Snakelike fin cluster with arc notches formed in single-side fin top and teeth formed in arc contour line

Abstract

The snakelike fin cluster is formed by bending a strip-shaped thin plate with a certain width, the single-side fins are provided with the arc notches in a jacking mode, the arc notches are used for being in contact with the outer circle face of a circular base tube to be connected, the arc contour lines of the arc notches are provided with the teeth and bent, and when the snakelike fin cluster is unfolded, the single-side fins abut against the arc notches to be connected with the outer circle face of the circular base tube. A plurality of tooth-shaped arc notch holes are formed in a single-side fin top line at certain intervals, the two ends of each tooth-shaped arc notch hole are symmetrical, the tooth-shaped arc notch holes are connected at certain intervals with the fin top line as the symmetry axis, teeth on the tooth-shaped arc notch holes are bent by 60-85 degrees towards one side at the tooth root position, after the fin is bent, a plurality of arc notches are formed with the single-side fin top line as the symmetry axis, and the bent teeth form a near cylindrical face with a certain width. The arc notches are provided with teeth and bent, so that the connecting area of the fin base material at the connecting part of the fin and the base tube is increased, the connecting reliability is improved, and the arc notch parts of the fin are favorably matched with the actual outer surface of the tube through tooth bending.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchange, and in particular to a detailed structure of an H-shaped finned tube with an outer tube expansion area. Background Art

[0002] To address the performance deficiencies of circular finned tube air coolers, widely used in the energy, petrochemical, and metallurgical industries, such as those characterized by high flow resistance, high scaling resistance, and low efficiency, the inventors have proposed a finned tube with zoned gas flow. Rectangular fin clusters are positioned on either side of the circular base tube, with a gas-zoned flow structure positioned between the fin clusters. This prevents gas from flowing through the front and back areas of the base tube, minimizing directional and velocity fluctuations outside the tube. This reduces inefficient and harmful localized resistance losses. Furthermore, it minimizes the stagnation of impurities in the air and prevents them from adhering to the fin surfaces, resulting in a low and stable scaling coefficient. The corrugations on the fin surface alter the airflow direction in the channels between the fins, disrupting the boundary layer of gas flow on the fin surfaces and enhancing convective heat transfer. While achieving the same heat transfer performance, this approach reduces flow power consumption; or, while maintaining the same power consumption, increases heat transfer, thus saving energy for convective heat transfer outside the tube. The inventors have applied for patents for "a continuous H-shaped finned tube with airflow partitions" and "a continuous H-shaped finned tube cluster with multiple tubes arranged in parallel to form airflow partitions."

[0003] During the process of implementing the technical solution and developing high-efficiency products, the inventor discovered that the arc notch at the top of the serpentine fins improved the compactness and finning ratio of the gas partitioned flow fin tubes. However, the arc notch at the top line of the fin cluster was difficult to manufacture and assemble. Therefore, the inventor proposed a utility model patent for a serpentine fin cluster with a concave arc at the top of one side. During the implementation of product development, the inventor further discovered that the tubes connected to the fin cluster had certain deviations in straightness and cross-sectional roundness, and the arc line size of the fin arc part also had deviations, making it difficult for the fin arc part to form a small-scale gap with the actual tube that can be brazed. When the gap size exceeds the brazing filler metal infiltration size, unwelded or poorly welded tubes will occur. There is an urgent need for a fin arc structure that can compensate for the actual quality deviation of the tube to meet the needs of actual product assembly, brazing and connection quality assurance.

[0004] To this end, the inventors added teeth of a certain shape and height to the contour line of the serpentine fin arc notch, and provided compensation gaps between adjacent arc notches. After the teeth on the arc notch are bent, a tooth thickness band with a certain elastic compensation capability is formed based on the tooth root line. When the teeth of the tooth thickness band are bent at a 90° orthogonal angle, a fin-thick connection band with the tube is formed on the arc. When the teeth are upright and not bent, part of the tooth tip contacts the tube, while part does not. Under the action of the clamping force, the teeth that first contact the tube bend at a certain angle, and then the teeth that are free and not in contact also contact the tube and bend at a smaller angle, forming a wrinkled contact line between the fin tooth-shaped arc notch and the outer surface of the tube. The maximum distance between the wrinkle line and the tube surface does not exceed the wetting scale of the solder, thus forming a good and reliable connection between the fin and the tube. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of easy manufacturing, high quality and reliability of high-performance fin tubes and to provide a serpentine fin cluster with arc notches and teeth on the fin top part.

[0006] The technical solution of the present invention is as follows: a serpentine fin cluster with an arc notch on the top of the wing on one side and teeth on the arc contour line. The serpentine fin cluster has a serpentine cross-section and is formed by bending a strip-like thin plate of a certain width. The arc notch is opened on the top of the wing on one side. The arc notch is used to contact and connect with the outer circular surface of the circular base tube. Teeth are opened and bent on the arc contour line of the arc notch. When the serpentine fin cluster is unfolded (before forming), a plurality of tooth-shaped arc notch holes that are symmetrical at both ends and connected are opened at a certain interval on the top line of the wing on one side with the wing top line as the axis of symmetry. The teeth on the tooth-shaped arc notch holes are bent to one side by 60 to 85 degrees at the tooth root position. After the fin is bent, a plurality of arc notches are formed with the top line of the wing on one side as the axis of symmetry. The bent teeth form a nearly cylindrical surface with a certain width.

[0007] Preferably, with the wing top line as the axis of symmetry, the connecting lines of the tooth roots on the single-sided circular arc notch form multiple arc chords located on the same circle, the outer contour of the teeth is triangular, and the tooth roots and tooth tops are smoothly transitioned. With the wing top line as the axis of symmetry, the teeth on both sides are staggered. After the wing is bent, the teeth on both sides are close together, forming a meshing structure with a gap. With the wing top line as the axis of symmetry, the area on both sides of the wing top line is not toothed. The contour of the circular arc notch in this area is approximately an ellipse, forming a circular arc after bending.

[0008] Preferably, a compensation seam of a certain length is cut longitudinally on the fin at the midpoint of the two arc gaps, with the wing top line as the axis of symmetry, and the two ends of the compensation seam are arc transitions. The length of the expansion slot is consistent with the arch height of the arc gap, and the diameter of the small hole at the end is generally 0.5-2mm.

[0009] Preferably, a fin bending positioning hole is opened on the fin top line with the arc notch at a certain distance from the fin edge, and the diameter of the fin bending positioning hole is 1-2 mm. This hole is a manufacturing process hole and is used for fin bending positioning.

[0010] The local shape of the bending part of the serpentine fin cluster is an arc shape, the diameter of the circle where the center line of the arc contour is located is equal to the fin pitch or it is a rectangular fillet, and the length of the rectangle is equal to the fin pitch.

[0011] When connected to a single circular base tube, the fin cluster has only one concave arc on one side; when connected to multiple circular base tubes, the inner side of the fin cluster is provided with a corresponding number of concave arcs.

[0012] Preferably, the surface of the non-bending section of the serpentine fin cluster is arranged with corrugated concave-convex portions, the cross-section of the corrugated concave-convex portions is trapezoidal, the ends of the corrugated concave-convex portions transition smoothly with the periphery, and the corrugated concave-convex portions present transverse or longitudinal corrugations between each other.

[0013] Preferably, the depth of the corrugated concave-convex is within half of the fin spacing, the corrugation pitch is 3 to 5 mm, and the corrugation expansion coefficient is 1.02 to 1.2.

[0014] Preferably, connecting holes are provided on the fin wall surface, the connecting holes are used to connect the air flow channels with each other, the opening ratio is 0.05-0.2, the connecting holes are circular, oblong or rectangular, and the equivalent diameter of the holes is 1-3 mm.

[0015] The beneficial effects of the present invention are as follows: the arc notch on one side of the fin top line is toothed, which increases the connection area between the fin and the circular base tube and improves the connection reliability; an expansion groove is provided at the center position between the arc notches, which makes it easy to form a reliable brazing connection between the arc notch and the circular base tube with manufacturing deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a cross-sectional front view of the serpentine fin cluster of the present invention; Figure 2 yes Figure 1 AA cross-section of Figure 3 yes Figure 1 BB cross-section diagram; Figure 4 is a side view of the serpentine fin cluster of the present invention; Figure 5 is an expanded view of the serpentine fin cluster of the present invention; Figure 6 This is an enlarged view of the toothed area of ​​the serpentine fin cluster of the present invention in the expanded state; Figure 7 is a cross-sectional view of a single serpentine fin cluster of the present invention (arc bending); Figure 8is a cross-sectional view of a single serpentine fin cluster of the present invention (with rounded corners); Figure 9 Schematic diagram of a non-bending area flat wall embodiment of a single serpentine fin cluster of the present invention; Figure 10 Schematic diagram of the embodiment of the transverse corrugation in the non-bending area of ​​a single serpentine fin cluster of the present invention; In the figure: 1, arc notch; 2, expansion slot; 3, fin bending positioning hole; 4, arc bend; 5, fillet bend; 6- non-bend section; 7- transverse corrugation; 1-1, tooth; 1-1-1, tooth side; 1-1-2, tooth top; 1-1-3, tooth root; 1-1-4, wing root bend; 2-1, expansion slot straight section; 2-2, stress relief arc at the expansion slot root. DETAILED DESCRIPTION

[0017] The present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. The following examples are intended to facilitate a better understanding of the present invention by those skilled in the art, but are not intended to limit the present invention in any way. Furthermore, it should be noted that any equivalent modifications based on the present invention, as known to those skilled in the art, fall within the scope of protection of the present invention.

[0018] like Figure 1 The present invention discloses a serpentine fin cluster having an arc notch on the top of one side of the fin and teeth along the arc contour line. The present invention comprises a cluster of continuously bent serpentine fins formed by bending a thin strip of sheet metal of a certain width. The length of the serpentine fin cluster is determined according to the product's usage requirements. The fin cross-section in the airflow direction has a serpentine-like, zigzag structure. In the cross-section of the serpentine fin cluster, the outer edge, top edge, and bottom edge are straight lines, and the inner edge of the serpentine fin cluster is a combination of a straight segment, an arc segment, and a straight segment. An arc notch is opened at the top of the wing of the serpentine fin cluster on the side where it connects to the circular base tube. The center angle of the arc notch (less than 180 degrees) is determined based on research on the optimization of the heat transfer and flow properties of fin tubes. The arc diameter of the contour line of the arc notch is equal to the outer diameter of the circular base tube. When connecting to a single circular base tube, the inner edge of the fin cluster has only one arc notch. When connecting to multiple base tubes, the inner edge of the fin cluster has a corresponding number of arc notches.

[0019] The serpentine fin clusters of the present invention are compatible with circular base tubes with outer diameters of typically 19, 25, or 32 mm. Standardized and serialized wave height parameters are 1 / 2, 3 / 4, 1, and 1.25 times the outer diameter of the circular tube. The fin cluster width is generally 0.75 to 1 times the row spacing of the circular base tubes in a rectangular arrangement of finned tubes. The thickness of the sheet metal forming the serpentine fin cluster is determined based on the requirements of the application.

[0020] To increase the contact width between the serpentine fin cluster and the circular base tube, teeth are cut along the contour line of the circular notch. On the inner fin top line (the side in contact with the circular base tube), multiple symmetrical, connected, tooth-shaped circular notches are cut at regular intervals, with the top line as the axis of symmetry. The teeth in these notches are bent 60-85 degrees to one side at the tooth root. After the fin is bent, the top line serves as the axis of symmetry, forming multiple circular notches. The bent teeth along the notch contour form a nearly cylindrical surface of a certain width. The connecting lines of the tooth roots on one side of the circular notch form multiple arc segments located on the same circle. The tooth contours are triangular, with smooth transitions between the tooth roots and tooth tips. With the top line as the axis of symmetry, the teeth are staggered on both sides. After the fin is bent, the teeth are close together, forming a meshing structure with clearance. In the bent area on either side of the fin top line, the contour line of the circular notch is not toothed, with the top line as the axis of symmetry. The circular notch contour in this area is approximately elliptical, forming a circular arc after bending.

[0021] The fin is bent in a serpentine shape based on the fin top line. The bending part usually adopts a straight line + rounded corner structure (i.e. rectangular rounded corner) or an arc-shaped bending structure. Figure 7 、 Figure 8 As shown, there are arc bends 4 and rounded corner bends 5. A straight line + rounded corner structure requires high manufacturing precision, so an arc-shaped bend structure is most appropriate for actual product manufacturing. If a straight line + rounded corner structure is used, the radius of the rounded corner is preferably 0.3-0.5mm, and half the length of the rectangle is equal to the fin pitch. If an arc-shaped structure is used, the diameter of the circle containing the centerline of the arc outline is equal to the fin pitch (here, the distance between the serpentine fin flat segments and adjacent flat segments).

[0022] On the longitudinal section of the fin cluster, the surface of the non-bending section 6 of the fin cluster is arranged with corrugated concave and convex along the airflow direction. The corrugated shape includes transverse corrugations 7 or longitudinal corrugations. The cross-sectional shape of the corrugated concave and convex is trapezoidal, and the end of the corrugated concave and convex transitions smoothly with the periphery. The spacing, depth, and inclination of the trapezoidal slope of the corrugation are determined according to performance optimization; the depth of the corrugated concave and convex is within half of the fin spacing, the corrugation pitch is 3 to 5 mm, and the expansion coefficient is 1.02 to 1.2. Figure 6 As shown, the shape of the tooth 1-1 in the toothed area of ​​the serpentine fin cluster in the unfolded state includes the tooth side 1-1-1, the tooth top 1-1-2, the tooth root 1-1-3, and the wing root bend 1-1-4.

[0023] Reducing the thermal resistance of gas flow and heat transfer within the inter-fin channels primarily relies on enhancing convective heat transfer between the gas and the fin walls, as well as internal heat conduction. Therefore, the non-bending sections of the fins are constructed with corrugated ridges and ridges to disrupt the gas flow boundary layer and enhance turbulence in the mainstream flow. The corrugation shape can vary in flow direction or flow area, depending on the function. Variable flow direction types offer significant heat transfer enhancement, while oblique corrugations not only alter flow direction but also enhance the intensity of cross-flow turbulence in the mainstream flow. Longitudinal corrugations, while increasing specific surface area, are generally less commonly used.

[0024] To improve the compactness, finning ratio, fin efficiency, and reduce local drag losses of finned tubes, the fin cluster should have a certain wrap angle (the center angle of the arc of contact between the fin and the circular base tube) at the junction with the circular base tube. The ideal wrap angle is generally 90° to 150°. Increasing the wrap angle improves compactness, finning ratio, and fin efficiency, but increases local drag. The wrap angle is optimized and determined based on the application through experimental research.

[0025] Connecting holes can be opened on the fin wall surface, and the connecting holes are used to connect the air flow channels with each other. The opening rate is 0.05-0.2, and the connecting holes are circular, oblong or rectangular, with an equivalent opening diameter of 1-3 mm.

[0026] A fin bending positioning hole 3 can also be opened on the fin top line of the circular arc notch at a certain distance from the fin edge, with a diameter of 1 to 2 mm. The fin bending positioning hole 3 facilitates the fin bending operation.

[0027] At the midpoint of the two arc notches, a certain length of expansion slot 2 is cut longitudinally on the fin with the wing top line as the axis of symmetry. The expansion slot 2 has arc transitions at both ends. The slot length of the expansion slot 2 is consistent with the arch height of the arc notch. The slot width and the end arc diameter are generally 0.5-2mm. The expansion slot 2 serves to compensate for and release the stress changes of the fin cluster, making it easier to form a reliable brazing connection between the arc notch and the circular base tube with manufacturing deviations. Figure 5 As shown, the serpentine fin cluster is in the expanded state, the two ends of the expansion slot 2 are in arc transition, the expansion slot straight section 2-1, and the expansion slot root stress release arc 2-2.

[0028] To achieve the concave arc, three methods can be used: material removal, stretching, and compression. Material removal machining is time-consuming, and the fins lack rigidity. When cutting ductile fin material, the material elements are difficult to position. Stretching causes uneven plastic thinning of the fin material, making it easy to break at the fin tip. Extended and bent surface machining are difficult to combine within the confined product space.

[0029] To achieve the manufacturability of the patented product, the holes are first machined using a multi-step reciprocating or continuous rotary punching method. The fin corrugations and fin bends are then rolled using a gear hobbing method, and the pitch is then determined using a fixed pitch mechanism. The structure of the present invention achieves high-quality product manufacturing. The holes are punched using a multi-step reciprocating or continuous rotary punching method, and the efficiency of the hole-making process is synchronized with the efficiency of the fin-rolling machine, enabling mass production.

Claims

1. A serpentine fin cluster with a circular arc notch on one side of the wing and teeth on the arc contour line, the serpentine fin cluster having a serpentine cross section and formed by bending a strip-shaped thin plate of a certain width, the circular arc notch (1) on one side of the wing being opened, the circular arc notch (1) being used to contact and connect with the outer surface of the circular base tube, and characterized by: The circular arc contour line of the circular arc notch (1) is toothed and bent. When the serpentine wing cluster is unfolded, a plurality of tooth-shaped circular arc notch holes are opened at a certain interval on the wing top line on one side, with the wing top line as the axis of symmetry, and are symmetrical at both ends and connected. The teeth (1-1) on the tooth-shaped circular arc notch holes are bent to one side at 60 to 85 degrees at the tooth root position. After the fin is bent, a plurality of circular arc notches (1) are formed with the wing top line on one side as the axis of symmetry. The bent teeth form a nearly cylindrical surface with a certain width.

2. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 1, characterized in that: With the wing top line as the axis of symmetry, the lines connecting the tooth roots (1-1-3) on the single-sided circular arc notch form multiple arc chords located in the same circle. The outer contour of the tooth is a triangle, and the tooth roots and tooth tops are smoothly transitioned. With the wing top line as the axis of symmetry, the teeth (1-1) on both sides are staggered. After the wing is bent, the teeth (1-1) on both sides are close to each other and form a meshing structure with a gap. With the wing top line as the axis of symmetry, there are no teeth in the bent area on both sides of the wing top line of the wing. The contour line of the circular arc notch in this area is an approximate elliptical line, and a circular arc is formed after bending.

3. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 1 is characterized in that: At the midpoint of the two arc notches, the fin is longitudinally cut into a certain length of expansion slot (2) with the wing top line as the symmetry axis, and the expansion slot (2) has arc transitions at both ends.

4. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 3, characterized in that: The slot length of the expansion slot (2) is consistent with the arch height of the arc notch, and the slot width and the end arc diameter are 0.5-2mm.

5. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 1, characterized in that: A fin bending positioning hole (3) is formed on the fin top line of the circular arc notch at a position close to the fin edge at a certain distance, and the diameter of the fin bending positioning hole (3) is 1 to 2 mm.

6. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 1, characterized in that: The local shape of the bending part of the serpentine fin cluster is an arc shape, that is, an arc bend (4), and the diameter of the circle where the center line of the arc contour is located is equal to the fin pitch, or it is a rectangular chamfer, that is, a rounded corner bend (5), and the length of the rectangle is equal to the fin pitch.

7. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 1, characterized in that: The surface of the non-bending section (6) of the serpentine fin cluster is arranged with corrugated concave-convex portions, the cross-sectional shape of the corrugated concave-convex portions is trapezoidal, and the ends of the corrugated concave-convex portions are smoothly transitioned to the periphery.

8. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 7, characterized in that: The corrugated bumps appear as transverse ripples (7) or longitudinal ripples between each other.

9. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 1, characterized in that: The depth of the corrugated concave and convex is within half of the fin spacing, the corrugation pitch is 3 to 5 mm, and the corrugation expansion coefficient is 1.02 to 1.

2.

10. The serpentine fin cluster with a circular arc notch on one side of the fin top and teeth on the circular arc contour line according to claim 1, characterized in that: The fin wall of the serpentine fin cluster is provided with connecting holes, which are used for connecting airflow channels with each other. The opening ratio is 0.05-0.2, and the connecting holes are circular, oblong or rectangular, with an equivalent opening diameter of 1-3 mm.

Images