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

Abstract

The utility model relates to a slot-curved vortex generator combined reinforced fin. The fin is provided with a circular hole for enveloping a circular tube, a plurality of slits are punched out in the circumferential direction at the upstream of the circular hole, and a pair of slots are punched out on both sides of the downstream of the circular hole. For the curved triangular vortex generator, the spacing of the fins on the tube-fin heat exchanger is determined by the flanged bosses. By arranging the slits in the circumferential direction upstream of the circular pipe, a flow channel is formed between the circular pipe and the slits, which can divert the incoming flow and reduce the loss of fluid flow resistance. The curved triangular vortex generator downstream of the circular pipe can It guides the fluid to flow through the tail of the circular tube, which effectively inhibits the separation of the fluid from the tube wall and reduces the flow resistance loss in the wake area. The formation and development of the boundary layer reduces the thickness of the boundary layer and induces a strong secondary flow, which further strengthens the mixing of hot and cold fluids, which is conducive to strengthening heat transfer.

Description

A slit-curved vortex generator combined reinforced fin

technical field

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

Background technique

Tube-fin heat exchangers are widely used in chemical, refrigeration, air conditioning and other fields. Most of the medium outside the tube of this type of heat exchanger is air, so that the heat transfer coefficient of the fin side is low and the thermal resistance is large, which greatly affects the heat exchange efficiency of the heat exchanger. In order to further improve the heat transfer performance of the air side, researchers have taken measures such as increasing the geometric size of the fins and enhancing the fluid disturbance intensity. However, due to economic constraints, the space for increasing the geometric size of the fins is limited, so more shutters are used. The discontinuous or broken structures such as type, slot type and discontinuous annular groove can enhance the strength of fluid disturbance, thereby changing the flow characteristics of the fluid in the channel of the finned tube bundle.

Slitting of fins is an effective method to enhance heat transfer on the air side. The mechanism of heat transfer enhancement is that the existence of slits improves the synergy of flow field and temperature field in flat fins. Generally, the position of the slotted fins is close to the "X" shape. The "X"-shaped slotted fins can make the fluid boundary layer develop intermittently, but the resistance loss is large when the fluid flows through the wake region of the circular tube. The arrangement of a pair of curved triangular vortex generators in the flow area can guide more fluid to flow through the tail of the circular tube, effectively inhibiting the separation of the fluid from the tube wall and reducing the flow resistance loss in the wake region. On the other hand, the curved triangular vortex The generator can also induce a strong secondary flow, which further strengthens the mixing of cold and hot fluids, which is conducive to strengthening heat transfer, and can achieve the dual effects of strengthening heat transfer and reducing resistance loss.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to further improve the heat exchange performance of the circular tube, tube and fin heat exchanger, to provide a method that can reduce the resistance loss of fluid flowing through the wake region of the circular tube, and continuously destroy the formation of the boundary layer. A slot-curved vortex generator combined reinforced fin that induces secondary flow to enhance the mixing of hot and cold fluids while developing and developing.

The present invention solves its technical problems by adopting the following technical solutions: providing a combined reinforced fin with a slit-curved vortex generator, including a fin, a parallelogram slit, a rectangular slit, a curved triangular vortex generator, an isosceles trapezoid Slots and flanging bosses, the fins are provided with a number of circular holes for fitting round tubes, and parallelogram slits, rectangular slits, curved triangular vortex generators, etc. are arranged around the circular holes arranged in staggered or sequential rows. Trapezoidal seam and cuff boss at waist.

A number of parallelogram slits and a number of rectangular slits are punched out in the upstream of the center of each two circular holes on the fin, and the edge of the parallelogram slits and the rectangular slits on one side of the circular hole is tangent to the circular arc concentric with the circular hole, Parallelogram slits and rectangular slits are symmetrically distributed on both sides of the circular hole.

The fins punch out a pair of curved triangular vortex generators on the downstream sides of the center of each circular hole, and leave a pair of curved triangular holes on the fins. The centers of the holes coincide.

One to two isosceles trapezoid slits are punched out of the fin at the downstream of the center of each two circular holes, and the side line where the waist of the isosceles trapezoidal slit is located is tangent to the arc concentric with the circular holes.

The fins are provided with flanging bosses on the circular holes of the round tubes sleeved on the fins, and the height of the flanging bosses is equal to the spacing between the fins after the fins are installed in the tube-fin heat exchanger.

The invention arranges slits in the circumferential direction upstream of the circular hole, the slits can make the fluid flow boundary layer develop intermittently, and at the same time form a thermal boundary layer with discontinuous development to strengthen heat transfer, and a pair of curved triangular vortex generators are arranged in the wake region of the circular tube It can guide more fluid to flow through the tail of the round tube, effectively suppress the separation of the fluid and the tube wall, and reduce the flow resistance loss in the wake region. On the other hand, the slit and curved triangular vortex generators can also induce strong The secondary flow can further strengthen the mixing of cold and hot fluids, which is conducive to strengthening heat transfer, and can achieve the dual effects of strengthening heat transfer and reducing resistance loss.

Description of drawings

Fig. 1 is the three-dimensional structure schematic diagram of the present invention;

2 is a schematic diagram of a two-dimensional structure of the present invention;

Fig. 3 is a partial enlarged view of A-A of Fig. 2;

Fig. 4 is a partial enlarged view of B-B of Fig. 2;

Figure 5 shows the relationship between the fluid flow resistance coefficient f and the Reynolds number Re calculated for the case.

Figure 6 shows the relationship between the enhanced heat transfer factor JF and the Reynolds number Re calculated for the case.

Detailed ways

In order to illustrate the purpose and advantages of the present utility model, the present utility model will be further described in conjunction with the following numerical calculation examples. It should be understood that the specific examples described herein are only used to explain the present invention, and are not intended to limit the present invention.

The main parameters of the selected computational domain are: longitudinal tube spacing S ₁ =13.64mm, transverse tube spacing S ₂ =21mm, fin spacing 1.34mm, fin thickness 0.11mm, net fin spacing T _p = 1.24mm, the outer diameter of the round tube D = 7.61mm, the thickness of the round tube δ _t = 0.21mm, the width of the slot W = 1.26mm, the net height of the slot is 0.93mm, the slot spacing S = 1.07mm, the arc where the slot is located The ratio to the diameter of the circular tube is 1.55, the inclination angle of the slit is α=35°, the height of the curved triangular vortex generator is H=1.05mm, the arc length L=4.21mm, and the thickness δ=0.11mm.

1 to 4, the present invention provides a slot-curved vortex generator combined reinforced fin, including fin 1, parallelogram slits (3, 4), rectangular slits 5, and curved triangular vortex generators 6. Isosceles trapezoid seam 7 and flanging boss 8. The fins 1 are provided with a number of circular holes 2 that are fitted with circular tubes. According to the position and number of the circular holes 2 arranged in the heat exchange tubes, the circular holes 2 are provided with flanging bosses 8, and the flanging bosses 8 are used. The space between the rear fins of the fixed fin 1 is installed in the tube-fin heat exchanger. Parallelogram slits (3, 4) and rectangular slits 5 are punched around the round hole 2. The edges of the parallelogram slits (3, 4) and the rectangular slit 5 on one side of the round hole are the same as those of the round hole 2. The arc at the center of the circle is tangent, and the parallelogram slits (3, 4) and the rectangular slit 5 are symmetrically distributed on both sides of the circular hole 2. A pair of curved triangular vortex generators 6 are punched out on both sides downstream of the center of each circular hole 2, and a pair of curved triangular holes 9 are left on the fin 1. The arc of the curved triangular vortex generator 6 is located at the center of the circle The centers of hole 2 coincide. One to two isosceles trapezoid slits 7 are punched out in the downstream of the center of each two circular holes 2 .

In the range of Reynolds number Re from 250 to 1600, the numerical simulation of fluid flow and heat transfer in the slot-curved vortex generator combined enhanced finned tube was carried out, and the results were compared with the calculation results of the ordinary "X"-shaped slotted finned tube. The comparison was carried out, and the comparison results are shown in Figures 5 and 6.

Figure 5 shows the relationship between the flow resistance coefficient f and the Reynolds number Re in the channel of the finned tube bundle. It can be clearly seen from the figure that the fluid flow resistance of the slot-curved vortex generator combined reinforced fin is smaller than that of the ordinary slot. The fins indicate that a pair of curved triangular vortex generators behind the circular tube can effectively inhibit the separation of the fluid from the tube wall and reduce the flow resistance loss in the wake region.

Figure 6 shows the relationship between the enhanced heat transfer factor JF and the Reynolds number Re in the channel of the finned tube bundle. The definition formula of the enhanced heat transfer factor JF is JF=(Nu/Nu _ref )/(f/f _ref ) ^1/3 , where Nu _ref and f _ref are the Nusselt number and drag coefficient of the ordinary "X"-shaped slotted fin tube, respectively. It can be seen from the figure that the slot-curved vortex generator combined reinforced fin has a Re of In the range of 250-1600, the enhanced heat transfer factors are all greater than 1, indicating that the comprehensive heat transfer enhancement effect is better.

Claims (5)

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).

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