Enhanced Passive Heat Dissipation Thermoelectric Leg and Its Design Method
By changing the geometric shape of the thermoelectric legs and increasing the side area to enhance passive heat dissipation, the problem of insufficient temperature difference between the hot and cold ends of existing thermoelectric devices is solved, and higher output power and energy conversion efficiency are achieved.
Patent Information
- Application Number
- CN202111631691.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-12-28
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2041-12-28
AI Technical Summary
Existing thermoelectric devices have limitations in improving output power and energy conversion efficiency, mainly because the thermal conductivity of thermoelectric materials is large and the Seebeck coefficient is small, resulting in insufficient temperature difference between the hot and cold ends, which in turn limits the thermoelectric conversion efficiency.
By changing the geometric shape of the thermoelectric legs, the side area is increased, thereby enhancing passive heat dissipation and increasing the temperature difference between the hot and cold ends. Specific methods include making the thermoelectric legs have a spiral structure, spoke structure or hoist shape, and optimizing the heat dissipation effect and internal resistance by adjusting geometric parameters such as spiral radius, number of turns, pitch, number of spokes and tension angle.
By enhancing passive heat dissipation and increasing the temperature difference between the hot and cold ends, the output power and energy conversion efficiency of thermoelectric devices are significantly improved. This method not only improves the performance of thermoelectric devices, but also reduces dependence on external cooling systems.
Smart Images
Figure CN114386257B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor thermal engineering and energy conversion, and particularly relates to a geometric design and preparation method of a thermoelectric leg with enhanced passive heat dissipation. Background Art
[0002] A thermoelectric device is a device that can convert thermal energy into electrical energy, and is mainly used in fields such as waste heat recovery and thermoelectric conversion. For example, it can convert the heat generated by industrial equipment, fireplaces, and other devices into electrical energy to achieve waste heat utilization, and can also be used as an energy conversion component of an isotope thermoelectric generator to convert the heat generated by the decay of an isotope source into electrical energy to supply electrical equipment. Among them, the thermoelectric leg is the core component for energy conversion inside the thermoelectric device, and the thermoelectric device is composed of multiple groups of thermoelectric legs connected to each other through electrodes.
[0003] A thermoelectric device is a device that directly converts thermal energy into electrical energy based on the Seebeck effect, without rotating components, belonging to static energy conversion. Its working principle can be briefly described as follows: when the thermoelectric leg is connected to the hot and cold ends of the thermoelectric device, a temperature difference will be formed at both ends of the thermoelectric leg, and the carriers inside it will aggregate under the action of the temperature gradient to form a built-in electric field. By connecting the thermoelectric legs made of N-type and P-type materials in series or parallel to form a thermoelectric device, an electric current will be generated when an external circuit is connected. In order to achieve a larger power output and energy conversion efficiency, researchers have found that the thermoelectric materials used in thermoelectric devices should have: 1) a smaller thermal conductivity and a larger Seebeck coefficient, so as to generate a larger temperature difference at both ends of the thermoelectric leg and convert the temperature difference into voltage with a large proportional coefficient; 2) a larger electrical conductivity, so that the thermoelectric leg has a smaller resistance. In addition, the temperature difference at both ends of the thermoelectric leg will also affect the thermoelectric conversion efficiency of the thermoelectric leg. Currently, researchers mainly increase the temperature difference by reducing the thermal conductivity of the thermoelectric material and using a water cooling device or a fan to forcibly cool the cold end of the thermoelectric device. Summary of the Invention
[0004] Aiming at the deficiencies of the prior art, the present invention provides a design method for a thermoelectric leg with enhanced passive heat dissipation, wherein the thermoelectric leg is connected to the hot and cold ends of the thermoelectric device, and the thermoelectric device converts thermal energy into electrical energy by using the temperature difference between the hot and cold ends. The design method includes: increasing the side area by changing the geometric shape of the thermoelectric leg to enhance the passive heat dissipation on the side, thereby increasing the temperature difference between the hot and cold ends and improving the output power of the thermoelectric device.
[0005] Furthermore, the method of increasing the side area by changing the geometric shape of the thermoelectric leg includes: making the orientation of the thermoelectric leg change continuously, so that the thermoelectric leg has a spiral structure.
[0006] Further, stretch the bottom surface along a spiral line to form the spiral shape of the above-mentioned thermoelectric leg, and adjust the side heat dissipation area and internal resistance of the above-mentioned thermoelectric leg through the spiral radius, the number of spiral turns, and the pitch.
[0007] Further, the method of increasing the side area by changing the geometric shape of the above-mentioned thermoelectric leg includes: the cross-section of the above-mentioned thermoelectric leg includes a spoke shape, thereby increasing the side area and internal resistance of the above-mentioned thermoelectric leg.
[0008] Further, adjust the side heat dissipation area and internal resistance of the above-mentioned thermoelectric leg through the first inner diameter, the first outer diameter, the number of spokes, the spoke opening angle, and the set height of the spoke-shaped thermoelectric leg.
[0009] Further, the method of increasing the side area by changing the geometric shape of the above-mentioned thermoelectric leg includes: setting the side surface of the above-mentioned thermoelectric leg to a concave-convex gourd shape, thereby changing the side shape of the above-mentioned thermoelectric leg.
[0010] Further, adjust the side heat dissipation area and internal resistance of the above-mentioned thermoelectric leg through the second inner diameter, the second outer diameter, the number of gourds, and the gourd height of the gourd-shaped thermoelectric leg.
[0011] The present invention also relates to a thermoelectric leg with enhanced passive heat dissipation obtained by using the above design method.
[0012] The present invention also relates to a method of stacking thermoelectric materials layer by layer through sintering to form a thermoelectric leg with a spiral shape, a spoke shape, or a gourd shape by using selective laser melting and stereolithography.
[0013] The present invention also relates to a method of preparing a thermoelectric leg with a spiral shape, a spoke shape, or a gourd shape from thermoelectric materials by using die pressing and subtractive manufacturing.
[0014] The inventor found that the performance parameters of thermoelectric devices are not only affected by the material properties of thermoelectric materials themselves, such as thermal conductivity, Seebeck coefficient, and electrical conductivity, but also related to the actual temperature difference between the hot and cold ends of the thermoelectric leg. Adjusting the geometric shape of the thermoelectric leg will also affect the temperature difference between the hot and cold ends, thereby optimizing and improving the output performance of thermoelectric devices.
[0015] The design method of the enhanced heat dissipation type thermoelectric leg proposed by the present invention increases the side area by adjusting the geometric shape of the thermoelectric leg, enhances the passive heat dissipation on the side, and changes its internal resistance and heat dissipation capacity by adjusting the geometric parameters of the thermoelectric leg, thereby improving its output performance and energy conversion efficiency. In the design method of the thermoelectric leg, the changes of the same geometric parameters on the side area and internal resistance of the thermoelectric leg are different due to different bottom areas. For thermoelectric legs with different bottom areas, there are optimal geometric parameters to make their output characteristics reach the best. According to the space size, working environment and heat source temperature where the thermoelectric leg is located, optimize the geometric parameters of the thermoelectric leg to make it have the best heat dissipation effect and internal resistance, and generate the best output performance parameters.
[0016] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Brief Description of the Drawings
[0017] Figure 1 Schematic diagram of the design method of the enhanced passive heat dissipation type electrothermal leg of the present invention.
[0018] Figure 2 Schematic diagram of the geometric shape of a spiral configuration thermoelectric leg provided in Embodiment 1 of the present invention;
[0019] Figure 3 Schematic diagram of spiral configuration thermoelectric legs with different geometric parameters provided in Embodiment 1 of the present invention;
[0020] Figure 4 Schematic diagram of the geometric shape of a spoke configuration thermoelectric leg provided in Embodiment 2 of the present invention;
[0021] Figure 5 Schematic diagram of spoke configuration thermoelectric legs with different geometric parameters provided in Embodiment 2 of the present invention;
[0022] Figure 6 Schematic diagram of the geometric shape of a gourd configuration thermoelectric leg provided in Embodiment 3 of the present invention;
[0023] Figure 7 Schematic diagram of gourd configuration thermoelectric legs with different geometric parameters provided in Embodiment 3 of the present invention;
[0024] Figure 8 Graph of the change of the Seebeck coefficient of the P-type thermoelectric material with temperature in the COMSOL simulation;
[0025] Figure 9 Graph of the change of the conductivity of the P-type thermoelectric material with temperature in the COMSOL simulation;
[0026] Figure 10It is a graph showing the variation of the thermal conductivity coefficient of a P-type thermoelectric material with temperature in COMSOL simulation. Specific implementation manners
[0027] The following will, in combination with the accompanying drawings and embodiments, provide a more detailed description of the specific implementation manners of the present invention, so as to better understand the solution of the present invention and the advantages of its various aspects. However, the specific implementation manners and embodiments described below are only for illustrative purposes and are not limitations on the present invention.
[0028] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.
[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection, an electrical connection or a connection capable of mutual communication; it may be directly connected, or indirectly connected through an intermediate medium, or it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0030] The following disclosure provides many different implementation manners or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various implementation manners and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.
[0031] The present invention provides a design method for enhancing a passive heat dissipation type thermoelectric leg, wherein the thermoelectric leg is installed inside a thermoelectric device and connects the hot and cold ends of the thermoelectric device. The thermoelectric device converts thermal energy into electrical energy by using the temperature difference between the hot and cold ends. The design method includes increasing the side area by changing the geometric shape of the thermoelectric leg to enhance the passive heat dissipation on the side, thereby increasing the temperature difference between the hot and cold ends and improving the output power of the thermoelectric device. Figure 1 It is a schematic diagram of the design method for the enhanced passive heat dissipation type electrothermal leg of the present invention. As shown in S110, the geometric shape of the thermoelectric leg can be changed, thereby increasing the side area of the thermoelectric leg and enhancing the heat dissipation. There are three methods to change the geometric shape of the thermoelectric leg, namely: 1) First, S121 is based on changing the orientation, and the corresponding S131 is a spiral configuration thermoelectric leg, and the model diagram is as shown in S131; 2) Second, S122 is based on increasing the cross-sectional perimeter of the thermoelectric leg, and the corresponding S132 is a spoke configuration thermoelectric leg, and the model diagram is as shown in S132; Third, S133 is based on changing the side shape, and the corresponding S133 is a gourd configuration thermoelectric leg, and the model diagram is as shown in S133. These three methods can all optimize the heat dissipation effect and output by adjusting the geometric parameters of the thermoelectric leg to adapt to different working environments (step S140). The following will be described in detail respectively.
[0032] Embodiment 1
[0033] The method of increasing the side area by changing the geometric shape of the thermoelectric leg includes: continuously changing the orientation of the thermoelectric leg, so that the thermoelectric leg has a spiral structure, as Figure 2 shown. The thermoelectric leg with this spiral structure is called a spiral configuration thermoelectric leg.
[0034] Figure 2 It is a schematic diagram of the geometric shape of a spiral configuration thermoelectric leg proposed based on changing the orientation of the thermoelectric leg provided in Embodiment 1 of the present invention, including the following parameters: the bottom radius R1, the spiral radius r1, the number of spiral turns n1, and the pitch L1 of the spiral configuration thermoelectric leg.
[0035] The spiral-shaped thermoelectric leg is based on changing the orientation of the thermoelectric leg to create an angle between the orientation of the thermoelectric leg and the direction of heat flow transmission, thereby increasing the side area. To reduce the space volume occupied by the thermoelectric leg, the orientation of the thermoelectric leg changes continuously and spirals upward, and the thermoelectric leg has a spiral structure. The spiral-shaped thermoelectric leg is formed by stretching its bottom surface along a helix, where the bottom surface is always parallel to the horizontal plane during the process along the helix. Therefore, the spiral radius r1, the number of spiral turns n1, and the pitch L1 do not change the volume of the spiral-shaped thermoelectric leg, and the bottom area and height of the spiral-shaped thermoelectric leg determine the volume of the spiral-shaped thermoelectric leg. Thus, the space volume occupied by the spiral-shaped thermoelectric leg is a cylinder with a bottom radius equal to the sum of the bottom radius R1 and the spiral radius r1. When the height of the spiral-shaped thermoelectric leg is fixed, there is an inverse correlation between the number of spiral turns n1 and the pitch L1. By changing the spiral radius r1, the number of turns n1, and the pitch L1, the angle between the orientation of the thermoelectric leg and the heat flow can be changed. The larger the spiral radius r1 and the number of turns n1, and the smaller the pitch L1, the larger the resulting angle, the larger the side area, and the better the heat dissipation effect. As the angle increases, the movement path of the carriers in the thermoelectric leg also extends, increasing the internal resistance of the spiral-shaped thermoelectric leg. In the optimization of the heat dissipation effect and internal resistance of the spiral-shaped thermoelectric leg, there is an inverse correlation in the geometric parameter design. Therefore, it is necessary to consider the working environment, the space occupied, and the temperature of the heat source in contact with the spiral-shaped thermoelectric leg, and change the spiral radius r1, the number of turns n1, and the pitch L1 according to the bottom area of the spiral-shaped thermoelectric leg to achieve the best-matched heat dissipation effect and internal resistance, and exhibit the best output performance.
[0036] Figure 3 It is a schematic diagram of spiral-shaped thermoelectric legs with different geometric parameters provided in Embodiment 1 of the present invention. Figure 3 (1) and (2) respectively represent schematic diagrams of the structure with the number of spiral turns n1 = 1 and reducing the bottom area of the spiral-shaped thermoelectric leg. The geometric design method of the thermoelectric leg with a spiral shape provided in the embodiment of the present invention does not limit the bottom shape to be circular, and can be set to any shape such as a rectangle, a polygon, etc. Figure 3 (3) represents a spiral-shaped thermoelectric leg with a square bottom shape. In the geometric design of the spiral-shaped thermoelectric leg, different combinations of the spiral radius r1 and the pitch L1 can be made to achieve specific heat dissipation effects and output parameters. Figure 3 (4) and (5) respectively represent schematic diagrams of the structures of spiral-shaped thermoelectric legs with different combinations of the pitch L1 and different spiral radii r1.
[0037] The geometric design method of the spiral configuration thermoelectric leg proposed in Embodiment 1 of the present invention. The spiral structure is formed by stretching the bottom surface along a spiral line to form the spiral shape of the thermoelectric leg. The side heat dissipation area and internal resistance of the thermoelectric leg are adjusted by the spiral radius, the number of spiral turns, and the pitch. Specifically, an angle is generated between the orientation of the thermoelectric leg and the heat flow, so that it has a larger side area, enhancing the heat dissipation on the side, thereby increasing the temperature difference between the hot and cold ends. The change in the geometric shape of the spiral configuration thermoelectric leg also brings about a change in resistance. In the design method of the spiral configuration thermoelectric leg, the change of the same geometric parameters in the side area and internal resistance of the thermoelectric leg is different due to different bottom surface areas. For spiral configuration thermoelectric legs with different bottom surface areas, there are optimal geometric parameters to make their output characteristics reach the best. According to the space size, working environment, and heat source temperature of the spiral configuration thermoelectric leg, the geometric parameters are optimized to make it have the best heat dissipation effect and internal resistance, and generate the best output parameters.
[0038] The preparation method of the spiral configuration thermoelectric leg proposed in Embodiment 1 of the present invention can use various thermoelectric materials such as bismuth telluride and lead telluride as the molding materials, including the following four preparation methods:
[0039] 1. Fill the thermoelectric material powder or thermoelectric slurry into a mold with the geometric shape proposed in the present invention, and after high-temperature pressing or low-temperature pressing and shaping, perform high-temperature sintering to prepare the spiral configuration thermoelectric leg proposed in the embodiment of the present invention;
[0040] 2. Use a processing tool such as a cutter to process a bulk material with thermoelectric performance by cutting, shaving, etc. through subtractive manufacturing to prepare the spiral configuration thermoelectric leg proposed in the embodiment of the present invention;
[0041] 3. Based on the forming method of extrusion molding 3D printing, stack the thermoelectric slurry with a certain viscosity layer by layer to form the spiral configuration thermoelectric leg proposed in the embodiment of the present invention, and then perform high-temperature sintering to obtain it;
[0042] 4. Use the method of selective laser melting or stereolithography to stack the spiral configuration thermoelectric leg proposed in the embodiment of the present invention by layer-by-layer sintering.
[0043] The preparation method of the spiral configuration thermoelectric leg proposed in the present invention includes but is not limited to the above four preparation methods or a combination of multiple preparation methods.
[0044] The output of spiral-configuration thermoelectric legs with different geometric parameters was simulated using the finite element analysis software COMSOL. The output performance of spiral-configuration thermoelectric legs with different geometric parameters and that of the control group of cylindrical thermoelectric legs are shown in Table 1. The bottom surface of the spiral-configuration thermoelectric leg is a circle with a radius R1 = 2 mm, and the bottom surface of the control group of cylindrical thermoelectric legs is a circle with a radius of 2 mm. The heights of both the spiral-configuration thermoelectric leg and the control group of cylindrical thermoelectric legs are 10 mm. Therefore, the spiral-configuration thermoelectric leg and the control group of cylindrical thermoelectric legs have the same mass. In the simulation calculation, the hot ends of all thermoelectric legs are placed on the surface of a heat source with a surface temperature of 400 K and are in air at a temperature of 293.15 K for natural heat dissipation. The surface convective heat transfer coefficient is 6 W / (m 2 ·K), and radiation heat dissipation is ignored; P-type bismuth telluride is used as the thermoelectric material for both the spiral-configuration thermoelectric leg and the cylindrical thermoelectric leg, Figure 8 , 9 , 10 respectively represent the relationships of the Seebeck coefficient, electrical conductivity, and thermal conductivity of P-type bismuth telluride with temperature.
[0045] Table 1. Output performance of spiral-configuration thermoelectric legs with different geometric parameters and the control group of cylindrical thermoelectric legs
[0046]
[0047]
[0048] From the comparison of the above embodiments, it can be seen that the output power of the spiral-configuration thermoelectric legs is higher than that of the control group of cylindrical ones in all cases. Moreover, in the above situation, the output power is the highest when r1 = 0.5 mm, n1 = 10, and L1 = 1 mm.
[0049] Example 2
[0050] This example proposes a second design method for enhancing the passive heat dissipation type of thermoelectric legs, that is, a spoke structure is set on the cross-section of the thermoelectric leg, thereby increasing the cross-sectional perimeter of the thermoelectric leg, further increasing the lateral area of the thermoelectric leg and enhancing heat dissipation. The thermoelectric leg with this spoke structure is simply referred to as a spoke-configuration thermoelectric leg.
[0051] Figure 4 is a schematic diagram of the geometric shape of a spoke-configuration thermoelectric leg provided in Example 2 of the present invention, which is proposed based on increasing the cross-sectional perimeter of the thermoelectric leg and setting a spoke structure on the cross-section of the thermoelectric leg, and includes the following parameters: the first outer diameter R2, the first inner diameter R3, the difference in inner and outer radii ΔR1, the spoke length L2, the number of spokes n2, and the spoke opening angle θ of the spoke-configuration thermoelectric leg.
[0052] The spoke-configuration thermoelectric leg is based on increasing the cross-sectional perimeter of the thermoelectric leg. A spoke structure is set in the cross-section of the thermoelectric leg, and the cross-sectional perimeter is increased by changing the number of spokes n2, the spoke opening angle θ, and the spoke length L2, thereby increasing the heat dissipation area of the thermoelectric leg and improving the heat dissipation effect. The spoke-configuration thermoelectric leg is formed by stretching a bottom surface with a spoke structure along a vertical line perpendicular to the bottom surface by a set height. The space volume occupied by the spoke-configuration thermoelectric leg is a cylinder with a bottom radius of the first outer diameter R2. Among them, the spoke length L2 is equal to the difference ΔR1 between the first outer diameter R2 and the first inner diameter R3 in the spoke-configuration thermoelectric leg. Increasing the number of spokes n2, the spoke opening angle θ, and the spoke length L2 can increase the cross-sectional perimeter of the spoke-configuration thermoelectric leg, and further increase the side heat dissipation area; although increasing the first inner diameter R3 can increase the cross-sectional perimeter, it will decrease the spoke length L2 and at the same time decrease the specific heat dissipation area (the ratio of the heat dissipation area to the volume) of the spoke-configuration, thereby reducing the heat dissipation effect. Therefore, in order to achieve the best heat dissipation effect, the first inner diameter R3 should be reduced, and the first outer diameter R2 and the spoke length L2 should be increased. Since the spoke-configuration thermoelectric leg is stretched vertically upward from the bottom surface, the internal resistance is only affected by the bottom area and the set height. By changing the geometric parameters of the spoke-configuration thermoelectric leg, the bottom area can be changed to adjust the internal resistance. According to the working environment, the space where the spoke-configuration thermoelectric leg is located, and the temperature of the heat source it contacts, optimize the parameters of the thermoelectric leg to make it have the best heat dissipation effect and internal resistance, and generate the best output parameters.
[0053] Figure 5 It is a schematic diagram of spoke-configuration thermoelectric legs with different geometric parameters provided in Embodiment 2 of the present invention. Figure 5 (1) represents a schematic structural diagram of reducing the first inner diameter R3 of the spoke-configuration thermoelectric leg and increasing the spoke length L2. Figure 5 (2) represents a schematic structural diagram of increasing the first inner diameter R3, reducing the spoke length L2, and increasing the number of spokes n2 (n2 = 9); in the geometric design of the spoke-configuration thermoelectric leg, spokes with different spoke lengths L2 and spoke opening angles θ can be combined to achieve specific heat dissipation effects and output parameters. Figure 5 (3) represents a schematic structural diagram of a spoke-configuration thermoelectric leg with different spoke lengths L2 and spoke opening angles θ. The design method of the spoke-configuration thermoelectric leg provided in the embodiment of the present invention does not limit the bottom surface shape to be circular, and can be set to any shape, and the position of the spokes can be at any position of the bottom surface shape. Figure 5 (4), (5) represent spoke-configuration thermoelectric legs with a square bottom surface shape, where Figure 5 In the spoke-configuration thermoelectric leg shown in (4), the spokes are set at the center position of the bottom side length. Figure 5 In the spoke-configuration thermoelectric leg shown in (5), the spokes are set at both ends of the bottom side length, and the spokes have different lengths L2.
[0054] The geometric design method of the spoke-configuration thermoelectric leg proposed in Embodiment 2 of the present invention adjusts the side heat dissipation area and internal resistance of the thermoelectric leg through parameters such as the first inner diameter, the first outer diameter, the number of spokes, the spoke opening angle, the spoke length, and the set height of the spoke-configuration thermoelectric leg. Specifically, a spoke structure is set in the cross-section of the thermoelectric leg to increase the cross-sectional perimeter, so that it has a larger side area, enhancing the heat dissipation on the side, thereby increasing the temperature difference between the hot and cold ends. The change in the geometric shape of the spoke-configuration thermoelectric leg also brings about a change in resistance. In the geometric design method of the spoke-configuration thermoelectric leg, the change in the side area and internal resistance of the thermoelectric leg caused by the same geometric parameters varies due to different bottom areas. For the spoke-configuration thermoelectric legs with different bottom areas, there are optimal geometric parameters to make their output characteristics reach the best. According to the space size, working environment, and heat source temperature of the spoke-configuration thermoelectric leg, optimize the geometric parameters to make it have the best heat dissipation effect and internal resistance, and generate the best output parameters.
[0055] The preparation method of the spoke-configuration thermoelectric leg proposed in Embodiment 2 of the present invention can use various thermoelectric materials such as bismuth telluride and lead telluride as the molding materials, including the following four preparation methods:
[0056] 1. Fill the thermoelectric material powder or thermoelectric slurry into a mold with the geometric shape proposed in the present invention, and after high-temperature pressing or low-temperature pressing and shaping, perform high-temperature sintering to prepare the spoke-configuration thermoelectric leg proposed in the embodiments of the present invention;
[0057] 2. Use processing tools such as a cutter to process a bulk material with thermoelectric performance by cutting, shaving, etc. through subtractive manufacturing to prepare the spoke-configuration thermoelectric leg proposed in the embodiments of the present invention;
[0058] 3. Based on the forming method of extrusion molding 3D printing, stack the thermoelectric slurry with a certain viscosity layer by layer to form the spoke-configuration thermoelectric leg proposed in the embodiments of the present invention, and then perform high-temperature sintering to obtain it;
[0059] 4. Use the method of selective laser melting or stereolithography to stack the spoke-configuration thermoelectric leg proposed in the embodiments of the present invention by layer-by-layer sintering.
[0060] The preparation method of the spoke-configuration thermoelectric leg proposed in the present invention includes but is not limited to the above four preparation methods or a combination of multiple preparation methods.
[0061] The output of thermoelectric legs with spoke configurations having different geometric parameters was simulated using the finite element analysis software COMSOL. The output performances of thermoelectric legs with spoke configurations having different geometric parameters and the control group of cylindrical thermoelectric legs are shown in Table 2. The bottom surface of the control group of cylindrical thermoelectric legs is a circle with a radius of 2 mm. The first outer diameter of the thermoelectric legs with spoke configurations is R2 = 2.25 mm, and the first inner diameter R3 varies with the number of spokes n2 and the spoke angle θ to achieve the same bottom surface area as the control group of cylindrical thermoelectric legs. The heights of both the thermoelectric legs with spoke configurations and the control group of cylindrical thermoelectric legs are 10 mm. Therefore, the thermoelectric legs with spoke configurations and the control group of cylindrical thermoelectric legs have the same mass. In the simulation calculation, the hot ends of all thermoelectric legs are placed on the surface of a heat source with a surface temperature of 400 K and are in air at a temperature of 293.15 K for natural heat dissipation. The surface convective heat transfer coefficient is 6 W / (m 2 ·K), and radiation heat dissipation is ignored. P-type bismuth telluride is used as the thermoelectric material for both the thermoelectric legs with spoke configurations and the cylindrical thermoelectric legs. Figure 8 , 9 , 10 represent the relationships of the Seebeck coefficient, electrical conductivity, and thermal conductivity of P-type bismuth telluride with temperature, respectively.
[0062] Table 2. Output performances of thermoelectric legs with spoke configurations having different geometric parameters and the control group of cylindrical thermoelectric legs
[0063]
[0064] From the comparison of the above embodiments, it can be seen that the output power of the thermoelectric legs with spoke configurations is higher than that of the control group of cylindrical ones. Moreover, in the above cases, when n2 = 9; θ = 25°, L = 0.757 mm, and R3 = 1.493 mm, the output power is the highest.
[0065] Example 3
[0066] Example 3 discloses another design method for enhancing the passive heat dissipation type of thermoelectric legs, which is to set the side surface of the thermoelectric legs into a concave-convex gourd shape, thereby changing the side surface shape of the thermoelectric legs. As Figure 6 shown. This gourd-shaped thermoelectric leg is simply referred to as a gourd configuration thermoelectric leg.
[0067] Figure 6 is a schematic diagram of the geometric shape of a gourd configuration thermoelectric leg proposed based on changing the side surface shape of the thermoelectric leg and setting a concave-convex gourd structure on the side surface of the thermoelectric leg provided in Embodiment 3 of the present invention, including the following parameters: the second inner diameter R4, the second outer diameter R5, the inner-outer radius difference ΔR2, the gourd length L3, the number of gourds n3, and the gourd height L4.
[0068] The gourd-shaped thermoelectric leg is based on changing the side shape of the thermoelectric leg, with a concave-convex gourd shape set on the side of the thermoelectric leg. By changing the gourd length L3, the number of gourds n3, and the gourd height L4, the side area is increased to improve the heat dissipation effect. The gourd-shaped thermoelectric leg is formed by stretching its bottom surface along a vertical line perpendicular to the bottom surface. During the stretching process, the bottom radius changes with the height of the vertical line to form a gourd structure. When the bottom radius is the largest, it corresponds to the second outer diameter R5, and when the bottom radius is the smallest, it corresponds to the second inner diameter R4. The space volume occupied by the gourd-shaped thermoelectric leg is a cylinder with a bottom radius of the second outer diameter R5. The second inner diameter R4 and the second outer diameter R5 are used to form the gourd structure, so the gourd length L3 is equal to the difference between the second outer diameter R5 and the second inner diameter R4. Increasing the number of gourds n3 and the gourd length L3 and decreasing the gourd height L4 can highlight the gourd structure on the side of the thermoelectric leg, thereby increasing the side area. Among them, when the height of the gourd-shaped thermoelectric leg is fixed, there is an inverse relationship between the number of gourds n3 and the gourd height L4. Therefore, to increase the side area, the gourd height L4 needs to be decreased while increasing the number of gourds n3; to increase the gourd length L3, the second inner diameter R4 should be decreased and the second outer diameter R5 should be increased. Since the cross-sectional radius of the gourd-shaped thermoelectric leg changes with the height of the vertical line during the vertical stretching process from the bottom surface upward, its internal resistance is affected by the height of the thermoelectric leg and the gourd structure. The second inner diameter R4 of the gourd-shaped thermoelectric leg should be increased to increase the cross-sectional area and decrease the internal resistance. In the optimization of the heat dissipation effect and internal resistance of the gourd-shaped thermoelectric leg, there is an inverse relationship in the geometric parameter design. Therefore, it is necessary to optimize the parameters of the thermoelectric leg according to the working environment, the space it occupies, and the temperature of the heat source it contacts to make it have the best heat dissipation effect and internal resistance and generate the best output parameters.
[0069] Figure 7 It is a schematic diagram of gourd-shaped thermoelectric legs with different geometric parameters provided in Embodiment 3 of the present invention. In the geometric design of the gourd-shaped thermoelectric leg, different numbers of gourds n3 can be set, and different combinations of the gourd length L3, the gourd height L4, as well as the different second inner diameter R4 and the second outer diameter R5 can be made to achieve specific heat dissipation effects and output parameters. Figure 7 (1) represents a schematic structural diagram of a gourd-shaped thermoelectric leg with the number of gourds n3 = 9 and different combinations of the gourd height L4; Figure 7 (2) represents a schematic structural diagram of a gourd-shaped thermoelectric leg with different combinations of the gourd length L3, the gourd height L4, as well as the second inner diameter R4 and the second outer diameter R5. The side of the gourd-shaped thermoelectric leg provided in the embodiment of the present invention is not limited to using an arc to connect the inner and outer radii, and can be set as any curve. Figure 5 (3) and (4) respectively represent gourd-shaped thermoelectric legs with straight lines and circles on the side to connect the inner and outer radii. The geometric design method of the gourd-shaped thermoelectric leg provided in the embodiment of the present invention is not limited to the bottom surface being circular, and can be set as any shape.Figure 7 (5) represents a spoke - shaped thermoelectric leg with a square bottom surface shape, and has different combinations of gourd lengths L3 and gourd heights L4.
[0070] In this embodiment, the side heat dissipation area and internal resistance of the thermoelectric leg are adjusted by the second inner diameter, the second outer diameter, the number of gourds, the gourd height, and the gourd length of the gourd - shaped thermoelectric leg. Specifically, the geometric design method of the gourd - shaped thermoelectric leg proposed in Embodiment 3 of the present invention sets concave - convex gourd shapes on the side surface of the thermoelectric leg to increase the side area and enhance heat dissipation on the side surface, thereby increasing the temperature difference between the hot and cold ends. The change in the geometric shape of the gourd - shaped thermoelectric leg also brings about a change in resistance. In the geometric design method of the gourd - shaped thermoelectric leg, the change in the side area and internal resistance of the thermoelectric leg caused by the same geometric parameters is different due to different bottom areas. For gourd - shaped thermoelectric legs with different bottom areas, there are optimal geometric parameters to make their output characteristics reach the best. According to the space size, working environment of the gourd - shaped thermoelectric leg and the temperature of the heat source it contacts, optimize the geometric parameters to make it have the best heat dissipation effect and internal resistance, and generate the best output parameters.
[0071] The preparation method of the gourd - shaped thermoelectric leg proposed in Embodiment 3 of the present invention can use various thermoelectric materials such as bismuth telluride and lead telluride as molding materials, including the following four preparation methods:
[0072] 1. Fill the thermoelectric material powder or thermoelectric slurry into a mold with the geometric shape proposed in the present invention, and after high - temperature pressing or low - temperature pressing for shaping, perform high - temperature sintering to prepare the gourd - shaped thermoelectric leg proposed in this embodiment of the present invention;
[0073] 2. Use a processing tool such as a cutter to process a bulk material with thermoelectric properties by subtractive manufacturing methods such as cutting and shaving to prepare the gourd - shaped thermoelectric leg proposed in this embodiment of the present invention;
[0074] 3. Based on the forming method of extrusion - based 3D printing, stack the thermoelectric slurry with a certain viscosity layer by layer to form the gourd - shaped thermoelectric leg proposed in this embodiment of the present invention, and then perform high - temperature sintering to obtain it;
[0075] 4. Use the method of selective laser melting or stereolithography, and stack layer by layer through sintering to form the gourd - shaped thermoelectric leg proposed in this embodiment of the present invention.
[0076] The preparation method of the gourd - shaped thermoelectric leg proposed in the present invention includes but is not limited to the above four preparation methods or a combination of multiple preparation methods.
[0077] The output of the gourd-shaped thermoelectric legs with different geometric parameters was simulated using the finite element analysis software COMSOL. The output performance of the gourd-shaped thermoelectric legs with different geometric parameters and the control group of cylindrical thermoelectric legs is shown in Table 3. The bottom surface of the cylindrical thermoelectric legs in the control group is a circle with a radius of 2 mm and a height of 10 mm. The height of the gourd-shaped thermoelectric legs is 10 mm. A spline curve is used to connect the inner and outer radii to form the side shape, so that when the inner and outer radii remain unchanged, the number of gourds n3 and the gourd height L4 do not affect the volume of the thermoelectric legs; the second inner diameter is set to two cases of R4 = 1.3 mm and 1.5 mm, corresponding to the second outer diameter of R5 = 2.315 mm and 2.232 mm, so that the gourd-shaped thermoelectric legs and the control group thermoelectric legs have the same height and volume. In the simulation calculation, the hot ends of all thermoelectric legs are placed on the surface of a heat source with a surface temperature of 400 K and are in the air at a temperature of 293.15 K for natural heat dissipation, and the surface convective heat transfer coefficient is 6 W / (m 2 ·K), ignoring radiative heat dissipation; P-type bismuth telluride is used as the thermoelectric material for the gourd-shaped thermoelectric legs and the cylindrical thermoelectric legs, Figure 8 , 9 , 10 respectively represent the relationships between the Seebeck coefficient, electrical conductivity, and thermal conductivity of P-type bismuth telluride and temperature.
[0078] Table 3. Output performance of gourd-shaped thermoelectric legs with different geometric parameters and control group cylindrical thermoelectric legs
[0079]
[0080]
[0081] From the comparison of the above embodiments, it can be seen that the output power of the gourd-shaped thermoelectric legs is higher than that of the control group of cylindrical ones. And in the above cases, when R4 = 1.5 mm, R5 = 2.232 mm, L3 = 0.732 mm, n3 = 10, and L4 = 1 mm, the output power is the highest.
[0082] The geometric design method of the enhanced passive heat dissipation type thermoelectric leg proposed in the embodiment of the present invention changes the geometric structure of the thermoelectric leg to make it have a larger side area, enhances the passive heat dissipation on the side, thereby increasing the temperature difference between the hot and cold ends. The change in the geometric structure of the thermoelectric leg also brings about a change in resistance. In the geometric design method of the thermoelectric leg, the change of the same geometric parameters in the side area and internal resistance of the thermoelectric leg is different due to different bottom surface areas. According to the space size, working environment of the thermoelectric leg and the temperature of the heat source it contacts, optimize the geometric parameters of the thermoelectric leg to make it have the best heat dissipation effect and internal resistance, and generate the best output parameters.
[0083] The method of changing the geometric shape of the thermoelectric leg to increase the side area is not limited to the above three or a combination of more than three. Thermoelectric legs with various different shapes and structures can also be set as long as the side area of the thermoelectric leg is larger than that of the commonly used cylindrical or square thermoelectric legs, so as to enhance the passive heat dissipation occurring on the side, and the purpose of increasing the output power can be achieved.
[0084] The enhanced passive heat dissipation type thermoelectric leg proposed by the present invention is based on changing the geometric shape of the thermoelectric leg to increase the side area, so as to enhance the passive heat dissipation on the side, thereby increasing the temperature difference between the hot and cold ends and improving the output power of the thermoelectric device. It can be used for thermoelectric devices that utilize the waste heat generated by industrial equipment, fireplaces and other heat generating devices to enhance the output; it can also be used for thermoelectric devices in isotope thermoelectric generators to enhance the electrical output, realize the efficient utilization of isotope decay heat, and extend the service life of isotope batteries.
[0085] The present invention also discloses an enhanced passive heat dissipation type thermoelectric leg obtained by using the above design method.
[0086] In addition, the preparation method of the enhanced passive heat dissipation type thermoelectric leg proposed by the present invention can use a variety of thermoelectric materials such as bismuth telluride and lead telluride as the molding materials, which have been shown in the above embodiments and will not be elaborated here.
[0087] Obviously, the above embodiments are only examples for clearly explaining the present invention, rather than limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.
Claims
1. A design method for a thermoelectric leg with enhanced passive heat dissipation, where the thermoelectric leg is installed inside a thermoelectric device and connects the hot and cold ends of the thermoelectric device. The thermoelectric device converts thermal energy into electrical energy using the temperature difference between the hot and cold ends. Characterized in that, The design method includes: Increasing the side area by changing the geometric shape of the thermoelectric leg to enhance passive heat dissipation on the side, thereby increasing the temperature difference between the hot and cold ends and improving the output power of the thermoelectric device; The method of increasing the side area by changing the geometric shape of the thermoelectric leg includes making the orientation of the thermoelectric leg change continuously, so that the thermoelectric leg has a spiral structure; or setting the cross-section of the thermoelectric leg as a spoke shape; or setting the side of the thermoelectric leg as a concave-convex gourd shape; Among them, using selective laser melting and stereolithography, the thermoelectric material is stacked layer by layer sintering to form a thermoelectric leg with a spiral shape, a spoke shape or a gourd shape; or using die pressing and subtractive manufacturing methods to prepare the thermoelectric material into a thermoelectric leg with a spiral shape, a spoke shape or a gourd shape.
2. The design method for a thermoelectric leg with enhanced passive heat dissipation according to claim 1, Characterized in that, Stretching the bottom surface along a spiral line to form the spiral shape of the thermoelectric leg, and adjusting the side heat dissipation area and internal resistance of the thermoelectric leg through the spiral radius, the number of spiral turns and the pitch.
3. The design method for a thermoelectric leg with enhanced passive heat dissipation according to claim 1, Characterized in that, Adjusting the side heat dissipation area and internal resistance of the thermoelectric leg through the first inner diameter, the first outer diameter, the number of spokes, the spoke opening angle, the spoke length and the set height of the spoke-shaped thermoelectric leg.
4. The design method for a thermoelectric leg with enhanced passive heat dissipation according to claim 1, Characterized in that, Adjusting the side heat dissipation area and internal resistance of the thermoelectric leg through the second inner diameter, the second outer diameter, the number of gourds and the gourd height of the gourd-shaped thermoelectric leg.
5. A thermoelectric leg with enhanced passive heat dissipation obtained by the design method according to any one of claims 1-4.