CN217236589U

CN217236589U - Concave-convex heat exchange tube

Info

Publication number: CN217236589U
Application number: CN202220612379.1U
Authority: CN
Inventors: 李小利; 王斌; 李玉海; 马青川; 陈焕倬; 林俊庆
Original assignee: Shandong Henghui Energy Saving Technology Group Co ltd
Current assignee: Shandong Henghui Energy Saving Technology Group Co ltd
Priority date: 2022-03-21
Filing date: 2022-03-21
Publication date: 2022-08-19
Anticipated expiration: 2032-03-21

Abstract

The utility model relates to an unsmooth heat exchange tube, unsmooth heat exchange tube include the body, the outer wall of body is provided with a plurality of interval arrangements's pit, the internal face of body corresponds a plurality of the position of pit forms a plurality of interval arrangements's convex closure, every the surface of convex closure all is provided with a plurality of edges the first channel of the length direction extension of body. The convex-concave heat exchange tube has high heat exchange coefficient, and the flow resistance in the tube is reduced, so that the use energy consumption of the heat exchange tube is reduced.

Description

Concave-convex heat exchange tube

Technical Field

The application relates to a concave-convex heat exchange tube.

Background

Various types of heat exchangers are used in various industries, among which a shell-and-tube heat exchanger is a widely used heat exchanger, the number of which accounts for about 75% among the various types of heat exchangers, and a heat exchange tube is a key element in the shell-and-tube heat exchanger, which determines the efficiency of the heat exchanger.

In recent years, heat exchange tubes with concave-convex surfaces are widely popularized, and the heat exchange tubes with the concave-convex surfaces are characterized in that spherical-crown-shaped pits are arranged on the outer surfaces of the heat exchange tubes, and spherical-crown-shaped convex hulls are formed on the corresponding inner surfaces of the heat exchange tubes. When fluid flows through the surface of the pit, secondary flow can be generated at the bottom of the pit to generate vortex, so that the convection heat transfer coefficient of the outer surface is improved. The convex hull on the inner surface of the heat exchange tube reduces the flow section at the position and correspondingly increases the flow velocity at the position, and conversely, the fluid velocity is lower at the position without the convex hull. Because the convex hulls on the inner surface of the heat exchange tube usually appear periodically, the flow cross section along the flow direction is changed periodically, and the corresponding fluid speed has a phenomenon of periodic change, namely oscillation. This oscillating flow enhances convective heat transfer within the tube. For example, chinese patent CN2293790Y proposes a heat exchange tube having a spherical concave on the outer surface and a spherical convex on the inner surface; in chinese patent CN200989745Y, a concave-convex heat exchange tube is proposed, in which circular arc concave pits are axially and symmetrically distributed on the outer circumferential surface of the tube body.

The above described heat exchange tubes with concave-convex surfaces have some disadvantages:

the convex hull of the inner surface of the heat exchange tube increases the flow resistance, and the flow resistance in the tube is increased by nearly 4 times when the heat exchange coefficient is increased by 2.7 times compared with that of a smooth tube according to numerical calculation. Therefore, the popularization and the application of the pipe type are difficult.

Disclosure of Invention

The application provides a unsmooth heat exchange tube, and this heat exchange tube not only has high heat transfer coefficient, and intraductal flow resistance reduces to some extent moreover to help reducing the use energy consumption of heat exchange tube.

The technical scheme of the application is as follows:

the concave-convex heat exchange tube comprises a tube body, wherein a plurality of pits are arranged at intervals on the outer wall surface of the tube body, a plurality of convex hulls are arranged at intervals on the inner wall surface of the tube body corresponding to the pits, and a plurality of first channels extending along the length direction of the tube body are arranged on the surface of each convex hull.

In an alternative design, the groove depth of the first channel is 0.1-0.6 mm.

In an alternative design, the first grooves on each convex hull are arranged at intervals along the circumferential direction of the pipe body.

In an alternative design, each of the first channels extends through the convex hull in the length direction.

In an alternative design, the inner wall surface of the pipe body is provided with a plurality of second channels arranged at intervals along the circumferential direction of the pipe body, each of the second channels penetrates through the pipe body in the length direction of the pipe body, and the second channels comprise the first channels.

In an alternative design, a plurality of the second channels are uniformly arranged along the circumferential direction of the pipe body, and the number of the second channels is 10-80, and the second channels are arranged in parallel with the axis of the pipe body.

In an alternative design, the second channel is arranged parallel to the axis of the tubular body.

In an alternative design, the plurality of convex hulls are arranged in a plurality of groups at intervals along the length direction of the pipe body, the number of convex hulls in each group of convex hulls is at least three, and the convex hulls in each group of convex hulls are arranged at intervals along the circumferential direction perpendicular to the axis of the pipe body.

In an alternative design, the number of convex hulls in each set of convex hulls is six;

in an alternative design, the distance between any two adjacent groups of convex hulls in the length direction of the pipe body is 10-20 mm.

In an alternative design, the pits are spherical-crown-shaped pits, correspondingly, the convex hulls are spherical-crown-shaped convex hulls, the depth of each pit is 0.8-2mm, and the projection diameter of each pit is 2-6 mm.

The first channels are arranged on the tube inner convex hull of the convex-concave heat exchange tube and extend along the length direction of the tube, the first channels enable the surface of the convex hull to form a rough surface, and under the action of the rough surface, a fluid boundary layer on the surface of the convex hull becomes a turbulent flow boundary layer or the turbulence degree is enhanced. Thereby delaying the boundary layer separation point and reducing the shape resistance caused by the convex hull in the pipe.

The vortex formed in the second channel in the non-convex hull region of the inner wall surface of the tube body reduces the velocity difference between the fluid and the wall surface, thereby reducing the frictional resistance of the fluid.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description only relate to some embodiments of the present application and are not limiting on the present application.

Fig. 1 is a schematic perspective cross-sectional view of a convex-concave heat exchange tube provided in an embodiment of the present application.

Fig. 2 is a schematic side view of a convex-concave heat exchange tube provided by the embodiment of the application.

Fig. 3 is a schematic sectional view taken along line a-a of fig. 2.

Description of the reference numerals:

the pipe comprises a pipe body 1, a pit 2, a convex hull 3, a first channel 4 and a second channel 5.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings of the embodiments of the present application. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the application without any inventive step, are within the scope of protection of the application. It will be understood that some of the technical means of the various embodiments described herein may be replaced or combined with each other without conflict.

In the description of the present application and claims, the terms "first," "second," and the like, if any, are used solely to distinguish one from another as between described objects and not necessarily in any sequential or technical sense. Thus, an object defined as "first," "second," etc. may explicitly or implicitly include one or more of the object. Also, the use of the terms "a" or "an" and the like, do not denote a limitation of quantity, but rather denote the presence of at least one of the two, and "a plurality" denotes no less than two.

In the description of the present specification and claims, if there is "direction" with respect to motion, including motion having a directional component, the term "in direction" is not necessarily to be construed as motion in only that one direction, and those skilled in the art will understand the specific meaning of the aforementioned terms in the present application as the case may be.

Fig. 1 to 3 show a specific embodiment of the concave-convex heat exchange tube of the present application, which includes a tube body 1, wherein the outer wall surface of the tube body 1 is provided with a plurality of concave pits 2 arranged at intervals, and a plurality of convex hulls 3 arranged at intervals are formed on the inner wall surface of the tube body 1 corresponding to the positions of the plurality of concave pits 2. The shape of the concave pits 2 is a spherical crown shape, and correspondingly, the shape of the convex hull 3 is also a spherical crown shape.

It can be understood that the concave pits 2 improve the heat exchange efficiency between the fluid outside the pipe and the outer wall surface of the pipe body 1, and the convex hulls 3 improve the heat exchange efficiency between the fluid inside the pipe and the inner wall surface of the pipe body 1, so that the heat exchange efficiency between the fluid outside the pipe and the fluid inside the pipe is improved.

Considering that in practical application, the fluid in the pipe mainly flows along the length direction of the pipe body 1, and the convex hull 3 in the pipe has a blocking effect on the flow as a blunt body, and can generate fluid boundary layer separation to cause shape resistance. So increased the flow resistance of intraductal fluid, and then promoted and used the energy consumption. In this regard, in order to reduce the resistance of the convex hull 3 to the fluid inside the tube, thereby reducing the energy consumption of the heat exchange tube, in the present embodiment, the surface of each convex hull 3 is provided with a plurality of first grooves 4 extending along the length direction of the tube body 1.

According to the theory of hydrodynamics, resistance is encountered when a fluid flows through a solid wall. The flow resistance is composed of two parts: frictional resistance and form resistance. The shape resistance is a pressure difference between the front and rear sides of the blunt body when the fluid passes through the blunt body, and may be referred to as shape resistance. The convex hull 3 protruding inwards on the inner wall of the tube body 1 is a blunt body, and when the fluid sweeps over the convex hull 3, the speed and direction change. Especially in the case where the convex hull 3 is of a spherical crown structure, the aforementioned change in the magnitude and direction of the velocity is more pronounced. The fluid in the pipe is at the front edge of the spherical convex hull 3, namely a stagnation point, the speed is minimum, and the pressure is maximum; the velocity increases gradually upwards along the convex hull 3, reaching a maximum near the top, whereupon the boundary layer enters the counter pressure gradient zone, and the pressure gradient of the fluid along the flow surface is zero at some locations on the object plane under the combined action of the viscous forces and the counter pressure gradient. Then the following fluid has negative pressure gradient to generate backflow, and under the displacement of the fluid of the boundary layer, part of the fluid is separated from the boundary layer to form a vortex. The point at which the pressure gradient at the wall is zero is generally referred to as the boundary layer separation point. Downstream of the point of boundary layer separation where the vortex occurs, the pressure drops sharply, forming a pressure difference with the pressure at the leading surface of the convex hull 3, creating a form resistance. Theoretical analysis shows that: the location of the separation point has a significant effect on the magnitude of the shape resistance. The fluid flows along the surface of the blunt body, and the resistance is smaller the farther the separation position appears, and conversely, the resistance is larger the farther the separation position appears. Experimental and theoretical analysis have confirmed that boundary layer separation points typically occur around 84 ° under ideal conditions for a smooth surfaced spherical object. However, for spherical objects with rough surfaces, the fluid boundary layer becomes a turbulent flow boundary layer quickly, the fluid in the boundary layer can obtain more kinetic energy from the outside under the action of the pulsating mixing of the turbulent flow, the adverse pressure gradient is overcome, and the position of a separation point is delayed, so that the shape resistance is reduced. In the embodiment, a plurality of fine first grooves 4 are arranged on the surface of the convex hull 3 in the pipe, the surface of the convex hull 3 becomes a rough surface, so that a fluid boundary layer near the surface quickly becomes a turbulent boundary layer, kinetic energy is obtained from an outer main flow through the pulsation mixing effect of fluid particles, and then the occurrence of separation points of the boundary layer is delayed, so that the shape resistance caused by the spherical crown-shaped convex hull 3 is reduced.

The first channel 4 should not be too large, and its groove depth is preferably 0.1-0.6 mm.

Referring to fig. 1 in combination with fig. 3, in the present embodiment, the plurality of first grooves 4 on each convex hull 3 are arranged at intervals along the circumferential direction of the pipe body 1, and each first groove 4 penetrates through the corresponding convex hull 3 in the length direction of the pipe body 1.

If the first channel 4 is separately formed on the convex hull 3 on the premise that the non-convex hull 3 area of the inner wall surface of the pipe body 1 is kept to be of a smooth structure, certain manufacturing difficulty exists. In this regard, we provide a relatively smart way to obtain the aforementioned first channel 4 on the convex hull 3: firstly, a plurality of second channels 5 which are arranged at intervals along the circumferential direction of the pipe body 1 are manufactured on the inner wall surface of the pipe body 1, and each second channel 5 penetrates through the pipe body 1 in the length direction of the pipe body 1; then, by means of physically extruding the outer wall surface of the pipe body 1, the concave pits 2 on the outer wall surface of the pipe body 1 and the convex hulls 3 on the inner wall surface of the pipe body 1 are obtained. Thus, after the convex hull 3 is formed, the second channel 5 at the convex hull 3 becomes the first channel 4, i.e. the first channel 4 is part of the second channel 5.

It will be appreciated that a portion of the second channel 5 not only lies on the convex hull 3 to form the first channel 4 described above, but also the second channel 5 is distributed over the non-convex hull region of the inner wall surface of the tubular body. These second channels 5, which are distributed in the non-convex area of the inner wall surface of the tubular body, contribute to reducing the frictional resistance of the fluid inside the tube, as analyzed in detail below:

when fluid flows through a solid wall, the velocity gradient at the wall is responsible for the frictional resistance at the wall. It is believed that the fluid velocity at the solid wall is zero, and the difference between the fluid velocity near the wall and the velocity at the wall is responsible for the resulting frictional resistance of the wall. In this embodiment, when the fluid sweeps the inner wall surface of the pipe body having the non-convex hull region of the second channel 5, and the flow direction coincides with the direction of the second channel 5, the friction force induces a plurality of small vortices in the second channel 5, the rotation direction of the vortices coincides with the main flow direction, and the small vortices act like a wheel to convert the sliding friction between the fluid and the solid wall surface into the rotating friction, thereby reducing the frictional resistance.

Therefore, the convex-concave heat exchange tube provided by the embodiment not only can reduce the shape resistance of the convex hull to the fluid in the tube, but also is beneficial to reducing the friction resistance of the fluid in the tube. Numerical simulation shows that compared with the heat exchange tube with the smooth spherical crown convex hull 3, the flow resistance is effectively reduced, and the energy consumption is obviously reduced.

In order to facilitate the manufacture of the heat exchange tube, the plurality of second grooves 5 may be uniformly arranged along the circumferential direction of the tube body 1, and the second grooves 5 are arranged in parallel with the axis of the tube body 1.

Referring to fig. 1 in combination with fig. 2, in order to generate periodic oscillation change in the velocity of the fluid in the pipe, in the present embodiment, the plurality of convex hulls 3 are arranged in a plurality of groups distributed at intervals along the length direction of the pipe body 1, the number of convex hulls 3 in each group of convex hulls 3 is six, and the convex hulls 3 in each group of convex hulls 3 are arranged at intervals along the circumferential direction perpendicular to the axis of the pipe body 1.

Generally, the wall thickness of the tube body 1 is preferably 0.6 to 1.2mm, the depth of the concave pits 2 is preferably 0.8 to 2mm, the projected diameter of the concave pits 2 is preferably 2 to 6mm, the total number of the second channels 5 in the tube is preferably 10 to 80, and the distance between any two adjacent groups of convex hulls 3 in the length direction of the tube body 1 is preferably 10 to 20 mm. Illustratively, the heat exchange tube is a copper tube, the outer diameter of the tube body 1 of the heat exchange tube is 19mm, the wall thickness of the tube body 1 is preferably 1mm, the depth of the concave pit 2 is 2mm, the projection diameter of the concave pit 2 is 5mm, the total number of the second channels 5 in the tube is 50, the groove depth of the first channel 4 is 0.2mm, and the distance between any two adjacent groups of convex hulls 3 in the length direction of the tube body 1 is 15 mm.

The above are merely exemplary embodiments of the present application and are not intended to limit the scope of the present application, which is defined by the appended claims.

Claims

1. The concave-convex heat exchange tube is characterized by comprising a tube body, wherein a plurality of pits are arranged at intervals on the outer wall surface of the tube body, a plurality of convex hulls are arranged at intervals on the inner wall surface of the tube body corresponding to the pits, and a plurality of first channels extending along the length direction of the tube body are arranged on the surface of each convex hull.

2. The corrugated heat exchange tube of claim 1, wherein the first channel has a groove depth of 0.1-0.6 mm.

3. The embossed heat exchange tube of claim 1, wherein the first channels of each convex hull are arranged at intervals along the circumferential direction of the tube body.

4. The embossed heat exchange tube of claim 3, wherein each of the first channels passes through the convex hull in the length direction.

5. The concavo-convex heat exchange tube of claim 4, wherein the inner wall surface of the tube body is provided with a plurality of second channels arranged at intervals in the circumferential direction of the tube body, each of the second channels penetrating the tube body in the lengthwise direction of the tube body, the second channels including the first channel.

6. The corrugated heat exchange tube of claim 5, wherein a plurality of the second grooves are uniformly arranged along the circumferential direction of the tube body, the number of the second grooves is 10 to 80, and the second grooves are arranged in parallel with the axis of the tube body.

7. The corrugated heat exchange tube of claim 5, wherein the second channel is disposed parallel to the axis of the tube body.

8. The concavo-convex heat exchange tube of claim 1, wherein a plurality of the convex hulls are arranged in plural groups at intervals along a length direction of the tube body, the number of convex hulls in each group of the convex hulls is at least three, and the convex hulls in each group of the convex hulls are arranged at intervals along a circumferential direction perpendicular to an axis of the tube body.

9. The embossed heat exchange tube of claim 8, wherein the number of the convex hulls in each set of convex hulls is six;

in the length direction of the pipe body, the distance between any two adjacent groups of convex hulls is 10-20 mm.

10. The concavo-convex heat exchange tube of claim 1, wherein the dimples are spherical-crown shaped dimples, correspondingly, the convex hulls are spherical-crown shaped convex hulls, the depth of the dimples is 0.8-2mm, and the projected diameter of the dimples is 2-6 mm.