A gravity and micro-nano structure enhanced thermosyphon heat spreader and a preparation method thereof

Abstract

The application discloses a gravity and micro-nano structure reinforced thermosyphon radiator and a preparation method thereof, and belongs to the field of thermosyphon radiators. The structure comprises a heat absorption end bottom plate, the top end of the heat absorption end bottom plate is provided with a heat dissipation mechanism, the heat dissipation mechanism is provided with a fixing mechanism on both sides and above, the heat absorption end bottom plate is in a box-shaped structure, the heat absorption end bottom plate is provided with positioning bolt holes at four corners, the heat absorption end bottom plate is internally provided with a heat absorption end supporting column and a heat absorption end inner wall surface reinforcing structure, and the box wall on one side of the heat absorption end bottom plate is provided with a suction and injection port. The application adopts the above structure and method, solves the problems that the steam diffusion direction of the current traditional thermosyphon pipe is single, the effective heat dissipation area is limited, the boiling heat transfer process of the smooth surface lacks vaporization cores, the re-wetting capacity is weak, and the heat transfer deterioration is advanced, and the problems that the heat dissipation demand of high heat flow chips cannot be met.

Description

Technical Field

[0001] This invention relates to the field of thermosiphon radiator technology, and in particular to a gravity-enhanced and micro / nano-structured thermosiphon radiator and its preparation method. Background Technology

[0002] With the development of technologies such as 5G communication and artificial intelligence, the demand for computing power has surged across society, leading to the continuous emergence of high-performance chips. However, this also presents the challenge of heat dissipation for high heat flux densities. Traditional pure solid-state air-cooled heat sinks have high thermal resistance, large size, and heavy weight, making them unable to meet the heat dissipation requirements of current and future high-performance chips. While immersion-based direct liquid cooling and cold plate-based indirect liquid cooling technologies offer high heat dissipation efficiency, they suffer from high investment and maintenance costs, system complexity, and the coolant leakage problem in the latter poses a significant challenge to the cooling system. Therefore, fully exploring the potential of air-cooling technology still holds considerable engineering application value.

[0003] In recent years, technologies such as air-cooled array heat pipes, two-phase vapor chambers, and thermosiphons have been developed based on heat pipes. These technologies leverage the superconducting thermal advantages of heat pipes to significantly increase the effective heat dissipation area, offering substantial advantages such as strong heat dissipation capacity, low thermal resistance, and good temperature uniformity. Among these, array heat pipes and two-phase vapor chambers exhibit high heat dissipation efficiency and low thermal resistance; however, their internal working fluid circulation requires the fabrication of porous capillary structures through sintering processes to provide capillary force, resulting in complex processes and high manufacturing costs. While thermosiphons rely on gravity for working fluid circulation, they offer advantages such as simple structure and reliable performance.

[0004] However, traditional thermosiphons mostly operate in a two-dimensional, unidirectional circulation mode, resulting in a single direction of vapor diffusion. The heat exchange fins can only be arranged on a single channel, limiting the effective heat dissipation area. Furthermore, thermosiphons rely on the boiling-condensation heat transfer of the internal working fluid, with boiling and condensation thermal resistances typically accounting for only 50-70% of the total thermal resistance. On the other hand, the boiling heat transfer process on smooth surfaces lacks vaporization nuclei and has weak rewetting capabilities, easily leading to premature heat transfer deterioration and failing to meet the heat dissipation requirements of high-heat-flux chips. Summary of the Invention

[0005] The purpose of this invention is to provide a gravity-enhanced thermosiphon radiator and its fabrication method, which solves the problems of the current traditional thermosiphon tubes having a single vapor diffusion direction, limited effective heat dissipation area, and premature heat transfer deterioration caused by the lack of vaporization nuclei and weak rewetting ability in the boiling heat transfer process of smooth surfaces, thus failing to meet the heat dissipation requirements of high heat flux chips.

[0006] To achieve the above objectives, the present invention provides a gravity-enhanced and micro / nano-structure-enhanced thermosiphon radiator, comprising a heat-absorbing end base plate, a heat dissipation mechanism at the top of the heat-absorbing end base plate, a fixing mechanism on both sides and above the heat dissipation mechanism, the heat-absorbing end base plate having a box-shaped structure, positioning bolt holes at the four corners of the heat-absorbing end base plate, heat-absorbing end support columns and heat-absorbing end inner wall reinforcement structure inside the heat-absorbing end base plate, and an injection port on one side of the box wall of the heat-absorbing end base plate.

[0007] Preferably, the heat-absorbing end inner wall reinforcement structure is located in the center of the heat-absorbing end base plate, and the heat-absorbing end support columns are evenly distributed around the heat-absorbing end inner wall reinforcement structure, with the bottom end of the heat-absorbing end support column being fixedly connected to the heat-absorbing end base plate.

[0008] Preferably, the inner wall reinforcement structure of the heat-absorbing end includes several micro-needle wings. Several nano-cavity structures are distributed on the surface of the micro-needle wings, the surface of the heat-absorbing end support column, and the inner surface of the heat-absorbing end base plate. The bottom end of the micro-needle wings is fixedly connected to the heat-absorbing end base plate.

[0009] Preferably, the heat dissipation mechanism includes a heat-absorbing end mounting partition and a heat-releasing end mounting partition. Several drawer-type multi-layer fins and several steam diffusion flat tubes are alternately arranged between the heat-absorbing end mounting partition and the heat-releasing end mounting partition. The top ends of the heat-absorbing end mounting partition and the heat-absorbing end support column are welded together.

[0010] Preferably, the steam diffusion flat tube is hollow inside, forming a steam diffusion channel. The inner wall of the steam diffusion flat tube is provided with several heat-releasing end double-stage radial ridge microgroove structures. The heat-releasing end double-stage radial ridge microgroove structures are arranged in parallel along the transverse direction on the inner wall surface of the steam diffusion flat tube. The heat-releasing end double-stage radial ridge microgroove structures include two stages of concave grooves along the height direction. The included angle of the tangent of the envelope line of the first stage concave groove is α, and the included angle of the tangent of the envelope line of the second stage concave groove is β, where α>β.

[0011] Preferably, the fixing mechanism includes a top fixing plate and two side fixing plates. The top fixing plate, side fixing plates, heat absorption end assembly partition and heat release section assembly partition are integrally welded to form a connected sealed cavity.

[0012] The present invention also includes a method for preparing a gravity-enhanced and micro / nano-structure-enhanced thermosiphon radiator: Various structural components are fabricated using a machine tool; slots are machined into the heat-absorbing end assembly partition and the heat-releasing end assembly partition after fabrication; then, the fabricated steam diffusion flat tubes are inserted between the slots of the heat-absorbing end assembly partition and the heat-releasing end assembly partition, and the outer sides of the slots are welded; simultaneously, drawer-type multi-layer fins are installed on both sides of each steam diffusion flat tube; then, a top fixing plate is welded onto the heat-releasing end assembly partition, and side fixing plates are welded to both sides of the top fixing plate; the lower side of the side fixing plates is connected to the heat-absorbing end assembly partition and the heat-absorbing end bottom plate, and then welded together and sealed.

[0013] Preferably, the length, width and height of the heat-absorbing end support column are all 2-4mm, the spacing between adjacent heat-absorbing end support columns is 2-4mm, and the side fixing plate, drawer-type multi-layer fins, heat-releasing end assembly partition and top fixing plate are all made by cutting aluminum alloy plate.

[0014] Preferably, the microneedle fins are columnar structures arranged in an array, with characteristic dimensions of 50-500 μm and height of 50-800 μm. The processing procedure is as follows:

[0015] Step 1: Clean and dry the microneedle wings using anhydrous acetone and deionized water;

[0016] Step 2: Process the micro-needle fins using a femtosecond laser. The power of the femtosecond laser is 5-15W, the scanning speed is 20-150mm / s, the processing frequency is 50-200kHz, and the number of processing times is 2-5.

[0017] Step 3: Clean again using the method described in Step 1, and then place in a dry place;

[0018] The nano-hole structure is uniformly distributed on the surface of the micro-needle fins, the surface of the heat-absorbing end support column, and the inner surface of the heat-absorbing end base plate. The characteristic size of the nano-hole is 0.1-1μm.

[0019] Preferably, the preparation method of the heat-releasing end double-stage radial ridge microgroove structure is as follows: a stainless steel mold is designed and prepared according to the outer contour dimensions of the heat-releasing end double-stage radial ridge microgroove structure, and then an aluminum alloy plate is placed on the mold and extruded to obtain a heat-releasing end double-stage radial ridge microgroove structure with the corresponding mold shape. The height of the heat-releasing end double-stage radial ridge microgroove structure is 0.5-2mm, the maximum width is 2-3mm, and the central axis spacing is 4-6mm.

[0020] Therefore, the present invention, employing the above-described structure, provides a gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator and its fabrication method, which has the following beneficial effects:

[0021] 1. By upgrading the working mode of the traditional thermosiphon from two-dimensional to three-dimensional, the extensive diffusion of steam in multi-dimensional space is achieved. This transformation greatly expands the steam condensation heat exchange area, thereby improving the heat exchange efficiency at the heat release end of the thermosiphon;

[0022] 2. Drawing inspiration from the ingenious microscopic bi-level radial ridge structure on the leaf lip of the pitcher plant in nature, an innovative biomimetic design was made for the inner wall of the heat-releasing end of the thermosiphon. This cleverly restricts the orientation of the meniscus of the condensate film, allowing the condensate to collect orderly at the bottom of the microgroove. This effectively controls the upper limit of the film thickness, enabling the condensate to flow rapidly to the boiling side. It also increases the structural area of ​​the inner wall of the steam and heat-releasing side, further improving the performance of the thermosiphon.

[0023] 3. A micro-needle fin-nano cavity composite structure is set on the inner wall of the heat absorption end. The nano-cavity structure provides a large number of vaporization nuclei, which improves the boiling heat transfer coefficient. The micro-needle fins provide flow channels for the micro liquid layer in the evaporation zone, which increases the critical heat flux density for boiling heat transfer, thereby improving the heat exchange efficiency of the boiling side of the thermosiphon tube.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an embodiment of a gravity-enhanced and micro / nano-structure-enhanced thermosiphon radiator according to the present invention;

[0026] Figure 2 This is an exploded view of an embodiment of a gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of the heat absorption end inner wall reinforcement structure of a gravity and micro / nano structure enhanced thermosiphon radiator embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram showing the distribution of micro-needle fins and nano-cavity structures in an embodiment of a gravity- and micro / nano-structure-enhanced thermosiphon radiator of the present invention.

[0029] Figure 5 This is a slanted cut schematic diagram of the steam diffusion flat tube structure of an embodiment of a gravity-enhanced and micro / nano-structured thermosiphon radiator according to the present invention;

[0030] Figure 6 This is a schematic diagram of the structure of a gravity-enhanced and micro / nano-structured thermosiphon radiator embodiment of the present invention, showing a dual-stage radial ridge microgroove at the heat dissipation end.

[0031] Figure Labels

[0032] 1. Absorber end base plate; 110. Absorber end support column; 111. Positioning bolt hole; 112. Injection port; 113. Inner wall reinforcement structure of absorber end; 1130. Micro needle fins; 1131. Nano-cavity structure; 2. Absorber end assembly partition; 3. Steam diffusion flat tube; 310. Steam diffusion channel; 311. Heat release end double-stage radial ridge microgroove; 4. Side fixing plate; 5. Drawer-type multi-layer fins; 6. Heat release end assembly partition; 7. Top fixing plate. Example

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this 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. Therefore, they should not be construed as limiting this invention.

[0037] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0039] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention.

[0040] The specific model and specifications need to be determined based on the actual specifications of the device. The specific selection and calculation method adopts the existing technology in this field, so it will not be described in detail here.

[0041] like Figures 1 to 2 As shown, the present invention provides a gravity and micro / nano structure enhanced thermosiphon radiator, including a heat-absorbing end base plate 1, a heat dissipation mechanism is provided at the top of the heat-absorbing end base plate 1, and a fixing mechanism is provided on both sides and above the heat dissipation mechanism. The heat-absorbing end base plate 1 is a box-shaped structure, and positioning bolt holes 111 are provided at the four corners of the heat-absorbing end base plate 1. The heat-absorbing end support column 110 and the heat-absorbing end inner wall reinforcement structure 113 are provided inside the heat-absorbing end base plate 1. An injection port 112 is provided on one side of the box wall of the heat-absorbing end base plate 1.

[0042] The lower surface of the heat-absorbing end base plate 1 is bonded to the chip through a thermal interface material, and is positioned and fastened using positioning bolt holes. The injection port 112 can be connected to an injection pipe to perform vacuuming and liquid injection operations on the heat sink.

[0043] The heat absorption end inner wall reinforcement structure 113 is located in the center of the heat absorption end base plate 1, and the heat absorption end support columns 110 are evenly distributed around the heat absorption end inner wall reinforcement structure 113. The bottom end of the heat absorption end support column 110 is fixedly connected to the heat absorption end base plate 1.

[0044] The heat dissipation mechanism includes a heat absorption end mounting plate 2 and a heat release end mounting plate 6. Several drawer-type multi-layer fins 5 and several steam diffusion flat tubes 3 are alternately arranged between the heat absorption end mounting plate 2 and the heat release end mounting plate 6. The top of the heat absorption end mounting plate 2 and the heat absorption end support column 110 are welded together.

[0045] The heat-absorbing end support column 110 is a square column, and its top is connected and fixed to the heat-absorbing end assembly partition 2 by brazing process to improve the pressure bearing capacity and prevent deformation caused by excessive internal pressure of the radiator.

[0046] The fixing mechanism includes a top fixing plate 7 and two side fixing plates 4. The top fixing plate 7, the side fixing plates 4, the heat absorption end assembly partition 2, and the heat release section assembly partition are welded together to form a connected sealed cavity.

[0047] like Figure 3 As shown, the inner wall reinforcement structure 113 of the heat-absorbing end includes several micro-needle fins 1130. Several nano-void structures 1131 are distributed on the surface of the micro-needle fins 1130, the surface of the heat-absorbing end support column 110, and the inner surface of the heat-absorbing end base plate 1. The bottom ends of the micro-needle fins 1130 are fixedly connected to the heat-absorbing end base plate 1. The specific structure of the nano-void structure is a pit with a scale of tens of nanometers; the specific size is related to the process flow and actual needs.

[0048] The micro-needle fins 1130 can significantly increase the specific surface area of ​​the upper surface of the heat-absorbing end plate 1; in addition, the arrayed micro-needle fins 1130 can provide capillary force, increase the liquid replenishment capacity of the heat exchange surface, delay the deterioration of boiling heat transfer on the upper surface of the heat-absorbing end plate 1, and increase the critical heat flux density; the nano-cavity structure 1131 can provide a large number of boiling vaporization nuclei, significantly improve the boiling heat transfer coefficient, and thus effectively reduce the thermal resistance of the radiator.

[0049] like Figure 4 As shown, the steam diffusion flat tube 3 includes a steam diffusion channel 310 and a heat-releasing end double-stage radial ridge microgroove structure 311. Several heat-releasing end double-stage radial ridge microgroove structures 311 are arranged in parallel along the transverse direction on the inner wall surface of the steam diffusion flat tube 3. The heat-releasing end double-stage radial ridge microgroove structure 311 includes two stages of concave grooves along the height direction. The included angle of the tangent of the envelope line of the first stage concave groove is α, and the included angle of the tangent of the envelope line of the second stage concave groove is β. α>β, that is, the characteristic size of the second stage concave groove is smaller than the characteristic size of the first stage concave groove.

[0050] In this structure, the second-stage concave grooves can generate significant capillary force. Driven by the capillary force gradient, the condensate automatically moves and collects from the top to the bottom of the double-stage radial ridge microgroove structure. This not only reduces the thickness of the condensate film at the top of the double-stage radial ridge microgroove structure, improving condensation heat transfer efficiency, but also increases the weight of the condensate at the bottom of the double-stage radial ridge microgroove structure, prompting the condensate to quickly detach and flow to the upper surface of the heat absorber bottom plate 1, forming rapid liquid replenishment and enhancing the radiator's ultimate heat dissipation capacity. The double-stage radial ridge microgroove structure can significantly expand the effective condensation area of ​​the inner wall of the vapor diffusion flat tube 3, improving condensation efficiency and reducing the radiator's thermal resistance.

[0051] All of the above components are made of aluminum alloy.

[0052] The working principle of the heat sink is as follows: The heat sink contains a liquid working fluid, mainly concentrated in the cavity between the heat-absorbing end base plate 1 and the heat-absorbing end mounting partition 2. The lower surface of the heat-absorbing end base plate 1 is in contact with the chip. The positioning bolt holes 111 are used to secure the chip after accurate positioning, ensuring a close fit and facilitating heat transfer. After the heat-absorbing end base plate 1 absorbs heat from the chip, the liquid working fluid boils and vaporizes on the upper surface of the heat-absorbing end base plate 1. The generated vapor diffuses upwards into the internal flow channel of the vapor diffusion tube 3. Heat is conducted through the wall of the vapor diffusion tube 3 to the fin surface of the drawer-type multi-layer fins 5, where it exchanges heat with the air. After releasing heat, the vapor condenses and liquefies, becoming the liquid working fluid again. Then, under the action of gravity, the liquid working fluid flows back into the cavity of the heat-absorbing end base plate 1 to continue boiling, and this process repeats.

[0053] The liquid working medium inside the radiator can be a low-boiling-point refrigerant, such as R134a, R245fa or R1233zd(E), or a low-boiling-point fluorinated coolant (boiling point 10~65℃), such as HFE-7100, Novec649, or an alcohol working medium, such as methanol or ethanol.

[0054] This invention also provides a method for preparing a gravity-enhanced and micro / nano-structure-enhanced thermosiphon radiator. The method involves machining various structural components using a machine tool. After the heat-absorbing end assembly partition 2 and the heat-releasing end assembly partition 6 are completed, slots are machined into them. Then, the completed steam diffusion flat tubes 3 are inserted between the slots of the heat-absorbing end assembly partition 2 and the heat-releasing end assembly partition 6, and the outer sides of the slots are welded. Simultaneously, drawer-type multi-layer fins 5 are installed on both sides of each steam diffusion flat tube 3. Then, a top fixing plate 7 is welded onto the heat-releasing end assembly partition 6, and side fixing plates 4 are welded to both sides of the top fixing plate 7. The lower side of the side fixing plates 4 is connected to the heat-absorbing end assembly partition 2 and the heat-absorbing end bottom plate 1, and then welded together for sealing.

[0055] The length, width and height of the heat-absorbing end support column 110 are all 2-4mm, and the spacing between adjacent heat-absorbing end support columns 110 is 2-4mm. The side fixing plate 4, the drawer-type multi-layer fins 5, the heat-releasing end assembly partition 6 and the top fixing plate 7 are all made by cutting aluminum alloy plates.

[0056] The micro-needle fin 1130 is an array of columnar structures, with characteristic dimensions of 50-500μm and height of 50-800μm. The manufacturing process is as follows:

[0057] Step 1: Clean and dry the microneedle wings 1130 using anhydrous acetone and deionized water;

[0058] Step 2: Use a femtosecond laser to process the micro-needle fin 1130. The power of the femtosecond laser is 5-15W, the scanning speed is 20-150mm / s, the processing frequency is 50-200kHz, and the number of processing times is 2-5.

[0059] Step 3: Clean again using the method described in Step 1, and then place in a dry place;

[0060] Nanohole structures 1131 are uniformly distributed on the surface of microneedle fins 1130, the surface of heat-absorbing end support column 110, and the inner surface of heat-absorbing end base plate 1. The characteristic size of the nanoholes is 0.1-1μm.

[0061] Preferably, the preparation method of the heat-releasing end double-stage radial ridge microgroove 311 structure is to design and prepare a stainless steel mold according to the outer contour dimensions of the heat-releasing end double-stage radial ridge microgroove 311 structure, and then use an extrusion process to prepare it. The height of the heat-releasing end double-stage radial ridge microgroove 311 structure is 0.5-2mm, the maximum width is 2-3mm, and the central axis spacing is 4-6mm.

[0062] Therefore, the present invention provides a gravity and micro / nano structure-enhanced thermosiphon radiator and its preparation method, which solves the problems of the current traditional thermosiphon tubes having a single vapor diffusion direction, limited effective heat dissipation area, and premature heat transfer deterioration caused by the lack of vaporization nuclei and weak rewetting ability in the boiling heat transfer process of smooth surfaces, thus failing to meet the heat dissipation requirements of high heat flux chips.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A gravity-enhanced and micro / nano-structure-enhanced thermosiphon radiator, characterized in that: It includes a heat-absorbing end base plate, a heat dissipation mechanism is provided at the top of the heat-absorbing end base plate, and a fixing mechanism is provided on both sides and above the heat dissipation mechanism. The heat-absorbing end base plate is a box-shaped structure. Positioning bolt holes are provided at the four corners of the heat-absorbing end base plate. Heat-absorbing end support columns and heat-absorbing end inner wall reinforcement structure are provided inside the heat-absorbing end base plate. An injection port is provided on one side of the box wall of the heat-absorbing end base plate. The heat dissipation mechanism includes a heat absorption end assembly partition and a heat release end assembly partition. Several drawer-type multi-layer fins and several steam diffusion flat tubes are alternately arranged between the heat absorption end assembly partition and the heat release end assembly partition. The top of the heat absorption end assembly partition and the heat absorption end support column are welded together. The steam diffusion flat tube is hollow inside, forming a steam diffusion channel. Several heat-releasing end double-stage radial ridge microgroove structures are provided on the inner wall of the steam diffusion flat tube. The heat-releasing end double-stage radial ridge microgroove structures are arranged in parallel along the transverse direction on the inner wall surface of the steam diffusion flat tube. The heat-releasing end double-stage radial ridge microgroove structures include two stages of concave grooves along the height direction. The included angle of the tangent of the envelope line of the first stage concave groove is α, and the included angle of the tangent of the envelope line of the second stage concave groove is β, where α>β.

2. The gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to claim 1, characterized in that: The heat absorption end inner wall reinforcement structure is located in the center of the heat absorption end base plate, and the heat absorption end support columns are evenly distributed around the heat absorption end inner wall reinforcement structure. The bottom end of the heat absorption end support column is fixedly connected to the heat absorption end base plate.

3. The gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to claim 1, characterized in that: The inner wall reinforcement structure of the heat-absorbing end includes several micro-needle fins. Several nano-cavity structures are distributed on the surface of the micro-needle fins, the surface of the heat-absorbing end support column, and the inner surface of the heat-absorbing end base plate. The bottom end of the micro-needle fins is fixedly connected to the heat-absorbing end base plate.

4. The gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to claim 1, characterized in that: The fixing mechanism includes a top fixing plate and two side fixing plates. The top fixing plate, side fixing plates, heat absorption end assembly partition and heat release section assembly partition are welded together to form a connected sealed cavity.

5. A method for fabricating a gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to any one of claims 1-4, characterized in that: Each structural component is manufactured using machine tools. After the heat absorption end assembly partition and the heat release end assembly partition are manufactured, slots are machined out. Then, the manufactured steam diffusion flat tubes are inserted between the slots of the heat absorption end assembly partition and the heat release end assembly partition, and the outer side of the slots is welded. At the same time, drawer-type multi-layer fins are installed on both sides of each steam diffusion flat tube. Then, a top fixing plate is welded to the heat release end assembly partition, and side fixing plates are welded to both sides of the top fixing plate. The lower side of the side fixing plates is connected to the heat absorption end assembly partition and the heat absorption end bottom plate, and then welded together and sealed.

6. The method for fabricating a gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to claim 5, characterized in that: The length, width, and height of the heat-absorbing end support column are all 2-4mm, and the spacing between adjacent heat-absorbing end support columns is 2-4mm. The side fixing plate, drawer-type multi-layer fins, heat-releasing end assembly partition, and top fixing plate are all made of aluminum alloy plate by cutting.

7. The method for fabricating a gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to claim 5, characterized in that: The microneedle fins are arrayed columnar structures with characteristic dimensions of 50-500 μm and heights of 50-800 μm. The fabrication process is as follows: Step 1: Clean and dry the microneedle wings using anhydrous acetone and deionized water; Step 2: Process the micro-needle fins using a femtosecond laser. The power of the femtosecond laser is 5-15W, the scanning speed is 20-150mm / s, the processing frequency is 50-200kHz, and the number of processing times is 2-5. Step 3: Clean again using the method described in Step 1, and then place in a dry place; The nano-hole structure is uniformly distributed on the surface of the micro-needle fins, the surface of the heat-absorbing end support column, and the inner surface of the heat-absorbing end base plate. The characteristic size of the nano-hole is 0.1-1μm.

8. The method for fabricating a gravity-enhanced and micro / nano-structure-reinforced thermosiphon radiator according to claim 5, characterized in that: The method for preparing the heat-releasing end double-stage radial ridge microgroove structure is as follows: a stainless steel mold is designed and prepared according to the outer contour dimensions of the heat-releasing end double-stage radial ridge microgroove structure. Then, an aluminum alloy plate is placed on the mold and extruded to obtain a heat-releasing end double-stage radial ridge microgroove structure with the corresponding mold shape. The height of the heat-releasing end double-stage radial ridge microgroove structure is 0.5-2mm, the maximum width is 2-3mm, and the central axis spacing is 4-6mm.

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