JP2009257608A - Fin tube, heat exchanger, and manufacturing method of fin tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fin tube having high durability and achieving high heat exchanging efficiency. <P>SOLUTION: This fin tube FT1 comprising a metallic tubular body 1, and a metallic fin 2 disposed at an outer circumference of the tubular body 1, further comprises a coating layer 3 made of an anticorrosive material, covering an outer peripheral face of the tubular body 1, and disposed in a state that at least a part of a metallic face of the fin is exposed to the external, the tubular body 1 and the fin 2 are kept into contact with each other without through the coating layer 3, or integrally connected with each other. Preferably, the fins 2 are provided with through-holes 22 in which a part of the coating layer 3 enters, and parts 30 adjacent to each other through each fin 2, of the coating layer 3 are integrally connected through the part entering into the through-hole 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fin tube used for heat exchange, a heat exchanger provided with the fin tube, and a method for manufacturing the fin tube.

  Specific examples of conventional fin tubes include those described in Patent Documents 1 and 2. The fin tube described in Patent Document 1 has a configuration in which a plurality of metal fins are externally attached to a metal tube body, and the entire outer surface of the tube body and each fin is resin-coated. Yes. According to such a configuration, even if the pipe body and the fins are made of a metal that is relatively easily corroded, the corrosion can be prevented and the durability can be enhanced.

  On the other hand, in the fin tube described in Patent Document 2, a spiral metal fin is attached to a metal tube. However, a resin coating layer is formed on the entire outer peripheral surface of the tubular body, and the inner peripheral portion of the fins bites into the resin coating layer. According to such a configuration, the fin can be easily attached to the tubular body. In addition, since the resin coating layer is formed on the outer peripheral surface of the tubular body, it is possible to prevent the tubular body from being easily corroded.

  However, in the above-described prior art, there is a point to be improved as described below.

  That is, in the fin tube described in Patent Document 1, since the entire outer surface of the tube body and each fin is covered with the resin coating layer, when heat exchange is performed using this fin tube, The heat medium existing outside cannot be brought into direct contact with the outer surface (metal surface) of the tube body or each fin. Therefore, there is a problem that the heat transfer coefficient between the heat medium and the fin tube is low and the heat exchange efficiency is low. In particular, since the resin coating layer has a low thermal conductivity, the above problem is more remarkable.

  On the other hand, in the fin tube described in Patent Document 2, the entire outer peripheral surface of the tubular body is covered with a resin coating layer, and the resin coating layer is also interposed between the tubular body and the fin. For this reason, the resin coating layer hinders heat transfer between the tube body and each fin, and the heat exchange efficiency is also low.

JP 2003-161595 A Japanese Patent Laid-Open No. 2005-98666

  The present invention has been conceived under the circumstances as described above, and is a fin tube, a heat exchanger, and such a fin that have good durability and can obtain high heat exchange efficiency. An object of the present invention is to provide a method for manufacturing a fin tube that can appropriately manufacture the tube.

  In order to solve the above problems, the present invention takes the following technical means.

  The fin tube provided by the 1st side surface of this invention is a fin tube provided with the metal pipe body and the 1 or several metal fin provided in the outer periphery of this pipe body. A coating layer of a corrosion-resistant material provided so as to cover the outer peripheral surface of the tube and to expose at least a part of the metal surface of the fin to the outside, the tube and the fin, It is characterized by being configured to be in contact with each other or integrally connected without interposing the coating layer.

According to such a configuration, the outer peripheral surface of the metal tube can be appropriately protected by the coating layer of the corrosion resistant material. On the other hand, since at least a part of the metal surface of the fin is exposed to the outside, the heat medium existing outside the fin tube can be brought into direct contact with the exposed portion. In addition, since no coating layer is provided between the fin and the tube, and the fin and the tube are in direct contact or integrally connected, heat transfer between the fin and the tube is performed. Or thermal conductivity can be improved. Therefore, it is possible to improve the heat exchange efficiency as compared with the conventional technique while improving the durability of the fin tube. In the present invention, since the metal surface of the fin is exposed, if the fin is made of, for example, copper, the fin may be corroded and thinned by long-term use. Even if the fins are slightly thinned, the heat exchange performance of the fin tube will not be greatly deteriorated, and the fluid flowing through the tube will not leak to the outside. Absent.
As described above, the present invention provides the pipe body with corrosion resistance to improve the durability of the entire fin tube, and the fins do not give priority to corrosion resistance but heat transfer performance with an external heat medium. As a configuration that can improve the heat transfer performance between the tube and the tube, it is intended to increase the heat exchange efficiency of the entire fin tube, and its practical value is great.

  In a preferred embodiment of the present invention, the fin has a through hole penetrating in the thickness direction, and a part of the coating layer enters the through hole.

  According to such a configuration, a part of the coating layer enters the through-hole formed in the fin, so that the effect of fixing the coating layer to the fin is exhibited. Therefore, for example, even when the coating layer is subjected to thermal strain, it is possible to prevent the coating layer from being easily peeled off from the fins and the tube due to this.

  In a preferred embodiment of the present invention, portions of the coating layer that are adjacent to each other with the fin interposed therebetween are integrally connected via a portion entering the through hole.

  According to such a configuration, the coating layer is not completely divided into a plurality of portions by fins, and the entire coating layer is integrally formed through the portion entering the through hole. A connected configuration can be adopted. Therefore, it is possible to prevent the coating layer from peeling off from the tube more thoroughly, and to further enhance the durability performance of the fin tube.

  The heat exchanger provided by the second aspect of the present invention includes the fin tube provided by the first aspect of the present invention.

  According to such a configuration, the same effect as described for the fin tube provided by the first aspect of the present invention can be obtained.

  In a preferred embodiment of the present invention, it has a plurality of fin tubes in which one or more metal fins are provided on the outer periphery of a metal tube, and from combustion gas or other gas including latent heat. A heat exchanger used for recovering sensible heat and latent heat to generate hot water, wherein only the fin tubes of the plurality of fin tubes that perform latent heat recovery are according to the first aspect of the present invention. The fin tube is provided.

  According to such a configuration, it is possible to achieve a favorable durability performance of the entire heat exchanger and to obtain a high heat exchange efficiency while suppressing an increase in the manufacturing cost of the heat exchanger. That is, condensate is generated during the recovery of latent heat, but the fin tube where such condensate is generated is a fin tube with corrosion resistance on the tube body, and is therefore attributable to the condensed water. Therefore, the tube body of the fin tube is not easily damaged. On the other hand, since the fin tube of the portion that collects sensible heat is configured so that the coating layer is not provided on the tube body, heat recovery using the tube body is also possible, and heat exchange efficiency can be improved. In addition, the manufacturing cost can be reduced as much as the coating layer is not provided.

  The manufacturing method of the fin tube provided by the 3rd side surface of this invention is a method for manufacturing the fin tube provided by the 1st side surface of this invention, Comprising: On the outer peripheral surface of metal pipes A fin tube intermediate product is provided in which one or a plurality of metal fins are in direct contact with each other or integrally connected, and a corrosion-resistant material is applied to substantially the entire outer peripheral surface of the tube and the outer surface of the fin. Applying a coating layer to form a coating layer, and immersing a part of the fin in a solvent to remove the coating layer formed on the surface of the fin. It is said.

  According to such a configuration, the fin tube provided by the first aspect of the present invention can be appropriately manufactured by a simple work process. That is, unlike the above-described configuration, for example, when a means for coating a corrosion-resistant material only on the outer peripheral surface of the pipe body is employed while preventing the fin from being coated, for example, the fins are arranged on the outer circumference of the pipe body at a narrow pitch. In the case where a plurality of fins are provided, it is necessary to finely apply a corrosion-resistant material to a narrow region between these fins, which makes this operation difficult. On the other hand, according to the above-described configuration of the present invention, such fine work is unnecessary and workability is good.

  Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  FIGS. 1-3 has shown an example of the heat exchanger provided with the fin tube to which this invention was applied. As clearly shown in FIG. 1, the heat exchanger HE <b> 1 of this embodiment includes a plurality of fin tubes FT <b> 1 and a casing 4.

  2 and 3, each fin tube FT1 is mounted on the outer periphery of the tube body 1 and the tube body 1 and arranged in a longitudinal direction of the tube body 1 at an appropriate pitch. The coating layer 3 which covers the fin 2 and the outer peripheral surface 10 of the tubular body 1 is provided. Tube 1 is made of, for example, copper. Each fin 2 is made of, for example, copper like the tubular body 1, and includes a cylindrical portion 20 that is externally fitted to the tubular body 1, and a disk-shaped flange portion 21 that is integrally connected to the cylindrical portion 20. Yes. The inner peripheral surface 20a of the cylindrical portion 20 is in contact with the outer peripheral surface 10 of the tubular body 1 without the coating layer 3 therebetween, and is configured so that heat transfer between the fin 2 and the tubular body 1 is good. Has been. Further, the width L1 of the cylindrical portion 20 is larger than the thickness t1 of the flange portion 21, and the heat transfer area between the fin 2 and the tubular body 1 is increased.

  The coating layer 3 is made of a resin having excellent corrosion resistance such as epoxy, urethane, or acrylic, for example, and covers substantially the entire outer peripheral surface 10 of the tubular body 1 and the outer peripheral surface of the cylindrical portion 20 of the fin 2. However, as described above, the outer peripheral surface 10 of the tubular body 1 and the inner peripheral surface 20a of the cylindrical portion 20 are in direct contact, and the coating layer 3 is not interposed between them. A plurality of through holes 22 penetrating in the thickness direction of the flange portion 21 are formed in the flange portion 21 of each fin 2. On the other hand, the coating layer 3 is formed so that each through-hole 22 is buried inside the coating layer 3 so as not to cover a large area of the flange 21, and a part of the coating layer 3 is formed. Has entered each through hole 22. Although the coating layer 3 is divided into a plurality of portions 30 by a plurality of fins 2 in the longitudinal direction of the tube body 3, the plurality of portions 30 are integrally formed through the portions that have entered the through holes 22. It is connected.

  In FIG. 1, the casing 4 has a cylindrical shape such as a cylindrical shape or a rectangular shape, and, for example, combustion gas or other heating gas flows therein as a heating medium. The plurality of fin tubes FT <b> 1 are arranged in the casing 4 so that both ends in the longitudinal direction thereof are exposed to the outside of the casing 4, and are connected in series via the U-shaped tube 5. Both ends of the plurality of fin tubes FT1 connected in this way are an inlet 19a and an outlet 19b for the fluid to be heated. The casing 4 is made of, for example, copper. However, for the purpose of preventing the casing 4 from being corroded, the inner surface thereof may be resin-coated.

  The fin tube FT1 described above can be manufactured by a method as shown in FIG. 4, for example.

  First, as shown in FIG. 4 (a), for example, the fin tube intermediate product FT ′ is immersed in the paint 3A, or as shown in FIG. 4 (b), the paint 3A is sprayed from the coating nozzle 8. For example, the outer surface of the fin tube intermediate product FT ′ is coated. The fin tube intermediate product FT ′ is different from the finished product of the fin tube FT1 shown in FIGS. 2 and 3 in that the coating layer 3 is not formed, and other configurations are the same as the finished product. It is. The paint 3A contains, for example, an epoxy resin, a urethane resin, or an acrylic resin. By the above-described painting operation, a coating layer 3 ′ is formed on the entire outer surface of the fin tube intermediate product FT ′ as shown in FIG. The coating layer 3 ′ is formed so as to enter the through holes 22.

  Next, as shown in FIG. 4D, the fin tube intermediate product FT ′ is rotated in a state in which a part of each fin 2 is immersed in the solvent 7, and the fin 2 is close to the outer peripheral edge of the flange portion 21. The large-area coating layer 3 'is removed. As a result, as shown in FIG. 5E, the coating layer 3 covering the outer peripheral surface of the tube body 1 can be formed in a state where a part of the plurality of through holes 22 has entered. FT1 can be manufactured appropriately.

  According to the manufacturing method as described above, even when the arrangement pitch of the fins 2 is small, the coating layer 3 can be easily and appropriately formed in a narrow region between the fins 2. . Accordingly, it is possible to make it difficult to cause a coating failure. Moreover, the manufacturing cost of fin tube FT1 can also be suppressed.

  Next, the operation of the heat exchanger HE1 including the above-described fin tube FT1 will be described.

  First, the heat exchanger HE1 is used in a state where a heated fluid is supplied into the tube body 1 of the fin tube FT1 and a heating heat medium such as combustion gas is supplied into the casing 1. Since the outer peripheral surface 10 of the tube 1 is covered with the coating layer 3, the heat of the heat medium is not directly transferred to the tube 1, but the heat medium is exposed to the outside of the fins 2. It directly contacts the metal surface and efficiently transfers heat to each fin 2. Further, the heat transmitted to each fin 2 is transmitted from the cylindrical portion 20 of each fin 2 to the tube body 1. As described above, the cylindrical portion 20 and the tube body 1 are in direct contact with each other, and their contact area is increased, so that heat transfer from each fin 2 to the tube body 1 is also efficiently performed. . Therefore, in this heat exchanger HE1, although the pipe body 1 is covered with the resin coating layer 3, the amount of heat recovered from the heat medium is increased to efficiently heat the fluid to be heated in the pipe body 1. Therefore, high heat exchange efficiency can be obtained.

  On the other hand, since the tube body 1 is covered with the resin coating layer 3, a corrosive drain is generated when the heat medium contains a component that corrodes copper or when heat is recovered from the heat medium. Even in this case, the tube body 1 does not easily corrode. Therefore, it is possible to improve the durability of the fin tube FT1, and it is possible to prevent a problem in which the tube body 1 is damaged by corrosion and the heated fluid leaks out from the damaged portion. . About each fin 2, although the metal surface is exposed outside, there is a possibility that it will be somewhat thin due to corrosion, but even if each fin 2 is so thin, due to this There is no particular problem because the heat recovery function is not greatly impaired or the fluid to be heated does not leak. Preferably, each fin 2 may have a design specification that takes into account that the thickness t1 of the fin 2 decreases with use.

  As described with reference to FIG. 2, in the coating layer 3, the portions 30 adjacent to each other with the fins 2 interposed therebetween are integrated with each other through the portions entering the through holes 22 of the fins 2. It is connected. According to such a configuration, the plurality of portions 30 of the coating layer 3 are not simply connected together, but the portion of the coating layer 3 entering the through hole 22 A function of positioning and fixing the whole to the fins 2 will be exhibited. Therefore, the coating layer 3 can be prevented from being easily peeled off from the tube body 1. Since the fin tube FT1 is used under conditions where the temperature changes frequently, unlike the present embodiment, for example, if the coating layer 3 is simply formed on the outer peripheral surface of the tube body 1, the coating layer 3 is There is a possibility that the tube body 1 is relatively easily peeled off due to frequent thermal strain. On the other hand, in this embodiment, it is possible to appropriately eliminate such a concern, and the durability of the fin tube FT1 is further improved.

  5 to 7 show other embodiments of the present invention. In these drawings, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as in the above embodiment.

  In the fin tube FT2 shown in FIG. 5, the tubular body 1A and the plurality of fins 2A are integrally formed. Since the tube body 1 </ b> A and the plurality of fins 2 </ b> A are integrally formed per se, the manufacturing method thereof is omitted. Even in the case where the tube body 1A and the fins 2A are integrally formed as in the present embodiment, heat transfer from the fins 2A to the tube body 1A is directly performed without passing through the coating layer 3. It will be. Therefore, the same effect as the fin tube FT1 of the embodiment can be obtained.

  The fin tube FT3 shown in FIG. 6 is a so-called plate fin type, and is configured such that a plurality of tube bodies 1 penetrates each of a plurality of plate-like fins 2B arranged at predetermined intervals. The coating layer 3 (portion indicated by a halftone dot pattern in the figure) covers the outer peripheral surface 10 of the tube body 1 and also covers the peripheral region of the tube body 10 among the fins 2B. Has also entered. Also in this embodiment, the same effect as the above-described embodiment can be obtained. The fin tube referred to in the present invention is a concept including a plate fin type as in this embodiment.

  The heat exchanger HE2 shown in FIG. 7 is for recovering sensible heat and latent heat from the combustion gas generated by the combustor 90 such as a gas burner or an oil burner to generate hot water, and is supplied with the combustion gas. Inside the casing 4A, a plurality of fin tubes FT1 to which the present invention is applied and a plurality of fin tubes 6 to which the present invention is not applied are provided. The plurality of fin tubes 6 are for sensible heat recovery, and are disposed closer to the combustor 90 than the plurality of fin tubes FT1. Each fin tube 6 has a configuration in which, for example, a plurality of copper fins 61 are attached to the outer periphery of a copper tube body 60 at an appropriate arrangement pitch. The tube body 60 and each fin 61 are resin-coated. In other words, almost the entire outer surface remains a metal surface. On the other hand, the plurality of fin tubes FT1 are for recovering latent heat from the combustion gas after the sensible heat has been recovered by the fin tubes 6, and the configuration thereof is the same as that of the fin tube FT1 of the embodiment. is there. The fin tubes FT1 and FT6 are connected to each other via the U-shaped tube 5A. The fin tubes FT1 and FT6 are allowed to enter the water from the inlet 19a and the hot water can be discharged from the outlet 19b. is there.

  According to this embodiment, when latent heat recovery is performed from combustion gas, a strongly acidic drain (condensate) containing nitrogen oxides in the combustion gas is generated, whereas such latent heat recovery is performed. Since the fin tube FT1 to which the present invention is applied is used for the portion to be performed, the pipe body 1 of the fin tube FT1 is not easily corroded due to the drain. On the other hand, a copper fin tube 6 that is not subjected to any resin coating is used for the portion that recovers sensible heat. However, since the strongly acidic drain as described above does not occur in this portion, the tube Again, the body 60 is not easily corroded. Since the fin tube 6 has high heat exchange efficiency as much as the tube body 6 is not coated with the resin, the total number of fin tubes 6 is reduced to reduce the size of this portion, and thus the overall size of the heat exchanger HE2. Can be achieved. As understood from the present embodiment, in the present invention, the present invention may be applied to only some of the fin tubes of the plurality of fin tubes constituting the heat exchanger.

  The present invention is not limited to the contents of the above-described embodiment. The specific configuration of each part of the fin tube and the heat exchanger according to the present invention can be varied in design in various ways. Moreover, the specific structure of each process of the manufacturing method of the fin tube which concerns on this invention can be changed variously.

  For example, the coating layer referred to in the present invention may be any material that is more excellent in corrosion resistance than a tubular body. The coating layer can be made of other materials such as ceramics other than resin.

  The tube body and the fin may be made of metal, and are not limited to copper. Aluminum or other various materials can be used. Of course, the tube and the fin may be made of different materials. As the fin, for example, a helical fin described in Patent Document 2 can be used. Although the present invention allows the fins to corrode, the fins may be made of stainless steel, for example, so that the fins have a corrosion resistance. However, stainless steel is inferior in thermal conductivity compared to copper or the like, and is expensive. Therefore, it is preferable to use a metal having high thermal conductivity and low cost for the fins and pipes without much consideration of corrosion resistance. The fin tube of the present invention can be used not only as a component of a heat exchanger for generating hot water, but also for various heat exchange applications (including cooling and heat dissipation).

It is a schematic sectional drawing which shows an example of the heat exchanger provided with the fin tube which concerns on this invention. It is a principal part expanded sectional view of the fin tube shown by FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 2. (A)-(e) is explanatory drawing which shows an example of the manufacturing method of the fin tube shown by FIG. It is principal part sectional drawing which shows the other example of the fin tube which concerns on this invention. It is a principal part perspective view which shows the other example of the fin tube which concerns on this invention. It is principal part sectional drawing which shows the other example of the heat exchanger which concerns on this invention.

Explanation of symbols

HE1, HE2 Heat exchangers FT1-FT3 Fin tube FT 'Fin tube intermediate product 1, 1A Tube 2, 2A, 2B Fin 3 Coating layer 10 Outer peripheral surface (of tube)
20 Cylindrical part (fin)
21 Buttocks (of fins)
22 Through-holes 30 Multiple parts (parts adjacent to each other with a fin in the coating layer)

Claims (6)

A metal tube,
One or more metal fins provided on the outer periphery of the tube;
A fin tube comprising:
A coating layer of a corrosion-resistant material provided to cover the outer peripheral surface of the tubular body and to expose at least a part of the metal surface of the fin to the outside;
The fin tube, wherein the tube and the fin are in contact with each other or integrally connected without the coating layer interposed therebetween.   The fin tube according to claim 1, wherein a through-hole penetrating in the thickness direction is formed in the fin, and a part of the coating layer enters the through-hole.   The fin tube according to claim 2, wherein portions of the coating layer adjacent to each other with the fin interposed therebetween are integrally connected via a portion entering the through hole.   A heat exchanger comprising the fin tube according to any one of claims 1 to 3. A plurality of fin tubes each having one or more metal fins provided on the outer periphery of the metal tube;
A heat exchanger used to generate sensible heat and latent heat from combustion gas and other gases containing latent heat to generate hot water,
5. The heat exchanger according to claim 4, wherein only the fin tube that performs latent heat recovery among the plurality of fin tubes is the fin tube according to claim 1. A method for producing a fin tube according to any one of claims 1 to 3,
A fin tube intermediate product is provided in which one or a plurality of metal fins are in direct contact with or integrally connected to the outer peripheral surface of a metal tube, and the outer peripheral surface of the tube and the fins are prepared. Applying a corrosion-resistant material to substantially the entire outer surface of the coating layer to form a coating layer;
Removing a coating layer formed on the surface of the fin by immersing a part of the fin in a solvent; and
The manufacturing method of a fin tube characterized by having.

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