Aperture self-adaptive response intelligent porous wick based on thermal expansion difference and heat transfer device

Abstract

The invention discloses a pore diameter self-adaptive response intelligent porous wick based on thermal expansion difference and a heat transfer device, the pore diameter of the pore diameter self-adaptive response intelligent porous wick can be self-adaptively adjusted along with the temperature, when the temperature is high, the volume of a coating material expands, the pore diameter of the wick is reduced, and the capillary suction force is improved; when the temperature drops, the coating material shrinks, the aperture of the wick is increased, and the flow resistance of the liquid working medium is reduced. And the aperture size of the wick is intelligently regulated along with the temperature, so that the heat pipe always works in the optimal aperture range, and the performance of the heat transfer device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of heat transfer devices, and in particular relates to an intelligent porous liquid-absorbing core and a heat transfer device with adaptive pore size response based on thermal expansion differences. Background Art

[0002] With the rapid development of electronic information technology, high-performance chips in the fields of electronic products, industrial equipment, aerospace, etc. are evolving towards miniaturization and integration, resulting in an exponential increase in heat flux density. Ordinary heat dissipation methods can no longer meet the needs of high heat flux density heat dissipation. Heat pipes, as an efficient phase change heat transfer device, use the evaporation and condensation of liquid working fluids to transfer a large amount of heat. It is an effective solution for heat dissipation of high heat flux density electronic chips. The liquid wick is an important component of the heat pipe. Traditional liquid wicks generally improve heat transfer efficiency through structural optimization, surface modification, and selection of high-quality materials.

[0003] 3D printing, also known as additive manufacturing technology, is a technology that manufactures solid parts by adding materials layer by layer based on three-dimensional CAD data. The process of preparing absorbent cores through 3D printing technology is simple and has high precision. The 3D printed absorbent cores not only have regular shapes, but also can be designed in size and pore size. They have greater geometric freedom and avoid the problems of high randomness, uneven pore size distribution and closed pores of traditional sintered capillary cores.

[0004] However, the pore size of the wick manufactured by 3D printing is fixed, and it is impossible to adjust the pore size when the heat flux density of the device changes so that the heat pipe can always maintain a high-performance working state. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide an intelligent porous liquid-absorbing core structure and a heat transfer device with an aperture adaptive response based on thermal expansion differences. The intelligent porous liquid-absorbing core structure with an aperture adaptive response includes a porous substrate made of a porous material and a temperature adaptive adjustment coating coated on the surface of the porous substrate. The coating has a high thermal expansion coefficient and can realize adaptive adjustment of the aperture according to temperature changes, so that the heat pipe can always maintain a high-performance working state.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] An intelligent porous liquid-absorbing core with adaptive pore size response based on thermal expansion difference comprises a porous substrate and a temperature adaptive regulating coating coated on the inner and outer pore diameter surfaces of the porous substrate;

[0008] Among them, the thermal expansion coefficient of the temperature-adaptive coating is greater than 17×10 -5 / ℃.

[0009] In a preferred embodiment of the present invention, the material of the temperature adaptive regulating coating layer is metal and / or polymer.

[0010] In a preferred embodiment of the present invention, the material of the temperature adaptive regulating coating layer includes at least one of polyvinylidene fluoride (PVDF), polypropylene (PP), polyethylene (PE) and low-density polyethylene terephthalate (PET).

[0011] In a preferred embodiment of the present invention, the coating process of the temperature-adaptive coating is at least one of physical vapor deposition, chemical vapor deposition, electroplating, solution deposition and spraying.

[0012] In a preferred embodiment of the present invention, the pore size of the porous substrate is 0.1-0.5 mm, and the thickness of the temperature-adaptive coating is 0.01-0.03 mm.

[0013] In a preferred embodiment of the present invention, the structure of the porous matrix is ​​a foam metal porous structure, a metal wire mesh porous structure, a powder sintered porous structure or a fiber sintered porous structure.

[0014] In a preferred embodiment of the present invention, the manufacturing technology of the porous matrix is ​​selected from at least one of 3D printing technology, laser technology, milling technology and micro-carving technology.

[0015] In a preferred embodiment of the present invention, the material of the porous matrix is ​​selected from at least one of metal, non-metal and composite material.

[0016] In a preferred embodiment of the present invention, the material of the porous matrix is ​​selected from at least one of copper, aluminum and stainless steel.

[0017] A heat transfer device, comprising the above-mentioned pore size adaptive response intelligent porous liquid wick, a shell and a working medium;

[0018] A working fluid flow cavity is formed in the shell, and the working fluid flows in the working fluid flow cavity. The pore size adaptive response intelligent porous liquid absorption core is embedded in the working fluid flow cavity.

[0019] In a preferred embodiment of the present invention, the shell is formed by milling technology, hot pressing technology or micro-machining technology.

[0020] In a preferred embodiment of the present invention, the housing is composed of an upper housing and a lower housing that cover each other, and the upper housing and the lower housing are sealed and packaged by a processing technique such as bolt connection, hydraulic process or welding process.

[0021] In a preferred embodiment of the present invention, the heat pipe is manufactured into a heat transfer device through processes such as sealing and packaging, vacuuming, and injecting working fluids, and the aperture is adaptively adjusted through thermal expansion and contraction of the coating.

[0022] In a preferred embodiment of the present invention, the shell is made of copper.

[0023] In a preferred embodiment of the present invention, the working fluid is selected from at least one of anhydrous ethanol, deionized water and acetone.

[0024] A heat transfer device, comprising the above-mentioned pore size adaptive response intelligent porous liquid wick, a shell and a working medium;

[0025] A working fluid flow cavity is formed in the shell, and the working fluid flows in the working fluid flow cavity. The pore size adaptive response intelligent porous liquid absorption core is embedded in the working fluid flow cavity.

[0026] In a preferred embodiment of the present invention, the shell is made of copper;

[0027] In a preferred embodiment of the present invention, the working fluid is selected from at least one of anhydrous ethanol, deionized water and acetone.

[0028] The present invention has at least the following beneficial effects:

[0029] 1. The aperture of the pore size adaptive response intelligent porous liquid absorbent core provided by the present invention can be adaptively adjusted with temperature. When the temperature is high, the volume of the coating material expands, which reduces the aperture of the liquid absorbent core and improves the capillary suction force; when the temperature drops, the coating material shrinks, the aperture of the liquid absorbent core increases, and the flow resistance of the liquid working medium is reduced. The aperture size of the liquid absorbent core is intelligently regulated with temperature, so that the heat pipe always works within the optimal aperture range, improving the performance of the heat transfer device.

[0030] 2. In a preferred embodiment, the wick is prepared by 3D printing technology, which has the advantages of high precision, regular shape, and self-designed pore size, avoiding the problems of high randomness, uneven pore size distribution, and pore closure of traditional sintered capillary wicks.

[0031] 3. In a preferred embodiment, the temperature adaptive regulating coating is a PVDF film, which has good corrosion resistance, wear resistance, high temperature resistance and low temperature resistance, as well as good adhesion to the wick substrate, can effectively extend the service life of the wick, and the performance of the wick with a larger pore size can be improved through the coating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of the heat transfer device provided in Example 1;

[0033] Figure 2 A schematic diagram of the porous matrix structure of the pore size adaptive response intelligent porous absorbent core provided in Example 1;

[0034] Figure 3 This is a schematic diagram showing the pore size change principle of the pore size adaptive response intelligent porous absorbent core provided in Example 1.

[0035] Reference numerals in the figure: 1-upper shell, 2-porous liquid absorption core, 3-lower shell, 4-capillary pores, 5-temperature self-adaptive regulating coating. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention; it is obvious that the embodiment described above is only one implementation method of the present invention, and all other embodiments obtained by ordinary technicians in this field without making creative work based on the following embodiments belong to the protection scope of the present invention.

[0037] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a central element at the same time. In the present invention, the terms "upper", "lower", "bottom", "rear", "side", etc. indicate that the orientation or position relationship is based on the orientation or position relationship shown in the accompanying drawings. It is only for the purpose of simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] Example 1

[0039] This embodiment provides a heat transfer device, which is a heat pipe, and its overall structure is as follows: Figure 1 As shown, it includes a shell, an intelligent porous absorbent core 2 (or porous absorbent core) with an pore size adaptive response based on thermal expansion difference, and a working medium (not shown in the figure), wherein the shell includes an upper shell 1 and a lower shell 3 covered up and down, a working medium flow cavity is formed between the upper shell 1 and the lower shell 3, and the intelligent porous absorbent core 2 with an pore size adaptive response is embedded in the working medium flow cavity.

[0040] The porous absorbent core 2 includes a porous substrate and a temperature-adaptive regulating coating (or coating) coated on the inner and outer pore surfaces of the porous substrate. Figure 2 As shown, it includes capillaries 4 in multiple directions. The pore size change mechanism of the absorbent core is as follows Figure 3 As shown, the temperature adaptively adjusts the expansion or contraction of the coating 5 with the temperature change to achieve the adaptive adjustment of the aperture of the capillary 4. When the temperature is high, the volume of the coating material expands, the aperture of the liquid wick is reduced, and the capillary suction force is improved; when the temperature drops, the coating material shrinks, the aperture of the liquid wick increases, and the flow resistance of the liquid working medium is reduced. Through the above settings, the heat transfer device can adjust the aperture when the heat flux density of the device changes so that the heat pipe can always maintain a high-performance working state.

[0041] The heat transfer device comprising a housing and a porous wick with adaptive pore size response is realized by the following steps:

[0042] 1. Manufacturing porous matrix: The size of the porous matrix is ​​80mm×40mm×2mm, and the size of the capillary is 0.3mm. 316L stainless steel material is selected, and the porous matrix is ​​3D printed by selective laser melting (SLM) technology. Printing is carried out in a sealed environment filled with protective gas (such as argon or nitrogen) to prevent the metal from reacting with oxygen in the air at high temperature. The printed porous matrix has high strength, high toughness and good ductility, and can withstand high mechanical stress and thermal stress.

[0043] 2. Adaptive adjustment of coating temperature 5: Weigh 3g PVDF powder (400,000 molecular weight) as solute, 100ml DMF solution as solvent, stir and heat in an electric blast drying oven to promote the dissolution of PVDF powder (heating at 80℃ for about 20min). Wash the porous substrate with deionized water, and after drying, put the porous substrate into the PVDF powder solution and heat for a certain time (heating at 80℃ for 60min) until the DMF solvent is completely volatilized, and then dry to cover the surface of the porous substrate and the inner wall of the pores with a white transparent coating, the coating is evenly covered, there is no obvious bubble or crack, and the surface is smooth, so as to obtain a porous liquid absorbent core 2.

[0044] 3. Manufacturing the shell: Select copper plates and process them through milling. First, cut the copper plates according to the design requirements, then place them on the processing table and fix them. Prepare the milling tools, fixtures and processing parameters, and perform milling according to the design drawings of the shell. Monitor the processing quality and equipment operation status, and adjust the processing parameters in time. After processing, polish and grind the surface of the shell, and finally obtain the upper shell 1 and lower shell 3 with an overall size of 100mm×60mm×3mm.

[0045] 4. Package the heat pipe: Take out the lower outer shell 3 of the heat pipe, and install the porous liquid absorbent core 2 on the lower outer shell 3 so that the bottom of the porous liquid absorbent core 2 is in close contact with the bottom of the lower outer shell 3. Install a brass tube with an outer diameter of 3mm, an inner diameter of 1mm and a length of 3cm at the liquid filling port of the outer shell and cover the upper outer shell 1 of the outer shell. Use M3×8 screws to fix the upper outer shell 1 and the lower outer shell 3 of the heat pipe through the bolt holes. Mix glue A and glue B in a ratio of 2:1 and apply them to the connection between the upper outer shell 1 and the lower outer shell 3 to seal the heat pipe. After the glue solidifies and reaches the mechanical strength for normal use (about 30 minutes), perform a vacuum test on the packaged heat pipe. Insert the brass tube at the front end of the heat pipe into a 40mm long PU tube, and connect the PU tube with Transfer The needle valve is connected to the heat pipe, and the other side of the needle valve is connected to a 40mm long PU tube. This PU tube is connected to a vacuum pump to evacuate the heat pipe. If the airtightness of the heat pipe is good (internal pressure is less than 10Pa), use a syringe to inject the working fluid (1g deionized water, the filling rate is about 20%) from the injection port of the heat pipe. After injecting the working fluid, vacuum treatment is performed again to reduce the vacuum degree to 10Pa or below. Finally, use hydraulic pliers to press the brass tube at the front end of the heat pipe tightly to prevent air leakage here.

[0046] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A smart porous absorbent core with adaptive pore size response based on thermal expansion difference, characterized in that: It comprises a porous substrate and a temperature self-adapting regulating coating coated on the inner and outer pore surfaces of the porous substrate; The thermal expansion coefficient of the temperature-adaptive coating is greater than 17×10 -5 / ℃.

2. The pore size adaptive response intelligent porous liquid absorbent core according to claim 1, characterized in that: The material of the temperature adaptive regulating coating is metal and / or polymer.

3. The pore size adaptive response intelligent porous liquid absorbent core according to claim 1, characterized in that: The material of the temperature adaptive regulating coating layer includes at least one of polyvinylidene fluoride, polypropylene, polyethylene and low-density polyethylene terephthalate.

4. The pore size adaptive response intelligent porous absorbent core according to any one of claims 1 to 3, characterized in that: The plating process of the temperature-adaptive plating layer is at least one of physical vapor deposition, chemical vapor deposition, electroplating, solution deposition and spraying.

5. The pore size adaptive response intelligent porous absorbent core according to any one of claims 1 to 3, characterized in that: The pore size of the porous matrix is ​​0.1-0.5 mm, and the thickness of the temperature-adaptive coating is 0.01-0.03 mm.

6. The pore size adaptive response intelligent porous absorbent core according to any one of claims 1 to 3, characterized in that: The structure of the porous matrix is ​​a foam metal porous structure, a metal wire mesh porous structure, a powder sintered porous structure or a fiber sintered porous structure.

7. The pore size adaptive response intelligent porous absorbent core according to any one of claims 1 to 3, characterized in that: The manufacturing technology of the porous matrix is ​​selected from at least one of 3D printing technology, laser technology, milling technology and micro-carving technology.

8. The pore size adaptive response intelligent porous absorbent core according to any one of claims 1 to 3, characterized in that: The material of the porous matrix is ​​selected from at least one of copper, aluminum and stainless steel.

9. A heat transfer device, characterized in that: It comprises the pore size adaptive response intelligent porous liquid absorbent core, shell and working medium as described in any one of claims 1 to 8; A working medium flow cavity is formed in the shell, the working medium flows in the working medium flow cavity, and the aperture adaptive response intelligent porous liquid absorption core is embedded in the working medium flow cavity.

10. The heat transfer device according to claim 9, characterized in that The material of the shell is copper; And / or, the working fluid is selected from at least one of anhydrous ethanol, deionized water and acetone.

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