Bionic liquid absorption core structure with transpiration suction effect and vapor chamber

Abstract

The application discloses a kind of bionic liquid absorption core structures with transpiration suction effect and heat spreading plate, the heat spreading plate includes lower cover plate, upper cover plate, sealed cavity, working medium, liquid filling port and bionic liquid absorption core structure arranged in sealed cavity.The bionic liquid absorption core structure includes capillary braided rope, catheter and porous transpiration membrane, capillary braided rope is at least partially threaded inside catheter, and extends from condensation zone to evaporation zone, capillary braided rope and catheter form liquid transport path together, and porous transpiration membrane is arranged at the end of liquid transport path.Cooling liquid is collected by capillary braided rope, and is transported to porous transpiration membrane by transport path formed by capillary braided rope and catheter, and is evaporated by heating in evaporation zone.The structure of the application can realize the hierarchical cooperation of condensate collection, directional transport and evaporation end liquid supply, and is suitable for electronic device heat dissipation and related phase change heat dissipation device.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation and phase change heat transfer technology, specifically to a biomimetic liquid-absorbing core structure with evaporation and suction effect, and a heat spreader using the liquid-absorbing core structure. Background Technology

[0002] With the continuous increase in the integration and power density of electronic devices, the heat flux density generated by these devices is increasing dramatically, posing a severe challenge to heat dissipation systems. A vapor chamber is a highly efficient two-phase heat transfer device that utilizes the evaporation, vapor transport, condensation, and liquid reflux of a working fluid within a sealed cavity to achieve rapid heat dissipation. Due to its excellent thermal conductivity, compact structure, and good temperature uniformity, vapor chambers are widely used in the heat dissipation of electronic devices, such as servers and high-end graphics cards.

[0003] The wick is a key component inside the vapor chamber for achieving condensate recirculation and continuous liquid supply to the evaporation zone. The wick primarily relies on capillary pressure generated at the vapor-liquid interface to drive the condensate back from the condensation zone to the evaporation zone. Its liquid transport performance is influenced by factors such as pore size, porosity, permeability, wettability, and transport distance. For example, when the wick pore size is small, although it can generate greater capillary pressure, its permeability is low, resulting in higher flow resistance along the flow path, which is unfavorable for long-distance condensate transport. When the wick pore size is large, the flow resistance is reduced, but its capillary suction capacity weakens, easily leading to insufficient liquid supply to the evaporation zone. Therefore, a wick with a single pore size cannot simultaneously meet the requirements of rapid condensate collection, low-resistance transport, and continuous liquid supply to the evaporation interface.

[0004] Commonly used wicking elements for vapor chambers include wire mesh wicking elements, sintered powder wicking elements, grooved wicking elements, and porous composite wicking elements. Wire mesh wicking elements offer advantages such as simple structure and easy processing, but their pore size is relatively large, limiting capillary suction capacity. Furthermore, the contact thermal resistance between the mesh and the wall is high, leading to insufficient liquid supply in the evaporation zone under high heat flux density or anti-gravity operation conditions. Sintered powder wicking elements provide high capillary pressure, but their permeability is low, resulting in significant resistance to long-distance liquid return. Grooved wicking elements offer low liquid flow resistance, but their capillary pressure is relatively weak, and their lateral liquid supply and uniform wetting ability on the evaporation surface are limited. While porous composite wicking elements can balance capillary suction and liquid transport capabilities to some extent, their complex structure and the connectivity between different pore layers or liquid transport structures significantly impact performance. In summary, existing traditional wicking element structures struggle to simultaneously meet the requirements of rapid condensate collection, low-resistance transport, and continuous uniform liquid supply in the evaporation zone, and also fail to satisfy the ever-increasing heat dissipation demands.

[0005] To address the aforementioned technical challenges, Chinese invention patent CN103542749B proposes a biomimetic vapor chamber wick with leaf vein-like fractal channels and microchannels. However, this requires precise control over the size, branching relationships, and processing depth of the multi-level channels. Some solutions also involve vacuum sintering and subsequent laser engraving or chemical etching, making the fabrication process quite complex. Chinese invention patent CN117628953B proposes a functionalized biomimetic micro / nanostructure vapor chamber, which enhances heat transfer by constructing superhydrophilic and superhydrophobic micro / nanostructures in the evaporation and condensation sections, respectively. However, this involves multiple processes, including polystyrene opal template preparation, electrochemical deposition, template removal, chemical oxidation, etching, and surface modification, requiring high consistency in the process, resulting in a relatively large fabrication cycle and cost. In the industrial production of vapor chambers, it is necessary to consider not only the comprehensive performance of the wick but also its processing difficulty and manufacturing cost, selecting a simpler structure while meeting heat transfer requirements.

[0006] In engineering, the maximum height for transporting liquid working fluids against gravity using capillary wicks is limited to 0.5-1m. Trees, however, can utilize a system composed of roots, trunk, and branches to draw water from the soil to the treetop through transpiration, with transport distances exceeding 100 meters. Therefore, referencing plant water transport systems and utilizing the negative pressure effect of transpiration, a biomimetic wick structure can be constructed that combines condensate collection, continuous and uniform liquid supply to the evaporation zone, and long-distance transport. This structure is relatively simple and easy to manufacture, and would significantly contribute to improving the heat transfer performance of vapor chambers and meeting the growing demands for electronic heat dissipation. Summary of the Invention

[0007] To address the bottleneck problem of high long-distance transport resistance of the working fluid and insufficient local liquid supply in the evaporation zone of a vapor chamber, which hinders the improvement of the ultimate transmission power, this invention proposes a biomimetic liquid-absorbing core structure with evaporation suction effect and a vapor chamber using this liquid-absorbing core structure.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a biomimetic liquid-absorbing core structure with evaporative suction effect, comprising a liquid collection unit, a transport unit, and an evaporative liquid supply unit; the liquid collection unit includes a capillary braided rope for absorbing and collecting liquid working fluid; the transport unit includes a conduit, and at least a portion of the capillary braided rope passes through the internal channel of the conduit, the capillary braided rope and the conduit together forming a liquid transport path from the liquid collection unit to the evaporative liquid supply unit; the evaporative liquid supply unit includes a porous evaporative membrane, the porous evaporative membrane being disposed at the end of the liquid transport path, so that the liquid working fluid transported via the capillary braided rope and the conduit can enter the porous evaporative membrane and form an evaporative liquid supply interface; the capillary braided rope, the conduit and the porous evaporative membrane together form a hierarchical liquid transport structure of liquid collection, directional transport and evaporative liquid supply.

[0010] Furthermore, the capillary braided rope is configured as multiple ropes, and arranged at equal or non-equal intervals in its plane; the capillary braided rope is a stainless steel braided rope, copper braided rope, nickel braided rope or other metal fiber braided rope with capillary pores.

[0011] Furthermore, the conduit has an internal channel through which the capillary braided rope passes, and the cross-sectional dimension of the internal channel is larger than the cross-sectional dimension of the capillary braided rope, so that a transport space for the flow of liquid working fluid is formed between the inner wall of the conduit and the outer surface of the capillary braided rope.

[0012] Furthermore, the porous evaporating membrane has hydrophilic properties and a connected pore structure, which is used to distribute the working medium within the porous evaporating membrane and provide an escape channel for the vapor.

[0013] Furthermore, the porous evaporation membrane is any one or more of the following: metal sintered porous membrane, metal foam porous membrane, metal wire mesh porous membrane, metal fiber porous membrane, or ceramic porous membrane.

[0014] Secondly, the present invention also provides a heat spreader, comprising a lower cover plate, an upper cover plate, a sealed cavity formed by the lower cover plate and the upper cover plate being sealed together, a filling port communicating with the sealed cavity, a working medium filled in the sealed cavity, and a biomimetic liquid-absorbing core structure as described above disposed in the sealed cavity.

[0015] Furthermore, the sealed cavity includes an evaporation zone, a transport zone, and a condensation zone; at least a portion of the capillary braided rope is threaded through the internal channel of the conduit and extends from the condensation zone to the evaporation zone; the capillary braided rope and the conduit together form a liquid transport path from the condensation zone to the evaporation zone; the porous evaporation membrane is disposed in the evaporation zone and located at the end of the liquid transport path, and the liquid working fluid is transported to the evaporation zone via the capillary braided rope and the conduit and enters the porous evaporation membrane.

[0016] Furthermore, the evaporation zone is located at a position corresponding to the external heat source, and the transport zone is located on at least one side of the evaporation zone and between the evaporation zone and the condensation zone; the condensation zone includes a lower condensation zone located on the inner surface of the lower cover plate and on the side of the transport zone away from the evaporation zone, and an upper condensation zone located on the inner surface of the upper cover plate.

[0017] Furthermore, the capillary braided rope is disposed on the inner surface of the lower cover plate and extends along the condensation zone, the transport zone and the evaporation zone.

[0018] Furthermore, the evaporation zone is a sunken groove structure disposed on the inner surface of the lower cover plate, and the porous evaporation membrane is disposed in the sunken groove structure and at least covers the projection area of ​​the external heat source on the heat spreader plate.

[0019] The technical solution of this invention draws on the hierarchical structure of "root-xylem-leaf" in plant transpiration transport systems to construct a multi-scale biomimetic liquid-absorbing core structure. Its working principle is as follows: an external heat source inputs heat into the evaporation zone, causing the liquid working medium within the porous transpiration membrane to evaporate. The resulting vapor escapes through the interconnected pores of the porous transpiration membrane and enters the vapor flow space within the sealed cavity, subsequently diffusing towards the condensation zone. Due to the continuous evaporation of the liquid working medium within the porous transpiration membrane, a dynamic replenishment demand is created in the evaporation zone. Under the synergistic effect of capillary action, the upstream liquid working medium is continuously replenished to the evaporation zone along the liquid transport path formed by the capillary braided rope and the duct, thus producing a suction effect similar to the transpiration process in plants. Furthermore, the vapor releases heat and condenses in the condensation zone to form condensate. The condensate is absorbed and collected by the capillary braided rope and transported from the condensation zone to the evaporation zone along the liquid transport path formed by the capillary braided rope and the duct. After entering the porous transpiration membrane, it participates in the evaporation process again, ultimately forming a vapor-liquid phase change cycle of evaporation, vapor diffusion, condensation, and condensate recirculation.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The biomimetic wick can generate an evaporation suction effect, thereby significantly improving the transport capacity of condensate from the condensation zone to the evaporation zone, achieving continuous liquid supply, preventing localized drying in the evaporation zone, and improving the ultimate transfer power and heat transfer performance of the heat spreader. Through the graded combination of capillary braided rope, conduit, and porous evaporation membrane, the problems of a single wick being unable to simultaneously address condensate collection, long-distance transport, and continuous and uniform liquid supply to the evaporation zone are alleviated. The biomimetic wick has a relatively simple structure and assembly process, low processing cost, and can be optimized according to different application scenarios and needs, making it suitable for the industrial production of heat spreaders. Attached Figure Description

[0022] Figure 1An isometric view of the appearance of a heat spreader with a biomimetic liquid-absorbing core structure having an evaporation and suction effect, provided in an embodiment of the present invention.

[0023] Figure 2 This is an exploded structural diagram of a heat spreader with a biomimetic liquid-absorbing core structure having an evaporation and suction effect, provided as an embodiment of the present invention.

[0024] Figure 3 This is a top view schematic diagram of the internal structure of the lower cover plate of a heat spreader with a biomimetic liquid-absorbing core structure having an evaporation and suction effect, provided in an embodiment of the present invention.

[0025] Figure 4 This is a side cross-sectional view and a partial enlarged schematic diagram of a heat spreader with a biomimetic liquid-absorbing core structure having an evaporation and suction effect, according to an embodiment of the present invention.

[0026] The components in the diagram are labeled as follows: 1 heat spreader, 2 lower cover plate, 3 upper cover plate, 4 porous evaporation membrane, 5 capillary braided rope, 6 conduit, and 7 liquid filling port. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] This embodiment provides a biomimetic liquid-absorbing core structure with evaporative suction effect, including a liquid collection unit, a transport unit, and an evaporative liquid supply unit. The liquid collection unit includes a capillary braided rope 5 for absorbing and collecting liquid working fluid. The transport unit includes a conduit 6, and at least a portion of the capillary braided rope 5 passes through the internal channel of the conduit 6. The capillary braided rope 5 and the conduit 6 together form a liquid transport path from the liquid collection unit to the evaporative liquid supply unit. The evaporative liquid supply unit includes a porous evaporative membrane 4, which is disposed at the end of the liquid transport path, allowing the liquid working fluid transported via the capillary braided rope and the conduit to enter the porous evaporative membrane and form an evaporative liquid supply interface. The capillary braided rope 5, the conduit 6, and the porous evaporative membrane 4 together form a hierarchical liquid transport structure for liquid collection, directional transport, and evaporative liquid supply.

[0030] Example 2

[0031] This embodiment provides a heat spreader 1 with a biomimetic liquid-absorbing core structure employing the evaporation and suction effect. The heat spreader 1 includes a lower cover plate 2, an upper cover plate 3, a porous evaporation membrane 4, a capillary braided rope 5, a conduit 6, a liquid filling port 7, and a working medium (not shown). The lower cover plate 2 and the upper cover plate 3 are arranged opposite each other along the thickness direction of the heat spreader 1 and are sealed together at the periphery to form a closed cavity. The closed cavity is used to contain the working medium, provide installation space for the biomimetic liquid-absorbing core structure, and provide space for vapor flow and condensation reflux.

[0032] The heat spreader 1 is a flat plate structure. In this embodiment, the heat spreader 1 has external dimensions of 206×60×5 mm (length×width×height). The upper cover plate 3 covers the lower cover plate 2 and is sealed to the lower cover plate 2 by one or more methods such as diffusion welding, brazing, laser welding, electron beam welding, or roll sealing. The filling port 7 is located on the side of the heat spreader 1 and communicates with the sealed cavity. It is used to evacuate the sealed cavity, fill it with the working medium, and seal it after filling. The sealing method can be achieved by welding, pressing, or solder sealing.

[0033] The working medium can be selected based on the application temperature range and material compatibility. Common working media for heat exchangers include deionized water, ethanol, methanol, acetone, and ammonia. In this embodiment, water is used as the working medium.

[0034] Based on the functions of heat transfer and liquid transport, the sealed cavity includes an evaporation zone, a transport zone, and a condensation zone. The evaporation zone is positioned corresponding to the location of the external heat source; the transport zone is located between the evaporation zone and the condensation zone; and the condensation zone is used to condense the released heat of vapor into condensate. In this embodiment, the evaporation zone is located in the middle of the inner surface of the lower cover plate 2, the transport zone is located on both sides of the evaporation zone, and the condensation zone is located on the side of the transport zone away from the evaporation zone and in all areas of the inner surface of the upper cover plate 3.

[0035] The biomimetic liquid-absorbing core structure with evaporation and suction effect includes a porous evaporation membrane 4, a capillary braided rope 5, and a conduit 6, which is disposed on the inner surface of the lower cover plate 2.

[0036] The porous evaporation membrane 4 is disposed in the evaporation zone. The size of the porous evaporation membrane 4 can be set according to the contact area of ​​the external heat source, the projection area of ​​the heat source, and the overall size of the heat spreader 1. Preferably, the porous evaporation membrane 4 at least covers the projection area of ​​the external heat source on the heat spreader 1. In this embodiment, the porous evaporation membrane 4 adopts a porous structure with dimensions of 50×30×3mm (length×width×height). The evaporation zone is a recessed groove structure disposed in the middle of the inner surface of the lower cover plate 2. The size of the recessed groove structure is slightly larger than the outer dimensions of the porous evaporation membrane 4 to facilitate the embedded installation of the porous evaporation membrane 4. Specifically, the groove size is set to 50.1×30.1×3.1 mm (length×width×depth) to form a fitting installation relationship between the porous evaporation membrane 4 and the groove. The shape and area of ​​the recessed groove structure are set according to the position and projection range of the external heat source.

[0037] In one optional embodiment, the porous evaporative membrane 4 can be a sintered metal porous membrane, a metal foam porous membrane, a metal mesh porous membrane, a metal fiber porous membrane, a ceramic porous membrane, or a porous membrane with a hydrophilic surface treatment. The hydrophilic treatment may include one or more of oxidation treatment, chemical etching, electrochemical treatment, coating treatment, or laser micro / nano processing. In this embodiment, copper foam is used as the porous evaporative membrane.

[0038] The capillary braided rope 5 is disposed on the inner surface of the lower cover plate 2 and extends along the condensation zone, transport zone and evaporation zone. When multiple capillary braided ropes 5 are provided, the multiple capillary braided ropes 5 can be arranged at intervals along the width direction of the heat spreader plate 1 and extend along the length direction of the heat spreader plate 1, thereby absorbing and collecting the condensate formed on the inner surface of the lower cover plate 2.

[0039] In one optional embodiment, the capillary braided rope 5 can be made of stainless steel, copper, nickel, or other metal fiber braided ropes with capillary pores. The capillary braided rope 5 can be a multi-strand braided structure, or a braided structure with different numbers of strands, diameters, or materials can be selected according to the condensate collection capacity, cavity size, conduit 6 size, and type of working medium. In this embodiment, the capillary braided rope 5 is a 1×7 stainless steel braided rope with a maximum outer diameter of 1 mm and a length of 200 mm.

[0040] The conduit 6 is disposed in the transport zone and is correspondingly disposed with the capillary braided rope 5. The portion of the capillary braided rope 5 located in the transport zone passes through the interior of the conduit 6. The internal channel size of the conduit 6 is slightly larger than the external size of the capillary braided rope 5, so that a transport space for the liquid working fluid to flow is formed between the capillary braided rope 5 and the conduit 6. The portions of the capillary braided rope 5 located in the condensation zone and the evaporation zone extend out of the conduit 6, thereby forming a continuous liquid transport path from the condensation zone to the evaporation zone.

[0041] The conduit 6 can be either a stand-alone tubular conduit or an integrally formed closed infusion channel with the lower cover plate. Its cross-sectional shape can be circular, rectangular, semi-circular, trapezoidal, or any other shape capable of accommodating the capillary braided rope 5 and guiding the transport of condensate. In this embodiment, the conduit 6 is a cylindrical metal conduit with an outer diameter of 1.3 mm, an inner diameter of 1.1 mm, and a length of 35 mm.

[0042] The porous evaporating membrane 4 contacts the portion of the capillary braided rope 5 corresponding to the evaporation zone and also contacts the condensate return outlet of the conduit 6, allowing the working medium transported to the evaporation zone via the conduit 6 to enter the porous evaporating membrane 4. The porous evaporating membrane 4 serves to uniformly distribute the working medium within the evaporation zone and form the liquid supply interface required for vapor-liquid phase change. The working medium evaporates upon heating within the porous evaporating membrane 4 or on its surface, and the resulting vapor enters the vapor flow space within the cavity and diffuses towards the condensation zone.

[0043] The conduit 6 is used together with the capillary braided rope 5 to form a directional transport channel for condensate. The capillary braided rope 5 uses capillary action to absorb and drive the condensate backflow, and the conduit 6 provides a low-resistance flow space for condensate transport to improve the condensate transport capacity to the evaporation zone.

[0044] When the heat spreader 1 is working, an external heat source inputs heat into the evaporation zone, and the working medium in the porous evaporation membrane 4 is heated and evaporates to form steam. The steam enters the steam flow space inside the cavity and diffuses towards the condensation zone. The steam releases heat and condenses in the condensation zone to form condensate. The condensate formed in the condensation zone on the inner surface of the upper cover plate 3 falls to the lower cover plate 2 under the action of gravity, and is then collected together with the condensate formed in the condensation zone on the inner surface of the lower cover plate 2 by the capillary braided rope 5.

[0045] After being collected by the capillary braided rope 5, the condensate flows back from the condensation zone to the evaporation zone in the liquid transport path formed by the capillary braided rope 5 and the conduit 6. The working medium entering the evaporation zone is absorbed and distributed by the porous evaporation membrane 4, and evaporates again under the action of an external heat source, thus forming a vapor-liquid phase change cycle of evaporation, vapor diffusion, condensation, and condensate recirculation.

[0046] This embodiment constructs a multi-scale biomimetic liquid-absorbing core structure by drawing inspiration from the hierarchical structure of "root-xylem-leaf" in plant transpiration transport systems. The capillary braided rope 5, the vascular bundle 6, and the porous transpiration membrane 4 correspond to the transpiration interfaces of plant roots, xylem, and leaves, respectively. During operation, the liquid working medium within the porous transpiration membrane 4 continuously evaporates, creating a dynamic replenishment demand at the evaporation end. Driven by capillary action, this promotes the continuous replenishment of the upstream liquid working medium along the transport path formed by the capillary braided rope 5 and the vascular bundle 6, thereby achieving a liquid suction effect similar to that of plant transpiration. Through the synergistic effect of the aforementioned biomimetic hierarchical structure, condensate collection, low-resistance transport, and continuous liquid supply to the evaporation zone can be achieved.

[0047] It should be noted that the specific dimensions and relative positions of the evaporation zone, transport zone, and condensation zone described in the above embodiments, the number and spacing of the capillary braided ropes 5, the number and cross-sectional shape of the conduits 6, and the pore structure and area of ​​the porous evaporation membrane 4 can all be adjusted according to the specific dimensions of the heat spreader 1, the location of the heat source, the heat dissipation power, the operating temperature range, and the operating posture.

[0048] Obviously, the described embodiments are only some embodiments of this application, not all embodiments, and are not intended to limit the present invention. Those skilled in the art can modify, combine, or substitute the above structures without departing from the concept of the present invention, and such modifications, combinations, or substitutions should all fall within the protection scope of the present invention.

Claims

1. A biomimetic liquid-absorbing core structure with evaporative suction effect, characterized in that, The system includes a liquid collection unit, a transport unit, and an evaporation supply unit. The liquid collection unit includes a capillary braided rope (5) for absorbing and collecting liquid working fluid. The transport unit includes a conduit (6), and at least part of the capillary braided rope (5) passes through the internal channel of the conduit (6). The capillary braided rope (5) and the conduit (6) together form a liquid transport path from the liquid collection unit to the evaporation supply unit. The evaporation supply unit includes a porous evaporation membrane (4), which is located at the end of the liquid transport path, so that the liquid working fluid transported by the capillary braided rope (5) and the conduit (6) can enter the porous evaporation membrane (4) and form an evaporation supply interface. The capillary braided rope (5), the conduit (6), and the porous evaporation membrane (4) together form a graded liquid transport structure for liquid collection, directional transport, and evaporation supply.

2. The biomimetic liquid-absorbing core structure with evaporative suction effect according to claim 1, characterized in that, The capillary braided rope (5) is configured as multiple ropes and arranged at equal or unequal intervals in its plane; the capillary braided rope (5) is a stainless steel braided rope, copper braided rope, nickel braided rope or other metal fiber braided rope with capillary pores.

3. The biomimetic liquid-absorbing core structure with evaporative suction effect according to claim 1, characterized in that, The conduit (6) has an internal channel through which the capillary braided rope (5) passes. The cross-sectional dimension of the internal channel is larger than that of the capillary braided rope (5), so that a transport space for the flow of liquid working fluid is formed between the inner wall of the conduit (6) and the outer surface of the capillary braided rope (5).

4. The biomimetic liquid-absorbing core structure with evaporative suction effect according to claim 1, characterized in that, The porous evaporating membrane (4) has hydrophilic properties and a connected pore structure, which is used to distribute the working medium within the porous evaporating membrane (4) and provide an escape channel for the vapor.

5. The biomimetic liquid-absorbing core structure with evaporative suction effect according to claim 1, characterized in that, The porous evaporation membrane (4) is any one or more of the following: metal sintered porous membrane, metal foam porous membrane, metal wire mesh porous membrane, metal fiber porous membrane or ceramic porous membrane.

6. A heat spreader (1), characterized in that, It includes a lower cover plate (2), an upper cover plate (3), a sealed cavity formed by the lower cover plate (2) and the upper cover plate (3) sealed together, a filling port (7) communicating with the sealed cavity, a working medium filled in the sealed cavity, and a biomimetic liquid-absorbing core structure as described in any one of claims 1 to 5 disposed in the sealed cavity.

7. The heat spreader according to claim 6, characterized in that, The sealed cavity includes an evaporation zone, a transport zone, and a condensation zone; at least a portion of the capillary braided rope (5) is inserted into the internal channel of the conduit (6) and extends from the condensation zone to the evaporation zone; the capillary braided rope (5) and the conduit (6) together form a liquid transport path from the condensation zone to the evaporation zone; the porous evaporation membrane (4) is disposed in the evaporation zone and located at the end of the liquid transport path, and the liquid working fluid is transported to the evaporation zone through the capillary braided rope (5) and the conduit (6) and enters the porous evaporation membrane (4).

8. The heat spreader according to claim 7, characterized in that, The evaporation zone is located at a position corresponding to the external heat source, and the transport zone is located on at least one side of the evaporation zone and between the evaporation zone and the condensation zone; the condensation zone includes a lower condensation zone located on the inner surface of the lower cover plate (2), a lower condensation zone located on the side of the transport zone away from the evaporation zone, and an upper condensation zone located on the inner surface of the upper cover plate (3).

9. The heat spreader according to claim 6, characterized in that, The capillary braided rope (5) is disposed on the inner surface of the lower cover plate (2) and extends along the condensation zone, the transport zone and the evaporation zone.

10. The heat spreader according to claim 6, characterized in that, The evaporation zone is a recessed groove structure set on the inner surface of the lower cover plate (2), and the porous evaporation membrane (4) is set in the recessed groove structure and at least covers the projection area of ​​the external heat source on the heat spreader plate.

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