Gradient porous medium heat transfer channel and preparation method thereof

Abstract

The invention discloses a gradient porous medium heat transfer channel and a preparation method thereof. The gradient porous medium heat transfer channel comprises a heat transfer pipe, porous media are arranged in the heat transfer pipes, and the porosity and aperture of the porous media are in gradient distribution in the axial direction or the radial direction of the heat transfer pipes. When the porosity and aperture of the porous medium are in gradient distribution in the axial direction of the heat transfer pipe, the porous medium is divided into multiple layers in the axial direction of the heat transfer pipe, the porosity or aperture of each layer is gradually increased or decreased in the axial direction of the heat transfer pipe, and the aperture of each layer is the same in size; when the porosity and the pore diameter of the porous medium are distributed in a gradient mode in the radial direction of the heat transfer tube, the porous medium is divided into multiple circles in the radial direction of the heat transfer tube, the pore diameter of each circle is distributed in a gradient mode in the radial direction of the heat transfer tube, the pore diameter is gradually increased or decreased, the porosity is gradually decreased, and the pore diameters of all the circles are the same in size from the inner circle to the outer circle. And fluid can be guided to form complex microscopic flow, gas-liquid flow is optimized, the heat transfer coefficient is remarkably increased, and the efficient and low-energy-consumption heat transfer process is achieved.

Description

Technical Field

[0001] This invention belongs to the field of heat transfer and relates to a gradient porous medium heat transfer channel and its preparation method. Background Technology

[0002] In various fields such as energy, chemical engineering, electronic heat dissipation, and power machinery, heat transfer efficiency directly affects system performance, energy consumption, and equipment reliability. Developing efficient heat transfer technologies is of great significance for improving energy utilization, optimizing industrial processes, and promoting equipment miniaturization and high performance. However, existing methods for enhancing heat transfer still have certain limitations. For example: 1. Traditional methods for enhancing heat transfer typically rely on altering the morphology of the heat exchange surface, such as adding fins (e.g., fins on a car engine radiator) to increase the contact area between the coolant and air, or using corrugated channels to generate fluid turbulence and enhance heat transfer. These methods of increasing surface area have limited effectiveness in improving the heat transfer coefficient and significantly increase the size and weight of the equipment, making them particularly unsuitable for space-constrained applications.

[0003] 2. Increasing pump power to boost flow rate can enhance convective heat transfer, but this also leads to a significant increase in fluid resistance, thus increasing pumping energy consumption. Furthermore, excessively high flow rates can cause channel vibration, noise, and other problems, shortening equipment lifespan.

[0004] 3. Adding nanoparticles to a base fluid to form nanofluids can improve the overall thermal conductivity and demonstrate good performance in heat dissipation experiments on electronic chips. However, nanoparticles are prone to agglomeration and sedimentation, leading to poor fluid stability and high preparation costs, which limits their large-scale application.

[0005] It can be observed that traditional methods of improving surface structure and simply increasing flow rate are gradually encountering bottlenecks in improving heat transfer efficiency, especially in the heat dissipation of very large-scale integrated circuits. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a gradient porous medium heat transfer channel and its preparation method, which can guide the fluid to form complex micro-flow, optimize gas-liquid flow, significantly improve the heat transfer coefficient, and realize a high-efficiency and low-energy-consumption heat transfer process.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A gradient porous medium heat transfer channel includes a heat transfer tube; The heat transfer tube is filled with a porous medium, and the porosity and pore size of the porous medium are distributed in a gradient along the axial or radial direction of the heat transfer tube. When the porosity and pore size of the porous medium are distributed in a gradient along the axial direction of the heat transfer tube, the porous medium is divided into multiple layers along the axial direction of the heat transfer tube. The porosity or pore size of each layer gradually increases or decreases along the axial direction of the heat transfer tube, and the pore size of each layer is the same. When the porosity and pore size of the porous medium are distributed in a gradient along the radial direction of the heat transfer tube, the porous medium is divided into multiple rings along the radial direction of the heat transfer tube. The pore size of each ring is distributed in a gradient along the radial direction of the heat transfer tube. From the inner ring to the outer ring, the pore size gradually increases or decreases, and the porosity gradually decreases. The pore size of each ring is the same.

[0008] Preferably, the porous medium has a porosity of 30%-80% and a pore size of 100-800μm.

[0009] Preferably, the first layer of the porous medium has a porosity of 30%-50% and a pore size of 100-300μm, and the last layer has a porosity of 70%-80% and a pore size of 500-800μm.

[0010] Preferably, the thickness of each layer of the porous medium along the axial direction is 20-100 μm.

[0011] Preferably, the outer radial diameter of the porous medium is 500-800 μm, and the inner radial diameter is 100-300 μm.

[0012] Preferably, the pores in the porous medium are circular or polygonal.

[0013] Preferably, the heat transfer tube is a circular heat transfer tube or a polygonal heat transfer tube.

[0014] Preferably, the porous medium occupies a portion of the area inside the heat transfer tube.

[0015] Preferably, the heat transfer tube is made of metal or a biodegradable polymer; the porous medium is made of copper or a biodegradable polymer.

[0016] A method for preparing a gradient porous medium heat transfer channel includes the following steps: Set the material and size of the heat transfer tube, and the material and gradient size of the porous medium; Create a three-dimensional model of a gradient porous medium heat transfer channel, and use parametric design or programming scripts to describe the porosity and pore size variation of the porous medium along the axial or radial direction of the heat transfer tube. Design the printing path based on the 3D model and set the printing parameters of the 3D printing equipment; 3D printing equipment was used to 3D print porous medium heat transfer channels.

[0017] Compared with the prior art, the present invention has the following beneficial effects: High-efficiency heat transfer: By partially filling the heat transfer channel with a gradient porous medium, the number of vaporization nuclei within the channel and the contact area between the channel surface and the heat exchange medium are increased, promoting bubble generation during boiling heat transfer and thus significantly improving heat transfer efficiency. For example, in electronic chip heat dissipation systems, the heat generated by the chip can be conducted away more quickly, ensuring stable chip operation and avoiding performance degradation due to overheating.

[0018] Low energy consumption: Compared to traditional methods that simply increase fluid velocity to enhance heat transfer, this invention achieves efficient heat transfer without significantly increasing pumping power. The gradient porous medium effectively guides and agitates the fluid, enabling it to achieve good heat transfer at lower flow rates, thereby significantly reducing system energy consumption and saving operating costs.

[0019] Compact Structure: The design of this invention does not require large-scale and complex modifications to the channel structure, and can achieve a significant improvement in heat transfer performance without significantly increasing the size and weight of the device. This is a significant advantage for space-constrained applications, such as aerospace and mobile electronic devices, as it meets their requirements for compact and lightweight design. Attached Figure Description

[0020] Figure 1 This is a three-dimensional schematic diagram and a transverse cross-sectional view of the axial gradient porous medium heat transfer channel of the present invention; Figure 2 This is a three-dimensional schematic diagram and a transverse cross-sectional view of the radial gradient porous medium heat transfer channel of the present invention. Wherein: 1-hole; 2-heat transfer tube; 3-porous medium. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] 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 invention pertains. The terms “installation,” “connection,” and “linkage” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection, an electrical connection, or a connection that allows communication; a direct connection or an indirect connection via an intermediate medium; or a connection within two elements or an interaction between two elements. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0026] The gradient porous medium heat transfer channel of the present invention includes a heat transfer tube 2, which is filled with a porous medium 3 in a gradient distribution.

[0027] The porous medium 3 is partially filled, not completely filling the heat transfer tube 2. That is, there is a certain gap between the porous medium 3 region and the wall of the heat transfer tube 2. A support rod is used to connect the porous medium 3 and the wall of the heat transfer tube 2.

[0028] The porosity and pore size of the porous medium 3 are distributed in a gradient along the axial or radial direction of the heat transfer tube 2.

[0029] like Figure 1 As shown, when the porosity and pore size of the porous medium 3 are distributed in a gradient along the axial direction of the heat transfer tube 2, the porous medium 3 is divided into multiple layers along the axial direction of the heat transfer tube 2. The thickness of each layer can be adjusted according to design requirements, typically between 20 μm and 100 μm. The porosity or pore size of each layer is distributed in a gradient along the axial direction of the heat transfer tube 2. The first layer has a lower porosity (30%-50%) and a smaller pore size (100-300 μm). The last layer has a higher porosity (70%-80%) and a larger pore size (500-800 μm). The pores 1 between adjacent layers are interconnected.

[0030] like Figure 2 As shown, when the porosity and pore size of the porous medium 3 are distributed in a gradient along the radial direction of the heat transfer tube 2, the porous medium 3 is divided into multiple rings along the radial direction of the heat transfer tube 2, and the pore size of each ring is distributed in a gradient along the radial direction of the heat transfer tube 2. The outer ring near the inner wall of the heat transfer tube 2 has a larger pore size, which is 500-800 μm. The inner ring near the center of the heat transfer tube 2 has a smaller pore size, which is 100-300 μm.

[0031] The porous medium 3 is filled along the axial direction of the heat transfer tube 2, and its pore size gradually increases or decreases along the length of the heat transfer tube 2, with each layer having the same pore size.

[0032] The porous medium 3 is filled radially along the heat transfer tube 2, and its pore diameter gradually increases or decreases outward from the center of the heat transfer tube 2, with the same pore diameter in each ring.

[0033] The holes 1 in the porous medium 3 are circular holes or polygonal holes.

[0034] Heat transfer tube 2 can be a circular heat transfer tube or a polygonal heat transfer tube.

[0035] The porous medium 3 adopts an overall continuous gradient design and uses 3D printing technology to precisely control the microstructure.

[0036] The fabrication process is as follows: Based on the specific application requirements, a 3D model with gradient variations is designed using modeling software. Suitable materials (copper alloy, stainless steel, or titanium alloy, etc.) are selected, ensuring uniform sieving of the metal powder and homogeneity of the plastic filaments. Depending on the chosen 3D printing process (e.g., SLS, FDM), appropriate printing parameters are set (including layer thickness: 20-100 μm, laser power: 50-400 W, scanning speed 100-2000 mm / s), and adjustments are made considering the gradient variations. During printing, the equipment status is closely monitored to ensure print quality. After printing, the support structure is removed, and surface grinding and polishing are performed. Finally, performance is tested, and optimization and improvement are carried out based on the results.

[0037] Among them, professional 3D modeling software, such as SolidWorks and CATIA, is used to design 3D models with gradient changes in porosity and pore size according to performance requirements, and save them in STL format for 3D printers to recognize.

[0038] The specific processing procedure is as follows: 1. Determine the parameters of heat transfer tube 2: Based on the actual application requirements, clarify the size specifications of heat transfer tube 2, such as length, outer diameter, inner diameter, as well as the gradient change requirements of porous medium 3 and the filling range, including porosity, pore size and its variation law along the axial or radial direction of heat transfer tube 2.

[0039] 2. Create a 3D model: Using CAD (Computer-Aided Design) software, construct a 3D solid model of heat transfer tube 2 based on the determined parameters. For axial gradient porous structures, the porosity, pore size, and other key structural parameters can be defined as variables using the modeling software.

[0040] 3. Parametric Design: The variation of porosity along the axial direction of heat transfer tube 2 is described using parametric design or programming scripts. For example, the formula for the variation of porosity along the axial direction of heat transfer tube 2 is set as follows: P (x) = P 0+ kz ,in P 0 represents the initial porosity of heat transfer tube 2. k The coefficient of variation, z This represents the position along the axial direction of heat transfer tube 2. By adjusting the coefficient, the gradient change in porosity can be precisely controlled.

[0041] 4. Parametric Design: The porosity variation along the radial direction of heat transfer tube 2 is described using parametric design or programming scripts, and the parameters are set... P (x)= P 0+ k ,in P 0 represents the initial porosity of heat transfer tube 2. k The coefficient of variation, x , y This refers to the radial position along heat transfer tube 2. By adjusting the coefficient, the gradient change in porosity or pore size can be precisely controlled.

[0042] 5. Modeling and File Conversion: After completing the modeling, save the model in STL (Standard Triangle Patch Language) format for import into the control system of the 3D printing equipment.

[0043] 6. Select Applicable Materials: Based on the application scenario and performance requirements of the heat transfer tube 2, select suitable 3D printing materials. For high-temperature and high-pressure industrial heat transfer tube 2, metal materials such as titanium alloys and stainless steel are more suitable, while copper is used for the porous medium 3. In the biomedical field, polymer materials with good biocompatibility and biodegradability, such as polylactic acid (PLA), are selected for both the heat transfer tube 2 and the porous medium 3.

[0044] 7. Material Pretreatment: Pretreatment of the selected materials is necessary to ensure they meet the requirements of the 3D printing process. For powder materials, drying is required to remove moisture and prevent defects such as air bubbles during printing; for filament materials, the diameter consistency must be checked to prevent feeding difficulties due to diameter fluctuations.

[0045] 8. Equipment Debugging: Based on the characteristics of the selected material and heat transfer pipe model 2, debug the 3D printing equipment, design the printing path according to the 3D model, and set printing parameters such as printing speed, nozzle temperature, layer thickness, and infill ratio. For gradient porous structures, it may be necessary to dynamically adjust the infill ratio during the printing process to achieve changes in porosity.

[0046] 9. Printing Process: Load the pre-treated material into the feeding system of the 3D printer, import the STL model file, and start the printing program. Throughout the printing process, it is necessary to closely monitor the operating status of the equipment to ensure print quality.

[0047] 10. Surface Treatment: To improve the surface quality and performance of the heat transfer tube 2, surface treatment is performed on the printed heat transfer tube 2. This includes grinding to remove rough surfaces, and polishing the metal heat transfer tube 2 to improve surface smoothness. In some cases, coating treatment may also be required to enhance the biocompatibility of the heat transfer tube 2.

[0048] 11. Heat treatment (optional): For heat transfer tubes 2 printed from certain metal or ceramic materials, heat treatment may be required to eliminate residual stress generated during the printing process and improve the microstructure and mechanical properties of the material.

[0049] After the heat transfer medium comes into contact with the wall of the heat transfer tube 2, the gradient porous medium 3 filling the heat transfer tube 2 will optimize the boiling heat transfer process in several ways, with the following specific effects: 1. Enhanced Liquid Flow and Distribution: The gradient porous medium 3 has a unique pore structure, with the pore size or distribution changing in a gradient from the inner wall of the heat transfer tube 2 outwards. Smaller pores are closer to the wall of the heat transfer tube 2, which can increase the adhesion of the liquid, making it easier for the liquid to spread near the wall, effectively preventing local drying, thus providing sufficient liquid phase and effectively improving boiling heat transfer efficiency.

[0050] 2. Promoting Bubble Generation and Detachment: The surface characteristics and pore structure of the gradient porous medium 3 are conducive to bubble nucleation. Its rough surface and abundant pores provide a large number of bubble generation sites, reducing the energy barrier for bubble formation. At the same time, the reduced constraint on bubbles during growth allows them to detach from the medium surface more quickly, thereby reducing bubble aggregation, lowering thermal resistance, and enhancing boiling heat transfer.

[0051] 3. Increased heat transfer area and heat storage capacity: The filled gradient porous medium 3 significantly increases the heat transfer area within the heat transfer tube 2. The complex pore structure significantly increases the contact area between the liquid and solid surfaces, thereby transferring heat more efficiently. In addition, the porous medium 3 itself has a certain heat storage capacity, and can absorb or release heat when the heat flux density fluctuates, stabilizing the temperature and maintaining the high efficiency and stability of boiling heat transfer.

[0052] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0053] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0054] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0055] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0056] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

[0057] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A gradient porous medium heat transfer channel, characterized in that: comprising a heat transfer tube (2); A porous medium (3) is arranged in the heat transfer tube (2), and the porosity and pore size of the porous medium (3) are distributed in a gradient along the axial direction or radial direction of the heat transfer tube (2); When the porosity and pore size of the porous medium (3) are distributed in a gradient manner along the axial direction of the heat transfer tube (2), the porous medium (3) is divided into multiple layers along the axial direction of the heat transfer tube (2), the porosity or pore size of each layer gradually increases or decreases along the axial direction of the heat transfer tube (2), and the pore size of each layer is the same; When the porosity and pore size of the porous medium (3) are distributed in a gradient manner along the radial direction of the heat transfer tube (2), the porous medium (3) is divided into a plurality of circles along the radial direction of the heat transfer tube (2), and the pore size of each circle is distributed in a gradient manner along the radial direction of the heat transfer tube (2). From the inner circle to the outer circle, the pore size gradually increases or decreases, and the porosity gradually decreases. The pore size of each circle is the same.

2. The gradient porous medium heat transfer channel according to claim 1, characterized in that: The porous medium (3) has a porosity of 30%-80% and a pore size of 100-800 μm.

3. The gradient porous medium heat transfer channel according to claim 2, characterized in that: The first axial layer of the porous medium (3) has a porosity of 30%-50% and a pore size of 100-300 μm, and the last layer has a porosity of 70%-80% and a pore size of 500-800 μm.

4. The gradient porous medium heat transfer channel according to claim 1, characterized in that: The thickness of each layer of the porous medium (3) in the axial direction is 20-100 μm.

5. The gradient porous medium heat transfer channel according to claim 1, characterized in that: The pore size of the radial outer ring of the porous medium (3) is 500-800 μm, and the pore size of the inner ring is 100-300 μm.

6. The gradient porous medium heat transfer channel according to claim 1, characterized in that: The holes (1) in the porous medium (3) are circular holes or polygonal holes.

7. The gradient porous medium heat transfer channel according to claim 1, characterized in that: The heat transfer tube (2) is a circular heat transfer tube or a polygonal heat transfer tube.

8. The gradient porous medium heat transfer channel according to claim 1, characterized in that: The porous medium (3) occupies a portion of the area inside the heat transfer tube (2).

9. The gradient porous medium heat transfer channel according to claim 1, characterized in that: The material of the heat transfer tube (2) is metal or a degradable polymer; the material of the porous medium (3) is copper or a degradable polymer.

10. A method for preparing a gradient porous medium heat transfer channel according to any one of claims 1 to 9, characterized in that: The process includes: Setting the material and size of the heat transfer tube (2), and the material and gradient change size of the porous medium (3); Creating a three-dimensional model of a gradient porous medium heat transfer channel, using parametric design or programming scripts to describe the porosity and pore size variation of the porous medium (3) along the axial or radial direction of the heat transfer tube (2); Design the printing path according to the 3D model and set the printing parameters of the 3D printing equipment; The porous medium (3) heat transfer channel is 3D printed using a 3D printing device.

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