CN113532181A - Welded heat exchange tube suitable for flowing boiling in tube and manufacturing method thereof - Google Patents

Abstract

The application relates to a welding heat exchange tube suitable for flowing boiling in the tube and a manufacturing method thereof, wherein the welding heat exchange tube comprises a tube body formed by bending and welding metal strips, and a plurality of convex column areas which are sequentially arranged at intervals along the axial direction of the tube body are arranged on the inner surface of the tube body; each convex column area respectively comprises a first convex column group, a second convex column group and a third convex column group which are sequentially arranged along the axis direction of the pipe body, the first convex column group comprises a plurality of first convex columns which are sequentially arranged at intervals in the circumferential direction vertical to the axis of the pipe body, the second convex column group comprises a plurality of second convex columns which are sequentially arranged at intervals in the circumferential direction vertical to the axis of the pipe body, and the third convex column group comprises a plurality of third convex columns which are sequentially arranged at intervals in the circumferential direction vertical to the axis of the pipe body; when the pipe body is observed along the axial direction of the pipe body, each second convex column is arranged between two corresponding adjacent first convex columns. The dry phenomenon in convex column district among the heat exchange tube has been alleviated or even eliminated completely in this application, helps promoting the heat exchange efficiency of heat exchange tube.

Description

Welded heat exchange tube suitable for flowing boiling in tube and manufacturing method thereof

Technical Field

The application relates to the field of heat exchange tubes, in particular to a welded heat exchange tube suitable for flowing boiling in the tube and a manufacturing method thereof.

Background

The air conditioning refrigeration industry and the chemical industries such as food, pharmacy and the like widely use the dry-steaming pipe heat exchanger. Wherein, the low-temperature working medium passing through the heat exchange tube is heated by the hot fluid outside the tube to generate phase change to generate steam. Classified according to the theory of heat transfer, this phenomenon is called flow evaporation. Specifically, liquid flows into the heat exchange tube and vapor flows out, and the flow process is a two-phase flow process, and the flow state is very complicated. This flow phenomenon can be roughly divided into three flow states, or called three flow patterns: discrete bubble flow (bubble flow), elongated bubble flow (block flow) and annular flow.

Bubble flow mainly appears in the inlet section, and after liquid flows into the heat exchange tube and is heated, bubbles are generated and mixed with the liquid to form two-phase flow. As the fluid flows and is heated, the bubbles gradually increase, merging to form large bubbles, now called elongated bubble flow (mass flow). The bubbles increase as flow continues and heat is applied, and when they increase to some extent, they further coalesce to form a gas core in the tube, displacing liquid against the wall, forming an annular flow. The annular flow occurs mainly in the outlet section. The heat exchange mechanism of the two-phase flow boiling heat transfer is as follows: the two mechanisms of convective heat transfer and nucleate boiling heat transfer are mutually superposed and act according to a certain proportion.

Heretofore, enhanced heat transfer to boiling in a tube has been accomplished primarily by machining various forms of helical ribs (teeth) on the inner surface. Chinese patent CN2539948Y provides an internal threaded tube, in which cutting ridge type grooves with regular/irregular intervals are opened along the top ridge of the spiral teeth on the inner surface to form discontinuous spiral teeth, commonly known as discontinuous-teeth internal threaded tube. Chinese patent CN201340220Y provides an internally threaded tube, the spiral teeth of which comprise primary teeth and secondary teeth, the secondary teeth are distributed on the bottom wall between adjacent primary teeth, and the height of the secondary teeth is less than 1/2 of the primary teeth. Is commonly called as a high-low tooth internal thread pipe. The inner surface of the internal thread tube provided by the Chinese patent CN2548109Y is provided with spiral teeth, which comprise a main part tooth and an auxiliary part tooth. The thread directions of the main tooth and the auxiliary tooth are different, the auxiliary tooth is intersected with the central line of the main tooth, and the auxiliary tooth penetrates through the bottom of the main tooth to form mutually crossed grid-shaped teeth. Commonly known as cross-teeth internal threaded tubes. The female screw tube provided in CN2534545Y has a triangular groove at the top of the spiral tooth to make the tooth profile of the female screw tube have an M-shape. There are many similar spiral tooth patents, not to mention one. The designed spiral teeth play a role of attaching rough elements to the wall surface. According to the theory of the fluid mechanics boundary layer, the existence of the rough elements can promote the collision phenomenon of fluid micro-clusters in the viscous bottom layer, the transmission capability of materials and energy is increased, and the efficiency of convective heat transfer is improved. Heat exchange tubes with helical teeth on the inner surface are widely used in convective heat transfer applications, including single phase flow applications where water or air is passed through the heat exchange tube to exchange heat with fluid outside the tube. The internally threaded tube described above is also employed. However, as mentioned above, the inlet of the dry distillation pipe is liquid, the outlet should be steam, and the flow and heat exchange process of single-phase flow heat exchange, phase change heat exchange, and two-phase flow heat exchange is finally formed. The heat transfer mechanism is not only single-phase convective heat transfer, but also nucleate boiling. Although the spiral teeth have a good strengthening effect on single-phase convective heat transfer, the strengthening effect on nucleate boiling is not good.

Disclosure of Invention

The technical problem that this application was solved is: the welding heat exchange tube suitable for flowing boiling in the tube and the manufacturing method thereof are provided, and the heat exchange efficiency of the heat exchange tube is improved.

The technical scheme of the application is as follows:

in a first aspect, the application provides a welded heat exchange tube suitable for in-tube flow boiling, which comprises a tube body formed by bending and welding metal strips, wherein the inner surface of the tube body is provided with a plurality of convex column areas which are sequentially arranged at intervals along the axial direction of the tube body;

each convex column area respectively comprises a first convex column group, a second convex column group and a third convex column group which are sequentially arranged along the axis direction of the pipe body, the first convex column group comprises a plurality of first convex columns which are sequentially arranged at intervals in the circumferential direction perpendicular to the axis direction of the pipe body, the second convex column group comprises a plurality of second convex columns which are sequentially arranged at intervals in the circumferential direction perpendicular to the axis direction of the pipe body, and the third convex column group comprises a plurality of third convex columns which are sequentially arranged at intervals in the circumferential direction perpendicular to the axis direction of the pipe body;

for each convex column area, when the convex column area is observed along the axial direction of the tube body, each second convex column is arranged between two corresponding adjacent first convex columns.

In an alternative design, each of the first boss, each of the second boss, and each of the third boss includes:

a shaft formed to protrude from an inner surface of the pipe body in a radial direction of the pipe body; and

a cap integrally formed at the top of the shaft;

wherein the cap comprises:

an overlapping portion overlapping with the top portion in the radial direction, an

An extension integrally surrounding the overlapping portion.

In an optional design, for each convex column area, when viewed along the axial direction of the tube body, each second convex column is arranged between two corresponding adjacent third convex columns.

In an optional design, for each of the convex column regions, the plurality of first convex columns are sequentially arranged at equal intervals along the circumferential direction of the pipe body at first intervals, the plurality of second convex columns are sequentially arranged at equal intervals along the circumferential direction of the pipe body at first intervals, and the plurality of third convex columns are sequentially arranged at equal intervals along the circumferential direction of the pipe body at first intervals.

In an optional design, for each of the convex-column regions, when viewed along the axial direction of the pipe body, the plurality of first convex columns and the plurality of third convex columns are completely overlapped, and each of the second convex columns is arranged at an intermediate position between two corresponding adjacent third convex columns.

In an optional design, the plurality of convex pillar regions are sequentially and equally spaced along the axial direction of the tube body at a second spacing, wherein the second spacing is greater than the first spacing.

In an alternative design, for each of the lug zones, the first, second, and third sets of lugs are equally spaced along the axis of the tubular body at a third pitch, wherein the third pitch is smaller than the second pitch.

In an alternative design, the first pitch is 0.3-1.5mm, the second pitch is not less than 2.5mm, and the third pitch is 0.3-1.5 mm;

the heights of the first convex column, the second convex column and the third convex column in the radial direction of the pipe body are 0.1-0.3mm respectively;

when the cylindrical cap is observed along the radial direction of the pipe body, the cylindrical body is a square with the side length of 0.2-0.8mm, and the cylindrical cap is a square with the side length of 0.25-1.3 mm.

In an optional design, each of at least one of the plurality of convex column regions respectively comprises a fourth convex column group, and the fourth convex column group comprises a plurality of fourth convex columns which are sequentially arranged at intervals along the circumferential direction of the pipe body;

for each of the at least one lug zone, the first, second, third, and fourth lug groups are arranged in sequence along an axial direction of the tubular body; when the tube body is observed along the axial direction of the tube body, each third convex column is arranged between two corresponding adjacent fourth convex columns.

In a second aspect, the present application provides a method of manufacturing a welded heat exchange tube as described in the first aspect, comprising:

providing a steel strip and a rolling wheel, wherein a rolling surface of the rolling wheel is provided with an inward concave groove;

rolling out a cylinder on the surface of the steel strip through the rolling wheel;

rolling the top of the column body to enable the top of the column body to extend to the periphery to form a column cap;

and bending the steel strip, enabling two opposite side edges of the steel strip to be in mutual contact to form a straight seam, and welding the straight seam to form a welded pipe.

The application has at least the following beneficial effects:

1, this application has formed rough surface at numerous projection on the body internal surface, destroys the boundary layer laminar flow state of fluid, has improved the convection heat transfer.

2, intraductal convex column district is discontinuously arranged at intervals in this application to a plurality of convex column groups in the convex column district and a plurality of convex columns in the convex column group are arranged according to certain law. On the one hand, the liquid in the pipe can easily flow into the smooth areas between the convex column areas, the liquid in the smooth areas can easily flow to each convex column of the convex column areas, particularly the corner areas and the grooves of the convex columns along the axial direction from the side surface, and sufficient liquid is provided for the convex columns as much as possible, so that the phenomenon of drying in the convex column areas is relieved to a certain extent or even completely eliminated. On the other hand, the convex column areas and the smooth areas are arranged in a staggered mode and are perpendicular to the axis of the heat exchange tube, convex and concave step-shaped steps are formed, according to the fluid mechanics theory, when liquid sweeps, transverse vortex can be caused in concave positions due to the viscous action of fluid, secondary flow is formed, and therefore the heat exchange coefficient of the heat exchange surface is improved again.

3, this application sets up the projection in the pipe to the structure of the approximate T style of calligraphy that constitutes by shaft and cap, has formed the corner district between the surface of projection, especially the lower surface of the epitaxial part of cap and the side surface of shaft to a round recess that encircles the shaft has been formed between the lower surface of the epitaxial part of cap, the side surface of shaft and the internal surface of body. In use, the aforementioned corner regions and grooves readily trap air and the remainder of the escaping bubbles, which are stored to form the vaporization core. Under the action of the superheat degree of the wall surface, the vaporization cores can be rapidly developed into bubbles to form a violent boiling phenomenon, so that the heat exchange efficiency of the heat exchange tube is improved.

4, thanks to the special T-shaped structure of the convex columns, the distance between the column bodies of all the convex columns is inevitably larger than the distance between the column caps, so that the liquid flowing axially in the pipe easily flows into the convex column area from the large gaps between the column bodies of all the convex columns, and the liquid flowing into the convex column area from the large gaps between the column bodies happens to directly reach the corner area and the groove part of the convex column serving as the gasification core.

5, the manufacturing method provided by the application solves the problem that the T-shaped convex column cannot be processed on the inner surface of the heat exchange tube in the traditional process.

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 partially expanded structural schematic view of a welded heat exchange tube in an embodiment of the present application.

FIG. 2 is a schematic sectional view taken along line A-A in FIG. 1.

Fig. 3 is a partially enlarged schematic view of fig. 2.

Fig. 4 is an enlarged schematic view of the X1 portion in fig. 1.

Fig. 5 is a comparison graph of heat exchange performance between a welded heat exchange tube and a smooth tube heat exchange tube in the first embodiment of the present application, in which the horizontal axis represents mass flow rate, the vertical axis represents boiling heat exchange coefficient, the round black dots represent the heat exchange tube in this embodiment, and the square black dots represent the smooth tube heat exchange tube.

Fig. 6 is a partially expanded structural schematic view of a welded heat exchange tube in the second embodiment of the present application.

Fig. 7 is a schematic sectional view taken along line B-B in fig. 6.

Fig. 8 is an enlarged schematic view of the X2 portion in fig. 6.

Description of reference numerals:

1000-pipe body, 1000 a-weld;

100-convex column area, 200-smooth area;

10-a first lug group, 20-a second lug group, 30-a third lug group and 40-a fourth lug group;

1-a first convex column, 2-a second convex column, 3-a third convex column, 4-a fourth convex column;

11-column body, 12-column cap;

12 a-overlap, 12 b-extension

D1-first distance, D2-second distance, D3-third distance, H-convex column height, L1-column body side length, and L2-column cap side length.

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 application and in the claims, the terms "connected," "mounted," "secured," and the like are used broadly, unless otherwise indicated. For example, "connected" may be a separate connection or may be integrally connected; can be directly connected or indirectly connected through an intermediate medium; may be non-detachably connected or may be detachably connected. The specific meaning of the foregoing terms in the present application can be understood by those skilled in the art as appropriate.

In the description of the present application and in the claims, if there is an orientation or positional relationship indicated by the terms "upper", "lower", "horizontal", etc. based on the orientation or positional relationship shown in the drawings, it is only for the convenience of clearly and simply describing the present application, and it is not indicated or implied that the elements referred to must have a specific direction, be constructed and operated in a specific orientation, and these directional terms are relative concepts for the sake of description and clarification and may be changed accordingly according to the change of orientation in which the elements in the drawings are placed. For example, if the device in the figures is turned over, elements described as "below" other elements would then be oriented "above" the other elements.

In the description of the specification and claims of this application, the term "configured to" if present is generally interchangeable with "… capable", "designed to", "for", or "capable", depending on the context.

Embodiments of the present application will now be described with reference to the accompanying drawings.

< example one >

Fig. 1-3 illustrate a first embodiment of such a welded heat exchange tube of the present application, which comprises a round tube body 1000 formed by bend welding of a metal strip. The inner surface of the pipe body 1000 is provided with a plurality of convex column regions 100 which are sequentially arranged at intervals along the axial direction of the pipe body 1000. The plurality of convex cylinder regions 100 are sequentially arranged at intervals along the axial direction of the pipe body 1000, so that a relatively smooth region 200 without convex cylinders is formed between any two adjacent convex cylinder regions 100. Each convex column region 100 further includes a plurality of convex column groups sequentially arranged along the axial direction of the pipe 1000.

Specifically, in this embodiment, each convex column region 100 includes three convex column groups, i.e., a first convex column group 10, a second convex column group 20, and a third convex column group 30, which are sequentially arranged along the axial direction of the pipe body 1000. Wherein, first pillar group 10 includes a plurality of first pillars 1 that interval in proper order arranged on the circumferencial direction perpendicular to the axis of body 1000, promptly, first pillar group 10 includes a plurality of first pillars 1, and this a plurality of first pillars 1 interval in proper order arranges on the circumferencial direction perpendicular to the axis of body 1000 in addition. The second boss group 20 includes a plurality of second bosses 2 arranged at intervals in order in a circumferential direction perpendicular to an axis of the pipe body 1000, that is, the second boss group 20 includes a plurality of second bosses 2, and the plurality of second bosses 2 are arranged at intervals in order in a circumferential direction perpendicular to an axis of the pipe body 1000. The third boss group 30 includes a plurality of third bosses 3 arranged at intervals in order in a circumferential direction perpendicular to the axis of the pipe body 1000, that is, the third boss group 30 includes a plurality of third bosses 3, and the plurality of third bosses 3 are arranged at intervals in order in the circumferential direction perpendicular to the axis of the pipe body 1000. A plurality of convex columns of each convex column group are arranged at intervals in sequence along the circumferential direction perpendicular to the axis of the pipe body 1000, liquid flowing axially in the pipe is perpendicular to the convex column groups, and the fluid can flow in the circumferential direction towards the two lateral sides under the blocking effect of the perpendicular convex column groups, so that the contact effect of the fluid and the heat exchange pipe, particularly the convex columns, is enhanced, and the heat exchange coefficient is further improved. And convex-concave step-shaped convex column areas which are arranged in a staggered mode and are perpendicular to the axis of the tube and the smooth areas are formed, and due to the viscous action of fluid, transverse vortex can be caused in the concave position to form secondary flow, so that the heat exchange coefficient of the heat exchange surface is improved again.

For each convex column region 100, the plurality of second convex columns 2 and the plurality of first convex columns 1 are arranged in a staggered manner in the circumferential direction of the tube body 1000, so that when viewed along the axial direction of the tube body 1000, each second convex column 2 is arranged between two corresponding adjacent first convex columns 1, as can be seen from fig. 4.

According to the fluid boundary layer theory, the flow field can be divided into three regions near the wall, where near the wall is the viscous bottom region, followed by the transition region and the turbulent flow region. The maximum thermal resistance and flow resistance are mainly in the viscous bottom layer region, and in the region, momentum and energy transfer is carried out by means of vibration of molecules and Brownian motion of the molecules, so that the transport capacity is poor. If an obstruction (e.g., a post in this embodiment) is placed in the viscous bed, the laminar flow conditions are disturbed, causing collisions between fluid micelles, which increases the energy transport capability. On the one hand, the numerous convex columns on the inner surface of the pipe body form a rough surface, the laminar state of the boundary layer of the fluid is destroyed, and the convection heat transfer is improved. On the other hand, because the convex column regions 100 are discontinuously arranged at intervals, the convex column regions 100 and the smooth regions 200 are staggered to form a convex-concave step shape. According to the fluid mechanics theory, when liquid sweeps over, a transverse vortex is caused in the concave part due to the viscous action of the fluid to form a secondary flow, so that the heat exchange coefficient of the heat exchange surface is improved again. For the flow boiling in the tube, the heat exchange mechanism is that the convection heat exchange of the single-phase fluid and the nucleate boiling are mutually superposed. Therefore, it is not enough to enhance the single-phase convective heat transfer, and it is also necessary to enhance the nucleate boiling.

In order to enhance the nucleate boiling of the heat exchange tube, the present embodiment provides the following structure for the convex pillar in the tube body 1000:

in the present embodiment, each first stud 1, each second stud 2 and each third stud 3 have substantially the same structure and dimensions. Specifically, referring to fig. 4 in combination with fig. 3, each of the first convex pillar 1, the second convex pillar 2, and the third convex pillar 3 respectively includes a pillar body 11 and a pillar cap 12. Shaft 11 is formed to protrude from the inner surface of tube 1000 in the radial direction of tube 1000, and cap 12 is integrally formed on the top of shaft 11. Further, the cap 12 includes an overlapping portion 12a overlapping the aforementioned top portion (i.e., the top portion of the shaft 11) in the radial direction of the tubular body, and an extended portion 12b integrally surrounding the overlapping portion 12 a. "overlap the top of the shaft in the radial direction of the tubular body" means: viewed in the radial direction of the pipe body 1000 (also in the height direction of the stud), the top of the shaft overlaps the top of the stud.

The surface of the stud of this embodiment, in particular, the lower surface of the extension 12b of the cap 12 and the side surface of the shaft 11, is formed with a corner region, and a ring of grooves surrounding the shaft is formed between the lower surface of the extension 12b of the cap 12, the side surface of the shaft 11 and the inner surface of the tube. In use, the aforementioned corner regions and grooves more readily trap air and the remainder of the escaping bubbles, which are stored to form the vaporization core. Under the action of the superheat degree of the wall surface, the vaporization cores can be rapidly developed into bubbles to form a violent boiling phenomenon, so that the heat exchange efficiency of the heat exchange tube is improved.

Generally speaking, the more the number of the convex columns is or/and the greater the arrangement density is, the better the heat exchange performance of the heat exchange tube is. Particularly, in the embodiment, the more the number of the T-shaped convex columns is, the more vaporization cores are, the more vaporization cores mean that the number of bubbles is large, so that the boiling is violent and vigorous, and the heat exchange amount is large. Therefore, in the present embodiment, the convex pillars in each convex pillar region 100 are compactly arranged, and the distance between adjacent fins is small, so as to form a micro channel. However, the dynamics of the bubbles in the micro-channel is different from that of the conventional channel, the movement of the bubbles in the micro-channel is limited by the friction force of the wall surface, the action of buoyancy is weakened, the separation speed of the bubbles is influenced, an air film is formed on the surface of the convex column area 100, and the liquid is inhibited from flowing into the corner area and the groove from the top of the convex column to cause intermittent drying, which is not beneficial to the improvement of the heat exchange efficiency.

In this embodiment, each convex cylinder area 100 is sequentially arranged at intervals in the axial direction of the tube 1000, so that a smooth area 200 without a convex cylinder and having a certain axial dimension is formed between any two adjacent convex cylinder areas 100. In this way, in use, the liquid in the tube can easily flow into the smooth region 200, and further, the liquid in the smooth region 200 (non-convex column region) can very easily flow into the convex column region 100, particularly the corner regions and grooves of the convex column, from the side in the axial direction, so that the dry-up phenomenon in the fin region is alleviated to some extent or even completely eliminated.

Owing to the special structure of the convex columns, the distance between the column bodies of the convex columns is necessarily larger than the distance between the column caps, so that the liquid flowing axially in the pipe easily flows into the convex column area from the large gaps between the column bodies of the convex columns, and the liquid flowing into the convex column area from the large gaps between the column bodies happens to directly reach the corner areas and the groove parts of the convex columns serving as gasification cores.

It will be appreciated that the adjacent convex column regions 100 are arranged at intervals, so that the smooth regions 200 formed between the convex column regions 100 can provide more sufficient liquid in the tube for the convex columns (such as the first convex column 1 and the third convex column 3) at the outermost side of the convex column regions 100. In order to make the second convex column 2 located at the middle position of the convex column region 100 obtain the liquid in the smooth region 200 more sufficiently, in the embodiment, the plurality of second convex columns 2 and the plurality of first convex columns 1 of each convex column region 100 are arranged in a staggered manner in the circumferential direction of the tube body 1000, so that each second convex column 2 is arranged between two corresponding adjacent first convex columns 1 when viewed along the axial direction of the tube body 1000. Thus, when the liquid in the smooth region 200 flows to the right along the axial direction of the tube 1000, at least a portion of the right flow liquid is not blocked by the first pillar 1 and flows to the second pillar 2 more easily, so as to provide more liquid for the second pillar 2, especially for the corner region and the groove of the second pillar 2.

With second projection 2 and first projection 1 in same projection group dislocation arrangement on the circumferencial direction of body 1000 to reduced the blockking of first projection 1 to 100 right side flows liquid in left side projection district, make second projection 2 can obtain more right side flows liquid. In the same way, in order to make the second convex column 2 obtain more left-flow liquid, so as to further increase the boiling intensity in the tank, in this embodiment, for each convex column region 100, the plurality of second convex columns 2 and the plurality of third convex columns 3 are also arranged in a staggered manner in the circumferential direction of the pipe body, so that when viewed along the axial direction of the pipe body 1000, each second convex column 2 is arranged between two corresponding adjacent third convex columns 3. Thus, when the liquid in the smooth region 200 flows leftwards along the axial direction of the tube 1000, at least a portion of the left-flowing liquid flows towards the second cylinder 2 without being blocked by the third cylinder 3, so as to provide more liquid for the second cylinder 2.

For each convex column area 100, when observing along the axial direction of the pipe body 1000, each second convex column 2 is not only arranged between two corresponding adjacent first convex columns 1, but also arranged between two corresponding adjacent first convex columns 1, so that the liquid in the smooth areas 200 on the left side and the right side of each convex column area 100 can easily flow to the second convex column 2, and each convex column of the convex column area 100 can obtain more sufficient liquid for boiling and heat absorption, thereby improving the heat exchange performance of the heat exchange pipe.

Please refer to fig. 1, fig. 2 and fig. 4 together, in order to more conveniently obtain the above arrangement structure of each convex column in the convex column region 100 and ensure that the second convex column 2 can more sufficiently obtain the fluid conveyed along the axial direction, in this embodiment, for each convex column region 100, when viewed along the axial direction of the pipe body 1000, each first convex column 1 in the first convex column group 10 is completely overlapped with a corresponding one of the third convex columns 3 in the third convex column group 30, and each second convex column 2 is arranged at the middle position between two corresponding adjacent third convex columns 3.

In this embodiment, for each convex column area 100, a plurality of first convex columns 1 are sequentially arranged at equal intervals along the circumferential direction of the tube 1000 at a first interval D1, a plurality of second convex columns 2 are sequentially arranged at equal intervals along the circumferential direction of the tube 1000 at a first interval D1, and a plurality of third convex columns 3 are sequentially arranged at equal intervals along the circumferential direction of the tube 1000 at a first interval D1. That is, the plurality of first studs 1 of each stud region 100 are arranged at equal intervals along the circumferential direction of the pipe body 1000, the plurality of second studs 2 of each stud region 100 are also arranged at equal intervals along the circumferential direction of the pipe body 1000, the plurality of third studs 3 of each stud region 100 are also arranged at equal intervals along the circumferential direction of the pipe body 1000, and the distance between any two adjacent first studs 1, the distance between any two adjacent second studs 2, and the distance between any two adjacent third studs 3 are equal, and are the first distance D1.

As mentioned above, in order to increase the number and/or arrangement density of the inner convex pillars, the convex pillars should be arranged as compactly as possible, so the first distance D1 is not preferably large, preferably 0.3-1.5mm, and in the embodiment, the first distance D1 is 0.6 mm.

In order to facilitate the fabrication of the heat exchange tube, in the present embodiment, the plurality of convex pillar regions 100 are arranged at equal intervals along the axial direction of the tube body 1000 by a second distance D2. That is, the plurality of convex pillar regions 100 are arranged at equal intervals along the axial direction of the tube 1000, and the interval distance between any two adjacent convex pillar regions 100 is the second interval D2.

It will be appreciated that the greater the second spacing D2, the greater the axial dimension of the smooth region 200, and the greater the amount of liquid that can be obtained by the smooth region 200; the smaller the second spacing D2, the smaller the axial dimension of the smooth zone 200, and the less amount of liquid the smooth zone 200 can achieve. However, for a fixed-size heat exchange tube, the larger the axial dimension of the smooth region 200, the smaller the total axial dimension of the convex cylindrical region 100, i.e., the smaller the total area of the convex cylindrical region 100; the smaller the axial dimension of smooth region 200, the larger the axial dimension of the lug region 100, i.e., the larger the total area of lug region 100. Although increasing the axial dimension of the smooth region 200 provides more liquid to the convex column region 100, the total distribution area of the convex column is reduced. Moreover, when the axial dimension of the smooth region 200 is too large, the liquid provided to the two side convex column regions 100 has surplus, and the effect of the large smooth region 200 cannot be fully exerted. It can be seen that the axial dimension of the smooth region 200 should not be too large, nor too small.

Generally, the axial dimension of the smooth zone 200, i.e. the second distance D2, is not preferably less than 2.5 mm. In the present embodiment, the second distance D2 is 3 mm.

In the present embodiment, for each convex column region 100, first convex column group 10, second convex column group 20, and third convex column group 30 are arranged at equal intervals along the axial direction of pipe 1000 by third distance D3. That is, first, second, and third boss groups 10, 20, and 30 in each boss region 100 are arranged at equal intervals along the axial direction of pipe body 1000, and the distance between first boss group 10 and second boss group 20 is third distance D3, and the distance between second boss group 20 and third boss group 30 is third distance D3.

It is understood that, in order to increase the number and/or arrangement density of each of the columns in first, second, and third column sets 10, 20, and 30, third distance D3 should be set to a value smaller than second distance D2, preferably 0.3-1.5mm, and particularly in this embodiment, third distance D3 is 0.6 mm.

In this embodiment, when viewed in the radial direction of pipe body 1000, both of shaft 11 and cap 12 are square, and the side length of cap 12 is greater than that of shaft 11. The side length of the square column 11 is preferably 0.2-0.8mm, and the side length of the square column cap 12 is preferably 0.25-1.3 mm. Specifically, in the present embodiment, the side length of the column body 11 is 0.6mm, and the side length of the column cap 12 is 0.8 mm.

The height of each of the bosses in the radial direction of the pipe body 100 is preferably 0.1-0.3mm, and particularly in the present embodiment, the height of each of the bosses is 2 mm. The heat exchange tube is a stainless steel tube with the outer diameter of 9.52 mm.

In order to test the heat exchange performance of the heat exchange tube, a comparison experiment of flowing boiling in the tube is carried out on the heat exchange tube and the smooth tube heat exchange tube of the embodiment, wherein the inner surface of the smooth tube heat exchange tube is a smooth surface without a convex column structure, and the material and the size of the smooth tube heat exchange tube are the same as those of the heat exchange tube of the embodiment. The method comprises the following specific steps:

the experimental section adopts a sleeve type experimental device, namely, refrigerant passes through R410A in the pipe, and the refrigerant is heated by deionized water outside the pipe, namely an interlayer between different pipe diameters. The evaporation temperature was 6 ℃.

The results of the experiment are shown in FIG. 5. The abscissa of the graph is the mass flow rate of R410A, and the ordinate of the graph is the boiling heat transfer coefficient in the tube, and the circle black dots in the graph represent the heat exchange tube of the present embodiment, and the square black dots represent the smooth tube heat exchange tube. The experimental results show that the heat exchange coefficient of the heat exchange tube of the embodiment is 1.2-1.7 times that of the smooth tube.

< example two >

Fig. 6 to 8 show a second specific embodiment of the welded heat exchange tube of the present application, which has substantially the same structure as the welded heat exchange tube of the first embodiment, and can be understood with reference to the description of the first embodiment, with the main difference that:

each boss area 100 in pipe body 1000 is provided with a fourth boss group 40 in addition to first boss group 10, second boss group 20, third boss group 30. The fourth stud group 40 includes a plurality of fourth studs 4 arranged at intervals in sequence along the circumferential direction of the pipe body 1000. For each convex column region 100, the first convex column group 10, the second convex column group 20, the third convex column group 30 and the fourth convex column group 40 are sequentially arranged at equal intervals along the axial direction of the pipe body 1000, and when observed along the axial direction of the pipe body 1000, each third convex column 3 is arranged between two corresponding adjacent fourth convex columns 4. Thus, the third convex column 3 can easily obtain the liquid flowing from the fourth convex column 4, and the second convex column 2 can easily obtain the liquid flowing from the first convex column 1.

In this embodiment, for each convex column region 100, when viewed along the axial direction of the tube 1000, each first convex column 1 is completely overlapped with a corresponding one of the third convex columns 3 in the tube 1000, each second convex column 2 is completely overlapped with a corresponding one of the fourth convex columns 4, each second convex column 2 is disposed at a middle position between two corresponding adjacent third convex columns 3, and each third convex column 3 is disposed at a middle position between two corresponding adjacent fourth convex columns 4.

In another embodiment, a portion of post areas 100 within a tube are provided with only first, second, and third sets 10, 20, 30, while the remaining post areas 100 are provided with first, second, third, and fourth sets 10, 20, 30, 40.

< example three: method for manufacturing welded heat exchange tube

The present embodiment proposes a manufacturing method for manufacturing the welded heat exchange tube of the first or second embodiment, the method comprising:

s101, providing a steel belt and a rolling wheel, wherein the rolling surface of the rolling wheel is provided with an inward concave groove, and the shape of the groove corresponds to the shape of the column body 11.

In order to improve the quality of products, chemicals can be used for cleaning the steel belt, and after the cleaned steel belt is dried, the steel belt is subjected to edge trimming treatment, so that the width and the thickness of the steel belt are uniform and consistent.

And S102, rolling the surface of the steel strip to form a column body through a rolling wheel.

After the step is finished, the convex structure rolled on the surface of the steel strip is a column body without a column cap and with relatively uniform thickness.

And S103, rolling the top of the column body to extend the top of the column body 11 to the periphery to form a column cap.

It will be appreciated that when the top of the shaft is subjected to mechanical crushing in the height direction, there is an outwardly extending deformation which results in the formation of a large area cap at the top of the shaft.

And S104, bending the steel strip on a forming machine, enabling two opposite side edges of the steel strip to be in mutual contact to form a straight seam, and welding the straight seam through an argon arc welding process to form a welded pipe.

In the implementation, after step S104 is completed, an online eddy current flaw detector can be used to inspect the weld of the welded pipe to ensure tight welding, and after the quality of the weld is confirmed to reach the standard, the welded pipe is subjected to solution treatment in a protective atmosphere to improve the quality of the welded pipe. The protective atmosphere may be an atmosphere having a hydrogen concentration of 25%.

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

Claims (10)

1. A welded heat exchange tube suitable for flow boiling in a tube, comprising a tube body formed by bending and welding metal strips, characterized in that,

the inner surface of the pipe body is provided with a plurality of convex column areas which are sequentially arranged at intervals along the axial direction of the pipe body;

each convex column area respectively comprises a first convex column group, a second convex column group and a third convex column group which are sequentially arranged along the axis direction of the pipe body, the first convex column group comprises a plurality of first convex columns which are sequentially arranged at intervals in the circumferential direction perpendicular to the axis direction of the pipe body, the second convex column group comprises a plurality of second convex columns which are sequentially arranged at intervals in the circumferential direction perpendicular to the axis direction of the pipe body, and the third convex column group comprises a plurality of third convex columns which are sequentially arranged at intervals in the circumferential direction perpendicular to the axis direction of the pipe body;

for each convex column area, when the convex column area is observed along the axial direction of the tube body, each second convex column is arranged between two corresponding adjacent first convex columns.

2. The welded heat exchange tube of claim 1, wherein each of said first boss, each of said second boss, and each of said third boss comprises:

a shaft formed to protrude from an inner surface of the pipe body in a radial direction of the pipe body; and

a cap integrally formed at the top of the shaft;

wherein the cap comprises:

an overlapping portion overlapping with the top portion in the radial direction, an

An extension integrally surrounding the overlapping portion.

3. A welded heat exchange tube according to claim 2,

for each convex column area, when the convex column area is observed along the axial direction of the tube body, each second convex column is arranged between two corresponding adjacent third convex columns.

4. A welded heat exchange tube according to claim 2 or 3,

for each convex column area, the first convex columns are sequentially arranged at equal intervals along the circumferential direction of the pipe body at first intervals, the second convex columns are sequentially arranged at equal intervals along the circumferential direction of the pipe body at first intervals, and the third convex columns are sequentially arranged at equal intervals along the circumferential direction of the pipe body at first intervals.

5. A welded heat exchange tube according to claim 4,

for each convex column area, when the convex column area is observed along the axial direction of the pipe body, the plurality of first convex columns and the plurality of third convex columns are completely overlapped, and each second convex column is arranged in the middle position between two corresponding adjacent third convex columns.

6. A welded heat exchange tube according to claim 4,

the plurality of convex column regions are sequentially arranged at equal intervals along the axis direction of the tube body at second intervals, wherein the second intervals are larger than the first intervals.

7. A welded heat exchange tube according to claim 6,

for each convex column area, the first convex column group, the second convex column group and the third convex column group are arranged at equal intervals along the axis direction of the pipe body at a third interval, wherein the third interval is smaller than the second interval.

8. A welded heat exchange tube according to claim 7,

the first distance is 0.3-1.5mm, the second distance is not less than 2.5mm, and the third distance is 0.3-1.5 mm;

the heights of the first convex column, the second convex column and the third convex column in the radial direction of the pipe body are 0.1-0.3mm respectively;

when the cylindrical cap is observed along the radial direction of the pipe body, the cylindrical body is a square with the side length of 0.2-0.8mm, and the cylindrical cap is a square with the side length of 0.25-1.3 mm.

9. A welded heat exchange tube according to claim 1 or 2 or 3,

each of at least one convex column area in the plurality of convex column areas respectively comprises a fourth convex column group, and the fourth convex column group comprises a plurality of fourth convex columns which are sequentially arranged at intervals along the circumferential direction of the pipe body;

for each of the at least one lug zone, the first, second, third, and fourth lug groups are arranged in sequence along an axial direction of the tubular body; when the tube body is observed along the axial direction of the tube body, each third convex column is arranged between two corresponding adjacent fourth convex columns.

10. A method of manufacturing a welded heat exchange tube as claimed in any one of claims 1 to 9, comprising:

providing a steel strip and a rolling wheel, wherein a rolling surface of the rolling wheel is provided with an inward concave groove;

rolling out a cylinder on the surface of the steel strip through the rolling wheel;

rolling the top of the column body to enable the top of the column body to extend to the periphery to form a column cap;

and bending the steel strip, enabling two opposite side edges of the steel strip to be in mutual contact to form a straight seam, and welding the straight seam to form a welded pipe.

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