A welded heat exchange tube applicable to in-tube flow boiling and a manufacturing method thereof

Abstract

The present application relates to a welded heat exchange tube applicable to in-tube flow boiling and a manufacturing method thereof. The welded heat exchange tube includes a tube body formed by bending and welding a metal strip. The inner surface of the tube body is provided with a plurality of convex column regions arranged at intervals in sequence along the axial direction of the tube body. Each convex column region respectively includes a first convex column group, a second convex column group, and a third convex column group arranged in sequence along the axial direction of the tube body. The first convex column group includes a plurality of first convex columns arranged at intervals in sequence in the circumferential direction perpendicular to the axis of the tube body. The second convex column group includes a plurality of second convex columns arranged at intervals in sequence in the circumferential direction perpendicular to the axis of the tube body. The third convex column group includes a plurality of third convex columns arranged at intervals in sequence in the circumferential direction perpendicular to the axis of the tube body. When observed along the axial direction of the tube body, each second convex column is arranged between two adjacent corresponding first convex columns. The present application alleviates or even completely eliminates the dry-out phenomenon in the convex column region of the heat exchange tube, which helps to improve the heat exchange efficiency of the heat exchange tube.

Description

Technical Field

[0001] This application relates to the field of heat exchange tubes, and in particular to a welded heat exchange tube suitable for flow boiling inside the tube and a manufacturing method thereof. Background Art

[0002] Dry steam tube heat exchangers are widely used in the air-conditioning refrigeration industry and in industries such as food, pharmaceuticals, and other chemical industries. The low-temperature working fluid flowing inside the heat exchange tube is heated by the hot fluid outside the tube to undergo a phase change to generate steam. Classified according to heat transfer theory, this phenomenon is called the flow evaporation phenomenon. Specifically, the fluid flowing into the heat exchange tube is liquid and the fluid flowing out is steam, and this flow process is a two-phase flow process with a very complex flow state. This flow phenomenon can be roughly divided into three flow states, or three flow patterns: discrete bubble flow (bubbly flow), elongated bubble flow (slug flow), and annular flow.

[0003] Bubbly flow mainly appears in the inlet section. After the liquid flows into the heat exchange tube and is heated, bubbles are generated, and the bubbles are mixed with the liquid to form a two-phase flow. As the fluid flows and is continuously heated, the bubbles gradually increase and merge to form large bubbles, which is then called elongated bubble flow (slug flow). As the fluid continues to flow and is continuously heated, the bubbles continue to increase. When the increase reaches a certain level, the bubbles further merge to form a gas core in the tube, squeezing the liquid to the wall surface to form annular flow. Annular flow mainly appears in the outlet section. The heat transfer mechanism of two-phase flow boiling heat transfer is that two mechanisms, convective heat transfer and nucleate boiling heat transfer, are superimposed and play a role in a certain proportion.

[0004] So far, the method of enhancing heat transfer in internal flow boiling has mainly been achieved by machining various forms of spiral ribs (teeth) on the inner surface. Chinese Patent CN2539948Y provides an internally threaded tube with cut-off ridge-type grooves with regular / irregular spacings on the spiral tooth top ridges of the inner surface, forming intermittent spiral teeth, commonly known as intermittently toothed internally threaded tubes. Chinese Patent CN201340220Y provides an internally threaded tube, the spiral teeth of which include main teeth and auxiliary teeth, and the auxiliary teeth are distributed on the bottom wall between adjacent main teeth and have a height less than 1 / 2 of the main teeth, commonly known as high-low toothed internally threaded tubes. The inner surface of the internally threaded tube provided by Chinese Patent CN2548109Y has spiral teeth, including main and auxiliary parts of teeth. The thread directions of the main and auxiliary teeth are different, the auxiliary teeth intersect the center line of the main teeth, and the auxiliary teeth penetrate the bottom of the main teeth, forming an intersecting grid-like tooth, commonly known as cross-toothed internally threaded tubes. The spiral teeth of the internally threaded tube provided by Chinese Patent CN2534545Y have a triangular groove opened at the top, making the tooth profile present an M shape. There are also many similar patents of spiral teeth, which will not be listed one by one. These designed spiral teeth play the role of rough elements attached to the wall surface. According to the fluid mechanics boundary layer theory, the existence of rough elements can promote the collision of fluid microclusters in the viscous sublayer, increase the mass and energy transfer capabilities, and improve the efficiency of convective heat transfer. Heat exchange tubes with spiral teeth on the inner surface are widely used in convective heat transfer occasions, including single-phase flow, such as occasions where water or air exchanges heat with the fluid outside the heat exchange tube through the inside of the heat exchange tube. The above-mentioned internally threaded tubes are also used. However, as described above, the inlet of the dry steam tube is liquid, and the outlet should be steam, experiencing a flow and heat transfer process of single-phase flow heat transfer, phase change heat transfer, two-phase flow heat transfer, and finally forming single-phase flow heat transfer again. The heat transfer mechanism not only includes single-phase convective heat transfer but also nucleate boiling. Although the spiral teeth play a good role in enhancing single-phase convective heat transfer, their role in enhancing nucleate boiling is poor. Summary of the Invention

[0005] The technical problem solved by this application is: to propose a welded heat exchange tube suitable for internal flow boiling and its manufacturing method, which helps to improve the heat transfer efficiency of the heat exchange tube.

[0006] The technical solution of this application is:

[0007] In the first aspect, this application proposes a welded heat exchange tube suitable for internal flow boiling, including a tube body formed by bending and welding a metal strip, and a plurality of convex column regions are arranged at intervals along the axial direction of the tube body on the inner surface of the tube body;

[0008] Each of the convex column regions respectively includes a first convex column group, a second convex column group, and a third convex column group arranged in sequence along the axial direction of the tube body. The first convex column group includes a plurality of first convex columns arranged at intervals in sequence in the circumferential direction perpendicular to the axis of the tube body. The second convex column group includes a plurality of second convex columns arranged at intervals in sequence in the circumferential direction perpendicular to the axis of the tube body. The third convex column group includes a plurality of third convex columns arranged at intervals in sequence in the circumferential direction perpendicular to the axis of the tube body;

[0009] For each of the convex column regions, when observed along the axial direction of the tube body, each of the second convex columns is arranged between two adjacent corresponding first convex columns.

[0010] In an optional design, each of the first convex columns, each of the second convex columns, and each of the third convex columns respectively includes:

[0011] A column body that protrudes from the inner surface of the tube body along the radial direction of the tube body; and

[0012] A column cap integrally formed at the top of the column body;

[0013] Wherein, the column cap includes:

[0014] An overlapping portion overlapping with the top in the radial direction, and

[0015] An extension portion integrally surrounding the overlapping portion.

[0016] In an optional design, for each of the convex column regions, when observed along the axial direction of the tube body, each of the second convex columns is arranged between two adjacent corresponding third convex columns.

[0017] In an optional design, for each of the convex column regions, the plurality of first convex columns are arranged at equal intervals in sequence along the circumferential direction of the tube body with a first pitch. The plurality of second convex columns are arranged at equal intervals in sequence along the circumferential direction of the tube body with the first pitch. The plurality of third convex columns are arranged at equal intervals in sequence along the circumferential direction of the tube body with the first pitch.

[0018] In an optional design, for each of the convex column regions, when observed along the axial direction of the tube body, the plurality of first convex columns and the plurality of third convex columns completely overlap, and each of the second convex columns is arranged at the middle position between two adjacent corresponding third convex columns.

[0019] In an optional design, the plurality of convex column regions are arranged at equal intervals in sequence along the axial direction of the tube body with a second pitch, wherein the second pitch is greater than the first pitch.

[0020] In an alternative design, for each of the convex column regions, the first convex column group, the second convex column group, and the third convex column group are arranged at equal intervals along the axial direction of the tube body with a third pitch, wherein the third pitch is smaller than the second pitch.

[0021] In an alternative design, the first pitch is 0.3 - 1.5 mm, the second pitch is not less than 2.5 mm, and the third pitch is 0.3 - 1.5 mm;

[0022] The heights of the first convex column, the second convex column, and the third convex column in the radial direction of the tube body are each 0.1 - 0.3 mm;

[0023] When viewed along the radial direction of the tube body, the column body is a square with a side length of 0.2 - 0.8 mm, and the column cap is a square with a side length of 0.25 - 1.3 mm.

[0024] In an alternative design, each of at least one of the plurality of convex column regions respectively includes a fourth convex column group, and the fourth convex column group includes a plurality of fourth convex columns arranged at intervals in sequence along the circumferential direction of the tube body;

[0025] For each of the at least one convex column region, the first convex column group, the second convex column group, the third convex column group, and the fourth convex column group are arranged in sequence along the axial direction of the tube body; wherein, when viewed along the axial direction of the tube body, each of the third convex columns is arranged between two adjacent corresponding fourth convex columns.

[0026] In a second aspect, the present application proposes a manufacturing method for the welded heat exchange tube as described in the first aspect, including:

[0027] Providing a steel strip and a rolling wheel, wherein the rolling surface of the rolling wheel is provided with a groove recessed inward;

[0028] Rolling out the column body on the surface of the steel strip through the rolling wheel;

[0029] Rolling the top of the column body so that the top of the column body extends outward to form a column cap;

[0030] Bending the steel strip to make two opposite side edges of the steel strip contact each other to form a straight seam, and welding the straight seam to form a welded pipe.

[0031] The present application has at least the following beneficial effects:

[0032] 1. In the present application, numerous convex columns on the inner surface of the tube body form a rough surface, which destroys the laminar flow state of the fluid boundary layer and improves convective heat transfer.

[0033] 2. In the present application, the convex column regions inside the tube are arranged at non - continuous intervals, and multiple convex column groups in the convex column regions and multiple convex columns in the convex column groups are arranged according to a certain rule. On the one hand, the liquid inside the tube can easily flow into the smooth regions between the convex column regions. The liquid in the smooth regions can very easily flow axially from the side to each convex column in the convex column regions, especially the corner regions and grooves of the convex columns, providing sufficient liquid for as many convex columns as possible, thereby alleviating or even completely eliminating the dry phenomenon in the convex column regions to a certain extent. On the other hand, the convex column regions and the smooth regions are arranged alternately and are both perpendicular to the axis of the heat - exchange tube, forming a stepped shape with convex and concave parts. According to the theory of fluid mechanics, when the liquid flows by, due to the viscous action of the fluid, transverse vortices will be formed at the concave parts, forming secondary flows, thereby once again increasing the heat - transfer coefficient of the heat - exchange surface.

[0034] 3. In the present application, the convex columns inside the tube are set to have an approximate T - shaped structure composed of a column body and a column cap. A corner region is formed between the surface of the convex column, especially the lower surface of the outer extension part of the column cap and the side surface of the column body, and a groove surrounding the column body is formed between the lower surface of the outer extension part of the column cap, the side surface of the column body and the inner surface of the tube body. During application, the aforementioned corner region and groove can easily capture air and the remaining parts of the escaped bubbles and store them to form vaporization nuclei. Under the action of the wall superheat, these vaporization nuclei can quickly develop into bubbles, forming a violent boiling phenomenon and improving the heat - transfer efficiency of the heat - exchange tube.

[0035] 4. Due to the special T - shaped structure of the convex columns, the distance between the column bodies of each convex column is necessarily greater than the distance between the column caps. Therefore, the liquid flowing axially inside the tube can easily flow into the convex column regions from the large gaps between the column bodies of each convex column, and the liquid that just flows into the convex column regions from the large gaps between the column bodies can directly reach the corner regions and groove parts of the convex columns serving as vaporization nuclei.

[0036] 5. The manufacturing method proposed in the present application solves the problem that the traditional process cannot process T - shaped convex columns on the inner surface of the heat - exchange tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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. Obviously, the drawings described below only relate to some embodiments of the present application and do not limit the present application.

[0038] Figure 1 It is a schematic structural diagram of the locally unfolded welded heat - exchange tube in the first embodiment of the present application.

[0039] Figure 2 is Figure 1 The sectional view taken along the A - A direction in

[0040] Figure 3Yes Figure 2 is a partially enlarged schematic view.

[0041] Figure 4 Yes Figure 1 is an enlarged schematic view of part X1 in

[0042] Figure 5 is a comparison chart of the heat transfer performance between the welded heat exchange tube and the smooth heat exchange tube in the first embodiment of the present application. In the figure, the horizontal axis represents the mass flow rate, the vertical axis represents the boiling heat transfer coefficient, the circular black dots represent the heat exchange tubes of this embodiment, and the square black dots represent the smooth heat exchange tubes.

[0043] Figure 6 is a structural schematic view of the welded heat exchange tube after partial unfolding in the second embodiment of the present application.

[0044] Figure 7 Yes Figure 6 is a sectional view taken along the B-B direction in

[0045] Figure 8 Yes Figure 6 is an enlarged schematic view of part X2 in

[0046] Explanation of reference numerals:

[0047] 1000 - tube body, 1000a - weld;

[0048] 100 - convex column area, 200 - smooth area;

[0049] 10 - first convex column group, 20 - second convex column group, 30 - third convex column group, 40 - fourth convex column group;

[0050] 1 - first convex column, 2 - second convex column, 3 - third convex column, 4 - fourth convex column;

[0051] 11 - column body, 12 - column cap;

[0052] 12a - overlapping part, 12b - extended part

[0053] D1 - first spacing, D2 - second spacing, D3 - third spacing, H - height of the convex column, L1 - side length of the column body, L2 - side length of the column cap. Detailed implementation manners

[0054] To make the objectives, 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 in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present application without creative efforts fall within the scope of protection of the present application. It can be understood that, without conflict, some technical means described in the various embodiments herein may be replaced or combined with each other.

[0055] In the description of the specification and claims of the present application, if there are terms such as "first", "second", etc., they are only used to distinguish the described objects and do not have any sequential or technical meaning. Thus, the objects defined with "first", "second", etc. may explicitly or implicitly include one or more of such objects. Also, words such as "one" or "a" do not represent a quantity limitation but rather indicate the existence of at least one, and "multiple" means not less than two.

[0056] In the description of the specification and claims of the present application, if there are terms such as "connected", "installed", "fixed", etc., unless otherwise specified, they should all be understood in a broad sense. For example, "connected" can be a detachable connection or an integral connection; it can be directly connected or indirectly connected through an intermediate medium; it can be a non-detachable connection or a detachable connection. For those skilled in the art, the specific meanings of the foregoing terms in the present application can be understood according to specific circumstances.

[0057] In the description of the specification and claims of the present application, if there are terms such as "upper", "lower", "horizontal", etc. indicating the orientation or positional relationship, it is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the purpose of clearly and simply describing the present application, rather than indicating or implying that the indicated elements must have a specific direction, be constructed and operated in a specific orientation. These directional terms are relative concepts used for relative description and clarification and can change accordingly with the change in the orientation of the components placed in the accompanying drawings. For example, if the device in the figure is flipped, the element described as "below" other elements will be positioned "above" other elements.

[0058] In the description of the specification and claims of the present application, if there is a term "configured to", depending on the context, it can generally be interchanged with "having the ability to", "designed to", "for", or "able to".

[0059] Now, the embodiments of the present application will be described with reference to the accompanying drawings.

[0060] <Example 1>

[0061] <000014> Figures 1 to 3The first specific embodiment of the welded heat exchange tube of the present application is shown, which includes a circular tube body 1000 formed by bending and welding a metal strip. The inner surface of the tube body 1000 is provided with a plurality of convex column areas 100 arranged at intervals in the axial direction of the tube body 1000. The plurality of convex column areas 100 are arranged at intervals in the axial direction of the tube body 1000, so that a relatively smooth smooth area 200 without convex columns is formed between any two adjacent convex column areas 100. Each convex column area 100 further includes a plurality of convex column groups arranged in sequence in the axial direction of the tube body 1000.

[0062] Specifically, in this embodiment, each convex column area 100 includes three convex column groups, namely, the first convex column group 10, the second convex column group 20, and the third convex column group 30 arranged in sequence in the axial direction of the tube body 1000. Among them, the first convex column group 10 includes a plurality of first convex columns 1 arranged at intervals in the circumferential direction perpendicular to the axis of the tube body 1000, that is, the first convex column group 10 includes a plurality of first convex columns 1, and the plurality of first convex columns 1 are arranged at intervals in the circumferential direction perpendicular to the axis of the tube body 1000. The second convex column group 20 includes a plurality of second convex columns 2 arranged at intervals in the circumferential direction perpendicular to the axis of the tube body 1000, that is, the second convex column group 20 includes a plurality of second convex columns 2, and the plurality of second convex columns 2 are arranged at intervals in the circumferential direction perpendicular to the axis of the tube body 1000. The third convex column group 30 includes a plurality of third convex columns 3 arranged at intervals in the circumferential direction perpendicular to the axis of the tube body 1000, that is, the third convex column group 30 includes a plurality of third convex columns 3, and the plurality of third convex columns 3 are arranged at intervals in the circumferential direction perpendicular to the axis of the tube body 1000. The plurality of convex columns of each convex column group are arranged at intervals in the circumferential direction perpendicular to the axis of the tube body 1000. The liquid flowing axially in the tube is perpendicular to the convex column group. The fluid is blocked by the convex column group and will generate a circumferential flow to the transverse sides, thereby enhancing the contact between the fluid and the heat exchange tube, especially the convex columns, and further increasing the heat transfer coefficient. Moreover, the convex column areas and the smooth areas arranged in a staggered manner and perpendicular to the tube axis form a concave-convex stepped shape. Due to the fluid viscosity effect, transverse vortices will be formed in the concave areas, forming secondary flows, thereby further increasing the heat transfer coefficient of the heat transfer surface.

[0063] For each convex column area 100, its plurality of second convex columns 2 and 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 adjacent corresponding first convex columns 1. Please refer to Figure 4 .

[0064] According to the fluid boundary layer theory, the flow field near the wall can be divided into three regions. The region close to the wall is the viscous sublayer, followed by the transition region and the turbulent region. The largest thermal resistance and flow resistance are mainly in the viscous sublayer. In this region, the transfer of momentum and energy depends on the vibration of molecules and the Brownian motion of molecules, so the transport ability is poor. If obstacles (such as the convex columns in this embodiment) are arranged in the viscous sublayer, disturbing the laminar flow state and causing collisions between fluid microclusters, the energy transport ability will be increased. On the one hand, in this embodiment, numerous convex columns on the inner surface of the tube form a rough surface, destroying the laminar state of the fluid boundary layer and improving the convective heat transfer. On the other hand, due to the non-continuous and spaced arrangement of the convex column regions 100, the convex column regions 100 and the smooth regions 200 are arranged in an alternating manner, forming a concave-convex stepped shape. According to the fluid mechanics theory, when the liquid flows by, due to the viscous action of the fluid, transverse vortices will be formed at the concave places, forming secondary flows, thereby further increasing the heat transfer coefficient of the heat transfer surface. For the flow boiling in the tube, its heat transfer mechanism is the superposition of the convective heat transfer of single-phase fluid and nucleate boiling. Therefore, it is not enough to only strengthen the single-phase convective heat transfer, and it is also necessary to strengthen the nucleate boiling.

[0065] In order to strengthen the nucleate boiling of this heat exchange tube, in this embodiment, the convex columns in the tube body 1000 are arranged in the following structure:

[0066] In this embodiment, each first convex column 1, each second convex column 2 and each third convex column 3 have basically the same structure and size. Specifically, please refer to Figure 4 and combine with Figure 3 as shown. Each first convex column 1, each second convex column 2 and each third convex column 3 respectively include a column body 11 and a column cap 12. The column body 11 protrudes from the inner surface of the tube body 1000 along the radial direction of the tube body 1000, and the column cap 12 is integrally formed on the top of the column body 11. Moreover, the column cap 12 includes an overlapping part 12a that overlaps with the aforementioned top (i.e., the top of the column body 11) in the radial direction of the tube, and an extension part 12b that integrally surrounds the overlapping part 12a. "Overlapping with the top of the column body in the radial direction of the tube" means that when observing along the radial direction of the tube body 1000 (which is also the height direction of the convex column), it overlaps with the top of the column body.

[0067] On the surface of the protruding column with this structure in this embodiment, especially at the corner area formed between the lower surface of the outer extension part 12b of the column cap 12 and the side surface of the column body 11, and a groove surrounding the column body is formed between the lower surface of the outer extension part 12b of the column cap 12, the side surface of the column body 11 and the inner surface of the tube body. During application, the aforementioned corner area and groove are more likely to capture air and trap the remaining part of the escaping bubbles, and store them to form vaporization nuclei. Under the action of the wall superheat degree, these vaporization nuclei can quickly develop into bubbles, forming a violent boiling phenomenon and improving the heat transfer efficiency of the heat exchange tube.

[0068] Generally speaking, the more the number of protruding columns or / and the greater the arrangement density, the better the heat transfer performance of the heat exchange tube. Especially in this embodiment, the more the number of such T-shaped protruding columns, the more the vaporization nuclei. More vaporization nuclei mean more bubble numbers, which will result in violent and vigorous boiling and a large heat exchange amount. Therefore, in this embodiment, each protruding column in each protruding column area 100 is arranged compactly, and the distance between adjacent fins is very small, forming a microchannel. However, the bubble dynamics in the microchannel is different from that in the conventional channel. The movement of bubbles in the microchannel is restricted by the wall friction force, and the role of buoyancy is weakened, affecting the bubble detachment speed, forming a gas film on the surface of the protruding column area 100, inhibiting the liquid from flowing into the aforementioned corner area and groove from the top of the protruding column, causing intermittent dry-out, which is not conducive to improving the heat transfer efficiency.

[0069] In response to this, in this embodiment, each protruding column area 100 is arranged at intervals in the axial direction of the tube body, so that a smooth area 200 without protruding columns and having a certain axial dimension is formed between any two adjacent protruding column areas 100. Thus, during application, the liquid in the tube can easily flow into the aforementioned smooth area 200. Further, the liquid in the smooth area 200 (non-protruding column area) can very easily flow into the protruding column area 100, especially the corner area and groove of the protruding column, along the axial direction from the side, thereby alleviating or even completely eliminating the aforementioned dry-out phenomenon in the fin area to a certain extent.

[0070] Benefiting from the above special structure of the protruding column, the distance between the column bodies of each protruding column must be greater than the distance between the column caps. Therefore, the liquid flowing axially in the tube can easily flow into the protruding column area from the large gap between the column bodies of each protruding column, and the liquid that just flows into the protruding column area from the large gap between the column bodies can directly reach the corner area and groove of the protruding column serving as the vaporization core.

[0071] It can be understood that by spacing adjacent boss sections 100, the smooth areas 200 formed between boss sections 100 can provide sufficient liquid within the tube for the outermost bosses in boss section 100 (e.g., each first boss 1 and third boss 3). To ensure that the second bosses 2 located in the middle of boss section 100 can also receive sufficient liquid from the smooth areas 200, the embodiment staggers the multiple second bosses 2 and the multiple first bosses 1 in each boss section 100 circumferentially around the tube body 1000. This ensures that, when viewed along the axis of the tube body 1000, each second boss 2 is positioned between two adjacent first bosses 1. This allows the liquid in the smooth areas 200 to flow rightward along the axis of the tube body 1000, without being blocked by the first bosses 1 and flowing more easily toward the second bosses 2. This provides more liquid for the second bosses 2, particularly the corners and grooves of the second bosses 2.

[0072] The second bosses 2 and first bosses 1 in the same boss group are staggered circumferentially around the tube 1000, reducing the obstruction of the first boss 1 on the rightward-flowing liquid in the left boss zone 100, allowing the second bosses 2 to receive more rightward-flowing liquid. Similarly, to allow the second bosses 2 to receive more leftward-flowing liquid and further enhance boiling intensity within the tank, in this embodiment, the multiple second bosses 2 and multiple third bosses 3 in each boss zone 100 are also staggered circumferentially around the tube. When viewed along the axis of the tube 1000, each second boss 2 is positioned between two adjacent third bosses 3. In this manner, when liquid in the smooth zone 200 flows leftward along the axis of the tube 1000, at least a portion of the leftward-flowing liquid is unobstructed by the third bosses 3 and readily flows toward the second bosses 2, providing more liquid for the second bosses 2.

[0073] For each convex column area 100, when observed along the axial direction of the tube body 1000, each of its second convex columns 2 is arranged not only between the corresponding two adjacent first convex columns 1, but also between the corresponding two adjacent first convex columns 1, so that the liquid in the smooth area 200 on the left and right sides of each convex column area 100 can flow more easily to the second convex columns 2, and then each convex column in the convex column area 100 can obtain relatively sufficient liquid for boiling heat absorption, thereby improving the heat exchange performance of the heat exchange tube.

[0074] Please join together Figure 1 、 Figure 2 and Figure 4As shown, in order to more conveniently obtain the above arrangement structure of each convex column in the convex column area 100 and ensure that the second convex column 2 can obtain the fluid transported axially more sufficiently, in this embodiment, for each convex column area 100, when observing along the axis direction of the pipe body 1000, each first convex column 1 in the first convex column group 10 completely overlaps with a corresponding third convex column 3 in the third convex column group 30, and each second convex column 2 is arranged at the middle position between two adjacent corresponding third convex columns 3.

[0075] In this embodiment, for each convex column area 100, multiple first convex columns 1 are arranged at equal intervals in sequence along the circumferential direction of the pipe body 1000 with a first pitch D1, multiple second convex columns 2 are arranged at equal intervals in sequence along the circumferential direction of the pipe body 1000 with a first pitch D1, and multiple third convex columns 3 are arranged at equal intervals in sequence along the circumferential direction of the pipe body 1000 with a first pitch D1. That is, multiple first convex columns 1 in each convex column area 100 are arranged at equal intervals along the circumferential direction of the pipe body 1000, multiple second convex columns 2 in each convex column area 100 are also arranged at equal intervals along the circumferential direction of the pipe body 1000, multiple third convex columns 3 in each convex column area 100 are also arranged at equal intervals along the circumferential direction of the pipe body 1000, and the distance between any two adjacent first convex columns 1, the distance between any two adjacent second convex columns 2, and the distance between any two adjacent third convex columns 3 are equal, all being the first pitch D1.

[0076] As mentioned above, in order to increase the number or / and arrangement density of the convex columns in the pipe, the various convex columns should be arranged as compactly as possible. Therefore, the above first pitch D1 should not be too large, preferably 0.3 - 1.5 mm. Specifically, in this embodiment, the first pitch D1 is 0.6 mm.

[0077] For the convenience of manufacturing this heat exchange pipe, in this embodiment, the above multiple convex column areas 100 are arranged at equal intervals along the axis direction of the pipe body 1000 with a second pitch D2. That is, multiple convex column areas 100 are arranged at equal intervals along the axis direction of the pipe body 1000, and the interval distance between any two adjacent convex column areas 100 is the second pitch D2.

[0078] It can be understood that the larger the second spacing D2 is, the larger the axial dimension of the smooth zone 200 is, and the more liquid the smooth zone 200 can obtain; the smaller the second spacing D2 is, the smaller the axial dimension of the smooth zone 200 is, and the less liquid the smooth zone 200 can obtain. However, for a heat exchange tube with a fixed size, the larger the axial dimension of the smooth zone 200 is, the smaller the total axial dimension of the convex column zone 100 is, that is, the smaller the total area of the convex column zone 100 is; the smaller the axial dimension of the smooth zone 200 is, the larger the axial dimension of the convex column zone 100 is, that is, the larger the total area of the convex column zone 100 is. Although increasing the axial dimension of the smooth zone 200 can provide more liquid for the convex column zone 100, it reduces the total distribution area of the convex columns. Moreover, when the axial dimension of the smooth zone 200 is too large, the liquid provided to the convex column zones 100 on both sides is redundant, and the efficiency of the large-size smooth zone 200 cannot be fully exerted. It can be seen that the axial dimension of the smooth zone 200 should not be too large or too small.

[0079] Generally speaking, the axial dimension of the smooth zone 200, that is, the second spacing D2 mentioned above, should not be less than 2.5 mm. Specifically, in this embodiment, the second spacing D2 is 3 mm.

[0080] In this embodiment, for each convex column zone 100, the first convex column group 10, the second convex column group 20, and the third convex column group 30 are arranged at equal intervals along the axial direction of the tube body 1000 with a third spacing D3. That is, the first convex column group 10, the second convex column group 20, and the third convex column group 30 in each convex column zone 100 are arranged at equal intervals along the axial direction of the tube body 1000, and the spacing distance between the first convex column group 10 and the second convex column group 20 is the third spacing D3, and the spacing distance between the second convex column group 20 and the third convex column group 30 is also the third spacing D3.

[0081] It can be understood that in order to increase the number and / or arrangement density of the convex columns in the first convex column group 10, the second convex column group 20, and the third convex column group 30, the above-mentioned third spacing D3 should be set to a value less than the above-mentioned second spacing D2, preferably 0.3 - 1.5 mm. Specifically, in this embodiment, the third spacing D3 is 0.6 mm.

[0082] In this embodiment, when observing along the radial direction of the tube body 1000, both the column body 11 and the column cap 12 are square, and the side length of the column cap 12 is greater than the side length of the column body 11. The side length of the square column body 11 is preferably 0.2 - 0.8 mm, and the side length of the square column cap 12 is preferably 0.25 - 1.3 mm. Specifically, in this implementation, the side length of the column body 11 is 0.6 mm, and the side length of the column cap 12 is 0.8 mm.

[0083] The height of each convex column in the radial direction of the tube body 100 is preferably 0.1 - 0.3 mm. Specifically, in this embodiment, the height of each convex column is 2 mm. The heat exchange tube is a stainless steel tube with an outer diameter of 9.52 mm.

[0084] To test the heat transfer performance of the heat exchange tube, we conducted a comparative experiment on the heat exchange tube of this embodiment and a smooth tube heat exchange tube. Among them, the inner surface of the smooth tube heat exchange tube is a smooth surface without convex column structures, and the material and size of the smooth tube heat exchange tube are the same as those of the heat exchange tube of this embodiment. Specifically as follows:

[0085] The test section uses a double-pipe experimental device. That is, R410A refrigerant passes through the inner tube, and deionized water is used to heat the refrigerant in the interlayer between different pipe diameters outside the tube, that is, outside the inner tube. The evaporation temperature is 6°C.

[0086] The experimental results are as Figure 5 shown. The abscissa in the figure is the mass flow rate of R410A, and the ordinate is the boiling heat transfer coefficient inside the tube. The circular black dots in the figure represent the heat exchange tubes of this embodiment, and the square black dots represent the smooth tube heat exchange tubes. The experimental results show that the boiling heat transfer coefficient of the heat exchange tubes of this embodiment is 1.2 - 1.7 times that of the smooth tubes.

[0087] <Second Embodiment>

[0088] Figures 6 to 8 The second specific embodiment of the welded heat exchange tube of the present application is shown. It has basically the same structure as the welded heat exchange tube in the first embodiment and can be understood by referring to the description of the first embodiment. The main difference is that:

[0089] In each convex column area 100 inside the tube body 1000, in addition to the first convex column group 10, the second convex column group 20, and the third convex column group 30, a fourth convex column group 40 is also provided. The fourth convex column group 40 includes a plurality of fourth convex columns 4 arranged at intervals in sequence along the circumferential direction of the tube body 1000. For each convex column area 100, its first convex column group 10, second convex column group 20, third convex column group 30, and fourth convex column group 40 are arranged at equal intervals in sequence along the axial direction of the tube body 1000. And when observing along the axial direction of the tube body 1000, each third convex column 3 is arranged between two adjacent corresponding fourth convex columns 4. In this way, the third convex column 3 can relatively easily obtain the liquid flowing from the direction of the fourth convex column 4, and the second convex column 2 can relatively easily obtain the liquid flowing from the direction of the first convex column 1.

[0090] In this embodiment, for each convex column area 100, when observing along the axial direction of the tube body 1000, each first convex column 1 completely overlaps with a corresponding third convex column 3 in the tube body 1000, each second convex column 2 completely overlaps with a corresponding fourth convex column 4, each second convex column 2 is arranged at the middle position between two adjacent corresponding third convex columns 3, and each third convex column 3 is arranged at the middle position between two adjacent corresponding fourth convex columns 4.

[0091] In another embodiment, only the first stud group 10, the second stud group 20, and the third stud group 30 are provided in a part of the stud area 100 inside the tube, while the remaining stud area 100 is provided with the first stud group 10, the second stud group 20, the third stud group 30, and the fourth stud group 40.

[0092] <Example Three: Manufacturing Method of Welded Heat Exchange Tube>

[0093] This embodiment proposes a manufacturing method for manufacturing the welded heat exchange tube of the above-mentioned Embodiment 1 or Embodiment 2. The method includes:

[0094] S101, providing a steel strip and a rolling wheel. Among them, the rolling surface of the rolling wheel is provided with a groove that is recessed inward, and the shape of the groove corresponds to the shape of the column body 11.

[0095] In order to improve the quality of the product, chemicals can be used to clean the steel strip. After the steel strip to be cleaned is dried, the steel strip is trimmed to make the width and thickness of the steel strip uniform.

[0096] S102, rolling out the column body on the surface of the steel strip through the rolling wheel.

[0097] After this step is completed, the protruding structure rolled out on the surface of the steel strip is a column body without a column cap and with relatively uniform thickness.

[0098] S103, then rolling the top of the column body to make the top of the column body 11 extend outward to form a column cap.

[0099] It can be understood that when the top of the column body is subjected to a mechanical rolling pressure in the height direction, it will produce a deformation that extends outward, and this deformation causes a column cap with a larger area to be formed at the top of the column body.

[0100] S104, bending the steel strip on a forming machine to make the two opposite side edges of the steel strip contact each other to form a straight seam, and welding the straight seam by an argon arc welding process to form a welded pipe.

[0101] In implementation, after completing step S104, an online eddy current flaw detector can also be used to inspect the weld of the welded pipe to ensure that the welding is tight. After confirming that the weld quality meets the standard, the welded pipe is subjected to a solution treatment in a protective atmosphere to improve the quality of the welded pipe. The aforementioned protective atmosphere can be an atmosphere with a hydrogen concentration of 25%.

[0102] The above is only an exemplary implementation manner of this application, rather than being used to limit the protection scope of this application. The protection scope of this application is determined by the appended claims.

Claims

1. A welded heat exchange tube suitable for flow boiling in the tube, comprising a tube body formed by bending and welding metal strips, characterized in that: The inner surface of the tube body is provided with a plurality of convex column areas sequentially arranged at intervals along the axial direction of the tube body, and a smooth area is formed between any two adjacent convex column areas; Each of the boss areas comprises a first boss group, a second boss group and a third boss group arranged in sequence along the axis of the tube body, wherein the first boss group comprises a plurality of first bosses arranged in sequence and at intervals in a circumferential direction perpendicular to the axis of the tube body, the second boss group comprises a plurality of second bosses arranged in sequence and at intervals in a circumferential direction perpendicular to the axis of the tube body, and the third boss group comprises a plurality of third bosses arranged in sequence and at intervals in a circumferential direction perpendicular to the axis of the tube body; For each of the convex pillar areas, when viewed along the axial direction of the tube body, each of the second convex pillars is arranged between corresponding two adjacent first convex pillars; Each of the first protrusions, each of the second protrusions, and each of the third protrusions respectively includes: a column body, the column body being formed by protruding from the inner surface of the tube body along the radial direction of the tube body; and A column cap, the column cap being integrally formed on the top of the column body; Wherein, the column cap comprises: an overlapping portion overlapping the top in the radial direction, and An extension portion integrally surrounds the overlapping portion.

2. The welded heat exchange tube according to claim 1, characterized in that: For each of the convex column areas, when viewed along the axial direction of the tube body, each of the second convex columns is arranged between corresponding two adjacent third convex columns.

3. The welded heat exchange tube according to claim 1 or 2, characterized in that: For each of the boss areas, the multiple first bosses are arranged in sequence at equal intervals at a first spacing along the circumferential direction of the tube body, the multiple second bosses are arranged in sequence at equal intervals at the first spacing along the circumferential direction of the tube body, and the multiple third bosses are arranged in sequence at equal intervals at the first spacing along the circumferential direction of the tube body.

4. The welded heat exchange tube according to claim 3, characterized in that: For each of the convex column areas, when viewed along the axial direction of the tube body, the multiple first convex columns completely overlap with the multiple third convex columns, and each of the second convex columns is arranged in the middle position between corresponding two adjacent third convex columns.

5. The welded heat exchange tube according to claim 3, characterized in that: The plurality of convex column areas are arranged in sequence at equal intervals along the axial direction of the tube body at a second interval, wherein the second interval is greater than the first interval.

6. The welded heat exchange tube according to claim 5, characterized in that: For each of the boss areas, the first boss group, the second boss group and the third boss group are equally spaced at a third interval along the axial direction of the tube body, wherein the third interval is smaller than the second interval.

7. The welded heat exchange tube according to claim 6, characterized in that: The first spacing is 0.3-1.5 mm, the second spacing is not less than 2.5 mm, and the third spacing is 0.3-1.5 mm; The heights of the first protrusion, the second protrusion, and the third protrusion in the radial direction of the tube body are 0.1-0.3 mm respectively; When observed along the radial direction of the tube body, the column body is a square with a side length of 0.2-0.8 mm, and the column cap is a square with a side length of 0.25-1.3 mm.

8. The welded heat exchange tube according to claim 1 or 2, characterized in that: Each of at least one of the plurality of boss areas comprises a fourth boss group, wherein the fourth boss group comprises a plurality of fourth bosses sequentially spaced apart along the circumferential direction of the tube body; For each of the at least one boss area, the first boss group, the second boss group, the third boss group and the fourth boss group are arranged in sequence along the axial direction of the tube body; wherein, when viewed along the axial direction of the tube body, each of the third bosses is arranged between corresponding two adjacent fourth bosses.

9. A method for manufacturing a welded heat exchange tube according to any one of claims 1 to 8, characterized in that: include: A steel belt and a rolling wheel are provided, wherein the rolling surface of the rolling wheel is provided with an inwardly concave groove; The column body is rolled out on the surface of the steel strip by the rolling wheel; Rolling the top of the column body so that the top of the column body extends outward to form a column cap; The steel strip is bent so that two opposite sides of the steel strip contact each other to form a straight seam, and the straight seam is welded to form a welded pipe.

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