A heat pipe structure based on metamaterial and a processing method thereof

Abstract

The application discloses a heat pipe structure based on metamaterial and a processing method, relates to the technical field of lightweight multifunctional structures, and the heat pipe structure comprises a metal structure, a sealed cavity is arranged in the metal structure, a filling lattice is arranged in the sealed cavity, and an unfilled area is arranged in the middle of the filling lattice; the filling lattice comprises at least two lattice layers with different porosities, and the porosity of the filling lattice decreases from the unfilled area to the edge of the sealed cavity. The integration of the metal solid structure or the honeycomb sandwich structure and the specific heat pipe structure is realized, the number of heat transfer interfaces is greatly reduced, and the heat transfer efficiency is greatly improved.

Description

Technical Field

[0001] This application relates to a novel heat pipe structure and processing method based on metamaterials, belonging to the field of lightweight multifunctional structure technology. Background Technology

[0002] New generation of high-power payloads such as microwave integrated circuits, high-throughput processors, and laser diodes have been gradually applied in spacecraft. The performance and reliability of electronic integrated devices in spacecraft are very sensitive to temperature, and the problem of efficient thermal management of local high heat flux density is particularly prominent.

[0003] Heat pipes utilize the phase change process of a medium evaporating at the hot end and condensing at the cold end to rapidly conduct heat. The inside of a heat pipe is evacuated to a negative pressure state and filled with a suitable liquid with a low boiling point and high volatility. The pipe wall has a wick composed of a capillary porous material. Traditional spin-forming heat pipes have smooth inner walls of microgrooves and relatively low capillary pressure. These heat pipes are typically connected to solid structures (metal solid structures or honeycomb sandwich structures) by welding or adhesive bonding. This type of structure has a large number of heat transfer interfaces, thus affecting heat transfer efficiency. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a heat pipe structure and processing method based on metamaterials, which can obtain an integrated heat pipe structure, greatly reduce the number of heat transfer interfaces and significantly improve heat transfer efficiency.

[0005] The technical solution of this invention is:

[0006] In a first aspect, a heat pipe structure based on metamaterials is provided, including a metal structure, a sealed chamber within the metal structure, a filling lattice within the sealed chamber, and an unfilled region in the center of the filling lattice; the filling lattice includes at least two lattice layers with different porosities, and the porosity of the filling lattice decreases from the unfilled region to the edge of the sealed chamber; the unfilled region serves as a gas channel, and the filling lattice at the edge of the sealed chamber serves as a liquid channel.

[0007] In some implementations of the first aspect, the filling lattice includes an outer filling lattice layer connected to the inner wall of the sealed cavity, and an inner filling lattice layer located within the outer filling lattice, wherein the porosity of the inner filling lattice layer is less than that of the outer filling lattice layer.

[0008] In some implementations of the first aspect, the inner filling lattice layer comprises at least two cell structures, the outer filling lattice layer comprises 1-3 cell structures, and the volume of the unfilled region is more than 4 times the total volume of the voids in the outer filling lattice.

[0009] In some implementations of the first aspect, the maximum size of the pores in the structure formed by the multilayer cell structure filled with inner lattice is 0.001-0.2 mm.

[0010] In some implementations of the first aspect, the cell size of the outer filling lattice is no greater than 2mm × 2mm × 2mm.

[0011] In some implementations of the first aspect, the filling lattice includes an outer filling lattice layer, a transition layer, and an inner filling lattice layer sequentially arranged from the inner wall of the sealed cavity to the unfilled area, wherein the porosity of the transition layer is between the porosity of the outer filling lattice layer and the porosity of the inner filling lattice layer.

[0012] In some implementations of the first aspect, the porosity of the transition layer is determined based on the percentage of the liquid channel volume to the total volume of the gas and liquid channels. When the percentage of the liquid channel volume to the total volume of the gas and liquid channels is greater than 20%, the inner ring portion within the outer filling lattice layer is densified to form the transition layer, so that the percentage of the liquid channel volume to the total volume of the gas and liquid channels ultimately does not exceed 20%. The cell structure of the transition layer is not less than one layer, and the thickness of a single layer of the transition layer cell structure is an integer multiple of the cell size of the inner filling lattice layer.

[0013] Through the above technical solution, the setting of the transition layer makes it easier for the liquid to generate capillary force. After the liquid flowing in the outer filling lattice layer turns into gas, it can more smoothly pass through the inner filling lattice layer into the unfilled area.

[0014] In some implementations of the first aspect, the metal structure includes an outer skin and an inner skin, with the inner skin forming a sealed cavity between the outer skin and the inner skin, or the inner skin forming a sealed cavity. The portion of the metal structure outside the sealed cavity is a lattice structure or a solid structure. The cross-sectional shape of the sealed cavity is arbitrary, and the depth direction of the sealed cavity can be a form of bending, turning, and / or extension in the depth direction.

[0015] In some implementations of the first aspect, the metal structure and the filling lattice are integrally processed by a heat-adding process.

[0016] In some implementations of the first aspect, the cells of the filling lattice can be selected from all existing lattice types and their variations, and can be arranged in single or multiple combinations. Specifically, the cells of the filling lattice include simple cubic, body-centered cubic, face-centered cubic, simple hexagonal, simple tetragonal, body-centered tetragonal, center hexagonal, simple orthogonal, center orthogonal, body-centered orthogonal, face-centered orthogonal, simple skew, center monoclinic, and simple triclinic, as well as their variations.

[0017] Secondly, a method for fabricating a metamaterial-based heat pipe structure is provided, wherein the metamaterial-based heat pipe structure according to any of the above-described embodiments includes:

[0018] S1: Determine the overall structure of the heat pipe based on the heat transfer requirements and the boundaries of the metal structure;

[0019] S2: Based on the overall structure of the heat pipe, additive manufacturing is carried out to obtain an integrated heat pipe shell with integrated interfaces at both ends of the sealed chamber;

[0020] S3: The integrated heat pipe is chemically or electrolyteally polished and cleaned through an integrated interface to reduce slag buildup and loose debris inside the heat pipe structure. Finally, one end of the integrated heat pipe is welded and sealed, and a metal filling tube is inserted into the other end. The ring welding ensures a tight seal. The heat pipe is then evacuated and filled with a working fluid such as ammonia. Finally, the metal filling tube is cut off and sealed to obtain the integrated heat pipe.

[0021] In step S1, the heat transfer requirements of the structure are obtained through thermodynamic simulation analysis, the heat transfer coefficient of the heat pipe is calculated, the heat pipe cross-section and its metamaterial gradient distribution are designed based on the structural boundary dimensions, and the longitudinal extension design of the heat pipe is carried out under the constraints of additive manufacturing; the mechanical and thermal performance of the new heat pipe and structure integrated component is checked based on finite element simulation, and the overall structure of the heat pipe structure is determined.

[0022] In step S2, the additive manufacturing process for the integrated heat pipe structure uses laser selective melting forming process. Materials can be selected from AlSi10Mg, TC4, aluminum alloy 6061 and 6063, etc. Based on the integrated heat pipe and structure integrated design model, the machining and polishing process allowances are added, and the structure at both ends of the integrated heat pipe interface is optimized to facilitate the subsequent sealing process. If the structure part of the integrated heat pipe and structure design model is a skin dot matrix design, the powder outlet position needs to be considered. Using the mature process parameters of laser selective melting forming of the above-mentioned metal materials, the integrated additive manufacturing of the structure is completed to obtain an integrated heat pipe with integrated interfaces at both ends of the sealed chamber.

[0023] In step S3, the integrated heat pipe shell is subjected to post-processing such as abrasive flow and electrolyte polishing through the integrated interface, the internal debris of the new heat pipe is removed, and conventional processes such as heat pipe cleaning, liquid filling, and testing are performed to obtain the integrated heat pipe.

[0024] In summary, this application includes at least the following beneficial technical effects:

[0025] (1) The size of capillary pores can be controlled by changing the cell size and microrod diameter of the metamaterial centripetal distribution. The cross-sectional shape can be square, elliptical, rectangular and other shapes. The depth direction can be bent, turned and extended. The designability of the new heat pipe is stronger.

[0026] (2) Based on additive manufacturing, the structure and heat pipe can be integrated into one, which eliminates the limitation of using molds in traditional heat pipe stamping.

[0027] (3) Based on the gradient distribution of the centripetal cell size and characteristic size of metamaterials, the additive manufacturing of skin lattice structures and novel heat pipe structures can achieve integrated manufacturing, turning dozens of parts into one, greatly reducing the number of heat transfer interfaces and significantly improving heat transfer efficiency. Adopting novel heat pipe structures based on additive manufacturing metamaterials is an effective technical approach to meet the above requirements. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a heat pipe cross-section in one of the embodiments of this application.

[0029] Figure 2 for Figure 1 A three-dimensional structural diagram of the heat pipe.

[0030] Figure 3 The diagrams show other heat pipe cross-sections, namely, a circular new heat pipe cross-section, an elliptical new heat pipe cross-section, and a flat new heat pipe cross-section.

[0031] The attached figures are labeled as follows: 1. Filling lattice; 11. Outer filling lattice layer; 12. Inner filling lattice layer; 13. Transition layer; 2. Metal structure; 21. Upper skin; 22. Lower skin; 23. Inner skin; 24. Lattice structure; 3. Sealed chamber. Detailed Implementation

[0032] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0033] This application discloses a heat pipe structure based on metamaterials, such as... Figure 1 and Figure 2 As shown, it includes a metal structure 2, a sealed chamber 3 inside the metal structure 2, and a filling lattice 1 inside the sealed chamber 3. The metal structure 2 and the filling lattice 1 are integrally processed by a lamination process. An unfilled area is provided in the middle of the filling lattice 1. The filling lattice 1 includes at least two lattice layers with different porosities. From the unfilled area to the edge of the sealed chamber 3, the porosity of the filling lattice 1 decreases.

[0034] The filling lattice 1 includes an outer filling lattice layer 11 connected to the inner wall of the sealed chamber 3, and an inner filling lattice layer 12 located within the outer filling lattice layer 11. The porosity of the inner filling lattice layer 12 is less than that of the outer filling lattice layer 11. The inner filling lattice layer 12 includes at least two cell structures, and the outer filling lattice layer 11 includes 1-3 cell structures. The volume of the unfilled area is more than 4 times the total volume of the voids in the outer filling lattice layer 11. The maximum pore size of the structure formed by the multi-layer cell structures of the inner filling lattice layer 12 is 0.001-0.2 mm. The cell size of the outer filling lattice layer 11 is no greater than 2 mm × 2 mm × 2 mm. Compared to traditional heat pipe structures, this design offers several advantages: Firstly, it liberates design freedom, allowing the heat pipe cross-section to vary from the traditional cross-section to an arbitrary one. Secondly, the capillary characteristic dimensions and structure of the heat pipe break free from the channel heat pipe design, forming gas and liquid cavities and capillary channels through a variable-density lattice, thus improving heat transfer performance. Customized performance design can be achieved by adjusting porosity and cavity cross-sectional dimensions. Thirdly, it enables variable cross-section forming along the length of the heat pipe, facilitating the design of non-uniform heat transfer coefficients. In terms of manufacturing, laser selective melting forming technology is used to achieve integrated heat pipe and structural forming, eliminating the need for a heat transfer interface. Compared to the traditional channel heat pipe drawing process, it allows for variable cross-section forming along the length of the heat pipe, significantly improving manufacturability.

[0035] Furthermore, a transition layer 13 can be provided between the outer filling lattice layer 11 and the inner filling lattice layer 12. The porosity of the transition layer 13 is between that of the outer filling lattice layer 11 and the inner filling lattice layer 12. The porosity of the transition layer 13 is determined based on the percentage of the liquid channel volume to the total volume of the gas and liquid channels. When the percentage of the liquid channel volume to the total volume of the gas and liquid channels is greater than 20%, the inner ring portion within the outer filling lattice layer 11 is densified to form the transition layer 13, so that the percentage of the liquid channel volume to the total volume of the gas and liquid channels ultimately does not exceed 20%. The cell structure of the transition layer 13 is not less than one layer, and the thickness of a single layer of the transition layer 13 cell structure is an integer multiple of the cell size of the inner filling lattice layer 12. The provision of the transition layer makes it easier for the liquid to generate capillary force, and the capillary region is increased. After the liquid flowing in the outer filling lattice layer becomes gas, it can more smoothly pass through the inner filling lattice layer into the unfilled area.

[0036] The metal structure 2 includes an outer skin and an inner skin 23. The inner skin 23 forms a sealed chamber 3 with or between the outer skin and the inner skin. The portion of the metal structure 2 outside the sealed chamber 3 is a lattice structure 24 or a solid structure. The cross-sectional shape of the sealed chamber 3 is arbitrary, and its depth direction can be curved, bend, and / or extended. In this embodiment, the outer skin consists of a parallel upper skin 21 and a lower skin 22, as well as an edge skin that seals the edge areas of the upper and lower skins 21 and 22. Two parallel inner skins 23 are provided, connected between the upper and lower skins 21 and perpendicular to them. The two inner skins 23, together with the upper and lower skins 21 and 22, form a rectangular sealed chamber 3. The remaining space between the upper and lower skins 21 and 22 is filled by the lattice structure 24.

[0037] The shape of the metal structure 2 and the cross-sectional shape of the sealed chamber 3 can be arbitrary, such as... Figure 3 The diagram shows the cross-sectional shapes of the holes as circular, elliptical, and oblong.

[0038] The cells included in the filling lattice 1 can be selected from all existing lattice types and their variations, and can be arranged in single or multiple combinations. Specifically, the cells of the filling lattice include simple cubic, body-centered cubic, face-centered cubic, simple hexagonal, simple tetragonal, body-centered tetragonal, heart-hexagonal, simple orthogonal, heart-orthogonal, body-centered orthogonal, face-centered orthogonal, simple skew, heart-monoclinic, and simple triclinic, as well as their variations.

[0039] A method for fabricating a heat pipe structure based on metamaterials includes the following steps:

[0040] Step 1: Obtain the thermal conductivity coefficient through thermodynamic simulation analysis and based on heat transfer requirements;

[0041] Step 2: Based on the structural boundary dimensions, design the heat pipe cross-section and its metamaterial gradient distribution shape, and design the longitudinal extension of the heat pipe under the constraints of additive manufacturing; use finite element simulation to verify the mechanical and thermal performance of the new heat pipe and structural integrated component, and determine the overall structure of the heat pipe structure when the thermal performance verification meets the thermal conductivity coefficient.

[0042] Step 3: The additive manufacturing process for the integrated heat pipe structure adopts laser selective melting forming process. Materials such as AlSi10Mg, TC4, aluminum alloy 6061 and 6063 can be selected. Based on the overall structure of the heat pipe, machining and polishing process allowances are added. Integrated interfaces with reduced end opening areas are set at both ends of the heat pipe to facilitate subsequent sealing processes. If the metal structure part of the overall structure of the heat pipe is a skin dot matrix design, the powder outlet position needs to be considered. Using the mature process parameters of laser selective melting forming of the above-mentioned metal materials, the integrated additive manufacturing of the structure is completed to obtain an integrated heat pipe shell with integrated interfaces at both ends of the sealed chamber.

[0043] Step 4: Using the integrated interface, apply post-processing methods such as chemical or electrolyte polishing to remove excess material from the inside of the integrated heat pipe shell;

[0044] Step 5: Fill the integrated heat pipe shell with liquid through the integrated interface, and finally seal the integrated interface to obtain the integrated heat pipe; carry out routine processes such as cleaning, filling and testing of the integrated heat pipe to complete the performance test of the new heat pipe structure product.

[0045] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0046] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A metamaterial-based heat pipe structure, characterized by: The metal structure (2) is provided with a sealed chamber (3) therein; the metal structure (2) comprises an outer skin and an inner skin (23), the inner skin (23) and the outer skin and / or the inner skin (23) form the sealed chamber (3), the part of the metal structure (2) outside the sealed chamber (3) is a dot matrix structure (24) or a solid structure; the sealed chamber (3) is provided with a filling dot matrix (1), and the middle part of the filling dot matrix (1) is provided with an unfilled area; The filling dot matrix (1) comprises at least two dot matrix layers with different porosities, and the porosity of the filling dot matrix (1) decreases from the unfilled area to the edge of the sealed chamber (3); The unfilled area is a gas channel, and the filling dot matrix (1) at the edge of the sealed chamber (3) is a liquid channel.

2. The metamaterial-based heat pipe structure of claim 1, wherein: The filling dot matrix (1) comprises an outer filling dot matrix layer (11) connected with the inner wall of the sealed chamber (3) and an inner filling dot matrix layer (12) located in the outer filling dot matrix layer (11), and the porosity of the inner filling dot matrix layer (12) is smaller than that of the outer filling dot matrix layer (11).

3. The metamaterial-based heat pipe structure of claim 2, wherein: The inner filling dot matrix layer (12) comprises at least two cell structures, the outer filling dot matrix layer (11) comprises 1-3 cell structures, and the volume of the unfilled area is more than 4 times the total volume of the voids of the outer filling dot matrix layer (11).

4. The metamaterial-based heat pipe structure of claim 2, wherein: The maximum size of the pores of the structure formed by the multi-layer cell structure of the inner filling dot matrix layer (12) is 0.001-0.2mm.

5. The metamaterial-based heat pipe structure of claim 2, wherein: The cell size of the outer filling dot matrix layer (11) is not greater than 2mmx2mmx2mm.

6. A metamaterial-based heat pipe structure according to any one of claims 1-5, characterized in that: The filling dot matrix (1) comprises an outer filling dot matrix layer (11), a transition layer (13) and an inner filling dot matrix layer (12) arranged in sequence from the inner wall of the sealed chamber (3) to the unfilled area, and the porosity of the transition layer (13) is between the porosities of the outer filling dot matrix layer (11) and the inner filling dot matrix layer (12).

7. The metamaterial-based heat pipe structure of claim 6, wherein: The porosity of the transition layer (13) is determined according to the percentage of the volume of the liquid channel in the total volume of the gas channel and the liquid channel, and when the percentage of the volume of the liquid channel in the total volume of the gas channel and the liquid channel is greater than 20%, the inner ring part in the outer filling dot matrix layer (11) is densified to form the transition layer (13), so that the percentage of the volume of the liquid channel in the total volume of the gas channel and the liquid channel is finally not greater than 20%; The cell structure of the transition layer (13) is not less than 1 layer, and the single layer thickness of the cell structure of the transition layer (13) is an integer multiple of the cell size of the inner filling dot matrix layer (12).

8. The metamaterial-based heat pipe structure of claim 1, wherein: The cross-sectional shape of the sealed chamber (3) is any shape, and the longitudinal direction of the sealed chamber (3) is curved, turned, and / or extended.

9. The metamaterial-based heat pipe structure of claim 1, wherein: The metal structure (2) and the filling dot matrix (1) are integrally processed by an additive process; the cells included in the filling dot matrix (1) include simple cubic, body-centered cubic, face-centered cubic, simple hexagonal, simple tetragonal, body-centered tetragonal, hexagonal, simple orthorhombic, orthorhombic, body-centered orthorhombic, face-centered orthorhombic, simple oblique, orthorhombic, simple triclinic and its deformation body.

10. A method of processing a metamaterial-based heat pipe structure according to any one of claims 1-9, characterized in that, Comprise: S1: according to the heat transfer requirement and the boundary of the metal structure (2), determine the overall structure of the heat pipe structure; S2: according to the overall structure of the heat pipe structure, additive manufacturing is carried out to obtain an integrated heat pipe shell with integrated interfaces at both ends of the sealed chamber (3); S3: through the integrated interface, the integrated heat pipe shell is polished by abrasive flow and electrolyte, and finally the integrated heat pipe shell is filled with liquid through the integrated interface, and finally the integrated interface is blocked to obtain an integrated heat pipe.

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