Flexible heat pipe with composite wick

Abstract

The present disclosure discloses a flexible heat pipe with a composite wick, comprising a sequentially connected evaporation section tube body, adiabatic section tube body, and condensation section tube body; wherein the evaporation section tube body, the adiabatic section tube body and the condensation section tube body are provided with a composite wick and a working fluid; the composite wick comprises mesh layers and zinc oxide / graphene composite particle layers; the composite wick of the adiabatic section tube body is provided with an elastic element; and the adiabatic section tube body is made of polyurethane material. The present disclosure effectively solves the technical problem that the heat pipe in the existing technology is a rigid structure, and a single-structure wick cannot meet the three core requirements of high capillary force, high permeability, and high thermal conductivity at the same time, resulting in limited heat-transfer performance of the heat pipe.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of electronic component heat sinks and relates to a flexible heat pipe with a composite wick.BACKGROUND

[0002] With the rapid advancement of electronics technology, electronic components are evolving toward higher integration, enhanced performance, miniaturization, and flexibility. This trend has significantly contributed to the functional enhancement and size reduction of electronic devices. However, it has also introduced unprecedented challenges to thermal management technologies. Driven by high integration and performance demands, the heat generated by electronic components during operation has increased dramatically, and the design of miniaturization and flexibility further limits the choice of heat dissipation space and heat dissipation mode. Effectively and flexibly managing this heat to ensure that electronic components operate reliably within safe temperature ranges has thus become a critical and urgent issue in the field of electronic engineering.

[0003] Against this backdrop, traditional heat pipes, as an efficient thermal management solution, are widely employed due to their superior heat-transfer performance. However, their rigid structures have become a bottleneck limiting its application in emerging fields. This is especially evident in scenarios that demand high design flexibility and spatial adaptability, such as wearable devices and flexible electronics, where the limitations of traditional heat pipes become increasingly prominent, making it difficult to meet the complex and changeable heat dissipation requirements.

[0004] Delving into the internal technology of heat pipes, the wick structure, as its core component, plays a decisive role in heat-transfer performance. An ideal wick should possess three key characteristics: High capillary pressure for rapid working fluid return, high permeability to ensure smooth fluid flow, and high thermal conductivity for efficient heat transfer. However, existing single-architecture wicks often struggle to balance these requirements. For instance, while mesh wicks can enhance heat exchange efficiency by increasing mesh density, excessively high mesh counts reduce porosity, causing the heat pipe to reach its capillary limit prematurely and compromising long-term stability. Similarly, sintered wicks composed of zinc oxide / graphene composite particles demonstrate strong capillary action and thermal conductivity, yet their unsatisfactory permeability constrains overall performance improvement. SUMMARY

[0005] In view of the problems existing in existing technology, this present disclosure provides a flexible heat pipe with a composite wick, which solves the technical problem that the heat pipe in the existing technology is a rigid structure, and a single structure wick cannot meet three core requirements of high capillary force, high permeability and high thermal conductivity at same time, resulting in limited heat-transfer performance of the heat pipe.

[0006] This present disclosure is realized by following technical schemes:

[0007] A flexible heat pipe with a composite wick, including an evaporation section tube body, an adiabatic section tube body, and a condensation section tube body connected sequentially;

[0008] the evaporation section tube body, the adiabatic section tube body, and the condensation section tube body are provided with a composite wick and a working fluid;

[0009] the composite wick includes mesh layers and zinc oxide / graphene composite particle layers;

[0010] the composite wick of the adiabatic section tube body is provided with an elastic element;

[0011] the adiabatic section tube body is made of polyurethane material.

[0012] In some embodiments, the mesh layers include fine mesh layers and coarse mesh layers; the fine mesh layer is arranged close to the zinc oxide / graphene composite particle layer.

[0013] In some embodiments, the fine mesh layer is a spiral structure.

[0014] In some embodiments, the coarse mesh layer is a diamond grid structure.

[0015] In some embodiments, a wire diameter of the fine mesh layer is 0.02-0.04 mm, and a thickness is 0.7-0.9 mm.

[0016] In some embodiments, in the fine mesh layer inside the evaporation section tube body, the adiabatic section tube body, and the condensation section tube body, a mesh number of the fine mesh decreases in turn.

[0017] In some embodiments, a thickness of the zinc oxide / graphene composite particle layer is 0.7-0.9 mm.

[0018] In some embodiments, a ratio of a filling rate of the zinc oxide / graphene composite particle layer inside the evaporation section tube body, the adiabatic section tube body, and the condensation section tube body is 80 %: 60 %: 40 %.

[0019] In some embodiments, the evaporation section tube body and the condensation section tube body are both copper tubes.

[0020] In some embodiments, the evaporation section tube body accounts for 25 %-35 % of an overall length, the adiabatic section tube body accounts for 30 %-50 % of the overall length, and the condensation section tube body accounts for 25 %-35 % of the overall length.

[0021] Compared with prior arts, the present disclosure has following beneficial technical effects:

[0022] The present disclosure discloses a flexible heat pipe with a composite wick, the wire mesh layer in the composite wick in the heat pipe generates a strong capillary force by virtue of the fine mesh, which can quickly absorb the working fluid of the condensation section and the adiabatic section back to the evaporation section, ensure continuous and efficient vaporization and heat absorption of the evaporation section, and provide sufficient power for a liquid circulation in the heat pipe. At the same time, a mesh of the mesh layer and a void structure of the zinc oxide / graphene composite particle layer give the composite wick a good permeability, which makes the working fluid flow more smoothly, and can transfer heat from the evaporation section to the condensation section in time to improve a heat transfer efficiency. The zinc oxide / graphene composite particle layer is a key to improving thermal conductivity, a high thermal conductivity of graphene combined with a good thermal conductivity of zinc oxide may quickly conduct a heat released by the condensation section, accelerate heat diffusion, and allow the heat pipe to transfer more heat under same conditions. In terms of flexibility, the adiabatic section tube body is made of polyurethane, its excellent flexibility and elasticity make the heat pipe adapt to a complex installation environment and use scenarios, and it is not easy to damage when it is deformed. Moreover, the elastic elements arranged in the composite wick of the tube body in the adiabatic section may provide a buffer and support when the heat pipe deforms, maintain a stability of the composite wick, and ensure a normal operation of the heat pipe in a flexible state. Through these innovative designs, this scheme comprehensively realizes high capillary force, high permeability, high thermal conductivity, and flexibility, along with significantly improving the heat-transfer performance of heat pipes.

[0023] In some embodiments, the mesh layer includes the fine mesh layer and the coarse mesh layer; the fine mesh layer is arranged close to the zinc oxide / graphene composite particle layer, and the mesh layer is provided with the fine mesh layer and the coarse mesh layer, along with the fine mesh layer is close to the zinc oxide / graphene composite particle layer. This layered design may give full play to characteristics of different mesh layers. The proximity of the fine mesh layer to the composite particle layer enables synergistic capillary action, effectively drawing the working fluid back. Meanwhile, the coarse mesh layer provides enlarged flow channels, ensuring adequate permeability, this configuration allows a fluid to circulate rapidly within the wick while maintaining efficient adsorption, thereby enhancing an overall heat-transfer performance of the heat pipe.

[0024] In some embodiments, the fine mesh layer is a spiral structure, this structure increases a contact area and contact path between the fine mesh layer and the working fluid. Under capillary action, the structure may more fully adsorb the working fluid, thereby enhancing capillary pressure. Concurrently, the spiral structure strengthens a guidance of the liquid, promoting smoother flow within the wick and further improving a internal fluid circulation efficiency of the heat pipe.

[0025] In some embodiments, the coarse mesh layer is a diamond grid structure, this structure has high strength and stability, and can withstand certain pressure and deformation to ensure an integrity of the wick structure. Moreover, a gap distribution of the diamond grid is uniform, which is beneficial to a uniform infiltration and flow of the working fluid, improves a permeability of the wick, and ensures that the heat pipe may work stably under different working conditions.

[0026] In some embodiments, the wire diameter of the fine mesh layer is 0.02-0.04 mm, and the thickness is 0.7-0.9 mm, a finer wire diameter can increase a mesh density and improve the capillary force; a appropriate thickness nay not only ensure that the fine mesh layer has sufficient strength, but also control an overall thickness of the wick, so that the heat pipe may achieve efficient liquid adsorption and conduction in a limited space, and improve heat-transfer performance.

[0027] In some embodiments, within the fine mesh layers of the evaporation section tube body, the adiabatic section tube body and the condensation section tube body, the mesh number decreases in turn, the evaporation section needs high capillary force to absorb liquid quickly, and a high-mesh fine mesh can meet a demand; the adiabatic section mainly plays a transitional role, and an appropriate mesh number ensures a liquid flow; several condensation section is smallest, which is conducive to a smooth flow of liquid, this design optimizes a circulation process of liquid in the heat pipe and improves the heat transfer efficiency.

[0028] In some embodiments, the thickness of the zinc oxide / graphene composite particle layer is 0.7-0.9 mm, this thickness may not only ensure that the composite particle layer has sufficient amount to give full play to its high thermal conductivity and fast heat conduction, but also avoid a increase of liquid flow resistance caused by excessive thickness, affecting the permeability, achieving a good balance between thermal conductivity and permeability, and improving a comprehensive performance of the heat pipe.

[0029] In some embodiments, the filling ratio of the zinc oxide / graphene composite particle layer inside the evaporation section tube body, the adiabatic section tube body and the condensation section tube body is 80 %: 60 %: 40 %; a high fill ratio in the evaporation section enables rapid absorption and conduction of heat generated during evaporation; a moderate fill ratio in the adiabatic section minimizes heat loss while maintaining fluid flow; and a low fill ratio in the condensation section facilitates heat dissipation and liquid outflow, this configuration optimizes heat transfer and fluid circulation across each section of the heat pipe, thereby enhancing overall thermal efficiency.

[0030] In some embodiments, the evaporation section tube body and the condensation section tube body are both copper tubes. Copper offers excellent thermal conductivity, enabling rapid heat transfer to or from the wick, thereby minimizing heat accumulation and loss in a tube wall and improving the heat transfer efficiency of the heat pipe. Additionally, copper tubing exhibits favorable mechanical strength and corrosion resistance, ensuring a reliability and service life of the heat pipe.

[0031] In some embodiments, the evaporation section tube body accounts for 25 %-35 % of the overall length, the adiabatic section tube body accounts for 30 %-50 % of the overall length, and the condensation section tube body accounts for 25 %-35 % of the overall length. This proportional design allows each section of the heat pipe to function optimally. The evaporation section provides sufficient length for effective heat absorption, the adiabatic section efficiently minimizes heat dissipation, and the condensation section ensures adequate heat release, rationally balanced lengths of these sections optimize both heat transfer and fluid circulation within the heat pipe, thereby enhancing its overall heat-transfer performance and operational stability.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly explain the technical scheme of the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present disclosure, so they should not be regarded as limiting the scope. Ordinary technicians in this field, can also obtain other relevant drawings based on these drawings without paying for creative work.

[0033] FIG. 1 is an axial cross-sectional view of a flexible heat pipe with a composite wick according to the present disclosure in a bent state;

[0034] FIG. 2 is a radial cross-sectional view of the flexible heat pipe with a composite wick according to the present disclosure;

[0035] FIG. 3 is an axial cross-sectional view of the flexible heat pipe with a composite wick according to the present disclosure in an extended state;

[0036] FIG. 4 is a schematic structural diagram of the flexible heat pipe with a composite wick bent at 135° according to the present disclosure;

[0037] FIG. 5 is a schematic structural diagram of the flexible heat pipe with a composite wick bent at 180° according to the present disclosure.

[0038] Where: 1, evaporation section tube body, 11, zinc oxide / graphene composite particle layer of the evaporation section, 12, fine mesh layer of the evaporation section, 13, coarse mesh layer of the evaporation section, 2, adiabatic section tube body, 21, zinc oxide / graphene composite particle layer of the adiabatic section, 22, fine mesh layer of the adiabatic section, 23, coarse mesh layer of the adiabatic section, 24, elastic element, 3, condensation section tube body, 31, zinc oxide / graphene composite particle layer of the condensation section, 32, fine mesh layer of the condensation section, 33, coarse mesh layer of the condensation section, 4, vapor channel.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] To provide a clearer understanding of the objectives, technical solutions, and advantages of the embodiments of the present disclosure, the technical solutions in the embodiments of the present disclosure will be described clearly and comprehensively below in conjunction with the accompanying drawings. It should be noted that the described embodiments are only a part of the embodiments of the present disclosure, rather than all of them. Generally, the components of the embodiments of the present disclosure illustrated and described in the accompanying drawings may be arranged and designed in various configurations.

[0040] Therefore, the detailed descriptions of the embodiments of the present disclosure provided in the accompanying drawings are not intended to limit the scope of the claimed present disclosure, but merely represent selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort shall fall within the scope of protection of the present disclosure.

[0041] It should be noted that similar reference numerals and letters in the accompanying drawings denote like items. Therefore, once an item is defined in one drawing, it may not require further definition and explanation in subsequent drawings.

[0042] In the description of the embodiments of the present disclosure, it should be clarified that terms such as “upper,”“lower,”“horizontal,” or “inner,” when used to indicate orientations or positional relationships, refer to those based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships conventionally assumed when the product of the present disclosure is in use. These terms are used merely for convenience in describing the present disclosure and simplifying the description, and do not indicate or imply that the referred apparatus or components must have specific orientations or be constructed and operated in specific orientations. Therefore, they should not be construed as limitations to the present disclosure. Furthermore, terms such as “first,”“second,” etc., are used solely for distinguishing descriptions and should not be interpreted as indicating or implying relative importance.

[0043] In addition, when the term “horizontal” is used, it does not imply that the component must be absolutely level, but rather allows for slight inclines. For instance, the term “horizontal” may refer to a substantially horizontal orientation that is acceptable within practical tolerances.

[0044] In the description of the embodiments of the present disclosure, it should also be noted that, unless otherwise explicitly specified or limited, terms such as “set,”“install,”“connect,” or “link” should be interpreted broadly. For example, a connection may be fixed, detachable, or integral; it may be a mechanical connection, an electrical connection, or a direct connection; it may also be an indirect connection achieved through an intermediary, or an internal communication between two components. Those skilled in the art can understand the specific meanings of these terms in the context of the present disclosure based on actual circumstances.

[0045] The following is a further detailed description of the present disclosure in combination with the drawings:

[0046] As shown in FIG. 1, the present disclosure discloses a flexible heat pipe with a composite wick, including an evaporation section tube body 1, an adiabatic section tube body 2, and a condensation section tube body 3 connected sequentially to work together to achieve efficient heat conduction. The inside of the evaporation section tube body 1, the adiabatic section tube body 2, and the condensation section tube body 3 are provided with a composite wick and a working fluid; the composite wick and working fluid are the core components of the heat pipe to achieve rapid liquid absorption and heat transfer. The composite wick includes a mesh layer and a zinc oxide / graphene composite particle layer, the mesh layer provides good support and liquid distribution channels, and the zinc oxide / graphene composite particle layer greatly improves the performance of the heat pipe by virtue of its excellent thermal conductivity and capillary performance.

[0047] In particular, in the composite wick of the adiabatic section tube body 2, an elastic element 24 is arranged, this design makes the adiabatic section have excellent flexibility while maintaining a certain structural strength, and may adapt to various complex bending and deformation scenarios, this design greatly expands the application range of the heat pipe.

[0048] The center position of the evaporation section tube body 1, the adiabatic section tube body 2, and the condensation section tube body 3 is the vapor channel 4. The vapor channel 4 provides an unimpeded path for the rapid flow of vapor. During the operation of the heat pipe, the vapor generated by the evaporation section can quickly migrate through the channel to the condensation section to achieve efficient heat transfer. At the same time, the reasonable layout of vapor channel 4 may also effectively reduce the resistance of vapor flow, reduce energy loss, further improve the overall heat-transfer performance of the heat pipe, and ensure that the heat pipe can operate stably and efficiently under various working conditions.

[0049] For the material of the tube body, the adiabatic section tube body 2 is made of a polyurethane material, that is, PU material. This material has excellent adiabatic performance, which can effectively block the transfer of heat, ensure that the heat in the adiabatic section will not be easily lost or entered, maintain the directional flow of heat inside the heat pipe, and provide a stable adiabatic environment for the efficient operation of the heat pipe. The evaporation section tube body 1 and the condensation section tube body 3 are both copper tubes. Furthermore, the evaporation section tube body 1 and the condensation section tube body 3 are all copper tubes, and copper itself possesses high thermal conductivity, enabling rapid heat transfer to meet the requirements for fast heat absorption in the evaporation section and efficient heat dissipation in the condensation section. The structure of the copper circular tube not only has excellent performance in heat transfer efficiency, but also realizes the ingenious combination of rigid-flexible-rigid materials from the perspective of the overall structure. The flexible PU material of the adiabatic section gives the heat pipe a certain bending deformation ability, which can adapt to different installation scenarios; the rigid copper tubes at the evaporation and condensation sections ensure the structural stability and reliability of the heat pipe at these critical heat transfer points. The installation of the composite wick within the tube is also vital. The composite wick is tightly fitted against and fixed to the inner wall of the tube, forming an interference fit, this connection method ensures full contact between the composite wick and the tube wall, enabling efficient liquid transport. Furthermore, welding both ends of the composite wick enhances its bond strength with the tube body, this prevents loosening or detachment during the heat pipe’s operation, ensuring long-term and stable performance.

[0050] The outer diameter of the evaporation section tube body 1, the adiabatic section tube body 2, and the condensation section tube body 3 is 5-7 mm, this thickness design not only ensures that the heat pipe has a certain structural strength, may withstand a certain external force without damage, but also does not increase unnecessary weight and cost due to excessive thickness. At the same time, the thickness of the tube wall is 0.2-0.3 mm, the thinner tube wall is conducive to the rapid transfer of heat and reduces the thermal resistance, so that the evaporation section may absorb heat more efficiently, and the condensation section may release heat more quickly, thereby improving the overall heat-transfer performance of the heat pipe.

[0051] In the preparation process of the composite wick, the mesh layer and the zinc oxide / graphene composite particle layer are tightly bonded by sintering. The sintering process plays a key role in the performance of the heat pipe, after a lot of experiments and optimization, the sintering temperature is accurately controlled at 800-900° C. In this temperature range, the two materials can achieve good atomic diffusion and combine to form a solid connection. At the same time, the holding time is set to 0.5-1 h, this duration ensures that the sintering reaction proceeds sufficiently to achieve the desired strength and performance at the bonding interface, while preventing material degradation caused by excessive sintering, this guarantees that the composite absorbent core possesses excellent liquid absorption and heat transfer capabilities.

[0052] To further improve the performance of the composite wick, the composite wick is treated with a mixed solution of NaOH and K2S2O8 for hydrophilic treatment, NaOH is used as a strong alkali to adjust the pH of the solution and provide a suitable environment for the chemical reaction; K2S2O8 has strong oxidizability and can undergo redox reaction with the surface material of the composite wick in the mixed solution. By precisely controlling the parameters such as the concentration of the mixed solution, the treatment temperature, and the treatment time, a large number of hydrophilic groups are formed on the surface of the composite wick, significantly enhancing the hydrophilicity of the composite wick. After this treatment, the composite wick may more efficiently adsorb working fluid, thereby improving the overall heat transfer efficiency and stability of the heat pipe.

[0053] In the fine design of the composite wick, in order to give full play to the performance advantages of each layer structure, a more optimized layout is carried out. Where the zinc oxide / graphene composite particle layer is specially arranged near the evaporation section tube body 1, the adiabatic section tube body 2, and the condensation section tube body 3. Such a layout allows the zinc oxide / graphene composite particle layer to interact more directly with the working fluid and vapor in the tube, and use its excellent thermal conductivity and capillary performance to quickly transfer the heat generated in the evaporation section. At the same time, it accelerates the condensation of vapor in the condensation section and improves the overall heat transfer efficiency of the heat pipe. Moreover, the mesh layer and the zinc oxide / graphene composite particle layer are coaxially arranged. This coaxial structure ensures the uniformity of the distribution of the composite wick inside the tube, makes the flow of the working fluid in the tube smoother, reduces the local resistance caused by the uneven structure, and further optimizes the heat-transfer performance of the heat pipe. For the zinc oxide / graphene composite particle layer, the particle size is strictly controlled at 75-95 nm, the particles in this particle size range have a large specific surface area, which can fully contact with the working fluid and enhance the liquid absorption effect. At the same time, the thickness of the composite particle layer is set to 0.7-0.9 mm, this thickness not only ensures that there are enough particles to play the role of liquid absorption and heat transfer, but also does not increase the flow resistance inside the heat pipe due to excessive thickness, it ensures that the heat pipe may maintain a stable operating state while maintaining efficient heat transfer and adapt to various complex working environments.

[0054] In the design of the evaporation section tube body 1, the adiabatic section tube body 2, and the condensation section tube body 3, the filling rate of the internal zinc oxide / graphene composite particle layer is accurately considered and set, the evaporation section: adiabatic section: condensation section = 80 %: 60 %: 40 %. That is, in the evaporation section, the filling rate of zinc oxide / graphene composite particles in the composite particle layer is 80 %, in the adiabatic section, the filling rate of zinc oxide / graphene composite particles in the composite particle layer is 60 %, and in the condensation section, the filling rate of zinc oxide / graphene composite particles in the composite particle layer is 40 %. As the key area for heat absorption, the higher 80 % filling rate in the evaporation section ensures sufficient contact between the composite particles and the working fluid, enabling rapid heat absorption and promoting vaporization. The filling rate of the adiabatic section is 60 %, which takes into account the adiabatic demand while maintaining a certain heat-transfer capacity. The filling rate of 40 % in the condensation section is conducive to the full condensation of vapor, and the reasonable distribution of the filling ratio may improve the overall heat transfer efficiency and stability of the heat pipe.

[0055] In the design of the composite wick of the flexible heat pipe, the mesh layer occupies a crucial position. Its unique layered and structural design provides a solid guarantee for the efficient operation of the heat pipe. The mesh layer is not a single structure. It is preferably composed of a fine mesh layer and a coarse mesh layer. Moreover, in the layout, the fine mesh layer is arranged close to the zinc oxide / graphene composite particle layer. Specifically, along the diameter direction of the flexible heat pipe, the zinc oxide / graphene composite particle layer, the fine mesh layer, and the coarse mesh layer are arranged in turn from the outside to the inside.

[0056] As a part closely adjacent to the zinc oxide / graphene composite particle layer, the fine mesh layer adopts a spiral structure. It is further preferred that the fine mesh layer is woven with double-layer copper spiral mesh. Copper itself has good thermal conductivity and flexibility, the weaving method of double-layer spiral mesh makes the fine mesh layer not only have a large specific surface area, but also can fully contact with the surrounding working fluid, which greatly enhances the capillary performance. The spiral structure also gives it a certain elasticity, when the heat pipe is bent and deformed, it can better adapt to the shape change and ensure the stability of the structure and the integrity of the function. At the same time, the wire diameter of the fine mesh layer is preferably 0.02-0.04 mm, such a fine wire diameter makes the mesh more fine and further improves the adsorption and transmission capacity of the working fluid, the thickness is set to 0.7-0.9 mm, the flow resistance inside the heat pipe will not be increased due to excessive thickness while ensuring sufficient liquid absorption effect.

[0057] The coarse mesh layer adopts a diamond grid structure, which plays a key supporting role in the heat pipe. In the working process of the heat pipe, the interior will bear a certain pressure and vapor impact, the diamond grid structure can effectively disperse these forces by virtue of its strong frame and reasonable mechanical distribution, maintain the overall shape and stability of the mesh layer, and prevent structural deformation or damage caused by external forces, to ensure that the composite wick can continuously and stably play the function of liquid absorption and heat transfer. Moreover, the diamond grid structure also provides a certain channel for the flow of the working fluid in the heat pipe, which is helpful for the circulation of the working medium and the transfer of heat.

[0058] The design of the mesh layer, combining the fine mesh layer and the coarse mesh layer, cooperates with the zinc oxide / graphene composite particle layer to form an organic whole. The zinc oxide / graphene composite particle layer quickly absorbs the heat of the evaporation section and promotes the vaporization of the liquid due to its excellent thermal conductivity and capillary properties; the fine mesh layer is like an efficient “liquid carrier”, which replenishes the vaporized working fluid to the evaporation section in time, and transports the condensed working fluid back to the place where it is needed; the coarse mesh layer provides a stable support for the whole structure to ensure that the heat pipe can operate normally under various working conditions. The three complement each other and jointly improve the heat transfer efficiency and stability of the flexible heat pipe, making it have broad application prospects in many fields such as heat dissipation of electronic equipment and thermal control of aerospace.

[0059] In the fine mesh layer inside the evaporation section tube body 1, the adiabatic section tube body 2, and the condensation section tube body 3, the mesh number of the fine mesh decreases in turn.

[0060] In a specific embodiment, as shown in FIGS. 2 and 3, in the interior of the evaporation section tube body 1, the zinc oxide / graphene composite particle layer of the evaporation section 11, the fine mesh layer of the evaporation section 12 and the coarse mesh layer of the evaporation section 13 are arranged from the outside to the inside along its radial direction; in the interior of the adiabatic section tube body 2, the zinc oxide / graphene composite particle layer of the adiabatic section 21, the fine mesh layer of the adiabatic section 22 and the coarse mesh layer of the adiabatic section 23 are arranged from the outside to the inside along the radial direction; in the interior of the condensation section tube body 3, the zinc oxide / graphene composite particle layer of the condensation section 31, the fine mesh layer of the condensation section 32 and the coarse mesh layer of the condensation section 33 are arranged from the outside to the inside along its radial direction.

[0061] In some embodiments, the mesh number of the fine mesh layer of the evaporation section 12, the fine mesh layer of the adiabatic section 22, and the fine mesh layer of the condensation section 32 are 300-400 mesh, 150-200 mesh, and 90-180 mesh, respectively.

[0062] The fine mesh layer of the evaporation section 12 adopts a fine mesh of 300-400 mesh, the higher mesh count results in finer pores, which can greatly enhance the adsorption capacity of the working fluid, quickly replenish the liquid to the evaporation area, and meet the demand for a large number of endothermic vaporization in the evaporation section. The fine mesh layer of the adiabatic section 22 adopts a fine mesh of 150-200 mesh, while ensuring a certain capillary performance. Appropriately reducing the mesh number may reduce the obstruction to the vapor flow and adapt to the relatively stable working medium state of the adiabatic section. The fine mesh layer of the condensation section 32 adopts a fine mesh of 90-180 mesh, the lower mesh number helps the vapor to diffuse and condense smoothly. At the same time, its structure may also provide a suitable reflux channel for the condensed liquid, ensuring the smooth circulation of the working fluid in the heat pipe and improving the overall heat transfer efficiency.

[0063] For the length of each tube body, the evaporation section tube body 1 accounts for 25 %-35 % of the overall length. This ratio makes the evaporation section have enough space to fully absorb the external heat, promote the rapid vaporization of the working fluid, and provide a sufficient power source for the heat transfer of the heat pipe. The adiabatic section tube body 2 accounts for 30 %-50 % of the overall length, the larger proportion range may better adapt to different working environments and heat pipe layout requirements, its main role is to reduce the loss of heat in the transfer process and ensure that the vapor reaches the condensation section with higher temperature and energy. The condensation section tube body 3 accounts for 25 %-35 % of the overall length. This length setting allows the vapor to condense sufficiently, releases the heat effectively, completes the heat transfer cycle of the heat pipe, and ensures the stability and efficiency of the overall performance of the heat pipe.

[0064] In some embodiments, the elastic element 24 can be a spring, and the spring can be used as a support structure to provide a stable and reliable support force for the adiabatic section tube body 2, ensuring that it maintains a certain shape and structural stability during the working process, and preventing excessive deformation due to external force or internal pressure changes. At the same time, the spring itself has good elasticity, which makes the adiabatic section tube body 2 have excellent flexibility while maintaining support. As shown in FIGS. 4 and 5, the heat pipes can be easily bent and twisted to adapt to various complex installation environments and usage scenarios, demonstrating excellent flexibility that significantly expands their application scope and practicality.

[0065] In order to ensure the stability and reliability of the flexible heat pipe during operation, the sealing device consists of a sealing ring and a clamp, which work together synergistically. Leveraging its excellent elasticity and sealing properties, the sealing ring is precisely installed at the interface, effectively filling microscopic gaps and preventing leakage of the internal working fluid. The clamp plays a crucial role in securing the sealing ring, after tightly fastening it around the interface, a bonding process is applied to further reinforce the fixation, ensuring comprehensive sealing at all tube body connections and preventing any potential leakage issues.

[0066] In addition, the interior of the flexible heat pipe is designed as a vacuum environment, and the vacuum degree in the cavity is 1×10-3-1×10-5Pa. Under such high vacuum conditions, the chamber contains virtually no air or other non-condensable gases, significantly reducing resistance to vapor flow and enabling smoother vapor circulation within the heat pipe. Simultaneously, this minimizes heat loss from convective heat transfer, allowing heat to be transferred more intensely and rapidly from the evaporation section to the condensation section. Consequently, the overall heat transfer efficiency and performance stability of the flexible heat pipe are markedly enhanced.

[0067] In addition, the working fluid in the present disclosure is one or more of deionized water, anhydrous ethanol, or methanol.

[0068] The preparation method of zinc oxide / graphene composite particles in the present disclosure is as follows:

[0069] 1, Graphene oxide is dissolved in ethylene glycol and treated with ultrasonication to obtain a brown dispersion; zinc acetate is dissolved in ethylene glycol and stirred magnetically until completely dissolved.

[0070] 2, The zinc acetate solution is added to the brown dispersion of graphene oxide, stirred magnetically, and mixed evenly.

[0071] 3, NaOH is weighed, added to the mixture, and stirred continuously for 30 min to obtain the growth solution.

[0072] 4, Finally, the mixture is transferred to a high-pressure reactor and placed in a blast drying oven, the reaction temperature is 160° C., and the reaction time is 24 h.

[0073] 5, The obtained composite material is centrifuged at 4000 rpm for 10 min;

[0074] 6, anhydrous ethanol is added for dissolution, followed by centrifugal washing, this process is repeated three times. Subsequently, the product is washed with deionized water, centrifuged again, and finally dried for storage.

[0075] 7, The required zinc oxide / graphene composite particles are screened out.

[0076] The preparation method of the composite wick in the present disclosure is:

[0077] 1, The CAD drawing software is used to draw the double-layer mesh wick, the diamond-shaped coarse mesh, that is, the coarse mesh layer, which plays a supporting role in the innermost part; the spiral fine mesh, that is, the fine mesh layer, is arranged on the outer layer of the diamond coarse mesh.

[0078] 2, The three-dimensional structure is sent into the 3D printing system to obtain the mesh structure layer.

[0079] 3, The graphite mold is customized according to the design of the wick, the zinc oxide / graphene composite particles are tiled in the graphite mold, and then the mesh layer is placed in the graphite mold. The filled mold is sent into a furnace with protective gas for high-temperature sintering. The protective gases are nitrogen and argon. When the temperature in the sintering chamber rises to 200-250° C., hydrogen is introduced into the furnace, so that the pressure in the furnace reaches 45-50 Pa. Continue to heat up to 800-950° C., and the heating rate is controlled at 7-8° C. / min. Keep sintering for 6-8 h, so that the zinc oxide / graphene composite particle layer and the screen layer are fully sintered to form a solid connection.

[0080] 4, The sintered wick was placed in an ultrasonic cleaner, using ethanol as the cleaning liquid, and ultrasonic cleaning for 10 min; subsequently, it was transferred to deionized water and ultrasonically cleaned again for 10 min. After cleaning, the wick was taken out and put into the drying box, and dried for 1-2 h at a temperature of about 60° C. to ensure complete drying.

[0081] 5, The hydrophilic treatment of the wick is carried out, the ratio of potassium persulfate to sodium hydroxide is 1:1.5, 15 g of potassium persulfate and 25 g of sodium hydroxide are taken, dissolved in 500 mL of deionized water, and stirred evenly to prepare an alkaline etching solution. The wick is placed in the liquid for uniform corrosion for 10 min and then taken out and placed in anhydrous ethanol for ultrasonic cleaning. Embodiment 2

[0082] Through this embodiment, the preparation method of a flexible heat pipe with a composite wick in the present disclosure is described, which includes the following steps: 1, Preparation and cleaning of tubes

[0083] First, two copper tubes with a length of 120 mm are carefully prepared for the evaporation section, and the condensation section, and a PU tube with a length of 180 mm is prepared as the adiabatic section. The dimensional accuracy of these tubes needs to be strictly controlled to ensure the stability of subsequent assembly and performance. Then, the inside of the pipe is thoroughly cleaned, and the appropriate cleaning agent and cleaning process are adopted to completely remove impurities such as oil and dust. Because the cleanliness of the inner wall of the shell directly affects the heat transfer efficiency and reliability of the heat pipe, any small impurity may hinder the flow of the working medium and the transfer of heat, so this step is very important.2, Interface welding

[0084] The evaporation section tube body 1, the adiabatic section tube body 2, and the condensation section tube body 3 of the clean heat pipe are carefully aligned to ensure the sealing and coaxiality at the interface. Then, professional welding techniques, such as argon arc welding, are used to firmly weld the interfaces together. In the welding process, the welding parameters, such as welding current, voltage, and welding speed, should be strictly controlled to ensure the welding quality and avoid welding defects, such as pores and cracks.3, Installation of composite wick

[0085] The composite wick is carefully placed inside the welded shell, and a special tool is used to assist the installation to ensure that the composite wick can be evenly covered on the inner wall of the shell. The uniform distribution of the composite wick plays a key role in the uniform distribution of the working fluid and the uniform heat transfer in the heat pipe.4, Welding at both ends of the wick

[0086] After the composite wick is closely attached to the inner wall of the shell, the two ends are welded to further fix the position of the composite wick to prevent its movement or deformation during subsequent operation and use.5, Install the memory alloy spring

[0087] The shape memory alloy spring is wrapped and compressed by a cladding at a temperature higher than the austenite phase transition end temperature of the spring, so that the outer diameter of the spring is less than the inner diameter of the wick by 2-2.5 mm. After that, the compression spring wrapped by the cladding is carefully placed in the adiabatic section cavity of the wick.6, Spring contact recovery

[0088] The shell is pulled out, and the compressed spring is restored to contact with the inner wall of the wick under the action of its own elasticity, providing the necessary support and elasticity for the heat pipe.7, Vacuum pumping and filling medium

[0089] The heat pipe is vacuumized to remove non-condensable gases such as air in the pipe and reduce the resistance of vapor flow. Then, the working fluid is inhaled into the syringe and introduced into the flexible heat pipe through a specific device.8, Seal sealing

[0090] After the filling process is completed, the flexible heat pipe is initially sealed by cold welding to prevent the leakage of the working fluid. Finally, the secondary sealing is carried out by argon arc welding to ensure that the sealing of the flexible heat pipe is strict and reliable, and the whole preparation process is completed.

[0091] The present disclosure focuses on flexible heat pipe technology and significantly improves the performance of heat pipes through innovative design. In terms of composite materials, the synergistic effect of graphene and zinc oxide has brought many advantages. The high thermal conductivity of graphene is combined with zinc oxide, which greatly improves the thermal conductivity of the composite material and meets the heat dissipation demand of high heat flux density; its high specific surface area and adjustable porosity endow the composite particles with excellent capillary performance, enhance the adsorption and transmission capacity of working fluid, and optimize the capillary driving force of heat pipe; the high strength and flexibility are combined with the chemical stability of zinc oxide, so that the composite particles remain stable under mechanical stress and complex working conditions, along with the service life of the heat pipe is prolonged.

[0092] The composite wick is the core highlight of the present disclosure. It adopts a unique design that combines segmented wire mesh with zinc oxide / graphene composite particles. In view of the different effects of the three sections of the heat pipe, the wire mesh is changed, the fine wire mesh and the high filling rate composite particles form a high density capillary core, which overcomes the high evaporation rate demand in the evaporation section and inhibits the liquid film fracture; the coarse wire mesh and the low filling rate composite particles form a low resistance transmission channel to avoid the blockage of the flow channel, and the high thermal conductivity of the composite particles strengthens the radial heat conduction, reduces the thermal resistance from the evaporation section to the condensation section, improves the circulation speed of the working fluid, and improves the heat-transfer performance.

[0093] The double-layer mesh structure in the composite wick effectively suppresses the gas-liquid interference problem in the flexible deformation process through the hierarchical pore design. During repeated bending of the flexible heat pipe, the vapor generated in the evaporation section tends to infiltrated into the wick due to the deformation of the flow channel and interferes with the liquid reflux, the small pore size characteristics of the outer fine mesh, like the “gas-liquid barrier”, may prevent the vapor from invading the inner liquid storage space in the opposite direction. At the same time, the large pores of the inner coarse mesh provide a low-resistance rising path for the vapor, forming a mechanism of gas-liquid separation flow, ensuring that the vapor is rapidly discharged along the axial direction and the liquid flows back stably through the double-layer mesh during dynamic deformation, thereby reducing the decrease of heat transfer efficiency caused by gas-liquid mixing.

[0094] The surface of the composite wick is chemically etched to form a microscopic rough structure on its surface for hydrophilic treatment, this treatment improves the capillary force through the synergistic effect of the nano-scale rough structure and the hydrophilic group, so that the transmission resistance of the working fluid in the pore of the wick is reduced, the accelerated spreading speed of the liquid film in the evaporation section effectively suppresses localized drying, maintaining stable working fluid circulation.

[0095] In addition, the shell in this present disclosure uses a rigid-flexible-rigid structure, and a support device is designed in the flexible part. The rigid structure provides a stable mechanical connection interface to ensure that the shell maintains the port shape accuracy when subjected to external loads, and avoids interface leakage or poor contact caused by flexible deformation. The support structure inside the flexible part may provide reverse support force when the flexible section deforms, so that it can better resist internal fluid pressure or external extrusion pressure, limit the wrinkle or collapse of the pipe wall caused by excessive bending, and maintain the patency of the pipe and the integrity of the structure. This structure is especially suitable for heat dissipation of electronic devices with complex shapes or narrow spaces, and may effectively fit the surface of electronic devices with complex shapes.

[0096] In summary, this invention achieves breakthroughs in multiple key components and performance aspects. In terms of composite materials, graphene and zinc oxide synergistically improve thermal conductivity, capillary performance, and structural stability. The composite wick has a unique structure, and the segmented wire mesh is combined with the composite particles to meet the needs of different stages of the heat pipe; the double-layer mesh solves the problem of gas-liquid interference; surface hydrophilic treatment reduces the transmission resistance of the working fluid. The shell adopts a rigid-flexible-rigid structure, and the flexible part has a support device to ensure a stable mechanical connection, resist internal and external pressure, and keep the pipeline unobstructed. These innovative designs significantly enhance the thermal performance, structural stability, and adaptability of flexible heat pipes, offering more effective solutions for heat dissipation in complex-shaped or confined-space electronic devices, they are expected to advance heat dissipation technology in related fields.

[0097] The above description is merely illustrative of preferred embodiments of the present invention and is not intended to limit the disclosure. For those skilled in the art, the present disclosure may be subject to various modifications and changes. Any modifications, equivalent substitutions, improvements, and the like made within the spirit and principles of the present disclosure shall fall within the scope of protection of the present disclosure.

Claims

1. A flexible heat pipe with a composite wick, comprising a sequentially connected evaporation section tube body (1), adiabatic section tube body (2), and condensation section tube body (3), wherein: the evaporation section tube body (1), the adiabatic section tube body (2), and the condensation section tube body (3) are provided with a composite wick and a working fluid;the composite wick comprises mesh layers and zinc oxide / graphene composite particle layers;the composite wick of the adiabatic section tube body (2) is provided with an elastic element (24); and,the adiabatic section tube body (2) is made of polyurethane material.

2. The flexible heat pipe with the composite wick according to claim 1, wherein the mesh layers comprise fine mesh layers and coarse mesh layers; and the fine mesh layer is arranged close to the zinc oxide / graphene composite particle layer.

3. The flexible heat pipe with the composite wick according to claim 2, wherein the fine mesh layer is a spiral structure.

4. The flexible heat pipe with the composite wick according to claim 2, wherein the coarse mesh layer is a diamond grid structure.

5. The flexible heat pipe with the composite wick according to claim 2, wherein a wire diameter of the fine mesh layer is 0.02-0.04 mm, and a thickness is 0.7-0.9 mm.

6. The flexible heat pipe with the composite wick according to claim 2, wherein in the fine mesh layer inside the evaporation section tube body (1), the adiabatic section tube body (2), and the condensation section tube body (3), a mesh number of the fine mesh decreases in turn.

7. The flexible heat pipe with the composite wick according to claim 1, wherein a thickness of the zinc oxide / graphene composite particle layer is 0.7-0.9 mm.

8. The flexible heat pipe with the composite wick according to claim 1, wherein a ratio of a filling rate of the zinc oxide / graphene composite particle layer inside the evaporation section tube body (1), the adiabatic section tube body (2), and the condensation section tube body (3) is 80 %: 60 %: 40 %.

9. The flexible heat pipe with the composite wick according to claim 1, wherein the evaporation section tube body (1) and the condensation section tube body (3) are both copper tubes.

10. The flexible heat pipe with the composite wick according to claim 1, wherein the evaporation section tube body (1) accounts for 25 %-35 % of an overall length, the adiabatic section tube body (2) accounts for 30 %-50 % of the overall length, and the condensation section tube body (3) accounts for 25 %-35 % of the overall length.

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