CN211178099U

CN211178099U - Strip seam-curved surface vortex generator combined type reinforced fin

Info

Publication number: CN211178099U
Application number: CN201920997792.2U
Authority: CN
Inventors: 林志敏; 武永和; 侯均川; 王良璧
Original assignee: Lanzhou Jiaotong University
Current assignee: Lanzhou Jiaotong University
Priority date: 2019-06-29
Filing date: 2019-06-29
Publication date: 2020-08-04
Anticipated expiration: 2029-06-29

Abstract

The utility model relates to a fin is reinforceed to strip seam-curved surface vortex generator combination formula has arranged the round hole of suit pipe on the fin, and a plurality of strip seams are gone out in round hole upper reaches circumference punching press, and a pair of curved surface triangle-shaped vortex generator is gone out in round hole low reaches both sides punching press, and the interval of fin on tube fin heat exchanger is confirmed through the turn-ups boss. The strip seam is circumferentially arranged at the upper stream of the circular tube, so that a flow channel is formed between the circular tube and the strip seam, the flow guiding effect on incoming flow is realized, the flow resistance loss of fluid is reduced, the curved surface triangular vortex generator at the lower stream of the circular tube can guide the fluid to flow through the tail part of the circular tube, the separation of the fluid and the tube wall is effectively inhibited, and the flow resistance loss of a wake flow region is reduced.

Description

Strip seam-curved surface vortex generator combined type reinforced fin

Technical Field

The invention relates to the technical field of heat exchangers, in particular to a combined type reinforced fin of a slit-curved vortex generator.

Background

The tube-fin heat exchanger is widely applied to the fields of chemical engineering, refrigeration, air conditioning and the like. The medium outside the tube of the heat exchanger is mostly air, so that the heat exchange coefficient of the fin side is low, the thermal resistance is large, and the heat exchange efficiency of the heat exchanger is greatly influenced. In order to further improve the air side heat exchange performance, researchers take measures of increasing the geometric dimension of the fin, enhancing the disturbance strength of fluid and the like, but the increase of the geometric dimension of the fin is limited by the economical limitation, so that more intermittent or broken structures such as louver type, slit type and intermittent annular groove are adopted to enhance the disturbance strength of the fluid, and further the flow characteristic of the fluid in the channel of the finned tube bundle is changed.

The fin slotting is a method for effectively strengthening air side heat transfer, and the strengthening heat transfer mechanism is that the cooperativity of a flow field and a temperature field in the straight fin is improved due to the existence of the slotting. The position of the slit fin slot is close to the X shape, the X-shaped slit fin can lead the fluid boundary layer to develop discontinuously, but the resistance loss is larger when the fluid flows through the circular tube wake region, and the curved surface triangular vortex generators are arranged in the circular tube wake region to lead more fluid to flow through the tail of the circular tube, thereby effectively inhibiting the separation of the fluid and the tube wall, reducing the flow resistance loss of the wake region, on the other hand, the curved surface triangular vortex generators can also induce strong secondary flow, further enhancing the mixing of cold fluid and hot fluid, being beneficial to enhancing heat transfer, and realizing the dual functions of enhancing heat transfer and reducing resistance loss.

Disclosure of Invention

The invention aims to further improve the heat exchange performance of a round tube fin heat exchanger, and provides a strip seam-curved surface vortex generator combined type reinforced fin which can reduce the resistance loss of fluid flowing through a round tube wake flow area, and can induce and generate secondary flow to enhance the mixing of cold and hot fluids while continuously destroying the formation and development of a boundary layer.

The invention adopts the following technical scheme to solve the technical problems: the strip seam-curved surface vortex generator combined type reinforced fin comprises a fin, parallelogram strip seams, rectangular strip seams, curved surface triangular vortex generators, isosceles trapezoid strip seams and flanging bosses, wherein a plurality of round holes sleeved with round pipes are formed in the fin, and the parallelogram strip seams, the rectangular strip seams, the curved surface triangular vortex generators, the isosceles trapezoid strip seams and the flanging bosses are arranged around the round holes which are arranged in a staggered or sequential manner.

A plurality of parallelogram slits and a plurality of rectangular slits are punched at the upper reaches of the centers of every two round holes on the fins, the side lines of the parallelogram slits and the rectangular slits at one side of the round holes are tangent to the circular arcs concentric with the round holes, and the parallelogram slits and the rectangular slits are symmetrically distributed at the two sides of the round holes.

The fin punches a pair of curved triangular vortex generators on two sides of the downstream of the center of each round hole, a pair of curved triangular holes are left on the fin, and the circle center of the arc of each curved triangular vortex generator coincides with the circle center of the round hole.

1-2 isosceles trapezoid strip seams are punched at the downstream of the centers of every two round holes of the fin, and the side line where the waist of each isosceles trapezoid strip seam is located is tangent to the circular arc concentric with the round holes.

And the round holes of the round tubes sleeved on the fins are provided with flanging bosses, and the height of the flanging bosses is equal to the distance between the fins after the fins are arranged on the tube fin type heat exchanger.

The circular hole is circumferentially provided with the strip seams at the upstream, the strip seams can lead a fluid flow boundary layer to develop discontinuously, and simultaneously form a heat boundary layer developing discontinuously to enhance heat transfer, the pair of curved surface triangular vortex generators arranged in the tail flow area of the circular tube can lead more fluid to flow through the tail part of the circular tube, thereby effectively inhibiting the separation of the fluid and the tube wall, and reducing the flow resistance loss of the tail flow area.

Drawings

FIG. 1 is a schematic three-dimensional structure of the present invention;

FIG. 2 is a schematic of a two-dimensional structure according to the present invention;

FIG. 3 is an enlarged view of a portion A-A of FIG. 2;

FIG. 4 is an enlarged view of a portion B-B of FIG. 2;

fig. 5 is a graph of the fluid flow resistance coefficient f versus the reynolds number Re calculated for the case.

FIG. 6 is a graph of the case-calculated enhanced heat transfer factor JF versus Reynolds number Re.

Detailed Description

For the purpose of illustrating the objects and advantages of the present invention, the present invention will be further described with reference to the following numerical calculation examples. It should be understood that the specific examples described herein are for purposes of illustration only and are not intended to limit the invention.

The selected calculation domain main parameters are as follows: longitudinal tube spacing S of finned tubes₁13.64mm, transverse tube spacing S₂21mm, fin pitch 1.34mm, fin thickness 0.11mm, and clear fin pitch T_p1.24mm, 7.61mm of external diameter D and thickness_tThe width W of the slit is 1.26mm, the net height of the slit is 0.93mm, the space S of the slit is 1.07mm, the diameter ratio of the arc where the slit is located to the round tube is 1.55, the inclination angle of the slit is α -35 degrees, the height of the curved surface triangular vortex generator is 1.05mm, the arc length L is 4.21mm, and the thickness is 0.11 mm.

With reference to fig. 1 to 4, the invention provides a slit-curved vortex generator combined type reinforced fin, which comprises a fin 1, parallelogram slits (3, 4), a rectangular slit 5, a curved triangular vortex generator 6, an isosceles trapezoid slit 7 and a flanging boss 8. The fin 1 is provided with a plurality of round holes 2 sleeved with round tubes, the round holes 2 are arranged according to the position and the number of the round holes 2, the round holes 2 are provided with flanging bosses 8, and the flanging bosses 8 are used for fixing the space between the fins of the fin 1 installed on the rear of the tube-fin heat exchanger. Parallelogram strip seams (3, 4) and a rectangular strip seam 5 are punched on one circle of the round hole 2, the side lines of the parallelogram strip seams (3, 4) and the rectangular strip seam 5 on one side of the round hole are tangent with the circular arc concentric with the round hole 2, and the parallelogram strip seams (3, 4) and the rectangular strip seam 5 are symmetrically distributed on two sides of the round hole 2. A pair of curved triangular vortex generators 6 are punched at two sides of the downstream of the center of each round hole 2, a pair of curved triangular holes 9 are left on the fins 1, and the circle center of the arc of each curved triangular vortex generator 6 is coincident with the circle center of the round hole 2. 1-2 isosceles trapezoid strip seams 7 are punched at the downstream of the centers of every two circular holes 2, and the side line where the waist of each isosceles trapezoid strip seam 7 is located is tangent to the circular arc concentric with the circular holes 2.

Numerical simulation is carried out on fluid flow and heat transfer in the slit-curved surface vortex generator combined type reinforced finned tube within the Reynolds number Re of 250-1600, and compared with the calculation result of the common X-shaped slit finned tube, and the comparison result is shown in FIGS. 5 and 6.

Fig. 5 shows the relationship between the flow resistance coefficient f and the reynolds number Re in the channel of the fin tube bundle, and it is obvious from the figure that the fluid flow resistance of the slit-curved vortex generator combined type reinforced fin is smaller than that of the common slit fin, which illustrates that a pair of curved triangular vortex generators behind a circular tube can effectively inhibit the separation of fluid from the tube wall and reduce the flow resistance loss in the wake region.

FIG. 6 shows the relationship between the heat transfer enhancement factor JF defined as JF ═ Nu/Nu (Nu/Nu)_ref)/(f/f_ref)^1/3Wherein Nu_refAnd f_refThe Knoop number and the resistance coefficient of the common X-shaped slit finned tube are shown in the figure, and the reinforcing heat transfer factors of the slit-curved vortex generator combined type reinforcing fin in the range of Re of 250-1600 are all larger than 1, which shows that the comprehensive reinforcing heat transfer effect is good.

Claims

1. The utility model provides a strip seam-curved surface vortex generator combination formula reinforces fin, includes fin (1), parallelogram strip seam (3, 4), rectangle strip seam (5), curved surface triangle-shaped vortex generator (6), isosceles trapezoid strip seam (7) and turn-ups boss (8), its characterized in that open round hole (2) that have a plurality of suit pipes on fin (1), arranged parallelogram strip seam (3, 4), rectangle strip seam (5), curved surface triangle-shaped vortex generator (6), isosceles trapezoid strip seam (7) and turn-ups boss (8) around round hole (2) of staggered arrangement or in the same direction as arranging.

2. The slot-curved vortex generator combined type reinforced fin according to claim 1, wherein a plurality of parallelogram slots (3, 4) and a plurality of rectangular slots (5) are punched at the upstream of the centers of every two round holes (2) on the fin (1), the side lines of the parallelogram slots (3, 4) and the rectangular slots (5) at one side of the round holes are tangent to an arc concentric with the round holes (2), and the parallelogram slots (3, 4) and the rectangular slots (5) are symmetrically distributed at two sides of the round holes (2).

3. The slit-curved vortex generator combined type reinforced fin according to claim 1, wherein the fin (1) is formed by punching a pair of curved triangular vortex generators (6) on two sides of the downstream of the center of each round hole (2), and a pair of curved triangular holes (9) are left on the fin (1), and the circle center of the circular arc of each curved triangular vortex generator (6) is coincident with the circle center of the round hole (2).

4. The slit-curved vortex generator combined type reinforced fin according to claim 1, wherein the fin (1) is formed by punching 1-2 isosceles trapezoid slits (7) at the downstream of the centers of every two circular holes (2), and the side line of the waist of each isosceles trapezoid slit (7) is tangent to the circular arc concentric with the circular hole (2).

5. The combined type strengthening fin of the slot-curved vortex generator as claimed in claim 1, wherein the fin (1) is provided with a flanging boss (8) on the round hole (2) of the sleeved round tube, and the height of the flanging boss (8) is equal to the distance between the fins of the fin-tube heat exchanger (1).