Variable capacitance vapor chamber with mechanical metamaterial composite support structure and method of manufacturing the same

Abstract

The application discloses a variable-capacity vapor chamber with a mechanical metamaterial composite support structure and a preparation method thereof. The variable-capacity vapor chamber comprises oppositely arranged upper and lower shells, liquid-absorbing cores fixed to the inner sides of the upper and lower shells, a plurality of superstructure columns arranged between the two liquid-absorbing cores, and a circumferentially arranged flexible sealing structure. The superstructure column is formed by wrapping the outer surface of the flexible liquid-absorbing core in the mechanical metamaterial in the full circumferential direction. The mechanical metamaterial serves as a bearing framework, and the flexible liquid-absorbing core serves as a capillary transport channel for working fluid return. The superstructure column is used for reversible deformation in the thickness direction to realize cavity volume change and maintain capillary transport continuity during the deformation process. Meanwhile, the nonlinear mechanical response of the mechanical metamaterial realizes vibration attenuation and impact energy absorption. The application integrates heat transfer, variable capacity, vibration isolation and energy absorption functions in one, and is suitable for application scenarios with dual stringent requirements for thermal management and vibration reduction, such as aerospace equipment and high-power electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of phase change heat transfer devices and multifunctional integrated thermal management technology. Specifically, it relates to a variable capacity heat exchanger that integrates mechanical metamaterials and flexible porous media to construct a composite support structure. It is particularly suitable for applications such as aerospace equipment and high power density electronic devices that have stringent requirements for both heat transfer efficiency and dynamic mechanical load-bearing capacity. Background Technology

[0002] As a typical phase change heat transfer element, the vapor chamber has been widely used in thermal control systems in aerospace, electronic equipment, and new energy fields due to its excellent thermal conductivity and rapid temperature homogenization characteristics. Its working principle is based on the cyclic process of the working fluid absorbing heat and vaporizing at the evaporation end and condensing and releasing heat at the condensation end. The continuous reflux of the working fluid is achieved through the capillary driving force provided by the internal wick, thus forming a stable heat transfer cycle. In this process, the structural characteristics of the wick directly determine the capillary heat transfer limit and overall heat transfer performance of the vapor chamber.

[0003] In terms of mechanical structure, vapor chambers typically require internal support structures to resist external pressure, prevent cavity collapse, and maintain a stable gap between the upper and lower cover plates. Traditional support structures often employ rigid columnar components, such as metal pillars or honeycomb structures, which have a single function, providing only static mechanical support. In recent years, researchers have attempted to combine absorbent cores with support structures, that is, to composite absorbent core materials onto the surface of the support columns, aiming to achieve the support function while utilizing the surface of the support columns for capillary transport, thereby improving space utilization.

[0004] However, existing technologies still have the following technical shortcomings: (1) Lack of dynamic mechanical response capability: Conventional heat exchanger designs mainly focus on static mechanical load-bearing capacity and steady-state heat transfer performance, and generally do not incorporate dynamic mechanical loads such as vibration and shock into the design system. Especially in the fields of aerospace equipment, high-maneuverability aircraft, and precision instruments, vibration and shock are typical service conditions. Traditional heat exchangers lack the ability to attenuate broadband vibration transmission, and also lack an effective absorption mechanism for transient impact energy.

[0005] (2) Functional separation and structural redundancy: Traditional spacecraft heat transfer and mechanical components mostly adopt the design mode of "functional separation and physical superposition", that is, heat transfer elements and vibration damping elements are set independently and combined by mechanical connection. This design mode is prone to problems such as space redundancy, low structural integration and increased interface thermal resistance, which makes it difficult to meet the comprehensive requirements of modern equipment for lightweight, high integration and high reliability.

[0006] (3) Insufficient volume adjustment capability in the thickness direction: In the existing technology, some solutions attempt to achieve compressible deformation of the heat exchange plate by introducing elastic elements (such as springs and corrugated structures) (such as CN118936170A and CN216694629U). However, its deformation capability is limited by the linear mechanical response range of traditional elastic elements, and it is difficult to maintain stable capillary transport performance during compression / stretching. Especially under the condition that there is continuous relative motion between the heat source and cold source surfaces, the existing solutions cannot simultaneously achieve adaptive volume adjustment and capillary transport function maintenance.

[0007] (4) Poor synergy between support structure and capillary transport function: Although the existing composite support structure has a liquid-absorbing core on the surface of the support column, the support column body is still a rigid material, and its deformation capacity is limited. When the heat spreader undergoes deformation in the thickness direction, the liquid-absorbing core on the surface of the support column is easily damaged by stretching or compression, resulting in deterioration or even failure of capillary transport performance.

[0008] In summary, there is an urgent need to develop an integrated multifunctional heat exchanger structure that combines high-efficiency heat transfer, dynamic mechanical load-bearing capacity, and adaptive volume adjustment capability in the thickness direction. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a variable-capacity heat exchanger with a mechanical metamaterial composite support structure and its preparation method.

[0010] The core concept of this invention lies in using a mechanical metamaterial as the load-bearing skeleton of the internal support structure of a heat exchanger, and then encasing it circumferentially with a flexible porous medium to construct a composite support column (hereinafter referred to as "metamaterial column") consisting of a "flexible liquid-absorbing core encasing a mechanical metamaterial". This structure achieves integrated heat transfer, volume change, and vibration reduction through the synergistic effect of three mechanisms: Mechanism of mechanical metamaterials: Through artificially designed periodic microstructures, mechanical metamaterials exhibit nonlinear mechanical properties that surpass those of natural materials, including high static stiffness, low dynamic stiffness, quasi-zero stiffness response, wide bandwidth, and high specific energy absorption. Using them as a load-bearing framework can effectively isolate low-frequency micro-vibrations and efficiently absorb transient impact energy while maintaining the static volume of a heat exchanger.

[0011] Flexible liquid-absorbing core mechanism: A flexible porous medium (such as metal fiber felt or polymer porous material) is wrapped around the mechanical metamaterial. On the one hand, it serves as a capillary transport channel for the return of the working fluid, ensuring the continuous liquid supply capacity of the heat exchange plate during the deformation process in the thickness direction. On the other hand, its own flexibility and deformability can conform to the deformation of the mechanical metamaterial, avoiding the destruction of the pore structure and ensuring the stability of capillary transport performance.

[0012] Composite synergistic mechanism: When the metamaterial is subjected to axial compression or tension, the mechanical metamaterial provides a nonlinear mechanical response. The flexible liquid-absorbing core drives the working fluid backflow through capillary force on the one hand, and on the other hand, the liquid working fluid inside converts vibration energy into heat energy through viscous dissipation during the periodic deformation process, thus realizing the active dissipation of vibration energy.

[0013] In a first aspect, the present invention provides a variable-capacity heat exchanger with a mechanical metamaterial composite support structure, comprising: An upper and lower outer shell arranged opposite each other along the thickness direction; An upper liquid-absorbing core is fixedly disposed on the inner surface of the upper outer shell, and a lower liquid-absorbing core is fixedly disposed on the inner surface of the lower outer shell; Multiple meta-pillars are sandwiched between the upper and lower liquid-absorbing cores, with the top end of each meta-pillar contacting the lower surface of the upper liquid-absorbing core and the bottom end of each meta-pillar contacting the upper surface of the lower liquid-absorbing core. A flexible sealing structure is disposed between the upper outer shell and the lower outer shell and arranged circumferentially, wherein the flexible sealing structure, together with the upper outer shell and the lower outer shell, forms a sealed cavity; The metastructure is formed by a flexible liquid-absorbing core wrapped around the outer surface of a mechanical metamaterial in the entire circumference. The mechanical metamaterial serves as the load-bearing skeleton of the metastructure, and the flexible liquid-absorbing core serves as a capillary transport channel for the return of the working fluid. The metamaterial is used to undergo reversible compression or stretching deformation in the thickness direction to achieve a volume change in the sealed cavity, while maintaining the capillary transport continuity of the flexible liquid-absorbing core during the deformation process. At the same time, the nonlinear mechanical response of the metamaterial enables vibration transmission attenuation and impact energy absorption.

[0014] As a preferred technical solution, the cross-sectional shape of the superstructure column includes, but is not limited to, any one of the following: circular, elliptical, square, rectangular, and regular hexagonal; the planar arrangement of the superstructure column inside the variable-capacity heat exchanger includes, but is not limited to, any one of the following: square array, regular hexagonal array, concentric ring arrangement, and radial arrangement.

[0015] As a preferred technical solution, the mechanical metamaterial adopts a periodic cell structure with extraordinary mechanical properties. The cell structure includes, but is not limited to, any one or more combinations of bistable buckling beam, arc beam, chiral honeycomb, concave honeycomb, star structure or lattice structure. The cell size, wall thickness and arrangement period of the mechanical metamaterial are parametrically designed according to the target vibration isolation frequency range and load-bearing requirements.

[0016] As a preferred technical solution, the flexible liquid-absorbing core is a flexible porous medium with a continuous pore structure, and its material includes, but is not limited to, metal fiber felt or polymer.

[0017] As a preferred technical solution, the upper liquid-absorbing core and the lower liquid-absorbing core are independent of each other and include, but are not limited to, any one or more combinations of the following structural types: flexible porous media, sintered metal powder layer, sintered metal fiber layer, microgroove structure, woven metal mesh layer, and multi-layer composite structure.

[0018] As a preferred technical solution, the flexible sealing structure is made of corrugated metal foil or elastic polymer material.

[0019] As a preferred technical solution, the heat transfer direction of the metamaterial-supported variable capacity heat exchanger includes the thickness direction and the span direction; the mechanical function of the metamaterial-supported variable capacity heat exchanger includes vibration transmission attenuation between the upper and lower outer shell surfaces, and impact buffering and energy absorption between the upper and lower outer shell surfaces.

[0020] As a preferred technical solution, the shape of the variable capacity heat spreader includes, but is not limited to, square, circular, elliptical, polygonal or other arbitrary shapes.

[0021] Secondly, the present invention provides a method for preparing the variable-capacity heat exchanger, comprising the following steps: (1) Component fabrication: a) The upper and lower outer shells are prepared by stamping, CNC machining or laser cutting, and a liquid injection port is reserved on the upper or lower outer shell; b) The upper and lower liquid-absorbing cores are prepared by processes such as powder sintering, fiber sintering, electroforming or chemical etching; c) Prepare mechanical metamaterials with periodic cellular structures using processes such as additive manufacturing, precision casting, or micro / nano fabrication; d) Flexible liquid-absorbing cores are prepared by high-temperature solid-state sintering, electrospinning, or template method; e) Flexible sealing structures are prepared by stamping or injection molding; (2) Primary assembly: Using diffusion welding, brazing or hot pressing, the upper liquid suction core is fixedly connected to the inner surface of the upper shell, and the lower liquid suction core is fixedly connected to the inner surface of the lower shell. (3) Composite support column forming: The flexible liquid-absorbing core is tightly wrapped around the outer surface of the mechanical metamaterial to form a metastructure column; (4) Assembly: The superstructure column is arranged on the upper surface of the lower liquid-absorbing core in a preset arrangement. The upper shell and the upper liquid-absorbing core are covered on the superstructure column. A flexible sealing structure is set in the circumferential direction. Vacuum brazing or laser welding and other processes are used to seal the upper shell, lower shell and flexible sealing structure. (5) Post-processing: Evacuate the sealed cavity to the predetermined vacuum level through the injection port, inject the phase change working fluid, seal the injection port, and obtain a variable volume heat exchange plate.

[0022] As a preferred technical solution, in step (3), the flexible liquid-absorbing core is wrapped around the outer surface of the mechanical metamaterial in the following ways: the mechanical metamaterial is embedded in the prefabricated groove of the flexible liquid-absorbing core, or the flexible liquid-absorbing core and the mechanical metamaterial are integrated into a composite structure by means of induction welding or other methods. In step (3), the cross-sectional shape of the metamaterial column includes, but is not limited to, any one or other shapes such as circle, ellipse, square, rectangle, regular hexagon, etc., and the planar arrangement inside the heat spreader includes, but is not limited to, any one or other shapes such as square array, regular hexagon array, concentric ring arrangement, radial arrangement, etc.; in step (5), the working fluid includes, but is not limited to, deionized water, acetone, methanol and other coolants, and the liquid injection rate range includes, but is not limited to, 20%-90%.

[0023] Advantages of this invention: Compared with the prior art, the present invention has the following significant advantages: 1. Large deformation in the thickness direction and volumetric adaptive capability This invention uses a flexible liquid-absorbing core to wrap a metamaterial-based metacolumn as an internal support structure. By utilizing the nonlinear deformation capability of the metamaterial and the conformal nature of the flexible liquid-absorbing core, the heat spreader can achieve reversible compression and tensile deformation in the thickness direction. This characteristic enables the heat spreader to adapt to changes in the relative position between the heat source and the heat sink, making it suitable for complex working conditions with thermal deformation, vibration displacement, or assembly tolerances.

[0024] 2. Capillary transport properties are maintained during deformation. Traditional rigid support columns are prone to pore damage to the surface wicking core during deformation. This invention employs a fully circumferentially wrapped flexible wicking core, which possesses deformation capabilities matching those of mechanical metamaterials. It maintains the continuity and stability of the pore structure during compression and tension, ensuring that the working fluid return path is unaffected by deformation. Simultaneously, the flexible wicking core provides continuous capillary driving force along the thickness direction, guaranteeing the heat transfer performance of the heat spreader under dynamic operating conditions.

[0025] 3. Decoupling of high static stiffness and low dynamic stiffness The periodic microstructure of the mechanical metamaterial enables it to achieve a mechanical property of "high static stiffness and low dynamic stiffness". Under static or quasi-static loads, the metamaterial column exhibits high stiffness, maintaining the structural stability and design volume of the heat exchanger; under dynamic vibration excitation, the metamaterial column exhibits low dynamic stiffness, achieving effective attenuation of vibration transmission.

[0026] 4. Synergistic effect of broadband vibration isolation and impact energy absorption The bandgap characteristics of mechanical metamaterials enable them to suppress vibrational waves in a specific frequency range. Combined with the viscous dissipation effect of the liquid working fluid inside the flexible wicking core, a dual energy dissipation mechanism of "solid structure dissipation + liquid viscous dissipation" is formed.

[0027] 5. Integrated structure and function This invention integrates heat transfer, support, volume change, vibration reduction, and energy absorption functions into a single heat spreader structure, breaking the traditional design paradigm of "separate functions and physical superposition". It significantly reduces system-level space occupation and mass, and improves overall reliability and integration. It has important value for applications that are sensitive to weight and space, such as spacecraft and high-end electronic equipment. Attached Figure Description

[0028] Figure 1 This is a three-dimensional structural diagram of the variable-capacity heat exchanger with a mechanical metamaterial composite support structure proposed in this invention.

[0029] Figure 2 This is an exploded view of the three-dimensional structure of the heat spreader.

[0030] Figure 3 This is a three-dimensional cross-sectional view of the heat spreader.

[0031] Figure 4 This is a structural diagram of the superstructure column in the heat exchanger.

[0032] In the diagram: 1-Upper shell, 2-Upper absorbent core, 3-Metamaterial column, 4-Lower absorbent core, 5-Lower shell, 6-Mechanical metamaterial, 7-Flexible absorbent core. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0034] Example 1 This embodiment provides a variable-capacity heat exchanger with a mechanical metamaterial composite support structure, the structure of which is as follows: Figures 1 to 4 As shown.

[0035] The variable-capacity heat exchanger includes: an upper outer shell 1, an upper liquid-absorbing core 2, superstructure columns 3, a lower liquid-absorbing core 4, a lower outer shell 5, and a flexible sealing structure (not shown in the figure). The upper outer shell 1 and the lower outer shell 5 are arranged opposite each other along the thickness direction and are connected by a circumferentially arranged flexible sealing structure to form a sealed cavity. The upper liquid-absorbing core 2 is fixedly disposed on the inner surface of the upper outer shell 1, and the lower liquid-absorbing core 4 is fixedly disposed on the inner surface of the lower outer shell 5. Multiple superstructure columns 3 are sandwiched between the upper liquid-absorbing core 2 and the lower liquid-absorbing core 4, with the top end of the superstructure column 3 embedded in a pre-set groove in the upper liquid-absorbing core 2 and the bottom end embedded in a pre-set groove in the lower liquid-absorbing core 4.

[0036] like Figure 4 As shown, the metastructure 3 is formed by a flexible liquid-absorbing core 7 wrapped around the outer surface of the mechanical metamaterial 6 in the entire circumference. The mechanical metamaterial 6 serves as the load-bearing skeleton of the metastructure 3, providing the main mechanical support and vibration damping functions; the flexible liquid-absorbing core 7 serves as a capillary transport channel for the return of the working fluid, and at the same time utilizes the viscous dissipation effect of the liquid inside to absorb vibration energy.

[0037] The method for preparing the variable-capacity heat exchanger described in this embodiment includes the following steps: Step 1: Component Preparation The outer shell 1 and the lower shell 5 of the heat spreader are made of C5191 copper alloy plate. The required size of 300mm×300mm×2mm is obtained by stamping. A 2mm through hole is reserved by drilling for placing the liquid injection pipe.

[0038] The upper liquid-absorbing core 2 and the lower liquid-absorbing core 4 are made of multi-layer copper woven mesh with a mesh count of 400 and the material is T2 copper.

[0039] The flexible liquid-absorbing core 7 is made of sintered metal fiber felt with a porosity of 85%. The raw material is drawn T2 copper fiber with a diameter of 0.1 mm and a static height of 30 mm, prepared by high-temperature solid-state sintering. This material has good flexibility and deformation recovery ability, and can conformally deform with the deformation of the mechanical metamaterial 6.

[0040] The mechanical metamaterial 6 structure employs a negative stiffness honeycomb structure, made from 316L stainless steel, with a static height of 30 mm, and is fabricated using laser selective melting 3D printing. This structure exhibits a nonlinear force-displacement response during compression. Initially, it possesses high static stiffness to resist working loads, but its dynamic stiffness significantly decreases after entering the negative stiffness range, effectively isolating it from vibration excitation.

[0041] The flexible sealing structure uses corrugated copper foil, which is processed from T2 copper foil using a hot-pressing method to create a corrugated shape. This structure provides the ability to expand and contract in the thickness direction and exhibits excellent fatigue life.

[0042] The injection tube is made of T2 copper tubing with an outer diameter of 2mm.

[0043] Phase change working fluid: Deionized water or other coolant is used, and the filling rate (the ratio of working fluid volume to the internal volume of the cavity) is 20%-90%.

[0044] Step 2: Initial Assembly The lower outer shell 5, with the lower suction core 4 welded on it, is placed on the worktable of the pressure diffusion welding machine. The upper outer shell 1, with the upper suction core 2 welded on it, is placed upside down on top of the lower outer shell 5, and kept coaxial by a positioning fixture. The upper and lower outer shells are welded to the suction core by holding the machine at 600℃ and 1MPa for 10 minutes.

[0045] Step 2: Using a pressure diffusion welding machine, weld the lower outer shell 5 to the lower liquid-absorbing core 4 and the upper outer shell 1 to the upper liquid-absorbing core 2 respectively, so that the three layers of woven wire mesh are firmly attached to the surface of the outer shell. Pressure 1MPa, temperature 600℃, welding time 10 minutes.

[0046] Step 3: The cylindrical metal fiber felt (flexible liquid-absorbing core 7) prepared in Step 1 is fitted onto the outside of the mechanical metamaterial 6, and the two are tightly bonded together by induction welding to form an integrated metastructure column 3.

[0047] Step 4: Connect the upper outer shell 1, lower outer shell 5, flexible sealing structure, and superstructure column 3 by brazing. Temporarily bond the above components using brazing filler metal and fix them with 304 stainless steel clamps, then place them in a vacuum sintering furnace for welding. The temperature is 650℃, and the holding time is 30 minutes. Seal the injection pipe to the through hole of the upper outer shell 1 using induction welding. The superstructure column 3 is cylindrical and arranged in a square pattern inside the heat spreader.

[0048] Step 5: After leak testing, connect the injection pipe to the vacuum pump, reduce the gas pressure inside the heat exchanger to below 1 Pa, and inject deionized water as the working fluid at an injection rate of 60%. Completely seal the injection pipe using resistance welding to obtain a metamaterial-supported variable-capacity heat exchanger. Its length and width are 300 mm, and its overall static height is 34 mm.

[0049] Example 2 In this embodiment, the variable-capacity heat spreader prepared in Example 1 is applied to the thermal management and vibration reduction system of a Stirling refrigerator for aerospace applications.

[0050] 1. Application Configuration The upper outer shell 1 of the variable-capacity heat spreader is tightly bonded to the heating surface of the refrigerator using thermally conductive silicone grease, while the lower outer shell 5 is connected to the spacecraft structural plate using fasteners. During operation, the refrigerator generates periodic vibrations with a frequency of 20-60Hz and an amplitude of 1mm, while the heating surface generates a continuous heat dissipation of 200W.

[0051] 2. Heat transfer, vibration damping, and impact energy absorption performance Under the influence of heat input, the working fluid on the surface of the upper wick 2 vaporizes and absorbs heat, then diffuses through the cavity inside the heat spreader to the lower wick 4, where it condenses and releases heat on its surface. Subsequently, the liquid working fluid is drawn back to the upper wick 2 by the capillary pressure of the flexible wick 7, and the next vaporization process begins, thus realizing the transport of heat from the upper outer shell 1 to the lower outer shell 5.

[0052] Under vibration input, the mechanical metamaterial 6 and the flexible liquid-absorbing core 7 deform and absorb vibration energy. As the flexible liquid-absorbing core 7 reciprocates, the liquid working medium inside undergoes periodic extrusion and reabsorption, converting kinetic energy into heat energy through viscous dissipation, thus absorbing vibration energy.

[0053] Tests showed that the equivalent thermal conductivity of the heat spreader under this operating condition was higher than 10,000 W / (m·K), the vibration force transmission rate was less than 0.1, and the impact force transmission rate was less than 0.4.

[0054] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the scope of protection of the present invention.

Claims

1. A variable-capacity heat exchanger with a mechanical metamaterial composite support structure, characterized in that, include: An upper and lower outer shell arranged opposite each other along the thickness direction; An upper liquid-absorbing core is fixedly disposed on the inner surface of the upper outer shell, and a lower liquid-absorbing core is fixedly disposed on the inner surface of the lower outer shell; Multiple meta-pillars are sandwiched between the upper and lower absorbent cores, with the upper part of each meta-pillar contacting the upper absorbent core and the lower part of each meta-pillar contacting the lower absorbent core. A flexible sealing structure is disposed between the upper outer shell and the lower outer shell and arranged circumferentially, wherein the flexible sealing structure, together with the upper outer shell and the lower outer shell, forms a sealed cavity; The metastructure is formed by wrapping a flexible liquid-absorbing core in a mechanical metamaterial. The mechanical metamaterial serves as the load-bearing skeleton of the metastructure and can be made of metal or non-metal. The flexible liquid-absorbing core serves as a capillary transport channel for the return of the working fluid. The metamaterial is used to undergo reversible compression or stretching deformation in the thickness direction to achieve a volume change in the sealed cavity, while maintaining the capillary transport continuity of the flexible liquid-absorbing core during the deformation process. At the same time, the nonlinear mechanical response of the metamaterial enables vibration transmission attenuation and impact energy absorption.

2. The variable-capacity heat spreader according to claim 1, characterized in that, The mechanical metamaterial employs a periodic cell structure with extraordinary mechanical properties. The cell structure includes any one or more combinations of bistable buckling beam, arc beam, chiral honeycomb, concave honeycomb, star structure, or lattice structure.

3. The variable-capacity heat spreader according to claim 1, characterized in that, The flexible liquid-absorbing core is a flexible porous medium, and its material includes metal fiber felt or polymer.

4. The variable-capacity heat spreader according to claim 1, characterized in that, The cross-sectional shape of the superstructure column includes any one of the following: circular, elliptical, square, rectangular, or regular hexagonal; the planar arrangement of the superstructure column inside the variable-capacity heat exchanger includes any one of the following: square array, regular hexagonal array, concentric ring arrangement, or radial arrangement.

5. The variable-capacity heat spreader according to claim 1, characterized in that, The upper and lower liquid-absorbing cores are independent of each other and are selected from any one or more combinations of flexible porous media, sintered metal powder layers, sintered metal fiber layers, microgroove structures, woven metal mesh layers, or multi-layer composite structures.

6. The variable-capacity heat spreader according to claim 1, characterized in that, The flexible sealing structure is made of corrugated metal foil or elastic polymer material.

7. The variable-capacity heat spreader according to claim 1, characterized in that, The heat transfer direction of the variable capacity heat exchanger includes the thickness direction and the span direction; the mechanical function of the variable capacity heat exchanger includes vibration transmission attenuation between the upper and lower outer shell surfaces, and impact buffering and energy absorption between the upper and lower outer shell surfaces.

8. The variable-capacity heat spreader according to claim 1, characterized in that, The shape of the variable capacity heat exchanger plate includes square, circular, elliptical, or polygonal.

9. A method for preparing a variable-capacity heat exchanger according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Preparation of upper shell, lower shell, upper liquid-absorbing core, lower liquid-absorbing core, mechanical metamaterial, flexible liquid-absorbing core and flexible sealing structure; (2) Fix the upper suction core to the inner surface of the upper shell and fix the lower suction core to the inner surface of the lower shell; (3) The flexible liquid-absorbing core is wrapped around the outer surface of the mechanical metamaterial in the entire circumference to form a metastructure column; (4) Arrange the superstructure column on the upper surface of the lower liquid-absorbing core in a preset arrangement, cover the upper shell and the upper liquid-absorbing core on the superstructure column, and set a flexible sealing structure in the circumferential direction to seal the upper shell, lower shell and flexible sealing structure. (5) After evacuating the sealed cavity through the reserved injection port, inject the phase change working fluid, seal the injection port, and obtain a variable volume heat exchange plate.

10. The preparation method according to claim 9, characterized in that, In step (3), the cross-sectional shape of the superstructure column includes any one of the following: circular, elliptical, square, rectangular, and regular hexagonal. The planar arrangement inside the heat exchanger includes any one of the following: square array, regular hexagonal array, concentric ring arrangement, and radial arrangement. In step (5), the working fluid includes deionized water, acetone, and methanol, and the injection rate ranges from 20% to 90%.

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