the thermal resistance at the interface between each fin and the partition wall is reduced. Furthermore, forming grooves of appropriate depth on the multiple fins, each with a curved portion, increases the heat transfer area of ​​the fins while smoothing the fluid flow near the fin surface. As a result, the heat exchange efficiency of the heat exchanger can be improved.

[0026] According to the aforementioned structure, a heat exchanger and a method for manufacturing such a heat exchanger can be provided, in which the thermal resistance at the interface between each fin and the partition wall is reduced, the heat transfer area of ​​the fins is increased, and the fluid flow near the fin surface is smoothed. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view showing a schematic structure of a heat exchanger 1 according to an embodiment of the present invention;

[0028] Figure 2 This is a perspective view showing a detail formed on the partition wall 3;

[0029] Figure 3 This is a partial top view of heat exchanger 1;

[0030] Figure 4 This is a perspective view of the heat exchanger 1 excluding the outer casing 9;

[0031] Figure 5 This is a cross-sectional view of fin 5;

[0032] Figure 6 This is an explanatory diagram showing the detailed structure of the fins 5 and the heat transfer surface 21;

[0033] Figure 7 This is a partial bottom view of heat exchanger 1; and

[0034] Figure 8 This is a three-dimensional view of pin-shaped fin 7. Detailed Implementation

[0035] The heat exchanger and its manufacturing method according to embodiments of the present invention will now be described with reference to the accompanying drawings.

[0036] like Figure 1 As shown, the heat exchanger 1 mainly consists of a partition wall 3, multiple plate-shaped fins 5, multiple pin-shaped fins 7, and a shell 9. In the heat exchanger 1, two fluids (a first fluid and a second fluid) at different temperatures, separated by the partition wall 3, are in indirect contact with each other, thereby exchanging heat between them.

[0037] The partition wall 3 forms the body of the heat exchanger 1 as a bottomed cylindrical body. The partition wall 3 has a generally cylindrical side circumferential portion 11 and a bottom 13, the bottom 13 being configured to close one of the openings of the side circumferential portion 11 (here, the lower opening). Inside the partition wall 3, a first fluid 14 is contained, which comprises a liquid with a relatively low temperature that will be heated (e.g., water at room temperature). Furthermore, a second fluid 15 flows outside the partition wall 3, and this second fluid 15 comprises a gas with a higher temperature than the first fluid (here, high-temperature combustion gas from a burner not shown in the figure).

[0038] The partition wall 3 is an integrally molded product that is integrated with the fin 5 and the pin-shaped fin 7. The partition wall 3, fin 5, and pin-shaped fin 7 are made of the same metal material (here, aluminum).

[0039] Multiple fins 5 are formed on the outer surface (one surface) 3A of the partition wall 3. Similarly... Figure 2 As shown, each fin 5 extends from the side circumferential portion 11 of the partition wall 3 to the bottom 13 in its longitudinal direction. Each fin 5 includes a side portion (first portion) 17 with its inner edge connected to the outer surface of the side circumferential portion 11 and a base portion (second portion) 19 with its inner edge connected to the outer surface of the bottom 13.

[0040] In this embodiment, the plurality of fins 5 include two types of fins. Specifically, as shown in the figure... Figure 1 As shown, the plurality of fins 5 include fins with relatively long bases 19 and fins with relatively short bases 19. In the following text, when distinguishing between these two types of fins, they will be referred to as long fins 5L and short fins 5S. Furthermore, the reference numerals indicating the portions of long fins 5L and short fins 5S may be supplemented with "L" and "S" as needed.

[0041] Each fin 5 has a pair of heat transfer surfaces 21, 21 (main heat transfer surfaces), which are configured to intersect or be perpendicular to the circumferential direction of the side circumferential portion 11. Additionally, as... Figure 3As shown, multiple fins 5 are arranged to be spaced apart from each other in the circumferential direction (i.e., the direction intersecting with a pair of heat transfer surfaces 21, 21) throughout the circumferential portion 11. Long fins 5L and short fins 5S are alternately arranged in the circumferential direction.

[0042] like Figure 4 As shown, the side portion 17 of each fin 5 forms a spirally curved portion extending obliquely upward (i.e., in the longitudinal direction) from the upper edge of the base 19 along the side circumferential portion 11 of the partition wall 3. In this way, by bending at least a portion of each fin 5, the fluid flow near the surface of the plurality of fins 5 can be made smoother (which can increase the fluid velocity).

[0043] The width of the side portion 17 of each fin 5 (the distance between the outer edge 17A and the inner edge 17B) is substantially the same over the entire side portion 17 in the longitudinal direction (see...). Figure 1 However, in the side view, the upper edge 17C of the side portion 17 is formed at an acute angle relative to the outer surface 3A of the partition wall 3. Note that it is only required that at least a portion of the side portion 17 forms a curved portion (i.e., a portion having a curved surface that serves as a heat transfer surface). Furthermore, the shape of the curved portion is not limited to a spiral shape, and the curved portion only needs to have at least a curved surface.

[0044] like Figure 5 As shown, the side portion 17 of each fin 5 is formed with a cross-section perpendicular to the longitudinal direction (along... Figure 2 The cross-section (taken from line V-V) gradually narrows from the inner edge 17B towards the outer edge 17A. Consequently, the space between adjacent fins 5 (i.e., the space between adjacent heat transfer surfaces 21) gradually increases from the inside (towards the partition wall 3) towards the outside. This effectively suppresses fluid stagnation between adjacent fins 5.

[0045] A portion of a pair of heat transfer surfaces 21, 21 in the side portion 17 is formed with a plurality of grooves 25 arranged at predetermined intervals from the inner edge 17B to the outer edge 17A. From the viewpoint of improving heat exchange efficiency, the depth D of the plurality of grooves 25 (the depth in the thickness direction of each fin 5, substantially perpendicular to the heat transfer surfaces 21, 21) is preferably set to 100 μm to 400 μm. Similarly, the width W of the plurality of grooves 25 is preferably set to about twice the depth D (200 μm to 800 μm). Furthermore, the interval L between adjacent grooves 25 is preferably set to 100 μm to 300 μm. Note that it is only required that the grooves 25 be formed on at least one of the pair of heat transfer surfaces 21, 21.

[0046] The base 19 of each fin 5 has a substantially straight shape in the longitudinal direction (as seen in the bottom view). The base 19 extends from the lower edge 17D of the side 17 (see...). Figure 6It extends along the bottom 13 of the partition wall 3. In the side view, the base 19 is provided with a protrusion 31 that projects downward to a generally right-angled tip. Although not shown in the figure, the base 19 is configured to taper from the inner edge to the outer edge, similar to the side 17.

[0047] A portion of a pair of heat transfer surfaces 21, 21 in the base 19 is formed with a plurality of grooves 125 similar to the grooves 25 in the side portion 17, but the extending direction of the grooves 125 is different from the extending direction of the grooves 25 in the side portion 17. Specifically, as Figure 6 As shown, the grooves 25 in the side portion 17 each extend in the longitudinal direction (generally vertical) along a portion of the outer surface 3A in the side circumferential portion 11 of the partition wall 3 (i.e., along the side circumferential surface). On the other hand, the grooves 125 in the base portion 19 each extend toward a portion of the outer surface 3A in the bottom portion 13 of the partition wall 3 (i.e., toward the bottom surface). Figure 6 It extends along the middle (in a direction that slopes to the left and upward). The depth, width, and spacing of the groove 125 can be set similarly to the depth, width, and spacing of the groove 25 in the side 17.

[0048] With the above configuration, the second fluid near the bottom surface of the bottomed cylindrical body is guided by a plurality of grooves 125 to flow toward the bottom surface, thereby promoting heat transfer at the bottom 13 of the bottomed cylindrical body. In addition, the second fluid near the side circumferential surface of the bottomed cylindrical body is guided by a plurality of grooves 25 to flow along the side circumferential surface, thereby promoting heat transfer at the side circumferential portion 11 of the bottomed cylindrical body.

[0049] Note that in this embodiment, the partition wall 3 is formed as a bottom cylindrical body, so each fin 5 has a base 19. However, if the partition wall 3 is formed as another structure (e.g., a cylindrical body), the base 19 can be omitted.

[0050] like Figure 7 As shown, the bottom 13 of the partition wall 3 is provided with a plurality of plate-shaped members 35, each plate-shaped member 35 being disposed between circumferentially adjacent long fins 5L. Each plate-shaped member 35 has a generally rectangular shape (see...). Figure 1 In the bottom view, each plate-shaped member 35 extends along the extension line of the end (inner edge) of the short base 19S of each short fin 5S (i.e., extends in the radial direction). Therefore, a plurality of plate-shaped members 35 are arranged in the same number as the number of short fins 5S.

[0051] The inner edges of each plate-shaped member 35 are located approximately at the same position in the radial direction as the inner edges of the bases 19L of each long fin 5L. Therefore, in the bottom 13 of the partition wall 3, the inner edges of the bases 19L of the multiple long fins 5L and the inner edges of the multiple plate-shaped members 35 together define a generally circular area where multiple pin-shaped fins 7 are provided. Note that in the bottom view (or in the horizontal section), the bases 19L of each long fin 5L are formed to taper in the radially inward direction.

[0052] Each plate-shaped component 35 is made of a metal material (here, stainless steel) with a higher emissivity than the metal material forming the fins 5 (here, aluminum). For example... Figure 1 As shown, multiple plate-shaped members 35 are respectively assembled into multiple mounting slots 37 formed on the outer surface 3A of the bottom 13 of the partition wall 3. Note that the material forming the plate-shaped members 35 is not limited to stainless steel, and any metal material with a higher emissivity than the metal material forming at least the fins 5 can be used.

[0053] like Figure 8 As shown, each pin-shaped fin 7 has a tapered cylindrical (or conical) shape. The circumferential surface of each pin-shaped fin 7 has multiple ridges 41 extending in the longitudinal direction (protrusion direction). The multiple ridges 41 are arranged at predetermined intervals along the circumference.

[0054] Due to the multiple ridges 41, the surface area of ​​each pin-shaped fin 7 increases. Furthermore, since the multiple ridges 41 are formed on each pin-shaped fin 7 having a tapered shape, the thickness of the temperature boundary layer formed near the surface of the pin-shaped fin 7 can be reduced. As a result, the thermal resistance of the first fluid 14 within the partition wall 3 is reduced, and convective heat transfer of the first fluid is promoted.

[0055] An unsealed anodic aluminum oxide coating is formed on the inner surface (another surface) 3B of the partition wall 3. The anodic aluminum oxide coating has multiple pores, each with a diameter of 10 nm to 30 nm. Thus, in the heat exchanger 1, the fins 5 formed on the outer surface 3A of the partition wall 3 facilitate heat transfer between the second fluid and the partition wall 3, while the pores formed on the inner surface 3B of the partition wall 3 facilitate heat transfer between the first fluid and the partition wall 3. However, the anodic aluminum oxide coating can be omitted. Furthermore, the anodic aluminum oxide coating may only form on a portion of the inner surface 3B of the partition wall 3 (e.g., only on the inner surface 13B of the bottom 13).

[0056] like Figure 1 As shown, the outer casing 9 is generally cylindrical in shape and is configured to cover the outer sides of the plurality of fins 5. Therefore, the inner surface 9A of the outer casing 9 and the outer surface 3A of the partition wall 3 define a flow path for the second fluid 15, and the plurality of fins 5 are positioned within this flow path.

[0057] The outer casing 9 has an upper portion 51 and a lower portion 53. The upper portion 51 is connected to the outer edges of a plurality of fins 5 located opposite the partition wall 3, and the lower portion 53 is connected to the lower edge of the upper portion 51 and extends downward. The lower edge 51A of the upper portion 51 is connected to the corner of the protrusion 31 of the base 19 of each fin 5. The lower portion 53 is located outside (below) the pin-shaped fin 7 and has an opening 55 of a generally circular shape. The opening 55 forms an inlet for the second fluid 15. Due to this outer casing 9, the second fluid can be effectively guided to the fins 5 disposed on the bottomed cylindrical body.

[0058] In the manufacture of the heat exchanger 1 having the above-described structure, the partition wall 3, the plurality of fins 5, and the plurality of pin-shaped fins 7 are integrally molded using known 3D printing technology (additive manufacturing). There are no particular limitations on the specific processing method used in additive manufacturing, as long as the above structure can be achieved. For example, the heat exchanger 1 is molded by simultaneously jetting metal powder and irradiating the target component with a laser (or electron beam) to form a layer of molten metal powder of the aforementioned shape.

[0059] The outer shell 9 can be integrally molded with the partition wall 3. Alternatively, the outer shell 9 can be formed of a different metal material than the metal material forming the partition wall 3, and subsequently attached by welding or the like to cover the outer side of the plurality of fins 5.

[0060] The unsealed anodized aluminum coating on the inner surface 3B of the partition wall 3 is formed by a known anodizing process (aluminum anodizing process). The structure (pore size, etc.) of the multiple pores in the anodized aluminum coating can be examined using, for example, a field emission scanning electron microscope (FE-SEM).

[0061] When using heat exchanger 1, the user pours water as the first fluid into the interior of partition wall 3 and then starts a burner (e.g., a gas burner) located below heat exchanger 1. Combustion gas, used as the second fluid, is then introduced through opening 55 in housing 9. The combustion gas flows between multiple fins 5 located between partition wall 3 and housing 9 and exits from the upper part of the opening in housing 9. At this time, heat from the combustion gas is transferred to partition wall 3, fins 5, and pin fins 7, and further to the first fluid (water) via the inner surface 3B of partition wall 3. Due to this heat exchange between the combustion gas and water, the temperature of the water inside partition wall 3 can be increased (ultimately causing the water to boil).

[0062] Thus, in heat exchanger 1, since the partition wall 3 and the plurality of fins 5 are integrally molded, the thermal resistance at the interface between each fin 5 and the partition wall 3 is reduced. Furthermore, forming grooves of appropriate depth on the plurality of fins 5, each having a curved portion (here, side portion 17), increases the heat transfer area of ​​the fins 5, while simultaneously smoothing the second fluid flow near the surface of the fins 5. As a result, the heat exchange efficiency of heat exchanger 1 can be improved.

[0063] The specific implementation methods have been described above, but the present invention is not limited to the above implementation methods and can be modified or changed in various ways.

[0064] The partition wall 3 of the heat exchanger 1 is not limited to a bottomed cylindrical body and can take various shapes known to be used in heat exchangers. For example, the partition wall 3 can be configured as a cylindrical body separating a first fluid and a second fluid. In this case, the first fluid flows in a predetermined direction within the partition wall 3. Furthermore, the fins 5 of the heat exchanger 1 only need to be formed on at least one of the outer surface 3A and the inner surface 3B of the partition wall 3.

[0065] Furthermore, the first and second fluids do not necessarily have to be a combination of liquid and gas; any combination of fluids can be used (e.g., a combination of liquids or a combination of gases). Heat exchanger 1 only requires the use of at least two fluids, and can use three or more fluids for heat exchange between them.

[0066] Furthermore, in the heat exchanger 1, even when there are limitations on the metal material used in the fins 5 integrally molded with the partition wall 3 (e.g., the metal materials that can be used for additive manufacturing are limited), the plate-shaped member 35 with a high emissivity can enhance thermal radiation (radiative heat transfer) to improve the uniformity of fluid temperature in the heat exchanger 1 and thus improve the heat exchange efficiency of the heat exchanger 1.

[0067] Heat exchanger 1 can be used in, for example, refrigerators, industrial heat exchangers, plate heat exchangers, and tubular channel heat exchangers. Furthermore, since heat exchanger 1 can be used as part of a device or machine with partition walls and fins, it can be used as a heat exchanger. Such heat exchanger 1 can be used in fluid passage structures such as air-cooled engine heads, radiators, oil coolers, water boilers, air conditioning equipment, exhaust gas recirculation (EGR) coolers, Stirling engines, etc.

Claims

1. A heat exchanger, the heat exchanger comprising: A partition wall that separates two fluids at different temperatures; as well as Multiple plate-shaped fins are formed on at least one surface of the partition wall and each has a pair of heat transfer surfaces. The partition wall and the plurality of plate-shaped fins are made of the same metal material to form an integrally molded product. The plurality of plate-shaped fins each have a curved portion and are arranged to be spaced apart from each other in a direction intersecting the pair of heat transfer surfaces, and Each of the pair of heat transfer surfaces is formed with a plurality of grooves with a depth of 100 μm to 400 μm in the thickness direction of each plate-shaped fin. The partition wall is formed into a bottom cylindrical body. Each plate-shaped fin includes: Side portion, the side portion being connected to the outer surface of the side circumferential portion of the partition wall; and The base is connected to the outer surface of the bottom of the partition wall. The plurality of plate-shaped fins include long fins and short fins alternately arranged in the circumferential direction. The heat exchanger further includes plate-shaped members, each plate-shaped member being made of another metallic material with a higher emissivity than the aforementioned metallic material. These plate-shaped members extend along the extension line of the base of the short fins and are attached to the partition wall between the bases of adjacent long fins in the long fins. The plate-shaped members are respectively assembled into mounting grooves formed on the outer surface of the bottom of the partition wall.

2. The heat exchanger according to claim 1, wherein, The other surface of the partition wall, which is not provided with the plate-shaped fins, has a plurality of holes, each hole having a diameter of 10 nm to 30 nm.

3. The heat exchanger according to claim 1, wherein, Each plate-shaped fin has a cross-section that tapers away from the partition wall.

4. The heat exchanger according to claim 1, wherein, Each of the plurality of plate-shaped fins is connected to the bottom surface and the side circumferential surface of the bottomed cylindrical body, which form the outer surface of the bottomed cylindrical body. In the first portion of the connection between the various plate-shaped fins and the bottom surface of the bottomed cylindrical body, the plurality of grooves each extend toward the bottom surface, and In the second portion of each plate-shaped fin connected to the side circumferential surface of the bottomed cylindrical body, the plurality of grooves each extend along the side circumferential surface.

5. The heat exchanger according to claim 4, wherein, The heat exchanger also includes a housing configured to cover the outer side of the plurality of plate-shaped fins, and the outer edge portions of the plurality of plate-shaped fins opposite to the partition wall are each connected to the housing.

6. The heat exchanger according to claim 4, wherein, The heat exchanger further includes a plurality of pin-shaped fins, which are arranged to protrude outwards from the areas on the bottom surface of the bottom cylindrical body where the plurality of plate-shaped fins are not formed. The inner edges of each plate-shaped member are located approximately at the same position in the radial direction as the inner edges of the base of each long fin, and In the bottom of the partition wall, the inner edge of the base of the long fin and the inner edge of the plate-like member together define a generally circular area where the pin-shaped fin is provided.

7. The heat exchanger according to claim 4, wherein, The curved portion of each of the plurality of plate-shaped fins is helically curved.

8. A method for manufacturing a heat exchanger, the method comprising the following steps: A partition wall and multiple plate-shaped fins are integrally molded using the same metal material based on additive manufacturing. The partition wall separates two fluids at different temperatures. The multiple plate-shaped fins are formed on at least one surface of the partition wall and each has a pair of heat transfer surfaces. Each of the multiple plate-shaped fins has a curved portion and is arranged to be spaced apart from each other in a direction intersecting the pair of heat transfer surfaces. Each of the pair of heat transfer surfaces is formed with a plurality of grooves with a depth of 100 μm to 400 μm in the thickness direction of each plate-shaped fin. The partition wall is formed into a bottom cylindrical body. Each plate-shaped fin includes: Side portion, the side portion being connected to the outer surface of the side circumferential portion of the partition wall; and The base is connected to the outer surface of the bottom of the partition wall. The plurality of plate-shaped fins include long fins and short fins alternately arranged in the circumferential direction. The heat exchanger further includes plate-shaped members, each plate-shaped member being made of another metallic material with a higher emissivity than the aforementioned metallic material. These plate-shaped members extend along the extension line of the base of the short fins and are attached to the partition wall between the bases of adjacent long fins in the long fins. The plate-shaped members are respectively assembled into mounting grooves formed on the outer surface of the bottom of the partition wall. The plurality of plate-shaped fins are each connected to the bottom surface and the side circumferential surface of the bottomed cylindrical body, which form the outer surface of the bottomed cylindrical body. In the first portion of the connection between the various plate-shaped fins and the bottom surface of the bottomed cylindrical body, the plurality of grooves each extend toward the bottom surface, and In the second portion of each plate-shaped fin connected to the side circumferential surface of the bottomed cylindrical body, the plurality of grooves each extend along the side circumferential surface.

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