A topology regulation method for regulating a macro heat transfer network by pressure and realizing function switching

Abstract

This invention discloses a topology control method for pressure-regulated macroscopic heat transfer networks to achieve functional switching. Based on the governing equations of Keller's law, this invention regulates the heat flow transmission path in the macroscopic network by adjusting the pressure, i.e., adjusting the anisotropic thermal conductivity of the background and functional regions of the macroscopic heat transfer network. This enables functions such as thermal stealth and heat accumulation during heat transfer. Furthermore, combining the design concepts of thermal switches and variable thermal resistance, this invention presents a metamaterial model of a macroscopic heat transfer network with continuously adjustable stealth and heat accumulation functions. Through geometric control, different functions can be exhibited under different pressure differences, achieving adjustable heat flow and thermal function switching in the macroscopic heat transfer network. This method has potential applications in fields such as electronic chips, power devices, and wearable electronic devices.

Description

Technical Field

[0001] This invention relates to the field of metamaterials technology, and more specifically, to a topology control method for pressure-regulated macroscopic heat transfer networks and the realization of functional switching. Background Technology

[0002] Macroscopic thermal management issues are widespread in applications such as heat dissipation of electronic devices, temperature control of energy systems, building energy conservation, and thermal comfort of wearable devices. These systems often require directional heat transfer and regulation within limited spaces. To analyze and design heat transfer processes in complex structures, the thermal conduction behavior in continuous media is typically represented as a macroscopic heat transfer network composed of nodes and connecting channels. The heat flow path is then controlled by adjusting the equivalent thermal resistance or thermal conductivity of the network channels. In recent years, metamaterial design methods such as transformation thermals have been increasingly applied to the field of thermally functional devices, achieving progress in both theory and application. The key theoretical basis lies in the fact that the heat transfer relationship in macroscopic heat transfer networks satisfies Keller's theorem. This theorem reveals the correspondence between equivalent thermal conductivity in different directions, providing an important theoretical basis for achieving specific heat flow regulation functions through structural design. Therefore, based on the theory of spatial coordinate transformation and utilizing the design and construction of macroscopic networks using thermal metamaterials and thermal switches, thermal functions not possessed by macroscopic heat transfer networks can be realized. However, related practical applications are rarely reported, mainly because existing research on macroscopic heat transfer networks still focuses on static structures. Most solutions rely on fixed network geometry and thermal conductivity distribution to achieve heat flow control under specific operating conditions. Once the structure is fabricated, the equivalent thermal resistance distribution of each bond within the network is locked, and the heat flow path is also fixed. When the location of the heat source, heat load, or boundary conditions change, static networks often need to be adapted by replacing the structure, redesigning the topology, or introducing additional external cooling systems, making it difficult to achieve real-time switching of heat flow modes on the same network platform. Furthermore, practical devices generally face problems such as complex parameter distributions, difficulties in manufacturing materials with anisotropy, and challenges in meeting parameter ranges, making it difficult to achieve continuous adjustability and reversible switching. Therefore, there is an urgent need for a macroscopic heat transfer network control method more suitable for engineering implementation. Summary of the Invention

[0003] To address the aforementioned challenges in regulating macroscopic heat transfer networks, this invention provides a topology control method for pressure-controlled macroscopic heat transfer networks, enabling functional switching. This method uses the macroscopic heat transfer network as a carrier, applying pressure to cause a continuous and reversible change in the network's equivalent thermal conductivity, thereby forming a programmable thermal resistance distribution. Simultaneously, the equivalent medium relationship from Keller's theorem is introduced to constrain the correspondence between the radial and tangential equivalent thermal conductivity of functional regions, allowing for a controllable anisotropic heat transfer parameter distribution within the functional regions under geometric control. By applying radial or tangential pressure to the functional regions, this invention enables thermal functionality on the macroscopic heat transfer network and supports continuous adjustment and state switching within a compressible range, thus solving the problems of static structure, non-adjustable parameters, difficulty in functional switching, and insufficient engineering adaptability in existing macroscopic heat transfer networks.

[0004] This invention provides a topology control method for pressure-regulated macroscopic heat transfer networks and functional switching. The heat network consists of numerous repeating units, each connected by several bonds to form a local heat transfer path. The macroscopic heat transfer network is divided into an outer background region and an inner functional region. The outer background region maintains isotropy and provides a stable reference field. The inner functional region employs a combination structure of multiple concentric rings and radial connections, with two principal directions in polar coordinates: radial and tangential. Based on the transformation equation of Keller's theorem, geometric control is achieved by applying radial or tangential pressure to the functional regions, thereby adjusting the anisotropic thermal conductivity of the background and functional regions of the macroscopic heat transfer network. This completes the manipulation of the macroscopic network by the thermal field and realizes the functions of thermal concealment or thermal accumulation during heat flow transmission.

[0005] In this invention, the radial connection of the aforementioned functional areas refers to interconnecting multiple concentric rings along the radial direction to form a radially continuous heat transfer path. This allows the functional areas to exhibit orthogonal anisotropy in both the radial and tangential directions, facilitating thermal function regulation through radial and tangential pressure.

[0006] In this invention, the material used to form the network in the thermal field is a compressible composite graphene foam (95% graphene and 5% polydimethylsiloxane).

[0007] In this invention, the thermal functional device is an orthogonal network when it is not regulated (that is, its internal heat transfer path is regularly and symmetrically distributed along two mutually perpendicular (orthogonal) directions, radial and tangential). After geometric regulation, it exhibits a multi-layered ring structure at the center as the functional area, and the remaining area as the background network area. The entire heat transfer network is composed of compressible composite graphene foam.

[0008] In this invention, the equivalent thermal conductivity of the repeating unit in the macroscopic heat transfer network before and after regulation is denoted as follows: and Radial equivalent thermal conductivity is adopted and tangential equivalent thermal conductivity Describe the heat transfer capacity of the functional area; within the functional area, and If we consider them as two types of locally equivalent heat-conducting phases, then radial heat transfer is closer to a series combination, while tangential heat transfer is closer to a parallel combination. Based on this equivalence concept, the anisotropy of the functional region is characterized in the following form: ; The specific methods for applying pressure to functional areas are as follows: First, determine whether the target thermal function is thermal stealth or thermal accumulation; Next, the required radial thermal conductivity of the functional area network is determined. With tangential thermal conductivity ratio Distribution: When At time 1, the functional regions tend to be isotropic, and their guiding effect on heat flow weakens; this state corresponds to thermal transparency. 1, that is At times, it achieves the function of stealth during heat flow transfer; when 1, that is At the same time, it realizes the function of heat accumulation during heat flow transfer; Then, the unregulated Equivalent thermal conductivity is set as The required formulas (6) and (7) are derived by deduction. ; Finally, the equivalent thermal conductivity is mapped to geometric control parameters to determine the direction and magnitude of the pressure to be applied: ; When geometrically controlled pressure is applied radially, let ; When geometric control pressure is applied tangentially, let ; In the formula, The compression factor is 1. This represents the change in length in the corresponding direction. This represents the change in length of the structure along the radial direction. This represents the change in length of the structure along the tangential direction. Represents the equivalent thermal conductivity after radial and tangential modulation, respectively. .

[0009] In this invention, by controlling the radial and tangential pressure directions and deformation combinations, the functional switching between thermal stealth and thermal accumulation can be achieved. The specific technical means are as follows: Firstly, radial inward pressure is applied to the functional area, causing radial compressive deformation. > 0), while coordinating with tangential tension ( < 0), which makes the functional area form anisotropy with small radial direction and large tangential direction, thus achieving thermal stealth; Secondly, apply radial outward stretching to the functional area to cause radial tensile deformation. <0), while cooperating with tangential compression ( > 0), which makes the functional area form anisotropy with large radial direction and small tangential direction, so as to realize heat accumulation; Third, by simply changing the combination of radial and tangential pressurization, the two functions can be switched stably, continuously, and reversibly.

[0010] In this invention, the high temperature and low temperature of the macroscopic heat transfer network are set at 303K and 273K, respectively.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention utilizes the variable thermal resistance method of thermal switches to present a macroscopic heat transfer network model with adjustable stealth and aggregation functions. The invention is verified using finite element software. The structural geometry is set as an orthogonal macroscopic network, with the functional area being a multi-layered ring structure and the remainder being a background network. In this invention, the macroscopic heat transfer network structure has high and low temperatures set at 303K and 273K, respectively. This invention achieves continuous dynamic control of the macroscopic heat transfer network by applying pressure using different geometric control methods.

[0012] 2) This invention achieves continuous control of the equivalent thermal conductivity of the functional area through the method of thermal switch variable thermal resistance, thereby achieving the function of stealth-aggregation.

[0013] 3) This invention enables the switching of thermal functions by applying different pressure methods on the same macroscopic heat transfer network in a thermal field.

[0014] 4) This invention can be fully realized in a steady state. Attached Figure Description

[0015] Figure 1 The left sub-figure shows the geometric control method for stretching, and the right sub-figure shows the geometric control method for compression.

[0016] Figure 2 The diagram shows a macroscopic heat transfer network; (a): static network, (b): inward compression network, (c): outward compression network.

[0017] Figure 3 The diagram shows a simulated network. (a), (b), and (c) represent an uncontrolled macroscopic heat transfer network, a macroscopic heat transfer network achieving thermal stealth, and a macroscopic heat transfer network achieving heat accumulation, respectively.

[0018] Figure 4The simulation results show the macroscopic heat transfer network. The left and right subplots simulate the effects of heat accumulation and heat cloaking, respectively, and the arrows indicate the direction of heat flow.

[0019] Figure 5 This is an analysis diagram of the radial equivalent thermal conductivity and tangential equivalent thermal conductivity when the functional area is thermally stealthy under radial compression.

[0020] Figure 6 The changes in the central heat flux ratio and radial and tangential thermal conductivity ratios under thermal accumulation and thermal stealth states with deformation: (a) is a functional diagram of thermal stealth and thermal accumulation achieved by the functional region under geometric control of compression and stretching, based on the ratio of central heat flux to background network heat flux; (b) is a functional diagram of thermal stealth and thermal accumulation achieved by the functional region under geometric control of compression and stretching, based on heat flux data; (c) is a transformation curve based on the anisotropy ratio of the innermost sublayer.

[0021] Figure 7 Heat flux distribution and functional effects of thermal stealth and heat accumulation under different levels of regulation: It shows that as compression continues to increase, the heat flux in the central region is gradually suppressed. Figure 7 (d–f) illustrates the entire process of achieving thermal cloaking or thermal aggregation after continuous geometric control of the uncontrolled background network.

[0022] Figure 8 Schematic diagrams of the complete network and the network containing 50% random bad nodes: (a) is the baseline network where both keys and nodes are in a normal state. Figure 8 (b) is a schematic diagram of the network after introducing 50% random bad nodes, where the gray part represents the node position randomly selected as a bad node.

[0023] Figure 9 Thermal stealth defect performance analysis: (ac) is a simulation diagram of three radial compressions to achieve thermal stealth effect; (d–f) is the average curve of observed line heat flux in the thermal stealth area under the conditions of 10%, 50%, and 90% defects (n=5).

[0024] Figure 10 Thermal aggregation failure performance analysis: (ac) shows that when the network reaches a thermal aggregation state through geometric control, the above failure verification is repeated under three tangential compression control ranges. Figure 10 (d–f) presents the average curves of the observed linear heat flux in the heat accumulation region under the conditions of 10%, 50%, and 90% defects (n=5). Detailed Implementation

[0025] The present invention will now be described clearly and completely with reference to the accompanying drawings and embodiments.

[0026] This invention provides a topology control method for pressure-regulated macroscopic heat transfer networks and functional switching. Keller's theorem, the derivation of equivalent thermal conductivity, and product constraints form the theoretical foundation, used to prove the rationality of the scheme. Network structure partitioning, pressurization direction, deformation symbol definition, anisotropic adjustment, and functional switching conditions are the technical features for practical implementation. This invention does not merely propose a general concept of pressure control, but rather forms a detailed technical solution with a clear structure, quantifiable parameters, and repeatable steps. This invention provides a complete, specific, and clear disclosure of everything from the structural design of the macroscopic heat transfer network, region partitioning, radial and tangential pressurization methods, deformation definition, equivalent thermal conductivity mapping relationship, to anisotropic adjustment and functional determination rules. Those skilled in the art can implement this invention without creative effort based on the disclosure in this specification.

[0027] This method utilizes Keller's theorem to design the equivalent thermal conductivity of functional regions, while simultaneously controlling the macroscopic heat transfer network through pressure to achieve the function of switching thermal functional devices from collectors to invisibility cloaks.

[0028] This invention uses a two-dimensional steady-state heat conduction problem as its theoretical starting point. This problem satisfies Laplace-type governing equations under conditions without internal heat sources. For isotropic or anisotropic heat-conducting media, the temperature field... satisfy ; In the formula This is the equivalent thermal conductivity tensor. This equation has the same form as the two-dimensional steady-state conductivity problem. Therefore, the duality theory in two-dimensional conductive composite materials can also be used for the equivalent property analysis of thermally conductive composite systems.

[0029] Keller's theorem initially introduced the concept of dual transformation in the conductivity problem of two-dimensional composite media. This concept connects a microstructured system with its reciprocal system. The reciprocal system is typically constructed in two steps: first, by exchanging the constitutive parameters of the two phases; second, by introducing a corresponding direction interchange related to the two-dimensional dual transformation (equivalently understood as an exchange or orthogonal mapping of the principal directions). Within this framework, the equivalent conductivity tensor of the original system and the equivalent conductivity tensor of the reciprocal system satisfy a product constraint. This constraint holds when the two-dimensional duality condition is satisfied and can be extended to the case of two-dimensional composite materials containing local anisotropy.

[0030] Since steady-state thermal conduction and steady-state electrical conduction are both governed by Laplace-type equations, this invention rewrites Keller's theorem using the terminology of thermal conductivity. (The following text uses...) The equivalent thermal conductivity tensor of the original system is represented by... Let represent the equivalent thermal conductivity tensor of a reciprocal system. For a system consisting of two isotropic phases (with thermal conductivities of and ), ... For a two-dimensional composite system consisting of , Keller's theorem can be written in the following form: ; Equation (2) states that the equivalent tensors of the original system and the reciprocal system satisfy the constraint that "the product is a constant" in the two-dimensional dual sense. A corollary to this result is... ; When the microstructure satisfies the self-dual condition, the original system and the reciprocal system are equivalent in an equivalent sense, that is... At this point, we can obtain from equation (3) ; Furthermore, if the equivalent medium is isotropic in Cartesian coordinates, that is... Then equation (4) gives: ; ; This geometric mean form is also commonly found in classical results for two-dimensional self-dual two-phase systems and is widely used to verify effective properties. The above derivation is only used as a theoretical framework. The relationship between functional region anisotropy will be constructed using product constraints later, and the mathematical proof of dual transformation will not be elaborated here.

[0031] This invention provides a concrete and implementable pressure regulation topology control scheme, rather than merely a theoretical concept. The specification includes not only theoretical derivations but also clearly defines the macroscopic network structure, partitioning settings, pressurization direction combinations, deformation control methods, and specific conditions for function switching. These technical features work together to form a complete technical solution, enabling those skilled in the art to implement pressure regulation and thermal function switching based on the disclosure in this specification.

[0032] The macroscopic heat transfer network of this invention consists of a large number of repeating units, each unit being connected by several bonds to form a local heat transfer path. To incorporate geometric control into the equivalent thermal conductivity, this invention denotes the equivalent thermal conductivity of the unit before and after control as follows: and Here and This represents the change in equivalent thermal conductivity caused by geometric changes (e.g., the effect of effective length on equivalent thermal resistance). Therefore, in this invention, geometric control is equivalent to "continuously adjustable equivalent thermal conductivity" at the network level. In the macroscopic heat transfer network of this invention... and This corresponds to different compression states. After geometric adjustment, the macroscopic heat transfer network is divided into an outer background region and an inner functional region. The outer background region maintains approximately isotropic properties to provide a stable reference external field. The inner functional region adopts a combination structure of multiple concentric rings and radial connections. This structure has two principal directions in polar coordinates: radial and tangential. Therefore, this invention uses radial equivalent thermal conductivity. and tangential equivalent thermal conductivity Describe the heat transfer capacity of the functional area.

[0033] Within the functional area, if... and If we consider them as two types of locally equivalent heat-conducting phases, then radial heat transfer is closer to a series connection, while tangential heat transfer is closer to a parallel connection. Based on this equivalence concept, the anisotropy of the functional regions will be characterized in the following form: ; ; Equation (6) corresponds to the equivalent series connection behavior of the two phases in the radial direction; Equation (7) corresponds to the equivalent parallel connection behavior of the two phases in the tangential direction. From equations (6) and (7), we can directly obtain... ; ; Equation (8) yields a key conclusion: the product of the equivalent thermal conductivity in the two principal directions of the functional region is determined by the product of the equivalent thermal conductivity of the two phases. This product relationship is formally consistent with the determinant constraint given by Keller's theorem under the self-dual framework.

[0034] In polar coordinates, equation (8) can also be written as ; in and These can correspond to two types of local equivalent states within the functional area (e.g., the two states corresponding to stretching and compression before and after regulation). This notation is consistent with equation (4) in a physical sense: the product invariant of equivalent anisotropy is determined by the two phases.

[0035] In this invention, the geometric control amount is uniformly represented by the length shortening amount. Defined as the difference between the uncompressed length and the compressed length, i.e. ; In the formula This represents the feature length in the uncompressed state. This represents the feature length in the corresponding direction after compression. This definition guarantees... >0 indicates that compression has occurred in that direction, which also makes it easier to establish a direct correspondence between geometric deformation and material equivalent parameters.

[0036] Since the functional area structure has two principal directions, radial and tangential, in polar coordinates, this invention further decomposes geometric control into two components: radial and tangential. This invention uses... The amount of compression in the radial direction is expressed by... This represents the amount of compression in the tangential direction, and adheres to the following: when the network structure is compressed radially, this invention defines... >0; When the network structure is compressed tangentially, this invention defines >0; When the tangential aspect exhibits stretching (i.e., an increase in length), this invention uses a negative value to represent the effect, i.e. <0. The purpose of this definition is to make compression and stretching distinguishable by sign.

[0037] In this invention, the equivalent thermal conductivity of the background region is denoted as... The equivalent thermal conductivity of the local unit of the functional area before regulation is set as After applying geometric manipulation, another type of local state is denoted as... Therefore, at the macroscopic heat transfer network level, this invention employs a material mapping to map geometric control quantities to equivalent thermal conductivity, such as a first-order approximation. ; In the formula The compression factor is 1. This represents the length change in the corresponding direction (such as radial compression or tangential compression). In this invention, this formula transforms geometric control into an equivalent thermal conductivity input. Its function is to provide calculable network parameters for the macroscopic heat transfer network model, thereby facilitating subsequent calculations and functional evaluation.

[0038] When geometrically controlled pressure is applied radially, i.e., compression, it causes... ; When geometrically controlled pressure is applied tangentially, i.e., during tension, it causes... .

[0039] This invention can directly achieve a stable functional switch between thermal stealth and thermal accumulation by changing the combination of radial and tangential pressure loading. There is a clear, unique and repeatable correspondence between the pressure loading direction and the functional effect, which is a specific and implementable technical means.

[0040] Under the premise of satisfying equation (8), the core of geometric control of the functional area is transformed into the adjustment of the anisotropy ratio. This invention uses the following equation as an indicator to characterize the anisotropy intensity of the functional area. ; when At time 1, the functional regions tend to be isotropic, and their guiding effect on heat flow weakens; this state corresponds to thermal transparency. 1 (i.e.) When radial heat transfer is suppressed and tangential heat transfer dominates, heat flux more easily travels along the annular region and bypasses the central region. This state is crucial for the working mechanism of thermal stealth, namely, the significant reduction in heat flux in the central region; when 1 (i.e.) When anisotropy is at its peak, radial heat transfer is dominant, and heat flow more easily converges towards the central region. This state corresponds to the working mechanism of heat accumulation, namely, the enhanced heat flux in the central region. The above classification is a physical explanation based on the direct influence of anisotropy on the heat flow path, which provides a clear criterion for subsequent simulations.

[0041] This invention interprets geometric control as a continuous structural deformation process, which can manifest as a coupling of radial and tangential compression, or as the sequential application of deformation in different directions. Regardless of the control sequence, as long as it is within the compression range, and All can change continuously with geometric control. Therefore, / It can continuously span different orders of magnitude ranges, a property that theoretically gives the same device the potential for continuous adjustment and switchability in stealth, transparency, and aggregation.

[0042] In summary, the above theoretical methods are scientifically feasible. We further extend them to finite element simulation to verify their feasibility through numerical simulation, and then apply them to thermal fields to analyze the simulation results. Through formula derivation and verification, we finally derive the continuously dynamic and adjustable effect of the macroscopic heat transfer network. Figure 1 The geometric control methods for compression and stretching are introduced separately, which are the control methods of this invention. Figure 2 and Figure 3 Using schematic diagrams and macroscopic heat transfer network simulation diagrams, the direction and distribution of heat flow are introduced in an uncontrolled network, as well as when achieving heat accumulation and thermal stealth functions. Specific examples are provided below.

[0043] Example 1

[0044] This invention uses COMSOL Multiphysics finite element simulation to design a model of a thermal superstructure material. First, it is designed in a steady-state heat transfer module: the macroscopic heat transfer network consists of rectangles with a length of 1.44 cm and a width of 0.2 cm, and nodes measuring 0.2 × 0.2 cm. 2 The network is composed of squares, and the multi-layered ring structure of the functional areas is designed with anisotropic thermal conductivity when pressure is applied. The left boundary of the network structure is 303 K, and the right boundary is 273 K.

[0045] Subsequently, this invention re-expresses Keller's theorem in a thermal manner, realizing continuous dynamic control and thermal function on macroscopic heat transfer networks. For example... Figure 4 As shown, it can be observed that when the functional area exhibits a gathering function, heat flow converges towards the center; when the functional area exhibits a stealth function, heat flow bypasses the central area. Furthermore, the heat flow of the background network is unaffected. Figure 5 As shown, when the macroscopic heat transfer network is compressed and geometrically controlled, the radial and tangential thermal conductivity changes synchronously. When the radial thermal conductivity is greater than the tangential thermal conductivity, the functional area exhibits thermal stealth function. When pressure is applied to the macroscopic heat transfer network, the thermal conductivity of the entire functional area changes synchronously.

[0046] like Figure 6 As shown, using the ratio of heat flux in the central region to the heat flux in the background network as a metric, pressure was applied to the heat transfer network through two geometric control methods: compression and stretching. The heat flux ratio of the uncontrolled macroscopic heat transfer network was 1. The results show that when the heat flux ratio increases, the macroscopic heat transfer network achieves the function of heat accumulation in the functional area; when the heat flux ratio decreases, the macroscopic heat transfer network achieves the function of thermal stealth in the functional area. Geometric control not only changes the thermal conductivity value, but also changes the working interval position of the functional area in the parameter space, thereby supporting the continuous switching between thermal stealth and heat accumulation of the same network structure under different geometric control methods.

[0047] The macroscopic heat transfer network is continuously regulated using geometric control methods involving compression and stretching. For example... Figure 7 As shown, with continued increase in compression, the heat flux in the central region is gradually suppressed. When the compression reaches 0.3 cm, the radial thermal conductivity of the innermost sublayer is 0.0875 W / (K∙m), and the tangential thermal conductivity is 0.9925 W / (K∙m). At this point, the functional region exhibits a thermal stealth effect, and the heat flux decreases significantly. Figure 7 (a) shows a trend of gradually decreasing stealth data with adjustment. After achieving thermal stealth response, this invention further applies tangential compression based on the original geometric control to achieve functional switching. When the tangential compression is 2.1911 cm, the radial thermal conductivity of the innermost sublayer is 0.0889 W / (K∙m), and the tangential thermal conductivity is 1.1496 W / (K∙m). At this time, the functional region exhibits a thermal accumulation effect, and the heat flux increases significantly. Figure 7 (a) shows that the clustered data gradually increases with regulation. Figure 7 (d–f) illustrates the entire process of achieving thermal cloaking or thermal aggregation after continuous geometric control of the uncontrolled background network.

[0048] like Figure 8 The image shows a macroscopic heat transfer network with 50% random defects.

[0049] Furthermore, this invention verifies the performance of macroscopic heat transfer networks with three different levels of regulation to achieve heat accumulation and thermal stealth functions from the perspective of robustness testing, and conducts failure verification under three tangential compression regulation ranges. The results verify the robustness and functional stability of this invention under structural defects.

[0050] like Figure 9 As shown, at 10% defects, the heat flux suppression capability of the central region remains good, and the curve is close to that of the defect-free or low-defect case, indicating that minor structural failure has a limited impact on stealth functionality. At 50% defects, the heat flux suppression capability of the central region decreases significantly, and the curve deviates from the ideal stealth trend, indicating that moderate defects weaken the heat flux suppression effect in the central region. At 90% defects, the curve change indicates that stealth functionality is difficult to maintain, and the overall stealth effect tends to fail. Meanwhile, with increasing control, the overall stealth effect shows an enhancing trend, and the results at different defect ratios maintain a consistent trend, but the higher the defect ratio, the more significant the performance degradation. Figure 10 As shown, at 10% defect rate, the heat flux enhancement effect in the central region is almost unaffected, and the curve is basically consistent with the low defect state. At 50% defect rate, the heat accumulation ability decreases significantly, but the overall accumulation trend is still maintained, indicating that moderate defects lead to performance degradation but not functional failure. At 90% defect rate, the heat accumulation enhancement is significantly impaired, and the curve shows that the accumulation effect is difficult to establish, and the function is close to failure. The above results indicate that under low defect rate perturbation, the heat flux enhancement effect in the central region is almost unaffected or decreases significantly; under high defect rate perturbation, the thermal function is significantly impaired, and the function is close to failure.

[0051] Based on the thermal expression of Keller's theorem and a metamaterial model of a macroscopic heat transfer network, this invention proposes a topology control method for pressure-controlled macroscopic heat transfer networks to achieve functional switching. This method realizes continuous dynamic control of the macroscopic heat transfer network and achieves stealth and aggregation functions. Continuous control of the thermal conductivity of functional regions of the macroscopic heat transfer network is achieved through different control methods. Further verification of this method is obtained by continuously applying pressure, realizing a continuously adjustable stealth cloak-aggregator function under pressure-controlled thermal fields. The heat flux distribution of the macroscopic heat transfer network is then functionally verified through finite element simulation, a conventional device function verification method in this field, which accurately reflects the thermal behavior under pressure control. The verification results show that the control method of this invention is real and effective. This invention can solve the problem that static networks cannot be dynamically controlled in real time, and introduces thermal functions into the network, expanding its application scenarios. More importantly, the network model naturally supports mapping local parameter changes to path selection and flux distribution changes, thus providing a convenient carrier for realizing and evaluating thermal field reconstruction at the macroscopic scale. Furthermore, macroscopic heat transfer networks have been widely used in areas such as heat dissipation of electronic devices, cold plate structure design, and thermal management of building and energy storage systems.

Claims

1. A topology control method for pressure-regulated macroscopic heat transfer networks and achieving functional switching, characterized in that: The macroscopic heat transfer network consists of a large number of repeating units, each connected by several bonds to form a local heat transfer path. The macroscopic heat transfer network is divided into an outer background region and an inner functional region. The outer background region is isotropic and is used to provide a stable reference field. The inner functional region adopts a combination structure of multiple concentric rings and radial connections. This structure has two principal directions in polar coordinates: radial and tangential. Based on the transformation equation of Keller's theorem, geometric control is achieved by applying radial or tangential pressure to the functional region, thereby adjusting the anisotropic thermal conductivity of the background region and functional region of the macroscopic heat transfer network, completing the control of the thermal field on the macroscopic network, and realizing the function of thermal concealment or thermal accumulation during heat flow transmission.

2. The topology control method according to claim 1, characterized in that, The equivalent thermal conductivity of the repeating unit in the macroscopic heat transfer network before and after regulation is denoted as follows: and Radial equivalent thermal conductivity is adopted and tangential equivalent thermal conductivity Describe the heat transfer capacity of the functional area; Within the functional area, and If we consider them as two types of locally equivalent heat-conducting phases, then radial heat transfer is closer to a series combination, while tangential heat transfer is closer to a parallel combination. Based on this equivalence concept, the anisotropy of the functional region is characterized in the following form: ； The specific methods for applying pressure to functional areas are as follows: First, determine whether the target thermal function is thermal stealth or thermal accumulation; Next, the required radial thermal conductivity of the functional area network is determined. With tangential thermal conductivity ratio Distribution: When At time 1, the functional regions tend to be isotropic, and their guiding effect on heat flow weakens; this state corresponds to thermal transparency. 1, that is At times, it achieves the function of stealth during heat flow transfer; when 1, that is At the same time, it realizes the function of heat accumulation during heat flow transfer; Then, the unregulated Equivalent thermal conductivity is set as ; The required formulas (6) and (7) are derived by reverse derivation. ; Finally, the equivalent thermal conductivity is mapped to geometric control parameters to determine the direction and magnitude of the pressure to be applied: ； When geometrically controlled pressure is applied radially, let ； When geometric control pressure is applied tangentially, let ； In the formula, The compression factor is 1. This represents the change in length in the corresponding direction. This represents the change in length of the structure along the radial direction. This represents the change in length of the structure along the tangential direction. Represents the equivalent thermal conductivity after radial and tangential modulation, respectively. .

3. The topology control method according to claim 1, characterized in that, To achieve thermal stealth, pressure is applied using radial compression and tangential stretching; to achieve thermal accumulation, radial stretching and tangential compression are used.

4. The topology control method according to claim 1, characterized in that, The material used to form the network in the suitable thermal field is compressible composite graphene foam.

5. The topology control method according to claim 1, characterized in that, The high and low temperatures of the macroscopic heat transfer network are set at 303K and 273K, respectively.

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