Heat conduction device and manufacturing method thereof

Abstract

The present invention provides a heat conduction device and a method for manufacturing the same. The heat conduction device comprises a heat conductive substrate and a porous layer. The heat conductive substrate has multiple raised structures and multiple recessed bottom surfaces. The recessed bottom surfaces are located between the raised structures. The porous layer is embedded between the raised structures. The present invention provides a high-temperature material transfer system comprising a cylindrical container and a heat conduction device disposed on the surface of the cylindrical container. The heat conduction device of the present invention is suitable for use with liquids to provide highly efficient heat dissipation.

Description

Technical Field

[0001] The present invention relates to a technique and mechanism for transferring thermal energy. More particularly, the present invention relates to a heat transfer device involving phase change heat transfer. Background Art

[0002] Stable, controllable, and efficient phase-change heat transfer devices are crucial in high-temperature consumer, commercial, industrial, and research applications, such as quenching, fire suppression, and cooling in power plants, smelters, and refineries, as well as computer data centers, internal combustion engines, jet engines, and explosion chambers. Many strategies have been proposed to improve phase-change heat transfer on high-temperature surfaces.

[0003] However, one of the bottlenecks in enhancing phase change heat transfer on high-temperature surfaces (e.g., over 300 degrees Celsius) is the Leidenfrost effect. The Leidenfrost effect is a physical phenomenon in which a liquid approaches a surface significantly hotter than its boiling point, creating an insulating vapor layer that prevents rapid boiling. Due to this "repulsive force," liquid droplets remain suspended above the surface rather than in physical contact. This insulating vapor layer blocks contact between the liquid and the solid, significantly reducing heat transfer efficiency. Summary of the Invention

[0004] An object of the present invention is to provide a novel, universal structure that can suppress the Leidenfrost effect on ultra-high temperature surfaces, even at temperatures as high as the melting point of the materials used in the structure, while not affecting the heat transfer effect over the entire temperature range. Under various embodiments of the present invention, when a droplet (e.g., a volume of about 17 microliters) impacts the structure and the temperature of the structure falls within a wide range, such as 100 degrees Celsius to 1200 degrees Celsius, the droplet always exhibits rapid diffusion and intense boiling, with little splashing and no formation of an insulating vapor layer. As a result, the evaporation time of the droplet is almost constant. Compared to tens of seconds required on a surface with a temperature of up to about 200 degrees Celsius and the Leidenfrost effect, the design proposed by the present invention can evaporate in less than a second over a wide range of 200 degrees Celsius to 1200 degrees Celsius.

[0005] Embodiments of the present invention provide a heat transfer device and a high-temperature material transfer system. The heat transfer device includes a heat-conducting substrate and a porous layer. The heat-conducting substrate has a plurality of raised structures and a plurality of curved (or concave) bottom surfaces. The concave bottom surfaces are located between the raised structures. The porous layer is embedded between the raised structures.

[0006] The high temperature material transfer system comprises a cylindrical container and the above-mentioned heat conduction device, which is arranged on the surface of the cylindrical container.

[0007] An embodiment of the present invention provides a method for manufacturing a heat conduction device, comprising providing a heat conductive substrate, forming a plurality of protruding structures and a plurality of recessed bottom surfaces between the protruding structures, and embedding a porous layer between the protruding structures.

[0008] In an embodiment of the present invention, the porous layer is placed so as to float above the bottom surfaces of the recesses, forming an interspace between the bottom surfaces of the porous layer and the bottom surfaces of the recesses; the material of the protruding structures has a high thermal conductivity; the recessed bottom surfaces form a plurality of first grooves and a plurality of second grooves; the first grooves and the second grooves intersect; the first grooves and the second grooves have a U-shaped profile; the protruding structures form an array; the perimeter of each protruding structure increases toward the bottom to form a prism or a truncated pyramid; the material of the porous layer is an inorganic material; the thermal conductivity of the material of the porous layer is N times smaller than that of the material of the protruding structures, and N is a number ranging from 100 to 1000; the porous layer is formed of a thermally conductive insulating material; the steps of forming the protruding structures include: micro-milling the thermally conductive substrate or cutting the thermally conductive substrate using molybdenum wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present disclosure will be more fully understood from the following detailed description which is provided for purposes of illustration only and not limitation thereof, wherein:

[0010] Figure 1 According to some embodiments of the present invention, a perspective view of a heat conduction device is depicted;

[0011] Figure 2 Another perspective view of a heat conducting device is shown according to some embodiments of the present invention;

[0012] Figure 3 According to some embodiments of the present invention, a top view of a thermally conductive substrate is depicted;

[0013] Figure 4 according to Figure 1 The cutting line S1 shows a side sectional view;

[0014] Figure 5 A side cross-sectional view of a heat conduction device is shown according to another embodiment of the present invention;

[0015] Figure 6 A side cross-sectional view of a heat conduction device is shown according to another embodiment of the present invention;

[0016] Figure 7 A side cross-sectional view of a heat conduction device is shown according to another embodiment of the present invention;

[0017] Figure 8 A side cross-sectional view of a heat conduction device is shown according to another embodiment of the present invention;

[0018] Figure 9 A top view of a thermally conductive substrate is shown according to another embodiment of the present invention;

[0019] Figure 10 Another embodiment of the present invention shows a top view of a thermally conductive substrate; and

[0020] Figure 11 A schematic diagram of a high temperature material delivery system is shown according to some embodiments of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described in detail through the following embodiments / examples in conjunction with the accompanying drawings. It should be understood that the specific embodiments are provided for illustrative purposes only and should not be interpreted in a limiting manner.

[0022] Figure 1 and Figure 2 A perspective view of a heat conducting device 1A is shown according to an embodiment of the present invention. The heat conducting device 1A includes a heat conducting substrate 11 and a porous layer 12 .

[0023] The thermally conductive substrate 11 has a plurality of raised structures 111 and a plurality of recessed bottom surfaces 112. In this embodiment, the raised structures 111 and the curved (or recessed) bottom surfaces 112 are formed on the same side of the thermally conductive substrate. The recessed bottom surfaces 112 are located between the raised structures 111. In other words, between each raised structure 111 and another adjacent raised structure 111, at least one recessed bottom surface 112 is formed at the bottom between the two raised structures 111.

[0024] The porous layer 12 is embedded between the protruding structures 111 . In this embodiment, the protruding structures 111 pierce or poke the porous layer 12 , and the porous layer 12 is firmly disposed on the thermally conductive substrate 11 via the protruding structures 111 .

[0025] In this embodiment, when a water droplet 2 strikes the porous layer 12 of the heat-conducting device 1A, and the temperature of the heat-conducting device 1A falls within a wide range of approximately 100 to 1200 degrees Celsius, the water droplet 2 does not produce the Leidenfrost effect, but rather rapidly spreads, violently boils, and minimally splashes. In other words, the water droplet 2 spreads out on the porous layer 12. When the heat-conducting device 1A is secured to the surface 31 of the cylindrical container 3 (only a portion of the layers and outer surface of the cylindrical container 3 are shown in the figure), the thermally conductive substrate 11 absorbs heat H1 from the cylindrical container 3, while the water droplet spread-out region 121 further absorbs heat H2, without generating an insulating vapor layer.

[0026] At the same time, the raised structures 111 of the heat conducting element 11 can act as a "thermal bridge" to "short-circuit," allowing heat to be transferred directly from the heat conducting substrate 11 to the liquid in the porous layer 12. Furthermore, the porous layer 12 is made of a thermally conductive insulating material and has sufficient capillary force to absorb and diffuse the liquid, thereby improving heat dissipation efficiency.

[0027] Specifically, the bottom of the thermally conductive substrate 11, i.e., the side opposite the protrusions 111, can contact a high-temperature material transfer system (i.e., a cylindrical container 3). The high-temperature material transfer system can be, but is not limited to, a generator, a reactor or its pipelines, a smelter, an explosion chamber, an engine cooling system, or a computer cooling system. When the thermally conductive substrate 11 absorbs heat from these devices, the heat is effectively transferred to the liquid in the porous layer 12. After the liquid changes phase to gas, it can dissipate the heat from the high-temperature devices.

[0028] In general, the synergistic cooperation between the protruding structures 111 and the porous layer 12 can significantly improve the performance at the Leidenfrost temperature point without sacrificing the heat transfer performance, thereby resolving the conflicting requirements between heat transfer and moisture absorption.

[0029] The material of the heat-conducting substrate 11 has a high thermal conductivity. In other words, the material of the protruding structures has a high thermal conductivity. In one embodiment, the heat-conducting substrate 11 is formed of steel, which has a thermal conductivity of about 25 W·m -1 ·K -1 In other embodiments, the material of the thermally conductive substrate 11 can be a material based on iron, cobalt, nickel, zirconium, titanium, or tungsten, rhenium, molybdenum, niobium, or a metal ceramic material, or silicon nitride, carbon nitride, tantalum carbide, or hafnium carbide.

[0030] The material of the porous layer 12 is an inorganic material. For example, this material can be silicon dioxide. Specifically, the porous layer 12 can be manufactured by electrospinning technology, and the porous layer 12 is composed of a silicon dioxide mixture, so that the porous layer 12 can have elasticity and the ability to withstand high temperatures (for example, 1200 degrees Celsius, which is the melting point of silicon dioxide). The porous layer 12 includes a plurality of nanofibers, and these nanofibers are interwoven together to form interfiber pores with a diameter of about 2 microns, and the porous layer 12 has a high porosity (about 0.95). In addition, the large roughness generated by the fiber structure makes the hydrophilic layer with an inherent contact angle of about 30 degrees become a super hydrophilic layer.

[0031] In this embodiment, the thermal conductivity of the porous layer 12 is about 0.02 W·m -1 ·K -1, which is approximately 1000 times less than the thermal conductivity of the material of the thermally conductive substrate 11. Specifically, the porous layer 12 is formed from a thermally conductive insulating material. Therefore, these raised structures 111 on the thermally conductive substrate 11 can act as a "thermal bridge," short-circuiting the heat, allowing heat to be transferred directly from the thermally conductive substrate 11 to the water droplet 2.

[0032] In various embodiments, the porous layer 12 can be made of carbon fiber, aramid fiber (polyaramid fiber), glass fiber, basalt fiber, polybenzimidazole fiber (PBI fiber), or high molecular weight polyethylene (UHMWPE). In other embodiments, the porous layer 12 may include one or more porous membranes formed by fibers, ceramics, or metals. In other embodiments, the material of the porous layer 12 may include one or more of silica, titanium dioxide, mullite (mullite), alumina, zirconium dioxide, yttrium oxide, and asbestos. In some embodiments, the porous layer 12 may be felt or aerogel. In some embodiments, the thermal conductivity of the material of the porous layer 12 is N times smaller than the thermal conductivity of the material of the thermally conductive substrate 11, where N is a number ranging from 100 to 1000.

[0033] Figure 3 A top view of the heat conducting substrate 11 in one embodiment is shown. In this embodiment, the protrusions 111 form an array, and the recessed bottom surfaces 112 form a plurality of grooves 113 and a plurality of grooves 114 , and the grooves 113 and the grooves 114 intersect.

[0034] Specifically, the grooves 113 extend along axes X1, X2, and X3, respectively, and these axes X1, X2, and X3 are parallel to direction d1. The grooves 114 extend along axes Y1, Y2, and Y3, respectively, and these axes Y1, Y2, and Y3 are parallel to direction d2. Directions d1 and d2 are perpendicular to each other, so the grooves 113 and 114 intersect.

[0035] Figure 4 is based on Figure 1 A side cross-sectional view of the heat conducting device 1A is shown by the cut plane line S1 in FIG. A gap g1 is formed between the bottom of the porous layer 12 and each recessed bottom surface 112. A plurality of vapor channels are formed between the recessed bottom surfaces 112 and the bottom surface 122 of the porous layer 12.

[0036] In this embodiment, the grooves 113 and 114 have a U-shaped profile and provide ample channels for vapor to escape. These vapor channels prevent water droplets from bouncing off the porous layer 12. In other words, the U-shaped grooves 113 and 114 between the porous layer 12 and the thermally conductive substrate 11 are used to escape vapor. As a result, liquid remains in the porous layer 12 and absorbs heat energy from the protruding structures 111 on the thermally conductive substrate 11.

[0037] Furthermore, the circumference of each protrusion 111 increases toward the bottom. In this embodiment, the width r1 of the protrusion 111 near the top is smaller than the width r2 near the bottom. The "U"-shaped groove 113 forms a rounded corner (i.e., a concave bottom surface 112) in the valley between these protrusions 111. Because these protrusions 111 have a circumference that increases toward the bottom, they can prevent the porous layer 12 from moving downward due to the thrust of water droplets impacting it.

[0038] For example, the fillet radius r3 is approximately 0.15±0.02 mm, and the width w, spacing g2, and height h of the protrusions 111 are approximately 300 μm, 300 μm, and 400 μm, respectively. The protrusions 111 are densely distributed to transfer heat, while the widths of the grooves 113 and 114 are sufficient to disperse and spread water droplets on the porous layer 12.

[0039] In another embodiment, the fillet radius r3 can be approximately 1.0 ± 0.02 mm, and the width w, spacing g2, and height h of the protruding structures can be approximately 2.0 mm, 2.0 mm, and 4.0 mm, respectively. This heat transfer device 1A can be used for quenching, fire extinguishing, and cooling in power plants, smelters, internal combustion engines, ejector engines, and explosion chambers. In other words, the fillet radius r3 can be in the range of 0.13 mm to 1.0 mm, the width w can be in the range of 300 μm to 3000 μm, the spacing g2 can be in the range of 300 μm to 3000 μm, and the height h can be in the range of 400 μm to 4000 μm.

[0040] The porous layer 12 has a thickness of t1 and provides three-dimensional channels. These channels provide rapid radial and vertical wicking during droplet contact, significantly enhancing the liquid distribution area and thermal conductivity. In other words, the porous layer 12 has multiple three-dimensional channels that are suitable for absorbing droplets, enhancing droplet adsorption efficiency, and thus improving thermal conductivity.

[0041] In addition, the thickness t1 of the porous layer 12 is smaller than the height h of each protrusion structure 111, and the circumference of each protrusion structure 111 increases toward the bottom, forming a pyramid or a frustum, so that these protrusion structures 111 can fix and suspend the porous layer 12 above the recessed bottom surface 112, and form a spacing space g1 between the bottom side of the porous layer and the recessed bottom surface 112.

[0042] In one embodiment, the protruding structures 111 are frustums with a square base as shown in the drawings. In other embodiments, the protruding structures 111 may be frustums or pyramids with a circular, elliptical, or other polygonal bases.

[0043] Figure 5 is a side cross-sectional view of a thermally conductive device 1B. In some embodiments, the porous layer 12 contacts the recessed bottom surfaces 112. The thermally conductive device 1B comprises a thermally conductive substrate 11 and a porous layer 12, which fills the bottoms of the grooves 113 of the thermally conductive substrate 11. In this embodiment, the thermally conductive substrate 11 and the porous layer 12 have a greater contact area, thereby improving the efficiency of heat transfer between them.

[0044] Figure 6 is a side cross-sectional view of the heat conducting device 1C. In some embodiments, the bottom surface 112 may have multiple stepped structures. Stepped grooves 113 form recessed bottom surface 112 in the valleys between these raised structures 111. These stepped structures can fix the porous layer 12 at an appropriate height, meaning that the height of the porous layer 12 can be more precisely controlled by these stepped structures.

[0045] Figure 7 is a side cross-sectional view of a heat conducting device 1D. In some embodiments, the bottom surface 112 may be formed with a plurality of tooth-like structures. Comb-like grooves 113 may form recessed bottom surface 112 in the valleys between these raised structures 111. These tooth-like structures can further enhance heat dissipation by increasing the surface area.

[0046] Figure 8 is a side cross-sectional view of the heat conducting device 1E. In some embodiments, the bottom surface 112 may have microstructures. Uneven grooves 113 may form recessed surfaces 112 in the valleys between the raised structures 111. These microstructures can also enhance heat dissipation by increasing the surface area.

[0047] Figure 9 1 is a top view of the thermally conductive substrate 11A. In some embodiments, the top surface shape of these protrusion structures 111 can be triangular. In this configuration, the thermally conductive substrate 11A can be appropriately configured in a triangular area.

[0048] Figure 101 is a top view of the thermally conductive substrate 11B. In some embodiments, the top surface shape of these protrusion structures 111 can be hexagonal. In this configuration, the thermally conductive substrate 11B can be appropriately arranged in a hexagonal area.

[0049] It will be understood by those skilled in the art that the top surfaces of the protruding structures 111 may be easily configured in other shapes without undue experimentation or departing from the spirit and purpose of the present invention.

[0050] Figure 11 This is a schematic diagram of a high-temperature material transfer system 3. This system includes a cylindrical container 31, which is used to transfer high-speed, high-temperature gas. A heat transfer device 1A is positioned on the surface of the container 31. Therefore, the system can be easily cooled by spraying water.

[0051] In one embodiment, the high-temperature material transfer system 3 can be an aircraft engine, and the high-temperature material transfer system 3 further includes a plurality of blades 32. These blades 32 are disposed within a cylindrical container 31, and the heat transfer device 1A is also disposed on the surface of these blades 32. Therefore, these blades 32 can be quickly cooled by spraying water.

[0052] In another embodiment, the container 31 may have other shapes, and the heat conducting device 1A may be disposed on the surface of the container 31. Those skilled in the art will appreciate that embodiments of the present invention having a flexible heat conducting device 1A may have many different applications. For example, the container 31 may also be a portion of a flexible heat dissipation protector.

[0053] In some embodiments, the heat transfer device 1A can be provided in the form of a thin film, which can be applied to the surface of a high-temperature material transfer system, such as a generator, a reactor or its piping, a smelter, an explosion chamber, an engine cooling system, or a computer cooling system. In some embodiments, the heat transfer device 1A can be provided as a small device, and multiple heat transfer devices 1A can be mixed with a liquid such as water to achieve a higher cooling rate and be applied to fire extinguishers and the above-mentioned high-temperature material transfer systems.

[0054] In other embodiments, the thickness of the thermally conductive substrate 11 may be in the range of 0.1 mm to 0.5 mm, and the thermally conductive device 1A may be soldered or adhered to various surfaces that are difficult to texture directly or to materials of different shapes.

[0055] Reference Figure 1 The present invention also provides a method for manufacturing a heat conducting device 1A. The method includes: providing a heat conducting substrate 11; and forming a plurality of protruding structures 111 and a plurality of concave bottom surfaces 112.

[0056] In this embodiment, the thermally conductive substrate 11 is formed of steel, and the array of protrusion structures 111 can be manufactured using a wire cutting machine. Specifically, in this embodiment, a molybdenum wire with a diameter of 0.18 mm is used to form the "U"-shaped groove.

[0057] In some embodiments, the thermally conductive substrate 11 and the raised structures 111 thereon can be fabricated using a mold, and this mold can be fabricated using 3D printing technology. In some embodiments, the thermally conductive substrate 11 can be directly fabricated using 3D printing technology. In other embodiments, the thermally conductive substrate 11 can be fabricated using micro-milling.

[0058] The method for manufacturing the heat conducting device 1A further comprises embedding a porous layer 12 between the protruding structures 111. In this embodiment, the porous layer 12 can be manufactured by electrospinning technology.

[0059] The porous layer 12 can be made of thermally conductive and insulating synthetic fibers. Generally, a PVA (polyvinyl alcohol) precursor solution (10 wt.%) is prepared by mixing PVA (Mw = 88,000 g·mol -1 ) was dissolved in deionized water at 80 degrees Celsius and stirred continuously for 12 hours to prepare it. Then, a TEOS (tetraethoxysilane) aqueous solution was stirred at room temperature for 10 hours using H3PO4 as a hydrolysis catalyst, wherein the molar ratio of TEOS:H3PO4:H2O was 1:0.01:10 to obtain a silane sol. Subsequently, 12 grams of silane sol was dropped into an equal weight of PVA precursor solution and stirred for 4 hours until a uniform solution was obtained. Electrospinning was carried out at an applied voltage of 18 kV and a flow rate of 1 ml·h -1 The precursor solution was injected at a rate of . A grounded rotating metal roller covered with aluminum foil served as a collector. The as-spun composite fibers were dried at 80 degrees Celsius for 2 hours and then calcined in air at 800 degrees Celsius for 2 hours to remove organic matter.

[0060] The present invention embeds the porous layer by means of a mold of the thermally conductive substrate 11. By using PDMS as the mold material, the porous layer 12 can be pressed and embedded between these protruding structures.

[0061] To further compact the heat conducting device 1A, the heat conducting substrate 11 and the porous layer 12 embedded to a specific depth are sintered at a temperature of 800 degrees Celsius. Thus, the porous layer 12 and the heat conducting substrate 11 are combined to provide a good heat conducting effect.

[0062] The above details of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed above. Many modifications and variations will be apparent to those skilled in the art.

[0063] The foregoing description of the embodiments chosen was presented in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated.

[0064] Furthermore, when interpreting the present invention, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "include" and "comprising" should be interpreted as referring to elements, components or steps in a non-exclusive manner, indicating that the referenced elements, components or steps may reference, use or combine with other elements, components or steps not explicitly stated.

Claims

1. A heat conduction device, characterized in that: include: a heat-conducting substrate having a plurality of protruding structures and a plurality of concave bottom surfaces, wherein the plurality of concave bottom surfaces are located between the plurality of protruding structures; as well as A porous layer, the thermal conductivity coefficient of which is N times smaller than the thermal conductivity coefficient of the material of the multiple protrusion structures, and N is a number ranging from 100 to 1000, the porous layer is embedded between the multiple protrusion structures, the porous layer has multiple nanofibers, and the multiple nanofibers are interwoven together, wherein the porous layer is suspended above the multiple recessed bottom surfaces, and the multiple top surfaces of the multiple protrusion structures are higher than the height of the porous layer relative to the multiple recessed bottom surfaces.

2. The heat conduction device according to claim 1, wherein The porous layer forms a plurality of separation spaces between the bottom of the porous layer and the plurality of recessed bottom surfaces.

3. The heat conduction device according to claim 1, wherein The material of the plurality of protruding structures has a relatively high thermal conductivity.

4. The heat conduction device according to claim 1, wherein The plurality of recessed bottom surfaces form a plurality of first trenches and a plurality of second trenches, and the plurality of first trenches intersect with the plurality of second trenches.

5. The heat conduction device according to claim 4, wherein: The plurality of first grooves and the plurality of second grooves have a U-shaped profile.

6. The heat conduction device according to claim 1, wherein The plurality of protruding structures form an array.

7. The heat conduction device according to claim 1, wherein The circumference of each of the raised structures increases toward the bottom.

8. The heat conduction device according to claim 1, wherein The material of the porous layer is an inorganic material.

9. The heat conduction device according to claim 1, wherein The porous layer is manufactured by electrospinning technology.

10. A method for manufacturing a heat conduction device, characterized in that: include: providing a thermally conductive substrate; forming a plurality of protruding structures and a plurality of concave bottom surfaces, wherein the plurality of concave bottom surfaces are located between the plurality of protruding structures; as well as A porous layer is embedded between the multiple protruding structures, the thermal conductivity coefficient of the material of the porous layer is N times smaller than the thermal conductivity coefficient of the material of the multiple protruding structures, and N is a number ranging from 100 to 1000, the porous layer has multiple nanofibers, and the multiple nanofibers are interwoven together, wherein the porous layer is suspended above the multiple recessed bottom surfaces, and the multiple top surfaces of the multiple protruding structures are higher than the height of the porous layer relative to the multiple recessed bottom surfaces.

11. The method according to claim 10, wherein The step of forming the plurality of protruding structures includes: micro-milling the thermally conductive substrate or cutting the thermally conductive substrate using a molybdenum wire.

12. The method according to claim 10, wherein The porous layer is manufactured by electrospinning technology.

13. The method according to claim 10, wherein Also includes: The plurality of protrusion structures and the porous layer are sintered.

14. A high temperature material transfer system, characterized in that: include: a drum-shaped container; as well as The heat conducting device according to claim 1, arranged on the surface of the cylindrical container.

15. The high temperature material transfer system of claim 14 further comprising a plurality of fan blades disposed in the cylindrical container.

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