Shape memory alloy plug and micro-channel heat exchanger leakage blocking method

Abstract

The invention discloses a shape memory alloy plug and a microchannel heat exchanger leakage blocking method.The plug comprises a guide head part, a deformation umbrella cover and a center supporting column, the center supporting column is arranged at one end of the guide head part in the axial direction, and the deformation umbrella cover is conical and arranged on the guide head part in a surrounding mode; the deformation umbrella cover is made of shape memory alloy, and under the action of external force, the deformation umbrella cover is folded to form a cylindrical structure surrounding the outer side of the central supporting column. After the plug is manufactured, the conical umbrella cover is changed into a cylindrical shape through external force, then the plug is injected into a flow channel, and by means of the temperature deformation recovery effect of the shape memory alloy plug, the shape of the conical umbrella cover is recovered near a leakage point, and after the conical umbrella cover makes contact with the wall face of the flow channel, rapid recognition of the leakage position and plugging treatment of the leakage point are achieved. The method is simple in principle, high in realizability, easy and convenient to operate, capable of rapidly recognizing the leakage flow channel and automatically achieving leakage point blocking treatment and good in market application prospect.

Description

Technical Field

[0001] This invention relates to the field of microchannel heat exchanger leakage treatment technology, specifically to a shape memory alloy plug and a method for sealing leaks in microchannel heat exchangers. Background Technology

[0002] Microchannel diffusion-welded heat exchangers (MCDs) are a novel type of heat exchanger characterized by high compactness and excellent heat exchange efficiency. They are widely used in traditional petrochemical, renewable energy utilization, and chemical extraction industries. These heat exchangers are primarily manufactured using advanced microchannel forming and diffusion welding technologies.

[0003] like Figure 1 As shown, the structure of a conventional MCD heat exchanger mainly consists of a medium-1 inlet tube box 1, a medium-1 outlet tube box 2, a medium-2 inlet tube box 3, a medium-2 outlet tube box 4, and a heat exchange core 5. The heat exchange core 5 is usually formed by periodically stacking upper and lower cover plates 51, medium-1 heat exchange plate 52, and medium-2 heat exchange plate 53, and then forming a tightly connected porous core block through diffusion welding.

[0004] The MCD heat exchanger uses a side inlet / outlet design on one side of the flow channel, achieving vertical deflection in the inlet / outlet area through microchannels (e.g.) Figure 1 The medium flows in two directions on one side, while the other side typically uses a straight-in / straight-out flow pattern (e.g., the medium flows in two directions on the other side). Figure 1 (Medium medium flow direction). The hot and cold side heat exchange plates are stacked sequentially at intervals, and the length, width, and number of heat exchange plates are adjusted according to the required heat exchange area, process limitations, and other factors. The numerous microchannel structures give this type of heat exchanger a large heat exchange specific surface area, and the diffusion welding process gives the MCD heat exchanger high weld joint strength, which is a significant feature that distinguishes the MCD heat exchanger from conventional heat exchangers.

[0005] Generally speaking, MCD heat exchangers have a high-pressure withstand capability far exceeding their design pressure; however, leakage problems caused by design errors, manufacturing deviations, or structural failures cannot be completely ignored. For example... Figure 2As shown, the first and second medium channels are periodically spaced along their height. Leaks in the MCD heat exchanger can be categorized into four types: 1) Leakage to the external environment through the weld seams at the edge of the heat exchange plate; 2) Cross-channel leakage between the medium channels on both sides due to heat exchange plate rupture, i.e., leakage between different layers of plates; 3) Cross-channel leakage between channels in the same layer due to the failure of the weld seams at the "ribs" between the heat exchange plate channels, i.e., leakage between channels in the same layer; 4) Leakage of the medium into the other side of the tube box due to the failure of the weld seams at the edge of the flow channel. Leaks of types I, II, and IV will cause the working medium to leak from the flow channel to the outside or into the other loop, posing the greatest threat to the safe operation of the MCD heat exchanger. These types of leaks should be avoided as much as possible during the design and manufacturing process of the heat exchanger. In industrial applications, if such leaks occur, leak detection and plugging should be carried out immediately. Type III leaks, however, have an extremely low probability of occurrence because the pressure between channels in the same layer is equal, and their impact on the safe operation of the MCD heat exchanger is also minimal; therefore, type III leaks can be ignored.

[0006] For conventional shell-and-tube heat exchangers, in the event of a tube rupture, the leaking tube can be detected by introducing gas into the shell side and applying soapy water to the tube sheet side. For Class I and Class IV leaks, detection and post-treatment can be performed on the outer surface of the heat exchanger or through the tube box interface. However, for Class II leaks (differential plate leaks), which occur inside the heat exchanger's microchannels, the numerous, small-diameter, and long microchannels make visual inspection extremely difficult, making it hard to determine the leak location. Currently, there is a severe lack of relevant methods, technologies, and equipment for leak detection and repair of microchannel heat exchangers. Therefore, to meet the practical needs of industrial applications, there is an urgent need to develop leak detection and repair methods suitable for microchannel heat exchangers. Summary of the Invention

[0007] The purpose of this invention is to address the lack of effective methods for handling leaks caused by dissimilar plates inside microchannel heat exchangers. This invention provides a shape memory alloy plug and a method for sealing leaks in microchannel heat exchangers. The shape memory alloy plug undergoes temperature deformation in the high-temperature affected zone near the leak point, restoring its shape and enabling rapid identification and sealing of the leak location. This invention is simple in principle, highly feasible, easy to operate, can quickly identify leaking channels, and can automatically seal leaks, thus possessing promising market application prospects.

[0008] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a shape memory alloy plug, comprising a guide head, a deformable umbrella surface, and a central support. The central support is axially disposed at one end of the guide head. The deformable umbrella surface is conical and surrounds the guide head. The deformable umbrella surface is made of shape memory alloy, and under the action of external force, the deformable umbrella surface contracts to form a cylindrical structure. The cylindrical structure surrounds the outside of the central support.

[0009] In the above scheme, after the shape memory alloy plug is manufactured, its deformed umbrella-shaped surface is closed into a cylindrical structure by external force, facilitating its entry into the flow channel with the medium. The central support ensures that it is parallel to the flow direction of the medium. Due to the unique properties of shape memory alloys, when subjected to certain temperature conditions, their shape memory function is restored, causing the deformed umbrella-shaped surface to gradually unfold and return to its original conical shape. Therefore, this shape memory alloy plug can be used to restore the conical umbrella-shaped surface near the leakage point in the flow channel, thus achieving the sealing of the leakage point.

[0010] As a feasible solution of the present invention, the shape memory alloy has a one-way memory effect, and the deformed umbrella surface can recover its original shape after being heated. Using this shape memory alloy with a one-way memory effect, the deformed umbrella surface will gradually recover to its original conical shape after being heated, so that leaking channels can be blocked.

[0011] As a feasible embodiment of the present invention, the guide head has a conical guide surface in the direction away from the central support. By providing a conical guide surface on the guide head, the shape memory alloy plug can flow smoothly in the microchannel during use.

[0012] As a feasible solution of the present invention, the guide head is made of the same material as the deformable umbrella surface. This makes the production and manufacturing of shape memory alloy plugs more convenient.

[0013] As a feasible solution of the present invention, the guide head and the deformable umbrella surface are integrally formed. This allows for a better connection between the deformable umbrella surface and the guide head, and also facilitates the production and manufacturing of shape memory alloy plugs.

[0014] As a feasible solution of the present invention, the material of the central support pillar is different from the material of the guide head and the deformable umbrella surface. By using a different material for the central support pillar, the cost of the entire plug can be reduced.

[0015] As a feasible solution of the present invention, the material of the central support pillar is the same as the material of the guide head and the deformable umbrella surface. This makes the production and manufacturing of shape memory alloy plugs more convenient.

[0016] As a feasible solution of the present invention, the guide head, the deformable umbrella surface, and the central support are integrally formed. This allows for better integration of the deformable umbrella surface, the central support, and the guide head, and also facilitates the production and manufacturing of shape memory alloy plugs.

[0017] As a feasible solution of the present invention, after the deformable umbrella surface shrinks into a cylindrical structure under the action of external force, the outer diameter of the entire shape memory alloy plug is smaller than the radial dimension of the microchannel, and the length is larger than the radial dimension of the microchannel. By limiting the overall external dimensions of the shape memory alloy plug, and in conjunction with the designed central support, the shape memory alloy plug can be kept as parallel as possible to the direction of medium flow when flowing in the channel, so that the conical umbrella surface fits better with the channel wall, thereby achieving a better sealing effect.

[0018] As a feasible solution of the present invention, after the deformable umbrella surface is closed to form a cylindrical structure under the action of external force, there is a gap between its inner wall and the outer wall of the central support.

[0019] Secondly, the present invention provides a method for sealing leaks in a microchannel heat exchanger, comprising: By controlling the temperature and pressure of the low-temperature medium and the high-temperature medium in the heat exchanger, and keeping the pressure of the high-temperature medium higher than that of the low-temperature medium, a high-temperature influence zone is formed in the microchannel of the low-temperature medium near the leak point. The shape memory alloy plug described in the first aspect is injected from the low-temperature medium inlet side of the heat exchanger, so that the shape memory alloy plug enters each low-temperature medium microchannel in the heat exchanger. After the shape memory alloy plug flows with the medium to the high-temperature affected area, its deformable umbrella surface gradually expands from a cylindrical shape to a conical shape until the deformable umbrella surface is in complete contact with the flow channel wall, thus sealing the leakage point.

[0020] This method controls the temperature and pressure of the low-temperature and high-temperature media in the heat exchanger, creating a high-temperature affected zone near the leak point within the microchannels of the low-temperature media. Shape memory alloy plugs are then injected into each of the low-temperature media microchannels within the heat exchanger. As the shape memory alloy plugs flow with the media to the high-temperature affected zone, their deformable umbrella-shaped surface gradually expands from a cylindrical shape to a conical shape until it fully contacts the channel wall, thereby sealing the leak point.

[0021] As a feasible solution of the present invention, it further includes: setting a filter screen on the low temperature medium outlet side of the heat exchanger to collect the outflowing shape memory alloy plug.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The shape memory alloy plug of this invention includes a guide head, a deformable umbrella surface, and a central support. After the shape memory alloy plug is manufactured, its deformable umbrella surface is closed up to form a cylindrical structure by external force. Due to the unique properties of shape memory alloy, when it is under certain temperature conditions, its shape memory function is restored, so that the deformable umbrella surface will gradually open up and return to the conical shape when it was just made. Therefore, this shape memory alloy plug can be used to restore the conical umbrella surface shape near the leakage point in the flow channel, thereby achieving the sealing treatment of the leakage point.

[0023] 2. The microchannel heat exchanger leakage sealing method in this invention controls the temperature and pressure of the low-temperature medium and the high-temperature medium in the heat exchanger, so that a high-temperature affected zone is formed in the microchannel of the low-temperature medium near the leak point. Shape memory alloy plugs are injected into each low-temperature medium microchannel in the heat exchanger. When the shape memory alloy plugs flow with the medium to the high-temperature affected zone, their deformable umbrella surface gradually expands from a cylindrical shape to a conical shape until it is in complete contact with the channel wall, thereby sealing the leak point. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the structure of an MCD heat exchanger in the prior art; Figure 2 A schematic diagram illustrating leakage types in existing MCD heat exchangers; Figure 3 This is a schematic diagram of the shape memory alloy plug in this invention; Figure 4 A schematic diagram illustrating the principle of leak detection and leak sealing for the shape memory alloy plug in this invention; Figure 5 This is a schematic diagram illustrating the operation of leak detection and leak sealing for the shape memory alloy plug in this invention.

[0025] The attached diagram shows the markings and corresponding component names: 1-Inlet pipe box for medium one, 2-Outlet pipe box for medium one, 3-Inlet pipe box for medium two, 4-Outlet pipe box for medium two, 5-Heat exchange core, 51-Cover plate, 52-Heat exchange plate for medium one, 53-Heat exchange plate for medium two, 54-Low temperature medium microchannel, 55-High temperature medium microchannel, 56-Leak point, 57-High temperature affected area, 6-Shape memory alloy plug, 61-Guide head, 62-Deformable umbrella surface, 63-Central support, 7-Filter screen. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0028] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0031] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0032] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0033] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0034] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0035] Generally speaking, MCD heat exchangers have a high pressure resistance capacity far exceeding their design pressure. However, leakage problems caused by design errors, manufacturing deviations, or structural failures cannot be completely ignored. Because the low-temperature medium heat exchange plates and high-temperature medium heat exchange plates are periodically spaced in the height direction, if a heat exchange plate breaks down, cross-cavity leakage will occur in the flow channels on both sides of the medium, i.e., leakage between different plates. This will seriously threaten the safe operation of the MCD heat exchanger.

[0036] For leaks in multilayer heat exchangers, visual inspection is extremely difficult due to the numerous, small-diameter, and long microchannels, making it hard to pinpoint the leak location. Furthermore, there is a severe lack of relevant methods, technologies, and equipment for leak detection and repair in microchannel heat exchangers. Therefore, there is an urgent need to develop leak detection and repair methods suitable for microchannel heat exchangers to meet the practical needs of industrial applications.

[0037] In light of this, the applicant, through in-depth research, has developed a highly feasible solution for microchannel leak detection and rapid leak repair in microchannel heat exchangers. This solution involves designing a shape memory alloy plug with a conical umbrella-shaped surface. External force is applied to transform this conical umbrella-shaped surface into a cylindrical shape. The plug is then injected into the flow channel. Utilizing the temperature deformation recovery effect of the shape memory alloy plug, the conical umbrella-shaped surface near the leak point is restored to its original shape. Upon contact with the flow channel wall, the leak location is quickly identified and the leak is sealed. This invention is simple in principle, highly feasible, easy to operate, can quickly identify leaking flow channels, and can automatically seal leak points, demonstrating promising market application prospects.

[0038] Please refer to Figures 3 to 5 The shape memory alloy plug 6 provided in this application embodiment includes a guide head 61, a deformable umbrella surface 62, and a central support 63. The central support 63 is axially disposed at one end of the guide head 61. The deformable umbrella surface 62 is conical and surrounds the guide head 61. The deformable umbrella surface 62 is made of shape memory alloy, and under the action of external force, the deformable umbrella surface 62 shrinks to form a cylindrical structure. The cylindrical structure surrounds the outside of the central support 63.

[0039] The shape memory alloy plug 6 in this application consists of a guide head 61, a deformable umbrella surface 62, and a central support 63. The deformable umbrella surface 62 is initially conical, meaning the original shape of the shape memory alloy plug 6 is an umbrella-shaped structure. Under external force, the deformable umbrella surface 62 contracts to form a cylindrical structure surrounding the central support 63, thus the shape memory alloy plug 6 at this point has an approximately cylindrical shape. It should be noted that the outer wall of this cylindrical structure can also be a rough surface, exhibiting wrinkles, similar to the wrinkles on the surface of a straight umbrella after it has been closed.

[0040] In this application, the deformable umbrella surface 62 and the central support 63 are connected by a guide head 61. The design of the guide head 61 facilitates the smooth flow of the plug in the microchannel. The deformable umbrella surface 62 is made of shape memory alloy material, which can utilize the property of shape memory alloy to restore its original shape at a specific temperature to seal the leakage point 56 of the microchannel heat exchanger.

[0041] Shape memory alloys are materials composed of two or more metallic elements that exhibit shape memory effects through thermoelasticity and martensitic phase transformation and its inverse. Shape memory alloys are the materials with the best shape memory performance among shape memory materials. To date, more than 50 alloys with shape memory effects have been discovered.

[0042] Shape memory alloys can include nickel-titanium based materials, copper-based materials, iron-based materials, and other alloys with shape memory functions. Among them, nickel-titanium alloys are one of the earliest applied shape memory alloy materials. Later, scientists added other elements to nickel-titanium alloys to further research and develop new nickel-titanium shape memory alloys such as titanium-nickel-copper, titanium-nickel-iron, and titanium-nickel-chromium. In addition, there are other types of shape memory alloys, such as copper-nickel alloys, copper-aluminum alloys, copper-zinc alloys, and iron alloys (Fe-Mn-Si, Fe-Pd), etc.

[0043] After the shape memory alloy plug 6 in this application is manufactured, its deformed umbrella surface 62 is brought together by external force to form a cylindrical structure, which facilitates its entry into the flow channel with the medium. The central support 63 can make it parallel to the direction of medium flow. Due to the unique properties of shape memory alloy, when it is under certain temperature conditions, its shape memory function is restored, causing the deformed umbrella surface 62 to gradually unfold and return to the conical shape it was when it was first manufactured. Therefore, this shape memory alloy plug 6 can be used to restore the conical umbrella surface shape near the leakage point 56 in the flow channel, thereby sealing the leakage point 56.

[0044] According to some embodiments of this application, the shape memory alloy has a one-way memory effect, and the deformed umbrella surface 62 can recover its original shape after being heated. Using this shape memory alloy with a one-way memory effect, the deformed umbrella surface 62 will gradually recover to its original conical shape after being heated, so that leaking channels can be blocked.

[0045] Shape memory alloys deform at low temperatures and recover their original shape upon heating; this shape memory phenomenon, which only exists during heating, is called the one-way memory effect. A plug made of a shape memory alloy with this one-way memory effect is deformed into a cylindrical shape under external force and then injected into the heat exchanger channel. Utilizing the temperature deformation recovery effect of the shape memory alloy plug 6, the conical umbrella shape is restored near the leak point 56, sealing the leak point 56 upon contact with the channel wall. Because it only has a one-way memory effect, once the plug recovers to its original umbrella shape, it will maintain this umbrella shape, thus keeping the leaking channel completely blocked.

[0046] According to some embodiments of this application, the guide head 61 has a conical guide surface in the direction away from the central support 63. By providing a conical guide surface on the guide head 61, the resistance to the movement of the plug in the flow channel can be reduced, facilitating the smooth flow of the shape memory alloy plug 6 in the microchannel during use.

[0047] According to some embodiments of this application, the guide head 61 and the deformable umbrella surface 62 are made of the same material. That is, both the guide head 61 and the deformable umbrella surface 62 are made of shape memory alloy, which makes it easier to manufacture the shape memory alloy plug 6.

[0048] According to some embodiments of this application, the guide head 61 and the deformable umbrella surface 62 are integrally formed. This allows for a better connection between the deformable umbrella surface 62 and the guide head 61, and also facilitates the production and manufacturing of the shape memory alloy plug 6.

[0049] According to some embodiments of this application, the material of the central support 63 is different from the materials of the guide head 61 and the deformable umbrella surface 62. By using a different material for the central support 63, the cost of the entire plug can be reduced, but the connection process between the central support 63 and the guide head 61 is increased, which is inconvenient for the production and manufacturing of the entire plug.

[0050] According to some embodiments of this application, the material of the central support 63 is the same as the material of the guide head 61 and the deformable umbrella surface 62. That is, the central support 63, the guide head 61, and the deformable umbrella surface 62 are all made of shape memory alloy, which makes it easier to manufacture the shape memory alloy plug 6.

[0051] According to some embodiments of this application, the guide head 61, the deformable umbrella surface 62, and the central support column 63 are integrally formed. This allows for a better connection between the deformable umbrella surface 62, the central support column 63, and the guide head 61, and also facilitates the production and manufacturing of the shape memory alloy plug 6.

[0052] According to some embodiments of this application, after the deformable umbrella surface 62 shrinks into a cylindrical structure under external force, the outer diameter of the entire shape memory alloy plug 6 is smaller than the radial dimension of the microchannel, and the length is larger than the radial dimension of the microchannel. By limiting the overall dimensions of the shape memory alloy plug 6, and in conjunction with the designed central support 63, the shape memory alloy plug 6 can be kept as parallel as possible to the direction of medium flow when flowing in the channel, so that the conical umbrella surface fits better with the channel wall, thereby achieving a better sealing effect.

[0053] According to some embodiments of this application, after the deformable umbrella surface 62 is folded into a cylindrical structure under the action of external force, there is a gap between its inner wall and the outer wall of the central support 63. This arrangement, since the inner wall of the deformable umbrella surface 62 is not in contact with the outer wall of the central support 63, allows the deformable umbrella surface 62 to unfold more easily into a conical umbrella surface when the temperature is reached.

[0054] This application provides a method for sealing leaks in a microchannel heat exchanger, comprising: By controlling the temperature and pressure of the low-temperature medium and the high-temperature medium in the heat exchanger, and keeping the pressure of the high-temperature medium higher than that of the low-temperature medium, a high-temperature influence zone 57 is formed near the leak point in the microchannel 54 of the low-temperature medium. The shape memory alloy plug 6 described in the first aspect is injected from the low-temperature medium inlet side of the heat exchanger, so that the shape memory alloy plug 6 enters each low-temperature medium microchannel 54 in the heat exchanger. After the shape memory alloy plug 6 flows with the medium to the high temperature affected zone 57, its deformable umbrella surface 62 gradually expands from a cylindrical shape to a conical shape until the deformable umbrella surface 62 is in complete contact with the flow channel wall, thus sealing the leakage point 56.

[0055] This method involves introducing media of different temperatures and pressures into the flow channels of a multilayer plate. By controlling the temperature and pressure of the low-temperature and high-temperature media, a high-temperature affected zone 57 can be established near the internal leakage point 56 within the low-temperature medium microchannel 54, thus providing temperature triggering conditions for the shape recovery of the shape memory alloy. A large number of shape memory alloy plugs 6 are injected into the low-temperature medium inlet tube box of the heat exchanger, allowing the shape memory alloy plugs 6 to disperse into each low-temperature medium microchannel 54. When the shape memory alloy plugs 6 flow with the medium to the high-temperature affected zone 57, their deformable umbrella surface 62 gradually expands from a cylindrical shape to a conical shape until it is in complete contact with the flow channel wall, thereby sealing the leakage point 56.

[0056] According to some embodiments of this application, the microchannel heat exchanger leakage sealing method further includes: setting a filter screen 7 on the low-temperature medium outlet side of the heat exchanger to collect the outflowing shape memory alloy plugs 6, thereby recovering the shape memory alloy plugs 6 that have not undergone temperature deformation recovery.

[0057] Figure 4A schematic diagram illustrating the principle of sealing leak point 56 using a shape memory alloy plug 6 is provided. First, after confirming the leakage inside the microchannel, i.e., a leak in the layered plate, hot and cold fluids of different temperatures are introduced into the heat exchanger channels on both sides (i.e., the low-temperature medium microchannel 54 and the high-temperature medium microchannel 55), maintaining the pressure of the hot fluid slightly higher than that of the cold fluid. Due to the presence of leak point 56 and the pressure difference between the hot and cold sides, the hot fluid continuously flows into the cold fluid side at leak point 56. The higher temperature of the hot fluid causes the cold fluid to be heated to an even higher temperature near the leak point, i.e., a high-temperature influence zone 57 exists near leak point 56. At this point, a shape memory alloy plug 6 is placed on the cold fluid side. Under the action of the cold fluid, the shape memory alloy plug 6 gradually moves towards the leak location. The temperature of the cold fluid gradually increases. When the temperature reaches a level sufficient to trigger the shape memory umbrella surface of the plug to recover its shape, the deformable umbrella surface 62 gradually expands, and the shape memory alloy plug 6 gradually changes from a cylindrical shape to a conical shape. The gap between the conical umbrella surface and the flow channel wall gradually decreases until the conical umbrella surface is in complete contact with the flow channel wall, thus sealing the leak point 56. During this process, the central column stabilizes the axis of the conical surface, making it parallel to the direction of medium flow, so that the conical umbrella surface fits better with the flow channel wall, thereby achieving a better sealing effect.

[0058] Figure 5 A schematic diagram of the operation for sealing leak point 56 using shape memory alloy plugs 6 is provided. On one side of the MCD heat exchanger, a large number of shape memory alloy plugs 6 are inserted through the low-temperature medium inlet pipe box (i.e., medium-inlet pipe box). Driven by the fluid, the shape memory alloy plugs 6 enter the low-temperature medium microchannels 54 inside the heat exchanger. Since there are numerous microchannels inside the heat exchanger, it is impractical to check each channel individually when a leak occurs in the internal flow channels. By inserting a large number of shape memory alloy plugs 6, they are dispersed into each low-temperature medium flow channel. For flow channels without leaks, the temperature of the cold fluid flowing inside is too low to trigger the shape memory alloy to restore its umbrella shape; therefore, its shape remains cylindrical and can flow out of the heat exchanger with the fluid. A collection device such as a filter screen 7 is installed after the low-temperature medium outlet pipe box (i.e., medium-outlet pipe box) for recycling. The leaking flow channel is already blocked by shape memory alloy plugs. As the flow channel is gradually filled with plugs that continue to be added, the blocked flow channel can be visually identified from the pipe interface after the pipe is disassembled. This allows the leaking flow channel to be identified, and other sealing measures can be taken.

[0059] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A shape memory alloy plug, characterized in that, It includes a guide head, a deformable umbrella surface, and a central support. The central support is axially disposed at one end of the guide head. The deformable umbrella surface is conical and surrounds the guide head. The deformable umbrella surface is made of shape memory alloy and, under the action of external force, the deformable umbrella surface retracts to form a cylindrical structure. The cylindrical structure surrounds the outside of the central support.

2. The shape memory alloy plug according to claim 1, characterized in that, The shape memory alloy has a one-way memory effect, and the deformed umbrella surface can recover its original shape after being heated.

3. The shape memory alloy plug according to claim 1, characterized in that, The guide head has a conical guide surface in the direction away from the central support.

4. The shape memory alloy plug according to claim 1, characterized in that, The guide head is made of the same material as the deformable umbrella surface.

5. The shape memory alloy plug according to claim 4, characterized in that, The guide head and the deformable umbrella surface are integrally formed.

6. The shape memory alloy plug according to claim 1, characterized in that, The material of the central support pillar is different from the material of the guide head and the deformable umbrella surface.

7. The shape memory alloy plug according to claim 1, characterized in that, The material of the central support pillar is the same as the material of the guide head and the deformable umbrella surface.

8. The shape memory alloy plug according to claim 7, characterized in that, The guide head, the deformable umbrella surface, and the central support are integrally formed.

9. The shape memory alloy plug according to claim 1, characterized in that, After the deformable umbrella surface shrinks to form a cylindrical structure under the action of external force, the outer diameter of the entire shape memory alloy plug is smaller than the radial dimension of the microchannel, and the length is greater than the radial dimension of the microchannel.

10. The shape memory alloy plug according to claim 1, characterized in that, After the deformable umbrella surface is closed into a cylindrical structure under the action of external force, there is a gap between its inner wall and the outer wall of the central support.

11. A method for sealing leaks in a microchannel heat exchanger, characterized in that, include: By controlling the temperature and pressure of the low-temperature medium and the high-temperature medium in the heat exchanger, and keeping the pressure of the high-temperature medium higher than that of the low-temperature medium, a high-temperature influence zone is formed in the microchannel of the low-temperature medium near the leak point. The shape memory alloy plug as described in any one of claims 1-10 is injected from the low-temperature medium inlet side of the heat exchanger, so that the shape memory alloy plug enters each low-temperature medium microchannel; After the shape memory alloy plug flows with the medium to the high-temperature affected area, its deformable umbrella surface gradually expands from a cylindrical shape to a conical shape until the deformable umbrella surface is in complete contact with the flow channel wall, thus sealing the leakage point.

12. The method for sealing leaks in a microchannel heat exchanger according to claim 11, characterized in that, Also includes: A filter screen is installed on the outlet side of the heat exchanger for the low-temperature medium to collect the outflowing shape memory alloy plug.

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