Vapor chamber and design method thereof
By designing directionally supported capillary walls and capillary structures in the heat spreader, the problem of low heat dissipation efficiency caused by concentrated distribution of capillary structures is solved, achieving a larger effective capillary volume and higher heat transfer capacity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHIYUE STAR (SHANGHAI) INTELLIGENT TERMINAL CO LTD
- Filing Date
- 2026-02-11
- Publication Date
- 2026-05-15
AI Technical Summary
The existing heat spreader's capillary structure is concentrated at the evaporation end, which affects heat dissipation efficiency and results in low heat transfer capacity.
Design a heat spreader comprising a shell, a heat-conducting cavity, a capillary wall, and a capillary structure. The capillary wall has mounting holes, and the capillary structure extends from the heat-absorbing end to the heat-dissipating end. It forms a directional support structure through the combination of curved and planar walls of the capillary wall to prevent the capillary structure from collapsing and increase the effective capillary volume.
The heat transfer capacity of the heat spreader is improved, the capillary structure can fill a larger area of the heat conduction cavity, the capillary force is increased by more than 60%, the temperature difference is reduced, and the heat transfer efficiency is significantly improved.
Smart Images
Figure CN122054526A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of heat dissipation structure technology, and in particular to a heat spreader and its design method. Background Technology
[0002] In related technologies, vapor chambers typically incorporate capillary structures with numerous micropores. The capillary force provided by these micropores promotes the recirculation of the condensed heat transfer medium (such as pure water) from the condenser end to the evaporator end, allowing the heat transfer medium to circulate between them and achieve heat dissipation. However, these capillary structures are usually made of copper mesh or sintered copper powder. During use, these structures are prone to collapse and concentrate at the evaporator end, resulting in a small effective volume and ineffective absorption of the condensed heat transfer medium, leading to low heat dissipation efficiency. Summary of the Invention
[0003] This invention provides a heat spreader and its design method to solve the problem in the prior art where the capillary structure of the heat spreader is concentrated at the evaporation end, affecting the heat dissipation efficiency.
[0004] In a first aspect, the present invention provides a heat spreader, comprising: The housing has a heat-absorbing end and a heat-dissipating end arranged opposite to each other along a first direction, and a heat-conducting cavity is provided between the heat-absorbing end and the heat-dissipating end; the heat-absorbing end is used to connect to a heat source, and the heat-dissipating end is used to dissipate heat; the heat-conducting cavity is filled with a heat transfer medium. At least one capillary wall is disposed in the heat-conducting cavity, and the capillary wall is provided with mounting holes; The capillary structure extends from the heat-absorbing end to the heat-dissipating end and passes through the mounting hole in the capillary layer wall.
[0005] According to the heat spreader of the present invention, the capillary wall comprises: A curved wall, wherein the concave surface of the curved wall faces the heat-absorbing end.
[0006] According to the heat spreader of the present invention, the mounting holes are arrayed on the curved wall. And / or, The end face of the capillary structure facing the heat dissipation end is arc-shaped and flush with the side wall of the curved wall facing the heat dissipation end.
[0007] According to the heat spreader of the present invention, the capillary wall further includes: A planar wall, which is perpendicular to the first direction; at least a portion of the edge of the planar wall is connected to at least a portion of the edge of the curved wall; The planar wall is provided with mounting holes, and the mounting holes on the planar wall are provided one-to-one with the mounting holes on the corresponding curved wall.
[0008] According to the heat spreader of the present invention, the capillary wall comprises: The first layer of wall has its planar wall attached to the cavity wall on the side of the heat-conducting cavity near the heat-absorbing end; the planar wall and the curved wall of the first layer of wall together form a first cavity; At least one second wall is provided within the first cavity; The capillary structure extends from the mounting hole on the planar wall of the first layer to the mounting hole on the curved wall of the first layer.
[0009] According to the heat spreader of the present invention, there are multiple second-layer walls, and the planar walls of the multiple second-layer walls are sequentially stacked and bonded together along the first direction, and are bonded together with the planar walls of the first-layer walls along the first direction.
[0010] According to the heat spreader of the present invention, the capillary structure comprises a plurality of columnar structures arranged in an array and extending along the first direction. or, The capillary structure includes multiple columnar structures perpendicular to the curved wall.
[0011] According to the heat spreader of the present invention, the capillary wall is made of copper or stainless steel. And / or, The capillary structure is a sintered metal structure.
[0012] In a second aspect, the present invention also provides a design method for a heat spreader according to any one of the preceding claims, comprising: The maximum capillary pressure difference, the physical properties of the heat transfer medium inside the heat exchanger, the basic geometric parameters of the capillary wall, and the surface tension of the heat transfer medium are obtained. The number of capillary layers is determined based on a capillary driving force balance model, wherein the capillary driving force balance model is a nonlinear functional relationship that includes the maximum capillary pressure difference, the physical properties of the heat transfer medium in the heat exchanger, the basic geometric parameters of the capillary layers, and the surface tension of the heat transfer medium.
[0013] The design method of the heat spreader according to the present invention includes: The thermal fluid parameters and geometric parameters of the heat exchange plate are obtained. The thermal fluid parameters include at least the average pressure difference within the heat exchange plate, the dynamic viscosity coefficient of the heat transfer medium, the mass flow rate of the heat transfer medium, and the theoretical density of the heat transfer medium. The geometric parameters include at least the equivalent diagonal length of the heat exchange plate, the diameter of the mounting holes on the capillary wall, and the number of capillary walls. Based on the capillary flow equilibrium constraint function, the relationship between the interlayer spacing of the capillary layer wall and the number of mounting holes on the capillary layer wall is determined, wherein the capillary flow equilibrium constraint function is a nonlinear function relationship that includes the thermal fluid parameters and geometric structure parameters.
[0014] According to the design method of the heat spreader of the present invention, The capillary driving force balance model is as follows: P1=2I(COS(A) / (R2-R1 / N*J)-COS(B) / (R3+R1 / N*J)); In the formula, P1 is the maximum capillary pressure difference, I is the surface tension of the heat transfer medium, A is the first wetting angle of the heat transfer medium on the end face of the capillary structure facing the heat absorption end, B is the second wetting angle of the heat transfer medium on the end face of the capillary structure facing the heat dissipation end, R1 is the radius of curvature of the arc-shaped wall of the capillary layer, R2 is the first radius of curvature of the wetting liquid surface of the capillary structure facing the heat absorption end, R3 is the second radius of curvature of the wetting liquid surface of the capillary structure facing the heat dissipation end, N is the number of capillary layers, and J is a correction constant. Based on the capillary flow equilibrium constraint function, and considering the relationship between the interlayer spacing of the capillary wall and the number of mounting holes on the capillary wall, the capillary flow equilibrium constraint function is: P2 = 4CqK / (h1 / N) 2 (d1 / 2) 2 S*logG*J; In the formula, P2 is the average pressure difference of the capillary structure, C is the dynamic viscosity coefficient of the heat transfer medium, q is the mass flow rate of the heat transfer medium in the mounting hole, K is the equivalent diagonal length of the heat spreader, h1 is the distance between the centers of the arcuate walls of adjacent capillary layers, d1 is the diameter of the mounting hole, S is the theoretical density of the liquid heat transfer medium under absolute vacuum conditions, and G is the number of mounting holes.
[0015] According to the design method of the heat spreader of the present invention, The maximum capillary pressure difference and the surface tension of the heat transfer medium were obtained by two-phase flow steady-state simulation. And / or, The physical properties of the heat transfer medium were determined using capillary micropump experiments. And / or, The basic geometric parameters of the capillary wall and the mass flow rate of the heat transfer medium in the mounting hole were determined by transient simulation of two-phase flow using a heat exchanger plate.
[0016] The heat spreader of this invention features a heat-conducting cavity between the heat-absorbing end and the heat-dissipating end of the shell. This cavity contains capillary walls and capillary structures, and is filled with a heat transfer medium such as pure water. The heat transfer medium, under the influence of heat generated by the heat source at the heat-absorbing end and the capillary force of the capillary pores within the capillary structure, undergoes a phase change and circulates between the heat-absorbing and heat-dissipating ends, continuously transferring heat from the heat source to the heat-dissipating end for heat dissipation. Simultaneously, the capillary walls within the heat-conducting cavity, with mounting holes for the capillary structures to pass through, provide directional support, preventing the capillary structures from collapsing towards the heat-absorbing end and concentrating there. This allows the capillary structures to fill a larger space within the heat-conducting cavity and achieve a larger effective equivalent capillary volume, thus improving the overall heat transfer capacity of the heat spreader. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 This is one of the cross-sectional schematic diagrams of the heat spreader provided in the embodiments of the present invention.
[0019] Figure 2 This is a second cross-sectional schematic diagram of the heat spreader provided in an embodiment of the present invention.
[0020] Figure 3 This is a schematic diagram of the capillary wall provided in an embodiment of the present invention.
[0021] Figure 4 This is a flowchart of the design method of the heat spreader provided in the embodiment of the present invention.
[0022] Figure label: 1. Heat spreader; 2. Heat source; 11. Shell; 111. Heat absorption end; 112. Heat dissipation end; 113. Heat conduction cavity; 1131. First cavity; 1132. Second cavity; 12. Capillary wall; 121. Mounting hole; 122. Curved wall; 123. Plane wall; 124. First layer wall; 125. Second layer wall; 13. Capillary structure. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0024] The following is combined Figures 1-3 The heat spreader of the present invention is described.
[0025] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a heat spreader 1, comprising: a shell 11, at least one capillary wall 12, and a capillary structure 13; the shell 11 has a heat-absorbing end 111 and a heat-dissipating end 112 disposed opposite to each other along a first direction, and a heat-conducting cavity 113 is provided between the heat-absorbing end 111 and the heat-dissipating end 112; the heat-absorbing end 111 is used to connect to a heat source 2, and the heat-dissipating end 112 is used to dissipate heat; the heat-conducting cavity 113 is filled with a heat transfer medium; the capillary wall 12 is disposed in the heat-conducting cavity 113, and the capillary wall 12 is provided with a mounting hole 121; the capillary structure 13 extends from the heat-absorbing end 111 to the heat-dissipating end 112 and passes through the mounting hole 121 of the capillary wall 12.
[0026] In this embodiment, the housing 11 of the heat spreader 1 is the main structure, providing an assembly base for the other components. The housing 11 can also be used to connect with the heat dissipation structure or the heat source 2, so as to transfer the heat from the heat source 2 to the heat dissipation structure for heat dissipation. It is understood that the housing 11 can be designed into various shapes according to actual needs, such as square or cylindrical, and this embodiment does not impose specific limitations. Taking a square shell 11 as an example, the shell 11 has two end faces distributed opposite each other along the first direction (corresponding to the height direction of the square). One end face serves as the heat absorption end 111 for contacting and connecting with the heat source 2 (e.g., a chip), and the other end face serves as the heat dissipation end 112. A heat conduction cavity 113 is provided between the heat dissipation end 112 and the heat absorption end 111. The capillary wall 12, capillary structure 13, and heat transfer medium in the heat conduction cavity 113 can cooperate with each other to absorb the heat generated by the heat source 2 and transfer it to the heat dissipation end 112. The heat dissipation end 112 can be provided with a corresponding heat dissipation structure (e.g., copper pipe, copper sheet) or can dissipate heat through water cooling or air cooling, thereby achieving heat dissipation of the heat source 2.
[0027] Specifically, when the heat source 2 operates and generates heat, the heat is transferred from the heat-absorbing end 111 of the shell 11 to the heat-conducting cavity 113, where it is absorbed by the liquid heat transfer medium. After absorbing heat and heating up, the liquid heat transfer medium evaporates into a gaseous state. The gaseous heat transfer medium flows towards the heat dissipation end 112, and after losing heat and cooling down at the heat dissipation end 112, it condenses back into a liquid state. The shell 11 is provided with a capillary structure 13 extending from the heat-absorbing end 111 to the heat dissipation end 112. Under the capillary force generated by the capillary pores distributed on the capillary structure 13, the liquid heat transfer medium flows back towards the heat-absorbing end 111, thus realizing the cyclic phase change flow of the heat transfer medium between the heat-absorbing end 111 and the heat dissipation end 112, thereby continuously dissipating heat from the heat source 2.
[0028] Meanwhile, by providing at least one capillary wall 12 in the heat conduction cavity 113, and each capillary wall 12 having mounting holes 121 for the capillary structure 13 to pass through, the capillary wall 12 can support the capillary structure 13, allowing the capillary structure 13 to fill a larger space in the heat conduction cavity 113 as much as possible, preventing the capillary structure 13 from collapsing towards the heat absorption end 111 and being concentrated in the area near the heat absorption end 111 in the heat conduction cavity 113. This design is beneficial to improving the effective equivalent capillary volume of the entire capillary structure 13, and solving the problem of poor heat transfer capacity caused by small capillary recovery force and easy attainment of the capillary limit and boiling limit.
[0029] The heat spreader 1 of the present invention provides a heat-conducting cavity 113 between the heat-absorbing end 111 and the heat-dissipating end 112 of the housing 11. A capillary wall 12 and a capillary structure 13 are provided within the heat-conducting cavity 113, which is filled with a heat transfer medium such as pure water. Under the influence of the heat generated by the heat source 2 at the heat-absorbing end 111 and the capillary force of the capillary pores within the capillary structure 13, the heat transfer medium undergoes a phase change and circulates between the heat-absorbing end 111 and the heat-dissipating end 112, thereby continuously transferring the heat generated by the heat source 2. The heat is directed to the heat dissipation end 112 for heat dissipation; at the same time, by setting a capillary wall 12 in the heat conduction cavity 113, and the capillary wall 12 is provided with mounting holes 121 for the capillary structure 13 to pass through, the capillary structure 13 is oriented and supported, preventing the capillary structure 13 from collapsing towards the heat absorption end 111 and being concentrated at the heat absorption end 111, so that the capillary structure 13 can fill a larger space in the heat conduction cavity 113 as much as possible and have a larger effective equivalent capillary volume. This design is beneficial to improving the heat transfer capacity of the entire heat spreader 1.
[0030] It is understandable that a single capillary wall 12 or multiple capillary walls 12 can be provided between the heat absorption end 111 and the heat dissipation end 112. When multiple capillary walls 12 are provided, the multiple capillary walls 12 can be stacked and arranged, which provides better support for the capillary structure 13.
[0031] In some embodiments, such as Figure 2 and Figure 3 As shown, the capillary wall 12 includes: a curved wall 122, the concave surface of which faces the heat-absorbing end 111; In this embodiment, by setting a portion of the capillary wall 12 as a curved wall 122, and setting the concave surface of the curved wall 122 toward the heat absorption end 111, the side of the curved wall 122 facing the heat dissipation end 112 forms an arc-shaped curved surface protruding toward the heat dissipation end 112. The liquid heat transfer medium condensed on the curved wall 122 can disperse and move to both sides under the guidance of the curved wall 122, and after contacting the capillary structure 13 that passes through the mounting hole 121, it is subjected to the capillary force of the capillary pore and penetrates into the capillary pore, and flows back to the heat absorption end 111 through the capillary pore.
[0032] Alternatively, in some embodiments, such as Figure 3 As shown, mounting holes 121 are arrayed on the curved wall 122. In this embodiment, by providing mounting holes 121 arranged in an array on the curved wall 122, the corresponding capillary structures 13 can also be distributed on the curved wall 122, so as to increase the contact area between the capillary structures 13 and the heat transfer medium, which is beneficial to improving the capillary conduction effect on the heat transfer medium.
[0033] Alternatively, in some embodiments, such as Figure 1 , Figure 2 and Figure 3 As shown, the end face of the capillary structure 13 facing the heat dissipation end 112 is arc-shaped and is flush with the side wall of the curved wall 122 facing the heat dissipation end 112.
[0034] In this embodiment, the end face of the capillary structure 13 facing the heat dissipation end 112 is designed as an arc-shaped surface that is flush with the side wall of the curved wall 122. This design can effectively improve the capillary force at the end of the capillary, which can facilitate the liquid heat transfer medium to penetrate into the capillary and flow back to the heat absorption end 111.
[0035] Furthermore, in some embodiments, such as Figure 3 As shown, the curved wall 122 is provided with multiple sets of mounting holes 121; wherein, each set of mounting holes 121 includes multiple mounting holes 121 arranged along the axial direction of the curved wall 122; the multiple sets of mounting holes 121 are arranged along the circumferential direction of the curved wall 122.
[0036] Optionally, in some embodiments not shown, the curved wall 122 can also be configured as a spherical wall. Similar to the arc-shaped curved wall 122, the concave surface of the spherical wall faces the heat-absorbing end 111. The spherical curved surface of the spherical wall can also guide the condensed liquid heat transfer medium, so as to better guide the liquid heat transfer medium to the capillary structure passing through the mounting hole 121. Multiple mounting holes 121 can be evenly distributed on the spherical wall.
[0037] In some embodiments, such as Figure 2 and Figure 3 As shown, each capillary wall 12 further includes: a planar wall 123, which is perpendicular to the first direction; at least a portion of the edge of the planar wall 123 is connected to at least a portion of the edge of the curved wall 122; the planar wall 123 is provided with mounting holes 121, and the mounting holes 121 on the planar wall 123 correspond one-to-one with the mounting holes 121 on the corresponding curved wall 122.
[0038] In this embodiment, a flat wall 123 corresponding to the curved wall 122 is provided. The flat wall 123 has a flat plate structure, and some of its edges are connected to some of the edges of the curved wall 122 so as to form an integral structure with the curved wall 122, thereby enhancing the support strength of the entire capillary wall 12. At the same time, the flat wall 123 is provided with mounting holes 121 that correspond one-to-one with the corresponding curved wall 122, so that the capillary structure 13 can be sequentially inserted into the mounting holes 121 of the flat wall 123 and the curved wall 122.
[0039] For example, such as Figure 1 , Figure 2 and Figure 3 As shown, when the curved wall 122 adopts an arc-shaped wall structure, the flat wall 123 can be connected to both ends (i.e., the two straight edges) of the arc-shaped wall respectively.
[0040] Alternatively, if the curved wall 122 adopts a spherical wall structure, the curved wall 122 can adopt a circular plate structure that is adapted to the edge of the spherical wall so as to connect with the edge of the spherical wall structure.
[0041] In some specific embodiments, such as Figure 2 and Figure 3 As shown, the capillary wall 12 includes: a first wall 124 and at least one second wall 125; the planar wall 123 of the first wall 124 is attached to the cavity wall of the heat-conducting cavity 113 on the side near the heat-absorbing end 111; the planar wall 123 and the curved wall 122 of the first wall 124 together form a first cavity 1131; the second wall 125 is disposed in the first cavity 1131; the capillary structure 13 extends from the mounting hole 121 on the planar wall 123 of the first wall 124 to the mounting hole 121 on the curved wall 122 of the first wall 124.
[0042] In this embodiment, the capillary wall 12 is composed of a first wall 124 and a plurality of second walls 125 nested together. The first wall 124 is located at the outermost layer. The planar wall 123 of the first wall 124 is in contact with the cavity wall of the heat conduction cavity 113 near the heat absorption end 111. The curved wall 122 of the first wall 124 protrudes from the planar wall 123 to the cavity wall of the heat conduction cavity 113 near the heat dissipation end 112, and together with the planar wall 123, forms a first cavity 1131. A second cavity 1132 is formed between the curved wall 122 of the first wall 124 and the cavity wall of the heat conduction cavity 113 near the heat dissipation end 112. It is understood that the heat transfer medium in the first cavity 1131 is mainly used to receive the heat transferred from the heat absorption end 111, undergo phase change evaporation, form vapor, and then flow through the capillary pores on the capillary structure 13 to the second cavity 1132 to dissipate heat through the heat dissipation end 112, and then re-condense into liquid. Under the action of the capillary force formed by the capillary pores of the capillary structure 13, it flows back to the heat absorption end 111 to absorb heat. In this embodiment, the curved wall 122 of the first layer wall 124 can cooperate with the capillary structure 13 to isolate the first cavity 1131 and the second cavity 1132 to the greatest extent, so that the heat transfer medium can only flow between the first cavity 1131 and the second cavity 1132 through the capillary pores of the capillary structure 13. This is beneficial to eliminate the capillary recovery viscous resistance of the gas-liquid two-phase surface of the heat transfer medium and improve the circulation efficiency of the heat transfer medium.
[0043] In some embodiments, there are multiple second-layer walls 125, which are located within the first cavity 1131 and arranged in a sequential manner to support the capillary structure 13 within the first cavity 1131.
[0044] It is understandable that by reasonably setting the dimensions of the first wall 124, the second wall 125 and the capillary structure 13, the space of the first cavity 1131 can be expanded as much as possible, and the capillary structure 13 can fill the internal space of the first cavity 1131 as much as possible, so as to increase the effective equivalent capillary volume of the capillary structure 13 and enhance the capillary force of the capillary structure 13.
[0045] Specifically, in some embodiments, such as Figure 2 and Figure 3 As shown, there are multiple second-layer walls 125, and the planar walls 123 of the multiple second-layer walls 125 are stacked and attached to each other in the first direction, and are attached to the planar walls 123 of the first-layer wall 124 in the first direction.
[0046] In this embodiment, by stacking and attaching the planar walls 123 of the multiple second-layer walls 125 and the planar walls 123 of the first-layer walls 124 together, it is beneficial to reduce the space occupied by the planar walls 123 of the first-layer walls 124 and the second-layer walls 125, so as to maximize the distribution space of the curved wall 122 of the spaced-apart second-layer walls 125, so that the capillary structure 13 is mainly in contact with the curved wall 122 and supported by the curved wall 122.
[0047] It is understandable that the capillary structure 13 can be configured as a directionally extended directional capillary structure or a flat, layered structure.
[0048] In one specific embodiment, such as Figure 1 and Figure 2 As shown, the capillary structure 13 includes a plurality of columnar structures extending along a first direction. In this embodiment, by setting the capillary structure 13 as a columnar structure, the columnar structure can pass through the mounting holes 121 of each capillary wall 12, and the interior of the columnar structure has a plurality of capillary pores extending from one end of the columnar structure to the other end, so as to allow the heat transfer medium to circulate.
[0049] It is understandable that, since the first layer wall 124 and the second layer wall 125 are both combined structures formed by connecting curved wall 122 and planar wall 123, multiple second layer walls 125 are nested together, with the first layer wall 124 nested outside the outermost second layer wall 125. The closer the columnar structure is to the central axis of the first layer wall 124 and the second layer wall 125, the more second layer walls 125 it needs to pass through, and the longer the columnar structure is; while the farther the cylindrical structure is from the central axis, the fewer second layer walls 125 it needs to pass through, and the shorter the length is.
[0050] Optionally, in some embodiments, the capillary structure 13 includes a plurality of columnar structures perpendicular to the curved wall 122.
[0051] In this embodiment, it should be noted that the capillary structure 13 is a columnar structure perpendicular to the curved wall 122. Specifically, the axis of the columnar structure is perpendicular to the tangent plane at the corresponding position of the curved wall 122. For example, when the curved wall 122 adopts an arc-shaped wall structure, each columnar structure extends radially along the curved wall 122 and is arranged radially along the arc surface; when the curved wall 122 adopts a spherical wall, each columnar structure extends radially along the curved wall 122 and is arranged radially along the spherical surface. This structure is more conducive to increasing the capillary force formed at both ends of the capillary structure 13, thereby promoting the return of the liquid heat transfer medium along the micropores within the capillary structure 13 to the heat absorption end 111 and improving heat transfer efficiency.
[0052] Optionally, the capillary wall 12 is made of copper or stainless steel. Copper or stainless steel walls allow the condensed heat transfer medium to adhere better to the sidewall surface and flow along the wall surface, guiding the liquid heat transfer medium to flow towards the end face of the capillary structure 13 and into the capillary pores, flowing back to the heat absorption end 111.
[0053] In some embodiments, the capillary structure 13 is a sintered metal structure. Specifically, the capillary structure 13 can be formed by sintering copper and other metal alloys, and the sintered metal structure can form a capillary structure inside.
[0054] Alternatively, the capillary wall 12 can also be made of other metallic or non-metallic materials. Specifically, in order to improve the heat transfer effect, the material of the capillary wall 12 needs to be selected according to the type and material of the heat transfer medium, capillary structure 13, shell 11 and heat source 2.
[0055] On the other hand, such as Figure 4 As shown, this embodiment also provides a design method for the heat spreader 1 provided in any of the above embodiments, including the following steps: Step S101: Obtain the maximum capillary pressure difference, the physical properties of the heat transfer medium in the heat exchanger, the basic geometric parameters of the capillary wall, and the surface tension of the heat transfer medium.
[0056] Step S102: Determine the number of capillary walls based on the capillary driving force balance model.
[0057] The capillary driving force balance model is a nonlinear functional relationship that includes the maximum capillary pressure difference, the physical properties of the heat transfer medium in the heat exchanger, the basic geometric parameters of the capillary wall 12, and the surface tension of the heat transfer medium.
[0058] The design method of this embodiment is mainly used to calculate and determine the number of capillary walls 12 and other structural parameters (mainly capillary structure 13) of the heat exchange plate 1 in the above embodiment, so as to improve the circulation and heat transfer efficiency of the heat transfer medium in the entire heat exchange plate 1.
[0059] This embodiment constructs a capillary driving force balance model based on experimental data and fitting. The capillary driving force model mainly covers the maximum capillary pressure difference, the physical property parameters of the heat transfer medium in the heat exchanger 1, the basic geometric parameters of the capillary wall 12, and the nonlinear functional relationship of the surface tension of the heat transfer medium, so as to optimize the design of the number of capillary wall 12 layers based on the above parameters.
[0060] In practical applications, it is necessary to first determine the heat transfer medium and other simulation parameters (including but not limited to the maximum heat transfer Qmax and minimum start-up heat flow Qmin and some geometric dimensions of the heat transfer plate 1) based on the actual application scenario of the heat spreader 1, such as the heat source, the heat dissipation structure configured at the heat dissipation end 112, and the size of the installation space. For example, pure water can be selected as the heat transfer medium.
[0061] After initially determining the heat transfer medium and simulation parameters, simulations and experiments can be conducted based on these parameters. The maximum capillary pressure difference, the physical properties of the heat transfer medium within the heat exchanger 1, the basic geometric parameters of the capillary wall 12, and the surface tension of the heat transfer medium can be obtained through these experiments and simulations. The maximum capillary pressure difference refers to the maximum pressure difference generated by the surface tension driving the liquid flow in the capillary pores of a phase change heat transfer device or microfluidic system. It is a key parameter that determines the system's heat transfer limit and the transport capacity of the working medium. The physical properties of the heat transfer medium within the heat exchanger include, but are not limited to, the vapor velocity and the liquid wave wavelength. The basic geometric parameters of the capillary wall 12 include, but are not limited to, the radius of curvature of the arc-shaped wall of the capillary wall 12.
[0062] After obtaining the above basic parameters, they can be input into the capillary driving force balance model to finally obtain the number of capillary wall layers 12. It can be understood that the capillary driving force balance model is an optimized model constructed based on extensive simulations, experiments, and theoretical calculations. Its function is to determine the number of capillary wall layers 12 using the above parameters, and to ensure that the final designed heat spreader 1 achieves better heat transfer performance through the interaction of the internal capillary wall layers 12 and the capillary structure 13.
[0063] Furthermore, in some embodiments, the design method of the heat spreader 1 further includes: Step S103: Obtain the thermal fluid parameters and geometric parameters of the heat exchanger.
[0064] The thermal fluid parameters include at least the average pressure difference within the heat exchanger 1, the dynamic viscosity coefficient of the heat transfer medium, the mass flow rate of the heat transfer medium, and the theoretical density of the heat transfer medium. The geometric parameters include at least the equivalent diagonal length of the heat exchanger 1, the diameter of the mounting holes on the capillary wall 12, and the number of capillary walls 12.
[0065] Step S104: Based on the capillary flow equilibrium constraint function, determine the relationship between the interlayer spacing of the capillary wall and the number of mounting holes on the capillary wall.
[0066] The capillary flow equilibrium constraint function is a nonlinear functional relationship that includes thermal fluid parameters and geometric parameters.
[0067] This embodiment constructs a capillary flow equilibrium constraint function based on experimental data and fitting. The capillary flow equilibrium constraint function mainly covers the nonlinear functional relationship between thermal fluid parameters and geometric structure parameters, so as to optimize the design of the number of capillary wall layers 12 based on the above parameters.
[0068] In practical applications, the thermal fluid parameters and geometric parameters of the heat exchanger 1 can be obtained through experiments and simulations. These parameters, along with the number of capillary walls 12 obtained in the previous steps, are then input into the capillary flow equilibrium constraint function to determine the relationship between the interlayer spacing of the capillary walls 12 and the number of mounting holes 121 on the capillary walls 12. After determining this relationship, the number of mounting holes 121 and the interlayer spacing of the capillary walls 12 can be designed according to actual needs. Ultimately, the number of capillary walls 12, the number of mounting holes 121, and the interlayer spacing of the capillary walls 12 within the heat exchanger 1 are determined, ensuring that the designed heat exchanger 1 has a good heat transfer effect.
[0069] In some specific embodiments, the capillary driving force balance model is as follows: P1=2I(COS(A) / (R2-R1 / N*J)-COS(B) / (R3+R1 / N*J)); In the formula, P1 (Pa) is the maximum capillary pressure difference, I is the surface tension of the heat transfer medium, A (rad) is the first wetting angle of the heat transfer medium on the end face of the capillary structure 13 facing the heat absorption end 111, B (rad) is the second wetting angle of the heat transfer medium on the end face of the capillary structure 13 facing the heat dissipation end 112, R1 (m) is the radius of curvature of the arc-shaped wall of the capillary layer 12, R2 (m) is the first radius of curvature of the wetted liquid surface of the capillary structure 12 facing the heat absorption end 111, R3 (m) is the second radius of curvature of the wetted liquid surface of the capillary structure 12 facing the heat dissipation end 112, N is the number of capillary layer walls 12, and J is a correction constant (the value ranges from 0.5 to 50, for example, any value among 0.5, 5, 15, 35 and 50 can be selected depending on the situation). Based on the capillary flow equilibrium constraint function, and considering the relationship between the interlayer spacing of the capillary wall 12 and the number of mounting holes 121 on the capillary wall 12, the capillary flow equilibrium constraint function is: P2 = 4CqK / (h1 / N) 2 (d1 / 2) 2 S*logG*J; In the formula, P2 (Pa) is the average pressure difference of the capillary structure 13, C (Pa·s) is the dynamic viscosity coefficient of the heat transfer medium, q (kg / s) is the mass flow rate of the heat transfer medium in the mounting hole 121, K (m) is the equivalent diagonal length of the heat spreader 1, and h1 (m) is the distance between the centers of the arcuate walls of adjacent capillary walls 12 (e.g., ...).Figure 2 As shown), d1 (m) is the diameter of the mounting hole, and S (kg / m²) is the diameter of the mounting hole. 3 ) represents the theoretical density of the liquid heat transfer medium under absolute vacuum conditions (obtained through theoretical calculation), and G represents the number of mounting holes 121.
[0070] It is understandable that the capillary driving force balance model and capillary flow balance constraint function mentioned above are model functions obtained after a large number of experiments, simulations and optimizations, used to design and optimize the key parameters of the capillary wall 12 inside the heat exchanger 1. Based on the relatively conventional experimental design and simulation process in this field, the input parameters of the capillary driving force balance model and capillary flow balance constraint function can be determined, and the key design parameters of the capillary wall 12 (the number of capillary walls 12, the spacing between the center positions of the arcuate walls of adjacent capillary walls 12, and the number of mounting holes 121) can be confirmed based on the above model functions, so that a heat exchanger 1 structure with better heat transfer effect can be designed.
[0071] Optionally, the maximum capillary pressure difference and the surface tension of the heat transfer medium can be obtained from the steady-state simulation of the two-phase flow.
[0072] In the field of vapor chamber simulation, the steady-state simulation of two-phase flow in a single vapor chamber refers to the numerical simulation established for a single vapor chamber unit in which the internal working fluid undergoes a gas-liquid phase change and the flow state does not change with time.
[0073] This embodiment performs steady-state simulation of two-phase flow in a single heat exchanger plate based on the type of heat transfer medium and simulation parameters to determine the maximum capillary pressure difference P1, vapor velocity V1 (m / s), average pressure difference P2, and liquid wave wavelength T1 (m). The liquid surface tension I (N / m) is then calculated using the following formula: W=y1V1 2 T1 / (2πI), where y1 (kg / m 3 ) represents the steam density; π represents pi; W represents the Weber coefficient, which is mainly determined by the type of heat transfer medium. Once the type of heat transfer medium is determined, W can be found using existing methods.
[0074] Optionally, capillary micropump experiments can be used to determine the physical properties of the heat transfer medium.
[0075] The capillary micropump experiment refers to the capillary wetting experiment performed on the capillary structure under the condition of zero vacuum. This experiment can detect the above-mentioned wetting angle and the curvature of each circle using equipment such as MEMS pressure sensors and six-axis gyroscopes.
[0076] The first wetting angle A of the heat transfer medium on the end face of the capillary structure facing the heat absorption end, the second wetting angle B of the heat transfer medium on the end face of the capillary structure facing the heat dissipation end, the radius of curvature R1 of the arc-shaped wall of the capillary layer, the first radius of curvature R2 of the wetting liquid surface of the capillary structure facing the heat absorption end, the second radius of curvature R3 of the wetting liquid surface of the capillary structure facing the heat dissipation end, and the dynamic viscosity coefficient C can be determined by capillary micropump experiments.
[0077] Optionally, transient simulation of two-phase flow in a heat exchanger plate can be used to determine the basic geometric parameters of the capillary wall 12 and the mass flow rate of the heat transfer medium in the mounting hole 121.
[0078] Then, the fluid density X (kg / m³) was determined through transient simulation of two-phase flow on a heat exchanger. 3 The maximum fluid velocity V2 (m / s) is calculated, and the range of the diameter d1 (m) of the mounting hole 121 is calculated according to the following formula: Re = X * V² * d¹ / C, where Re is the normal Reynolds number.
[0079] After the above simulation and experimental process, the input values of the capillary driving force balance model can be obtained and substituted into the corresponding formula (P1=2I(COS(A) / (R2-R1 / N*J)-COS(B) / (R3+R1 / N*J))) to determine the number of capillary wall layers N of 12; then, the number of capillary wall layers N of 12 and the remaining input values of the other capillary flow balance constraint functions are substituted into the corresponding formula (P2=4CqK / (h1 / N)). 2 (d1 / 2) 2 The relationship between the spacing h1 of the center position of the arc-shaped wall of the capillary wall 12 and the number G of the mounting holes 121 on the capillary wall 12 is determined in S*logG*J).
[0080] The design parameters of the capillary wall 12 determined by the above method (number of capillary wall layers 12, radius of curvature of the arc-shaped wall of the capillary wall 12, spacing between the centers of adjacent capillary walls, number of mounting holes 121 of the capillary wall, and diameter of mounting holes 121) can be used as the design basis for the capillary wall 12 to obtain a heat spreader 1 with good heat transfer effect under the required operating conditions.
[0081] The heat spreader 1 obtained by adopting the structure and design method of the above embodiment can theoretically reach more than 70% of the volume of the entire heat conduction cavity 113 through the combination of capillary wall 12 and capillary structure 13. The capillary penetration is greatly improved, and the capillary force is improved by more than 60% compared with the conventional structure.
[0082] This application has conducted simulation based on the heat spreader 1 of the above embodiments: Specifically, when the power of heat source 2 is 5W, the temperature of the capillary structure 12 near the heat source 2 is 62℃, and the temperature of the end away from the heat source 2 is 61.7℃, with a temperature difference of only 0.3℃; when the power of heat source 2 is 10W, the temperature of the capillary structure 12 near the heat source 2 is 72℃, and the temperature of the end away from the heat source 2 is 71.1℃, with a temperature difference of only 0.9℃; that is to say, the structure of the heat spreader 1 in the above embodiment can play a good heat transfer role, so that the two ends of the capillary structure 12 have a small temperature difference.
[0083] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A heat spreader, characterized in that, include: The housing has a heat-absorbing end and a heat-dissipating end arranged opposite to each other along a first direction, and a heat-conducting cavity is provided between the heat-absorbing end and the heat-dissipating end. The heat-absorbing end is used to connect to the heat source, and the heat-dissipating end is used to dissipate heat; the heat-conducting cavity is filled with a heat transfer medium. At least one capillary wall is disposed in the heat-conducting cavity, and the capillary wall is provided with mounting holes; The capillary structure extends from the heat-absorbing end to the heat-dissipating end and passes through the mounting hole in the capillary layer wall.
2. The heat spreader according to claim 1, characterized in that, The capillary walls include: A curved wall, wherein the concave surface of the curved wall faces the heat-absorbing end.
3. The heat spreader according to claim 2, characterized in that, The mounting holes are arranged in an array on the curved wall. And / or, The end face of the capillary structure facing the heat dissipation end is arc-shaped and flush with the side wall of the curved wall facing the heat dissipation end.
4. The heat spreader according to claim 2, characterized in that, The capillary wall also includes: A planar wall, which is perpendicular to the first direction; at least a portion of the edge of the planar wall is connected to at least a portion of the edge of the curved wall; The planar wall is provided with mounting holes, and the mounting holes on the planar wall are provided one-to-one with the mounting holes on the corresponding curved wall.
5. The heat spreader according to claim 4, characterized in that, The capillary walls include: The first layer of wall has its planar wall attached to the cavity wall on the side of the heat-conducting cavity near the heat-absorbing end; the planar wall and the curved wall of the first layer of wall together form a first cavity; At least one second wall is provided within the first cavity; The capillary structure extends from the mounting hole on the planar wall of the first layer to the mounting hole on the curved wall of the first layer.
6. The heat spreader according to claim 5, characterized in that, There are multiple second-layer walls, and the planar walls of the multiple second-layer walls are stacked and bonded together in sequence along the first direction, and are bonded to the planar walls of the first-layer walls along the first direction.
7. The heat spreader according to claim 2, characterized in that, The capillary structure comprises a plurality of columnar structures arranged in an array and extending along the first direction. or, The capillary structure includes multiple columnar structures perpendicular to the curved wall.
8. The heat spreader according to claim 1, characterized in that, The capillary wall is made of copper or stainless steel. And / or, The capillary structure is a sintered metal structure.
9. A design method for a heat spreader according to any one of claims 1 to 8, characterized in that, include: The maximum capillary pressure difference, the physical properties of the heat transfer medium inside the heat exchanger, the basic geometric parameters of the capillary wall, and the surface tension of the heat transfer medium are obtained. The number of capillary layers is determined based on a capillary driving force balance model, wherein the capillary driving force balance model is a nonlinear functional relationship that includes the maximum capillary pressure difference, the physical properties of the heat transfer medium in the heat exchanger, the basic geometric parameters of the capillary layers, and the surface tension of the heat transfer medium.
10. The design method of the heat spreader according to claim 9, characterized in that, include: The thermal fluid parameters and geometric parameters of the heat exchange plate are obtained. The thermal fluid parameters include at least the average pressure difference within the heat exchange plate, the dynamic viscosity coefficient of the heat transfer medium, the mass flow rate of the heat transfer medium, and the theoretical density of the heat transfer medium. The geometric parameters include at least the equivalent diagonal length of the heat exchange plate, the diameter of the mounting holes on the capillary wall, and the number of capillary walls. Based on the capillary flow equilibrium constraint function, the relationship between the interlayer spacing of the capillary layer wall and the number of mounting holes on the capillary layer wall is determined, wherein the capillary flow equilibrium constraint function is a nonlinear function relationship that includes the thermal fluid parameters and geometric structure parameters.
11. The design method of the heat spreader according to claim 9 or 10, characterized in that, The capillary driving force balance model is as follows: P1=2I(COS(A) / (R2-R1 / N*J)-COS(B) / (R3+R1 / N*J)); In the formula, P1 is the maximum capillary pressure difference, I is the surface tension of the heat transfer medium, A is the first wetting angle of the heat transfer medium on the end face of the capillary structure facing the heat absorption end, B is the second wetting angle of the heat transfer medium on the end face of the capillary structure facing the heat dissipation end, R1 is the radius of curvature of the arc-shaped wall of the capillary layer, R2 is the first radius of curvature of the wetting liquid surface of the capillary structure facing the heat absorption end, R3 is the second radius of curvature of the wetting liquid surface of the capillary structure facing the heat dissipation end, N is the number of capillary layers, and J is a correction constant. Based on the capillary flow equilibrium constraint function, and considering the relationship between the interlayer spacing of the capillary wall and the number of mounting holes on the capillary wall, the capillary flow equilibrium constraint function is: P2=4CqK / (h1 / N) 2 (d1 / 2) 2 S*logG*J; In the formula, P2 is the average pressure difference of the capillary structure, C is the dynamic viscosity coefficient of the heat transfer medium, q is the mass flow rate of the heat transfer medium in the mounting hole, K is the equivalent diagonal length of the heat spreader, h1 is the distance between the centers of the arcuate walls of adjacent capillary layers, d1 is the diameter of the mounting hole, S is the theoretical density of the liquid heat transfer medium under absolute vacuum conditions, and G is the number of mounting holes.
12. The design method of the heat spreader according to claim 9 or 10, characterized in that, The maximum capillary pressure difference and the surface tension of the heat transfer medium were obtained by two-phase flow steady-state simulation. And / or, The physical properties of the heat transfer medium were determined using capillary micropump experiments. And / or, The basic geometric parameters of the capillary wall and the mass flow rate of the heat transfer medium in the mounting hole were determined by transient simulation of two-phase flow using a heat exchanger plate.