JPH0443738Y2 - - Google Patents

Description

[Detailed explanation of the idea]

INDUSTRIAL APPLICATION FIELD The present invention relates to a heat transfer finned tube fin for a heat exchanger used to recover the thermal energy of exhaust gas and heat another fluid. BACKGROUND ART Conventionally, when attaching plate-type fins to increase the heat transfer area to a heat transfer tube of a heat exchanger, as shown in FIGS. Fin elements 7 are punched and formed in advance so that they abut each quarter circle.
2.73, one pair of fin elements are welded to each tube by electric resistance welding,
The finned tube 74 was manufactured by repeating this operation. After a predetermined number of fin elements were attached to each tube in this manner, the plurality of finned tubes were connected by a U-bend pipe 75 to form a tube nest 76 of the heat exchanger. Problems to be solved by the invention When attaching this type of fin element by electric resistance welding, it is necessary to ensure that current flows uniformly across the welding surface, so the length of contact between the fin element and the outer circumference of the tube must be Therefore, it was not possible to increase the contact length between the fin element and the outer circumference of the tube. Further, even with such restrictions, it is actually impossible to flow the current completely uniformly, so it has not been possible to obtain complete welding over the entire contact surface. Due to these reasons, the fin efficiency decreases, and a larger heat transfer area is required for the same amount of heat exchanged, resulting in a problem that the size, weight, and cost of the heat exchanger increase. Furthermore, because it is necessary to uniformly flow current to the contact surface, it is necessary to attach fin elements one pair at a time to each tube, and it takes a lot of work time to install a large number of fin elements. In addition, when assembling the tubes into the tube nest after the fin elements have been attached, the tubes must be welded to the U-bent tube one by one, but not only is this process time-consuming, but the welded parts are susceptible to thermal stress and There was a problem that it often broke due to vibration. The purpose of this invention is to reduce the required heat transfer area by increasing the fin efficiency of the finned tube.
Tube 1, inherent in reducing heat exchanger size, weight, cost, and electric resistance welding
To provide fins that enable welding by arc welding by eliminating the trouble of welding a pair of fin elements to each book, and to eliminate the need to connect tubes with each other with a U-bend pipe after installing fin elements. There is a particular thing. Means for Solving the Problems In order to achieve the above object, the finned tube according to the present invention is obtained by bending a straight tube into a meandering shape having a plurality of bent portions and straight portions, and A pair of half-split fin elements each having a length extending over a plurality of straight pipe portions, having a plurality of semicircular recesses for contacting the outer periphery of each tube, and having a slit bored between the recesses. The fin elements are punched out from a plate material in advance and attached to the outer periphery of each tube one by one by arc welding. Further, the slits are provided with a narrow width that leaves a slight web between each of the recesses of the fin element. Therefore, the heat generated during welding between the outer periphery of one tube and the concave part of the fin element that contacts it is blocked by the slit, so the fin element is distorted and the adjacent concave part makes proper contact with the outer periphery of the tube. prevent it from disappearing. Effects According to the configuration of the present invention, the fin element is provided with slits to block the transmission of welding heat and the propagation of welding distortion. Can be handled with just one pair of elements,
Moreover, it can be attached by arc welding. Unlike electric resistance welding, with arc welding, the length of contact between the fin element and the tube is the entire circumference of the tube, and the adhesion is perfect.
This saves you the trouble of attaching a pair of fin elements to each book. Furthermore, there is no need to weld and connect each tube with a U-bent pipe after installing the fin element. Due to these effects,
In addition to reducing the size, weight and manufacturing costs of the heat exchanger, the investment in welding equipment is significantly reduced compared to traditional electrical resistance methods. Further, since the plurality of tubes are integrated with a large number of fin elements, the strength of the tube group is increased, and since a part of the fin elements can also be used as a support for the tube, a tube support is not required. Embodiment An embodiment of the present invention will be described below based on the drawings. In FIGS. 1 to 4, numeral 1 designates a tube, which is formed into a meandering shape by inverting a straight tube at a U-bend portion 11 to form a plurality of tubes in parallel. A continuous strip-shaped (flat plate-shaped) fin element 2 is formed over the entire span of the plurality of parallel parts (straight pipe parts) 12 of the tube 1 formed in a meandering shape and between the outer peripheries of each tube. can be installed. This fin element 2 is made up of a combination of a pair of left and right half-split fin elements 2A, 2B, and the opposing surfaces 21A, 21B of these half-split fin elements 2A, 2B are provided with a plurality of parallel parts (straight pipe parts) of the tube 1. ) Recesses 22A and 22B that fit the outer periphery of 12
A plurality of tubes are formed in accordance with the pitch of the plurality of parallel tube sections (straight tube sections) 12. In addition, the recess 22
A and the recess 22A, and between the recess 22B and the recess 22B, and the opposing surfaces 21A, 21
A slight web 23 in the direction perpendicular to B (width direction)
Leaving A, 23B, narrow slits 24A, 2
4B will be provided. In this case, the webs 23A, 23B
As shown in FIGS. 1 and 2, the opposing surfaces 21A,
The slits 24A and 24B exhibit the same effect even if they are left on the opposite side of the slit 21B, or even if they are left on the facing sides 21A and 21B as shown in FIG. As shown in FIG. 1, the pair of half-split fin elements 2A and 2B are approached from the left and right so as to sandwich the tube 1, and as shown in FIG.
A, 22B are brought into contact with the outer periphery of the tube 1, and the facing surfaces 21A, 21B are brought into contact with each other. In this state, halved fine elements 2A, 2B
The fin element 2 is attached to the tube 1 by welding the concave portions 22A, 22B and the outer periphery of the tube 1 in the circumferential direction by arc welding. Further, the facing surfaces 21A and 21B may be welded if necessary. In this case, welding can be performed continuously. By similar operation, as shown in FIG. 3, a large number of fin elements 2 are installed in parallel at a predetermined pitch in the tube axis direction to form a finned tube 3, and multiple rows of finned tubes 3 are Inlet header 4 and outlet header 5
By connecting with , as shown in Figure 4,
A finned tube nest 6 can be formed as a heat exchanger. Effects of the invention According to the configuration of the invention described above, the following effects can be expected. In other words, since the fin element is provided with a slit, the heat and distortion of the fin element generated when welding the outer periphery of a certain tube and the concave part of the fin element that is in contact with it is transferred to the adjacent fin including the concave part. In order to prevent heat transfer and strain propagation to the element part, the fin element that spans the entire span of multiple parallel tubes that have been bent into a serpentine shape in advance is
It can be attached to multiple parallel tubes in sequence by arc welding. (a) Because of arc welding, the fin element and the outer circumference of the tube are perfectly welded, and the contact length is the entire circumference of the tube, so the fin efficiency is maximized and the heat transfer area is reduced. can. (a) Only one pair of fin elements can be used for multiple tubes, saving the effort of installing one pair of fin elements for each tube. (c) The difficult work of welding the tubes together with a U-bend pipe after attaching the fin element to the tubes is eliminated, and troubles caused by this are eliminated. (d) Continuous fin elements reduce gas flow resistance and reduce soot adhesion in exhaust gas. (e) Since the fin element is integrated with several tubes, the strength of the tube group increases, and furthermore, it can be used as a support for the tubes, so no support is required. Therefore, it is possible to reduce the size, weight, and manufacturing cost of a heat exchanger composed of finned tubes manufactured in this way, and also to reduce equipment costs compared to electric resistance welding. can be significantly reduced. Incidentally, when the results of a fabrication experiment of a finned tube according to the present invention and the results of a trial design of a heat exchanger constructed from this finned tube were compared with those using conventional electric resistance welding, the following values were obtained.

【table】

[Table] Furthermore, in the case of arc welding, it is usually necessary to remove a groove at the welding site, but in the case of the present invention, better welding was achieved when the groove was not removed.
Therefore, after punching out the fin element from the plate material, there is no need for machining to create a groove, which is a great advantage.

[Brief explanation of the drawing]

Figures 1 to 4 show one embodiment of the present invention, Figures 1 and 2 are side views showing the structure and manufacturing state of the fin element and tube, and Figure 3 shows one row of finned tubes. 4 is a perspective view of a tube nest with fins, FIG. 5 is a side view of a fin element of another embodiment, FIGS. 6 to 9 show a conventional example, and FIG. 7 is a front view, FIG. 7 is a side view of the same, FIG. 8 is a perspective view of the same tube nest, and FIG. 9 is a side view showing another conventional example. 1...Tube, 11...U-bend pipe, 12...
...Multiple parallel part (straight pipe part), 2...Fin element, 2A, 2B...Half fin element, 21
A, 21B... Opposite surfaces, 22A, 22B... Concavity, 23A, 23B... Web, 24A, 24B
...Slit, 3...1 row finned tube,
4...Fluid inlet header, 5...Fluid outlet header,
6...Tube nest with fins.

Claims (1)

[Scope of utility model registration request] A pair of half-split fin elements in a rectangular shape having a length spanning the entire span of tubes arranged in parallel over multiple stages are provided with recesses that contact the outer periphery of each tube on opposing surfaces, and the pair of half-split fin elements are A fin for a finned tube in which the outer periphery of each tube is brought into contact with each concave part of the element and fixed by welding is characterized by providing a narrow slit that leaves a slight web between each concave part. Fins for tubes with fins.