A structural design method of near-zero refractive index thermal metamaterial with non-reciprocal heat transfer characteristics

Abstract

The application discloses a structure design method of near-zero refractive index thermal metamaterial with non-reciprocal heat transfer characteristics, which comprises a central heat source region, a near-zero refractive index thermal metamaterial structure layer surrounding the central region, and a thermal diode integrated on the outer layer of the structure layer; the thermal diode is composed of a high-thermal-conductivity base material and a plurality of regularly arranged low-thermal-conductivity air columns embedded in the high-thermal-conductivity base material, and unidirectional conduction of heat flow is realized by breaking structural symmetry. The metamaterial realizes efficient heat dissipation by using the near-zero refractive index thermal metamaterial, and effectively blocks the reverse transmission of external heat flow into the central region by using the non-reciprocal heat transfer characteristics of the thermal diode. The application overcomes the limitation of traditional heat conduction reciprocity, and provides an innovative solution for the thermal management of high-power-density electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of thermal management technology, specifically relating to a structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer characteristics. Background Technology

[0002] In the thermal management design of electronic packaging and high-power-density systems, a common and critical challenge is that certain core components or functional areas require efficient heat dissipation while also effectively isolating themselves from heat flow disturbances from the external environment or other heat-generating components. However, traditional heat conduction follows Fourier's law, which is a linear and symmetrical process, meaning that heat flux density is proportional to the temperature gradient but in the opposite direction. This reciprocal nature determines that the propagation of heat in the medium is bidirectional and symmetrical, making it difficult to achieve unidirectional, directional, and active control of heat flow.

[0003] In recent years, the development of thermal metamaterials has provided new ideas for thermal field control. For example, although near-zero refractive index thermal metamaterials have good heat dissipation performance, some heat energy can still be conducted to the central region that needs protection through various pathways. Long-term accumulation will accelerate material aging and affect system reliability. Therefore, there is an urgent need for a non-reciprocal thermal management solution that can efficiently remove internal heat while effectively blocking external heat flow. Current technologies lack a thermal diode with a simple structure, easy fabrication, and significant thermal rectification effect, as well as a solution for integrating it with thermal metamaterials. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer characteristics, overcoming the problems of reciprocity in the heat conduction process and the difficulty in achieving unidirectional control of heat flow in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution: A structural design method for a near-zero refractive index thermal metamaterial with non-reciprocal heat transfer properties is disclosed. The near-zero refractive index thermal metamaterial structure includes a central heat source region, a near-zero refractive index thermal metamaterial structural layer surrounding the central heat source region, and thermal diodes integrated on the outer layer of the near-zero refractive index thermal metamaterial structural layer. The thermal diodes are arranged in a predetermined direction, so that internal heat is rapidly discharged to the external environment along a forward path, while blocking external heat from entering the central heat source region along a reverse path.

[0006] Preferably, the thermal diode includes a substrate material and a plurality of regularly arranged void fillers embedded within the substrate material; the substrate material is a high thermal conductivity material and the void fillers are low thermal conductivity materials.

[0007] Preferably, the geometry of the thermal diode breaks the structural symmetry by designing the cone angle and length, so that when heat is conducted in the forward direction, a continuous low thermal resistance channel is formed, while when conducted in the reverse direction, the void filler interrupts the high thermal conductivity path, forcing heat to be conducted through the high thermal resistance channel.

[0008] Preferably, the substrate material is alumina ceramic, and the void filler is air.

[0009] Preferably, the near-zero refractive index thermal metamaterial has an overall size of 10 cm × 10 cm and a thickness of 0.3 cm; the central heat source region is a circle with a radius of 1 cm; the near-zero refractive index thermal metamaterial structural layer includes two ring structures with radii of 1.5 cm and 3 cm, respectively.

[0010] Preferably, in the near-zero refractive index thermal metamaterial structure layer, the inner annular structure near the central heat source region is a water-filled channel, in which the water circulates at an angular velocity of 100π rad / s.

[0011] Preferably, the near-zero refractive index thermal metamaterial with non-reciprocal heat transfer properties exhibits non-reciprocal heat transfer properties under different boundary conditions, and the thermal rectification coefficient... η Calculate using the following formula: T f and T r These represent the temperature difference between the hot and cold ends of the thermal diode during forward and reverse heat transfer, respectively.

[0012] Furthermore, based on the equivalent medium theory, a near-zero refractive index thermal metamaterial structure layer is combined with thermal diodes arranged in a predetermined direction. By adding thermal diodes to the outer layer of the near-zero refractive index thermal metamaterial structure, a near-zero refractive index thermal metamaterial with non-reciprocity is realized.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention proposes a near-zero refractive index thermal metamaterial with non-reciprocal heat transfer properties. Based on the equivalent medium theory, the near-zero refractive index thermal metamaterial structure is combined with thermal diodes arranged in a predetermined direction, breaking the reciprocity limitation of traditional heat conduction. This metamaterial can achieve efficient heat dissipation while the outer thermal diodes effectively block external heat flow disturbances, ensuring directional heat transfer along a positive path. Simulation results show that this thermal metamaterial achieves excellent non-reciprocal heat transfer performance under different boundary conditions, with a high thermal rectification coefficient. ηThe thermal conductivity can reach over 27.13. This invention overcomes the shortcomings of existing technologies, such as reciprocal heat conduction and difficulty in unidirectional heat flow control, and has broad application prospects in fields such as thermal management. Attached Figure Description

[0014] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a detailed dimensional drawing of the thermal diode; Figure 2 These are temperature distribution diagrams of a thermal diode during forward and reverse heat transfer: (a) forward heat transfer, (b) reverse heat transfer. Figure 3 This is a schematic diagram of a near-zero refractive index thermal metamaterial with non-reciprocity. Figure 4 The temperature distribution diagrams of the thermal diode during forward and reverse heat transfer when the temperature of both sides is 293.15 K are shown. (a) Forward heat transfer, (b) Reverse heat transfer. Figure 5 The temperature distribution diagrams of the thermal diode during forward and reverse heat transfer when the temperature of both sides is 283.15 K are shown. (a) Forward heat transfer, (b) Reverse heat transfer. Figure 6 The temperature distribution diagrams of the thermal diode during forward and reverse heat transfer when the temperature of both sides is 303.15 K are shown. (a) Forward heat transfer, (b) Reverse heat transfer. Figure 7 The temperature distribution diagrams of the thermal diode during forward and reverse heat transfer are as follows: (a) forward heat transfer, (b) reverse heat transfer. (The boundary conditions at the temperature measurement point are thermally insulated) are 293.15 K. Detailed Implementation

[0016] 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 some embodiments of the present invention, and not all embodiments. 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.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Example 1 The analogy between zero-refractive-index materials in photonics and near-zero-refractive-index materials in thermal science stems from their fundamental similarities in physical behavior. From the perspective of governing equations, under limiting conditions, both equations degenerate into the Laplace equation. From the perspective of interface behavior, the boundary conditions satisfied by the electric and magnetic fields when a zero-refractive-index optical material is matched with a conventional material correspond precisely to the temperature and heat flux density matching conditions when a material with infinite thermal conductivity is matched with a conventional material. The core of this analogy lies in the fact that both types of materials can achieve homogenized field distribution and transport characteristics with no phase difference (or no temperature difference). When the refractive index of an optical material approaches zero, the phase change of electromagnetic waves within it is almost zero, and the electric and magnetic fields are uniformly distributed, resulting in a tunneling effect. Similarly, in thermal science, when the thermal conductivity of a material approaches infinity, the temperature gradient approaches zero, the heat flux is uniformly distributed, and heat can pass through the material without obstruction, also forming a tunneling effect. Furthermore, combining near-zero-refractive-index thermal metamaterials with thermal diodes can achieve efficient heat dissipation while obtaining non-reciprocal heat transfer capabilities.

[0019] A thermal diode, as a device capable of non-reciprocal heat conduction, is key to high forward thermal conductivity and high reverse thermal resistance, enabling directional heat flow. Thermal rectification coefficient. η This reflects the difference in heat transfer capabilities between forward and reverse directions of a thermal diode, and its fundamental significance lies in quantifying the "unidirectional" characteristic of heat flow. An ideal thermal diode is similar to an electronic diode, ideally allowing heat to pass through in one direction while being significantly impeded in the opposite direction. The thermal rectification factor quantifies this characteristic into a specific numerical value. Thermal Rectification Factor η The calculation formula is: T f and T r These represent the temperature difference between the hot and cold ends of the thermal diode during forward and reverse heat transfer, respectively. η The larger the value, the better the unidirectional heat transfer effect of the thermal diode.

[0020] Therefore, the present invention provides a structural design method for thermal metamaterials with non-reciprocal heat transfer characteristics. Based on the equivalent medium theory, by adding thermal diodes to the outer layer of the near-zero refractive index thermal metamaterial structure, the design of a near-zero refractive index thermal metamaterial with non-reciprocity is realized, so that the metamaterial has good heat dissipation performance and excellent non-reciprocity.

[0021] The aforementioned thermal diode with non-reciprocal heat transfer characteristics includes a substrate material and multiple regularly arranged void fillers embedded within the substrate material. The substrate material is a high thermal conductivity material, and the void fillers are low thermal conductivity materials (such as air). By precisely designing the geometry of the thermal diode (including the cone angle and length), the structural symmetry is broken, allowing heat to form a continuous low thermal resistance channel when conducted in the forward direction. However, when conducted in the reverse direction, the void fillers interrupt the high thermal conductivity path, forcing heat to be conducted through the low thermal conductivity material, thereby achieving unidirectional heat flow. The substrate material is alumina ceramic with a thermal conductivity of 27 W / (m·K); the void fillers are air. The geometric parameters of the thermal diode can be adjusted according to the required equivalent thermal conductivity.

[0022] The structure of the near-zero refractive index thermal metamaterial with non-reciprocal properties includes: a central heat source region, a near-zero refractive index thermal metamaterial structural layer outside the central region, and a thermal diode integrated on the outer layer of the near-zero refractive index thermal metamaterial structural layer. The substrate size is 10 cm × 10 cm, and the overall thickness is 0.3 cm. The central region is a circle with a radius of 1 cm, and the radii of the two annular structures outside the central region are 1.5 cm and 3 cm, respectively.

[0023] The thermal diodes are arranged in a set direction so that internal heat can be quickly discharged to the external environment along the forward path, while blocking external heat from entering the internal area along the reverse path.

[0024] The aforementioned thermal metamaterial exhibits significant non-reciprocal heat transfer characteristics under different boundary conditions (such as different ambient temperatures and different cold source locations), and its thermal rectification coefficient is [missing information]. η It can reach over 27.13, which is higher than that of conventional structures.

[0025] In one embodiment of the present invention, the substrate of the thermal diode is alumina ceramic (thermal conductivity 27 W / (m·K)), and the air column is used as a low thermal conductivity filler. Figure 1 Detailed dimensions of two structures are shown. Transient simulation (300 s) was performed using COMSOL Multiphysics, with forward and reverse heat transfer boundary conditions set. The initial temperature was set to 293.15 K, with the left and right sides designated as a cold source and a heat source respectively. The heat source had a power of 1 W, and the remaining surfaces were thermally insulated. The temperature distribution is as follows. Figure 2 As shown. The temperature difference between the hot and cold ends is measured during forward and reverse heat transfer, and the thermal rectification coefficient is calculated according to formula (1). η It is 0.22.

[0026] As one embodiment of the present invention, such as Figure 3As shown, based on the equivalent medium theory, the aforementioned thermal diode structure is introduced into the outer layer of the original near-zero refractive index thermal metamaterial structure. This design aims to achieve: internal heat can be rapidly dissipated in the forward direction; external heat is effectively blocked, preventing its reverse transfer to the central region. Figure 3 Numerical simulations were performed on the structure shown. Alumina was chosen as the substrate material, with a thermal conductivity of 27 W / (m·K). The central element was SiC(6H). The inner annular structure near the central element was a water-filled channel, with the liquid circulating within it at an angular velocity of 100π rad / s. The outer annular structure was also made of alumina, combined with air according to the equivalent medium theory to achieve the required thermal conductivity while forming a thermal diode structure. A 10 W heat source was applied to the center of the structure, the left and right boundaries were set to 293.15 K, and the remaining boundaries were thermally insulated. The temperature distribution was as follows. Figure 4 As shown. The thermal rectification coefficient is calculated. η The value of 27.13 indicates that the structure has excellent non-reciprocal heat transfer performance.

[0027] In one embodiment of the present invention, the substrate material is alumina, with a thermal conductivity of 27 W / (m·K); the central element is SiC(6H); the inner annular structure near the central element is a water-filled channel in which the liquid circulates at an angular velocity of 100π rad / s; the outer annular structure is also made of alumina, combined with air according to the equivalent medium theory to achieve the required thermal conductivity while forming a thermal diode structure. A 10 W heat source is applied to the center of the structure, the left and right boundaries are set at 283.15 K, and the remaining boundaries are thermally insulated, with the temperature distribution as shown below. Figure 5 As shown. The thermal rectification coefficient is calculated. η The value is 34.42, indicating that the structure has excellent non-reciprocal heat transfer performance.

[0028] In one embodiment of the present invention, the substrate material is alumina, with a thermal conductivity of 27 W / (m·K); the central element is SiC(6H); the inner annular structure near the central element is a water-filled channel in which the liquid circulates at an angular velocity of 100π rad / s; the outer annular structure is also made of alumina, combined with air according to the equivalent medium theory to achieve the required thermal conductivity while forming a thermal diode structure. A 10 W heat source is applied to the center of the structure, the left and right boundaries are set at 303.15 K, and the remaining boundaries are thermally insulated, with the temperature distribution as shown below. Figure 6 As shown. The thermal rectification coefficient is calculated. η The value is 31.61, indicating that the structure has excellent non-reciprocal heat transfer performance.

[0029] In one embodiment of the present invention, the substrate material is alumina, with a thermal conductivity of 27 W / (m·K); the central element is SiC(6H); the inner annular structure near the central element is a water-filled channel in which the liquid circulates at an angular velocity of 100π rad / s; the outer annular structure is also made of alumina, combined with air according to the equivalent medium theory to achieve the required thermal conductivity while forming a thermal diode structure. A 10 W heat source is applied to the center of the structure, the three side boundaries are set to 293.15 K, and the remaining boundaries are thermally insulated, with the temperature distribution as shown below. Figure 7 As shown. The thermal rectification coefficient is calculated. η The value of 33.20 indicates that the structure has excellent non-reciprocal heat transfer performance.

[0030] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer properties, characterized in that, The structure of the near-zero refractive index thermal metamaterial includes a central heat source region, a near-zero refractive index thermal metamaterial structural layer surrounding the central heat source region, and thermal diodes integrated on the outer layer of the near-zero refractive index thermal metamaterial structural layer. The thermal diodes are arranged in a set direction so that internal heat is quickly discharged to the external environment along the forward path, while blocking external heat from entering the central heat source region along the reverse path.

2. The structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer properties according to claim 1, characterized in that, The thermal diode includes a substrate material and a plurality of regularly arranged void fillers embedded within the substrate material; the substrate material is a high thermal conductivity material and the void fillers are low thermal conductivity materials.

3. The structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer properties according to claim 2, characterized in that, The geometry of the thermal diode breaks the structural symmetry by designing the cone angle and length, so that when heat is conducted in the forward direction, a continuous low thermal resistance channel is formed, while when it is conducted in the reverse direction, the void filler interrupts the high thermal conductivity path, forcing heat to be conducted through the high thermal resistance channel.

4. The structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer properties according to claim 3, characterized in that, The substrate material is alumina ceramic, and the void filler is air.

5. The structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer properties according to claim 4, characterized in that, The near-zero refractive index thermal metamaterial has an overall size of 10 cm × 10 cm and a thickness of 0.3 cm; the central heat source region is a circle with a radius of 1 cm; the near-zero refractive index thermal metamaterial structural layer includes two ring structures with radii of 1.5 cm and 3 cm, respectively.

6. The structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer properties according to claim 5, characterized in that, In the near-zero refractive index thermal metamaterial structure layer, the inner annular structure near the central heat source region is a water-filled channel, in which the water circulates at an angular velocity of 100π rad / s.

7. The structural design method for near-zero refractive index thermal metamaterials with non-reciprocal heat transfer properties according to claim 6, characterized in that, The near-zero refractive index thermal metamaterial exhibiting non-reciprocal heat transfer properties demonstrates these properties under various boundary conditions, and the thermal rectification coefficient... η Calculate using the following formula: T f and T r These represent the temperature difference between the hot and cold ends of the thermal diode during forward and reverse heat transfer, respectively.

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