CN102200405A - Combined triangular curved vortex generator type circular tube fin heat exchanger - Google Patents

Abstract

The invention provides a combined triangular curved surface vortex generator type circular tube-fin heat exchanger, which includes circular tubes arranged along the gas flow direction and fins sleeved on the circular tubes, and is characterized in that the fins are provided with For the hole of the round tube, an elliptical convex hull is punched out in front of each hole, and the long axis of the ellipse is along the main flow direction, leaving a transverse elliptical pit on the back of the fin; the back of each hole on the fin is punched out A pair of arc-shaped triangular curved surface vortex generators leave a pair of arc-shaped small holes on the fins, and the bottom edge of the curved surface vortex generators connected to the fins and the circular holes are located on concentric circles. In the present invention, the long axis of the elliptical convex hull at the front end of the round tube formed by stamping on the fins is consistent with the flow direction, and the streamline is better, which suppresses the separation of the fluid at the rear side of the round tube, reduces the wake area behind the round tube, and improves the The heat transfer performance on the joint surface of the fin and the wake region reduces the flow resistance loss in the wake region.

Description

Combined triangular surface vortex generator type round tube fin heat exchanger

technical field

The invention relates to the technical field of heat exchangers, in particular to a combined triangular curved surface vortex generator type round tube fin heat exchanger.

Background technique

Round tube fin heat exchangers are very versatile. With the continuous improvement of the production level of the national economy and the requirements of energy saving and emission reduction, it is very important to enhance the heat transfer of the round tube fin heat exchanger. Researchers are committed to enhancing the heat transfer capacity of the tube-fin heat exchanger while reducing the increase in resistance loss as much as possible, that is, reducing the operating cost of the tube-fin heat exchanger. Fins are usually installed on the outside of the tube to increase the heat transfer area and reduce thermal resistance, but the area of the fins cannot be increased indefinitely due to the limitation of economy and fin efficiency. In order to further improve the heat transfer performance of the round tube fin heat exchanger, the fin surface is made into various structures. Among them, the measure of introducing secondary flow is called the third generation enhanced heat transfer technology. The vortex generator punched out on the surface of the fin can cause secondary flow in the main flow, which can effectively enhance the heat transfer performance of the surface of the fin.

The mechanical processing performance of the round tube fin heat exchanger is better than that of the flat tube fin heat exchanger, and the manufacturing energy consumption is small. However, the flow linearity of the fluid flowing through the circular tube is worse than that of the flat tube, and the resistance loss is large when the fluid flows near the stagnation point at the front end of the circular tube and the wake area of the circular tube, and the heat transfer capacity of the fin surface The poorer area is the area in contact with the wake area of the tube.

Contents of the invention

In order to further improve the heat transfer performance of the round tube fin type and reduce the loss of flow resistance, the present invention relates to a triangular curved surface vortex generator that reduces the size of the wake region of the round tube and reduces the size of the upstream round tube near the front end. Elliptical convex hull stamped on fins for flow resistance loss. The invention provides a combined curved surface vortex generator type round tube fin heat exchanger which can reduce the flow resistance loss near the front end of the round tube and enhance the heat exchange performance.

The present invention adopts following technical scheme to solve its technical problem:

A combined triangular curved surface vortex generator type round tube fin heat exchanger, including round tubes arranged along the gas flow direction and fins sleeved on the round tubes, characterized in that the fins are equipped with sleeved round tubes punch out an elliptical convex hull in the front direction of each hole, and the long axis direction of the ellipse is along the main flow direction, leaving a transverse elliptical pit on the back of the fin; a pair of circles are punched out in the rear of each hole The arc-shaped triangular curved surface vortex generator leaves a pair of arc-shaped small holes on the fins, and the bottom edge of the curved surface vortex generator connected to the fins and the circular holes are located on the concentric circle.

The vortex generator is symmetrically distributed up and down with the longitudinal center line of the circular tube, the midpoint of the bottom edge of the vortex generator is located on _the circular arc concentric with the hole, and the ratio of the radius of the circular arc to the radius of the hole is r1 / r = 1.15~1.35, the range of the arc angle is θ =50°~60°, the angle between the starting point of the bottom edge of the vortex generator and the center of the hole and the incoming flow direction is β=90°~115°.

The side perpendicular to the base of the triangular curved surface vortex generator is located at the front end and is perpendicular to the fins.

The height of the side perpendicular to the bottom side of the curved vortex generator is 0.6-0.95 times the pitch of the fins.

The major axis of the elliptical convex hull is consistent with the flow direction, the center of the elliptical convex hull is on the longitudinal centerline of the hole, and is located on an arc concentric with the hole, and the ratio of the radius of the arc to the radius of the hole is r ₂ / r = 1.3~1.6; the projection of the elliptical convex hull on the fin is an ellipse, the ratio of the major axis to the minor axis is 2, the major axis is 0.3~0.4 times the outer diameter of the circular tube, and the height of the elliptical convex hull is 0.5~0.8 times of the fin pitch.

The edges of the upper holes of the fins are provided with flanging bosses whose height is equal to the distance between the fins.

In the present invention, the long axis of the elliptical convex hull at the front end of the circular tube formed by stamping on the fins is consistent with the flow direction, and the flow is relatively good. The front of the tube reduces the flow resistance loss caused by the fluid directly scouring the round tube vertically. The triangular curved vortex generators stamped on both sides of the downstream of the center line of the circular tube form a fluid channel between the circular tube and the vortex generator, and part of the fluid reaches the wake area of the circular tube through this channel, which inhibits the separation of the fluid at the back of the circular tube. The wake area behind the circular tube is reduced, the heat transfer performance on the joint surface of the fin and the wake area is improved, and the flow resistance loss in the wake area is reduced. The vortex generator and the boss are stamped in the same direction, and the stamping die is relatively simple to manufacture.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Figure 2 is a schematic diagram of the fin structure.

Detailed ways

Below in conjunction with accompanying drawing, the present invention is described in further detail:

A combined triangular curved surface vortex generator type circular tube-fin heat exchanger, including circular tubes 3 arranged along the direction of gas flow and fins 4 sleeved on the circular tubes 3, the circular tubes can be arranged in a fork row or in a straight row In the arrangement, a pair of triangular curved surface vortex generators 1 are punched out at the rear of each hole 8 on the fin 4 , and a pair of triangular small holes 5 are left on the fin 4 . The midpoint of the bottom edge of the vortex generator is located on the concentric circular arc with the hole 8 , and the side perpendicular to the bottom edge of the triangular curved surface vortex generator 1 is located at the front end and is perpendicular to the fins 4 . The longitudinal center line of the vortex generator 1 and the circular tube 3 is distributed symmetrically up and down, the midpoint of the bottom edge of the vortex generator is located on the arc concentric with the hole 8, and the ratio of the radius of the arc to the radius of the hole 8 is r ₁ / r =1.15~1.35, the range of the arc angle is θ =50°~60°, the angle between the line connecting the starting point of the base of the vortex generator 1 and the center of the hole 8 and the incoming flow direction β=90°~115°.

An elliptical convex hull 6 is punched out at the midline of the front end of each hole 8 on the fin 4 , the long axis of the ellipse is along the main flow direction, and an elliptical pit 7 is correspondingly left on the back of the fin 4 . The long axis of the elliptical convex hull 6 is consistent with the flow direction, the center of the elliptical convex hull 6 is on the longitudinal centerline of the hole 8, and is located on the arc concentric with the hole 8, the ratio of the radius of the arc to the radius of the hole 8 It is r ₂ / r =1.3~1.6. The projection of the elliptical convex hull 6 on the fin 4 is an ellipse, the ratio of the major axis to the segment axis is 2, the major axis is 0.3~0.4 times the outer diameter of the circular tube 3, and the height of the elliptical convex hull 6 is the distance between the fins 4 0.5~0.8 times of that.

The edge of the hole 8 on the fin 4 is provided with a flanging boss 2. The height of the flanging boss 2 is equal to the distance between the fins 4. The flanging boss 2 plays the role of fin positioning. At the same time, the gap between the round tube and the tube sheet During the expansion joint, the flanging boss 2 can be tightly connected with the round tube 3 to improve the expansion and tightness of the tube and the fin 4 .

In the present invention, after the fins are stamped and formed, the fins 4 are set on the round tube 3, and the fins 4 are positioned through the round hole flanging boss 2, and the whole tube is completed after a series of processes such as tube expansion and pressure test inside the tube. Fabrication of vortex generator type round tube fin heat exchanger.

Claims (6)

1. A combined triangular surface vortex generator type circular tube-and-fin heat exchanger, comprising circular tubes (3) arranged along the gas flow direction and fins (4) sleeved on the circular tubes (3), which It is characterized in that the fins (4) are provided with holes (8) for fitting round tubes (3), and an elliptical convex hull (6) is punched out in front of each hole (8), and the long axis of the ellipse is along the main flow direction , leaving a transverse elliptical pit (7) on the back of the fin (4); a pair of arc-shaped triangular surface vortex generators (1) are punched out at the rear of each hole (8) on the fin (4) , while leaving a pair of arc-shaped small holes (5) on the fins, the bottom edge of the curved surface vortex generator (1) connected to the fins (4) and the circular holes are located on concentric circles. 2. The combined triangular curved surface vortex generator type round tube fin heat exchanger according to claim 1, characterized in that the longitudinal centerlines of the vortex generator (1) and the round tube (3) are distributed symmetrically up and down, The midpoint of the bottom edge of the vortex generator is located on the arc concentric with the hole (8), and the ratio of the radius of the arc to the radius of the hole (8) is r ₁ / r =1.15~1.35, and the range of the arc angle is θ =50°~60°, the angle between the starting point of the bottom edge of the vortex generator (1) and the center of the hole (8) and the incoming flow direction is β=90°~115°. 3. The combined triangular curved surface vortex generator type round tube-fin heat exchanger according to claim 1, characterized in that the side perpendicular to the bottom edge of the triangular curved surface vortex generator (1) is located at the front end, and is perpendicular to Fins (4). 4. The combined triangular curved surface vortex generator type round tube-fin heat exchanger according to claim 1, characterized in that the height of the side perpendicular to the bottom edge of the curved surface vortex generator (1) is the fin (4 ) 0.6~0.95 times of the spacing. 5. The combined triangular curved surface vortex generator type circular tube-fin heat exchanger according to claim 1, characterized in that the long axis of the elliptical convex hull (6) is consistent with the flow direction, and the elliptical convex hull (6) The center of the center is on the longitudinal center line of the hole (8), and it is located on the arc concentric with the hole (8), and the ratio of the radius of the arc to the radius of the hole (8) is r ₂ / r =1.3-1.6 The projection of the elliptical convex hull (6) on the fin is an ellipse, the ratio of the major axis to the minor axis is 2, the major axis is 0.3-0.4 times the outer diameter of the round tube (3), and the elliptical convex hull (6) The height is 0.5-0.8 times of the pitch of the fins (4). 6. The combined triangular curved surface vortex generator type round tube-fin heat exchanger according to claim 1, characterized in that the edge of the upper hole (8) of the fin (4) is provided with a flanging boss (2 ), the height of the flanging boss (2) is equal to the spacing of the fins (4).