Preparation method of thermoelectric fabric based on variable cross-section thermoelectric units

Abstract

The invention discloses a preparation method of a thermoelectric fabric based on a variable cross-section thermoelectric unit, which comprises the following steps of: 1, calculating thermoelectric units with different shapes obtained by rotating or folding different strip functions, and selecting an optimal shape; 2, selecting the thermoelectric fabric with the maximum output power; 3, weaving a corresponding fabric and processing the fabric into a P-type thermoelectric unit and an N-type thermoelectric unit with optimal geometrical shapes; the thermoelectric units are alternately arranged in the holes of the fabric; step 4, the conductive wires and the welding material form welding surfaces at the top and the bottom of the thermoelectric unit; 5, the P-type thermoelectric units and the N-type thermoelectric units are electrically connected in series in a pi shape in the thickness direction of the fabric, and a conductive path is formed. The thermal resistance of the thermoelectric fabric is improved by optimizing the shapes and organization structures of the thermoelectric units, the heat exchange thermal resistance with the environment and the contact thermal resistance with the skin are reduced, and thermal resistance matching among the human skin, the thermoelectric fabric and the environment is achieved.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric fabric design, specifically a method for preparing thermoelectric fabric based on variable cross-section thermoelectric units. Background Technology

[0002] Thermoelectric power generation utilizes the Seebeck effect of thermoelectric semiconductor materials to directly convert heat energy into electrical energy. Since the human body temperature is relatively constant and there is a certain temperature difference between the body surface and the external environment, this heat can be used for thermoelectric conversion to achieve continuous power generation based on temperature difference. Currently, existing inorganic thermoelectric materials, whether mass-produced products or used in non-mass-production scientific research, are typically in the shape of regular cuboids or cubes. These materials have low thermal resistance and are generally suitable for environments with strong temperature differences. However, in wearable applications, the smaller temperature difference between the environment and the skin results in lower output power, limiting their widespread application.

[0003] Traditional thermoelectric conversion devices are typically covered with a rigid insulating ceramic plate. However, during wear, the ceramic plate cannot fit snugly against the skin, and the resulting interfacial gaps further increase interfacial thermal resistance, reducing the output performance of the thermoelectric generator. In contrast, thermoelectric fabrics can adapt to skin surfaces with varying curvatures, achieving a closer fit, thereby reducing interfacial thermal resistance, improving thermal efficiency, and making them more suitable for the power supply needs of wearable electronic devices.

[0004] Existing thermoelectric fabrics are divided into organic-based and inorganic-based thermoelectric fabrics. Organic-based thermoelectric fabrics are generally formed by attaching organic thermoelectric inks to yarns or films through methods such as soaking or coating to create thermoelectric units, which are then attached or sewn into the fabric substrate. However, because the temperature difference direction of organic-based thermoelectric fabrics is generally in-plane, or their thermoelectric performance is poor, the self-built temperature difference is very small, which cannot meet the requirements of common small electronic devices. Furthermore, organic-based thermoelectric fabrics cannot provide cooling due to their relatively poor performance. Existing inorganic-based thermoelectric fabrics typically embed or weave rectangular thermoelectric units directly into the fabric substrate (e.g., a weaving method for embedded inorganic semiconductor-based thermoelectric fabrics disclosed in application number 202310681803). Although such thermoelectric fabrics have greatly improved wearing comfort and thermoelectric output performance by optimizing the fabric structure, their thermal resistance (less than 250 cm²) remains a concern. 2 The K / W ratio is relatively low, making it difficult to achieve thermal resistance (500-1000 cm⁻¹) with the environment and the human body. 2The thermoelectric fabric (K / W) achieves a good match. Therefore, in wearable scenarios, the self-built temperature difference is relatively small, only capable of powering simple electronic devices, and the cooling capacity is also weak, unable to maintain cooling for extended periods, requiring a heat dissipation system to sustain cooling. The main reason for the small self-built temperature difference and low thermal resistance is the low resistance of the thermoelectric unit. If the thermal resistance of the thermoelectric fabric can be increased to match its contact thermal resistance with human skin and its exchange thermal resistance with air, the output power and cooling efficiency of the thermoelectric fabric can be significantly improved. Therefore, it is necessary to develop a thermoelectric fabric with high thermal resistance to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide a method for preparing thermoelectric fabrics based on variable cross-section thermoelectric units.

[0006] The technical solution of this invention to solve the aforementioned technical problem is to provide a method for preparing thermoelectric fabric based on a variable cross-section thermoelectric unit, characterized in that the method includes the following steps:

[0007] Step 1: Use numerical calculation software to calculate the thermoelectric units with different shapes obtained by rotating or folding different strip functions; then use the thermal resistance calculation formula to perform integration to obtain the thermal resistance θ of the thermoelectric unit. pillar The interfacial thermal resistance θ between the human body surface and the thermoelectric unit pillar-skin and the interfacial thermal resistance θ between the thermoelectric unit and the environment pillar-air And check whether the thermal resistance of the thermoelectric unit matches the thermal resistance of the two interfaces; if they match, the shape of the thermoelectric unit is the optimal shape.

[0008] Step 2: Based on the optimal shape of the thermoelectric unit obtained in Step 1, use finite element analysis software to simulate the effects of different thermal resistance fabric structures, thermoelectric unit shapes and sizes, and different filler ratios on the built-in temperature difference and output power of the thermoelectric fabric, and select the thermoelectric fabric with the highest output power.

[0009] Step 3: Based on the thermoelectric fabric with the highest output power obtained in Step 2, weave the corresponding fabric and process it into P-type thermoelectric units and N-type thermoelectric units with optimal geometric shapes; then arrange the P-type thermoelectric units and N-type thermoelectric units with optimal geometric shapes alternately in the holes of the fabric.

[0010] Step 4: Print the welding material onto the top of the thermoelectric unit; then sew the conductive wire into the fabric and pass through the top of the thermoelectric unit to form an electrode; then heat it to melt the welding material, so that the conductive wire and the welding material form a welding surface on the top of the thermoelectric unit, completing the circuit welding on the top of the thermoelectric fabric.

[0011] Similarly, the welding material is printed onto the bottom of the thermoelectric unit; then the conductive wire is sewn into the fabric and passes through the bottom of the thermoelectric unit to form an electrode; then the welding material is heated to melt, so that the conductive wire and the welding material form a welding surface on the bottom of the thermoelectric unit, thus completing the circuit welding on the bottom of the thermoelectric fabric.

[0012] Step 5: Connect the P-type thermoelectric unit and the N-type thermoelectric unit in a π-shaped series connection in the fabric thickness direction to form a conductive path, thereby obtaining a thermoelectric fabric based on variable cross-section thermoelectric units.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) This invention establishes a general design model through mathematical calculation methods, which can calculate the optimal thermoelectric unit geometry based on the selected spline curve. By optimizing the thermoelectric unit geometry and the fabric structure, the thermal resistance of the thermoelectric fabric is improved, and the thermal resistance of heat exchange with the environment and the thermal resistance of contact with the skin are reduced, so as to achieve thermal resistance matching between human skin, thermoelectric fabric and environment, thereby improving the built-in temperature difference (i.e., the temperature difference that the thermoelectric fabric can build up when in contact with an actual heat source), output power and cooling effect of the thermoelectric fabric, and obtaining high thermoelectric output performance.

[0015] (2) The present invention improves the thermal resistance matching of thermoelectric fabrics: optimizes the geometric structure of thermoelectric units and fabric structure to achieve thermal resistance matching between human skin, thermoelectric fabric and environment, thereby improving temperature difference and output power.

[0016] (3) This invention optimizes the heat flow path: the variable cross-section design effectively regulates the heat flow, improves the thermoelectric conversion efficiency, and reduces environmental heat exchange losses. Furthermore, the optimized thermal resistance distribution, combined with the small total cross-sectional area and large surface area, effectively regulates the heat flow path.

[0017] (4) The present invention enhances the heat dissipation capacity: the cross-sectional area in the middle is small to increase thermal resistance, the cross-sectional area near the hot end is large to absorb heat, and the cross-sectional area near the cold end is large to dissipate heat, thereby enhancing the heat dissipation capacity, effectively improving the heat dissipation efficiency, reducing contact thermal resistance, and significantly improving the heat exchange efficiency at the cold end.

[0018] (5) The present invention improves flexibility and wearability: the highly conductive flexible silver wire and the adjustable fabric structure give the thermoelectric fabric good stretchability and softness, which can comfortably fit the human skin.

[0019] (6) This invention improves design efficiency: a general design model is established, and the best thermoelectric unit geometry is quickly selected by combining Matlab calculation and finite element simulation, thereby reducing the experimental optimization time.

[0020] (7) The working principle of this invention is based on the thermoelectric effect, that is, when there is a temperature difference between the two ends of the thermoelectric fabric, the charge carriers (electrons or holes) in the thermoelectric unit generate a potential difference under the drive of the temperature gradient, thereby outputting electrical energy. By optimizing the geometric structure of the thermoelectric unit and the fabric's weave design, the fabric achieves thermal resistance matching between human skin and the environment, thereby improving the self-built temperature difference and enhancing the thermoelectric conversion efficiency.

[0021] (8) This thermoelectric fabric can be used in wearable devices, sports and health monitoring, smart homes, medical devices and other fields, using the human body as a heat source to achieve high power output. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the hourglass-shaped thermoelectric unit of Embodiment 1 of the present invention;

[0023] Figure 2 This is a three-dimensional structural diagram of the S-shaped electrode thermoelectric fabric of Embodiment 1 of the present invention;

[0024] Figure 3 This is a schematic diagram of the main structure of the S-shaped electrode thermoelectric fabric of Embodiment 1 of the present invention;

[0025] Figure 4 This is a top view of the S-shaped electrode thermoelectric fabric of Embodiment 1 of the present invention;

[0026] Figure 5 The thermoelectric output performance of the S-shaped electrode thermoelectric fabric in Embodiment 1 of the present invention;

[0027] Figure 6 This is a schematic diagram of the structure of the frustum-shaped thermoelectric unit in Embodiment 2 of the present invention;

[0028] Figure 7 This is a three-dimensional structural diagram of the warp-lined electrode thermoelectric fabric of Embodiment 2 of the present invention.

[0029] In the figure, 1 is the welding surface, 2 is the S-shaped electrode, 3 is the fabric, 4 is the thermoelectric unit, and 5 is the liner electrode. Detailed Implementation

[0030] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0031] This invention provides a method for preparing thermoelectric fabric based on a variable cross-section thermoelectric unit (hereinafter referred to as the method), characterized in that the method includes the following steps:

[0032] Step 1: Use numerical calculation software to calculate the thermoelectric unit 4 with different cross-sections obtained by rotating or folding different strip functions; then use the thermal resistance calculation formula to perform integral solution to obtain the thermal resistance θ of the thermoelectric unit 4. pillar The interfacial thermal resistance θ between the human body surface and thermoelectric unit 4 pillar-skin and the interfacial thermal resistance θ between thermoelectric unit 4 and the environment pillar-air And test the thermal resistance θ of thermoelectric unit 4. pillar Whether it matches the thermal resistance of the two interfaces; if it matches, then the shape of the thermoelectric unit 4 is the optimal shape;

[0033] Preferably, in step 1, the numerical calculation software used is Matlab.

[0034] Preferably, in step 1, the spline function is a linear function or a nonlinear function; the nonlinear function is a quadratic function, an exponential function, a hyperbolic tangent function, or a trigonometric function.

[0035] Preferably, in step 1, the formula for checking whether the thermal resistance of the thermoelectric unit 4 matches the thermal resistance of the two interfaces is: In the formula, ZT is the thermoelectric figure of merit at the average temperature of the hot and cold ends of thermoelectric unit 4.

[0036] Step 2: Based on the optimal shape of thermoelectric unit 4 obtained in Step 1, use finite element analysis software to simulate the effects of fabric structure with different thermal resistances, the shape and size of thermoelectric units, and different filling rates on the built-in temperature difference and output power of the thermoelectric fabric, and select the thermoelectric fabric with the highest output power.

[0037] Preferably, in step 2, the finite element analysis software used is ANSYS.

[0038] Preferably, in step 2, the fabric structure is a weft-knitted fabric, a warp-knitted fabric, or a spacer fabric, preferably a spacer fabric, and more preferably a high thermal resistance spacer fabric.

[0039] Step 3: Based on the thermoelectric fabric with the highest output power obtained in Step 2, weave the corresponding fabric 3 and process it into P-type thermoelectric units 4 and N-type thermoelectric units 4 with optimal geometric shapes; then arrange the P-type thermoelectric units 4 and N-type thermoelectric units 4 with optimal geometric shapes alternately in the holes of the fabric 3.

[0040] Preferably, in step 3, the fabric 3 is a fabric with an array of holes.

[0041] Preferably, in step 3, the thermoelectric unit 4 is formed by processing a thermoelectric crystal rod; the material of the thermoelectric crystal rod is bismuth telluride (Bi2Te3), lead telluride (PbTe), selenium-silver sulfide solid solution or silver selenium-silver sulfide-silver telluride solid solution; the processing method is: machine tool, wire cutting, hot drawing and mold shaping.

[0042] Preferably, in step 3, the alternating arrangement is as follows: each P-type thermoelectric unit 4 is adjacent to at least one N-type thermoelectric unit 4, and each N-type thermoelectric unit 4 is adjacent to at least one P-type thermoelectric unit 4; preferably, all units adjacent to the P-type thermoelectric unit 4 are N-type thermoelectric units 4, and all units adjacent to the N-type thermoelectric unit 4 are P-type thermoelectric units 4.

[0043] Step 4: Print the welding material onto the top of the thermoelectric unit 4; then sew the conductive wire into the fabric 3 and pass through the top of the thermoelectric unit 4 to form an electrode; then heat it to melt the welding material, so that the conductive wire and the welding material form a welding surface 1 on the top of the thermoelectric unit 4, and complete the circuit welding on the top of the thermoelectric fabric.

[0044] Similarly, the welding material is printed onto the bottom of the thermoelectric unit 4; then the conductive wire is sewn into the fabric 3 and passes through the bottom of the thermoelectric unit 4 to form an electrode; then the welding material is heated to melt, so that the conductive wire and the welding material form a welding surface 1 at the bottom of the thermoelectric unit 4, thus completing the circuit welding at the bottom of the thermoelectric fabric.

[0045] At this time, the conductive wire and the welding material form welding surfaces 1 at both the top and bottom of the thermoelectric unit 4;

[0046] Preferably, in step 4, solder paste is used as the welding material.

[0047] Preferably, in step 4, the printing is done using screen printing.

[0048] Preferably, in step 4, the conductive wire is sewn into the fabric 3 in an S-shape, a spring shape, or a lining shape to form an S-shaped electrode 2, a spring-shaped electrode, or a lining electrode 5.

[0049] Preferably, in step 4, the conductive wire is made of a flexible material with high electrical conductivity, specifically gold, silver, copper, carbon nanotubes, or graphene.

[0050] Preferably, in step 4, the heating temperature is the melting temperature of the welding material, and the heating time is 1 to 5 minutes (preferably 2 minutes).

[0051] Step 5: Connect the P-type thermoelectric unit 4 and the N-type thermoelectric unit 4 in a π-shaped series connection in the fabric thickness direction to form a conductive path, thereby obtaining a thermoelectric fabric based on the variable cross-section thermoelectric unit.

[0052] Example 1:

[0053] (1) Use Matlab to calculate the hourglass-shaped thermoelectric unit obtained by rotating a quadratic function (e.g.) Figure 1 (as shown); then, the thermal resistance θ of thermoelectric unit 4 is obtained by integral solution using the thermal resistance calculation formula. pillarThe interfacial thermal resistance θ between the human body surface and thermoelectric unit 4 pillar-skin and the interfacial thermal resistance θ between thermoelectric unit 4 and the environment pillar-air The shape of the thermoelectric unit 4 was determined to be the optimal shape.

[0054] (2) The shape and size of the thermoelectric unit and its filling rate in the spacer fabric were optimized using ANSYS finite element simulation. The thermoelectric fabric with the highest built-in temperature difference and the highest output power was selected. The simulation results showed that the shape and size of the optimal hourglass thermoelectric unit 4 were: the diameter of the top and bottom circles were 4 mm, the diameter of the middle circle was 1 mm, the height was 5 mm, and the optimal filling rate was 20%.

[0055] (3) Based on the thermoelectric fabric with the highest output power obtained in step (2), spacer fabric 3 is woven. The yarn used in the fabric is a composite yarn formed by combining elastic yarn and spandex filament. The spandex filament is 400D and the elastic yarn is nylon-spandex wrapped yarn (i.e., 40D spandex yarn wrapped with 70D nylon yarn). Based on the thermoelectric fabric with the highest output power obtained in step (2), the bismuth telluride crystal rod is processed by machine tool processing technology to process the crystal rod into P-type thermoelectric unit 4 and N-type thermoelectric unit 4 with optimal geometric shape. The test results show that when the hot end temperature is 35℃, the built-in temperature difference of the thermoelectric fabric is 10.58K.

[0056] Subsequently, P-type thermoelectric units 4 and N-type thermoelectric units 4 with optimal geometry are alternately arranged in the holes of the fabric 3, that is, a row of P-type thermoelectric units 4 and a row of N-type thermoelectric units 4 are alternately arranged.

[0057] (4) The welding material is screen printed onto the top of the thermoelectric unit 4; then the conductive silver wire with a diameter of 0.15mm is sewn into the fabric 3 in an S-shaped weft stitch and passes through the top of the thermoelectric unit 4 to form an S-shaped electrode 2; then it is placed on the heating table and heated for 2 minutes to melt the welding material, so that the conductive wire and the welding material form a welding surface 1 on the top of the thermoelectric unit 4, thus completing the circuit welding on the top of the thermoelectric fabric.

[0058] Similarly, the welding material is screen-printed onto the bottom of the thermoelectric unit 4; then, a conductive silver wire with a diameter of 0.15 mm is sewn into the fabric 3 in an S-shaped weft weft manner and passes through the bottom of the thermoelectric unit 4 to form an S-shaped electrode 2; then it is placed on a heating table and heated for 2 minutes to melt the welding material, so that the conductive wire and the welding material form a welding surface 1 at the bottom of the thermoelectric unit 4, thus completing the circuit welding at the bottom of the thermoelectric fabric.

[0059] (5) P-type thermoelectric unit 4 and N-type thermoelectric unit 4 are connected in series in a π-shaped manner in the fabric thickness direction to form a conductive path, thereby obtaining a thermoelectric fabric based on variable cross-section thermoelectric unit.

[0060] The thermal resistance of the prepared thermoelectric fabric was tested to be 502.2 cm. 2 ·K·W -1 The thermal resistance of the thermoelectric fabric to the environment is 314.4 cm. 2 ·K·W -1 The thermal resistance between the thermoelectric fabric and the skin is 89.2 cm. 2 ·K·W -1 The data shows that the thermoelectric fabric basically achieves thermal resistance matching between human skin, the thermoelectric fabric, and the environment. Test results indicate that when the ambient temperature is 16℃ and the wind speed is 1 m / s... -1 At that time, the temperature difference generated when the thermoelectric fabric is placed on the skin is 9.02K, and the maximum output power is 235.8μW·cm. -2 .

[0061] Thermoelectric properties of thermoelectric fabrics under other environmental conditions are shown in [reference]. Figure 5 .Depend on Figure 5 It can be seen that, with constant wind speed, the maximum output power of the thermoelectric fabric increases rapidly and non-linearly as the ambient temperature rises. For example, when the ambient temperature is 278K, the maximum output power can reach 700μW·cm. -2 .

[0062] Example 2:

[0063] (1) Use Matlab to calculate the frustum-shaped thermoelectric unit obtained by rotating a linear function (e.g.) Figure 6 (as shown); then, the thermal resistance θ of thermoelectric unit 4 is obtained by integral solution using the thermal resistance calculation formula. pillar The interfacial thermal resistance θ between the human body surface and thermoelectric unit 4 pillar-skin and the interfacial thermal resistance θ between thermoelectric unit 4 and the environment pillar-air The shape of the thermoelectric unit 4 was determined to be the optimal shape.

[0064] (2) The shape and size of the thermoelectric unit and its filling rate in the warp-knitted mesh structure spacer fabric were optimized using ANSYS finite element simulation. The thermoelectric fabric with the highest built-in temperature difference and the highest output power was selected. The simulation results showed that the shape and size of the optimal frustum-shaped thermoelectric unit 4 were: the diameter of the top circle was 3.28 mm, the diameter of the bottom circle was 0.82 mm, the height was 5 mm, and the optimal filling rate was 20%.

[0065] (3) Based on the thermoelectric fabric with the highest output power obtained in step (2), warp-knitted mesh structure spacer fabric 3 is woven, wherein the yarn used in the fabric is wrapped composite yarn, wherein 40D spandex yarn is used as core yarn and 70D nylon yarn is used as wrapping yarn; based on the thermoelectric fabric with the highest output power obtained in step (2), the bismuth telluride crystal rod is processed by machine tool processing technology, and the crystal rod is processed into P-type thermoelectric unit 4 and N-type thermoelectric unit 4 with optimal geometric shape;

[0066] Subsequently, P-type thermoelectric units 4 and N-type thermoelectric units 4 with optimal geometry are alternately arranged in the holes of the fabric 3, that is, a row of P-type thermoelectric units 4 and a row of N-type thermoelectric units 4 are alternately arranged.

[0067] (4) The welding material is screen printed onto the top of the thermoelectric unit 4; then a conductive silver wire with a diameter of 0.15 mm is sewn into the fabric 3 in a lining manner and passes through the top of the thermoelectric unit 4 to form a lining electrode 5; then it is placed on the heating table and heated for 2 minutes to melt the welding material, so that the conductive wire and the welding material form a welding surface 1 on the top of the thermoelectric unit 4, and the circuit welding on the top of the thermoelectric fabric is completed.

[0068] Similarly, the welding material is screen-printed onto the bottom of the thermoelectric unit 4; then, a conductive silver wire with a diameter of 0.15 mm is sewn into the fabric 3 in a lining manner and passes through the bottom of the thermoelectric unit 4 to form a lining electrode 5; then it is placed on a heating table and heated for 2 minutes to melt the welding material, so that the conductive wire and the welding material form a welding surface 1 at the bottom of the thermoelectric unit 4, thus completing the circuit welding at the bottom of the thermoelectric fabric.

[0069] (5) P-type thermoelectric unit 4 and N-type thermoelectric unit 4 are connected in series in a π-shaped manner in the fabric thickness direction to form a conductive path, thereby obtaining a thermoelectric fabric based on variable cross-section thermoelectric unit.

[0070] The thermal resistance of the prepared thermoelectric fabric was tested to be 404.2 cm. 2 ·K·W -1 The thermal resistance of the thermoelectric fabric to the environment is 314.4 cm. 2 ·K·W -1 The thermal resistance between the thermoelectric fabric and the skin is 89.2 cm. 2 ·K·W -1 The data shows that the thermoelectric fabric achieves near-perfect thermal resistance matching between human skin, the thermoelectric fabric, and the environment. Test results indicate that when the ambient temperature is 16℃ and the wind speed is 1 m / s... -1 At that time, the temperature difference generated when the thermoelectric fabric is placed on the skin is 7.00K, and the maximum output power is 40.1μW·cm. -2 .

[0071] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for preparing a thermoelectric fabric based on a variable cross-section thermoelectric unit, characterized in that, The method includes the following steps: Step 1: Use numerical calculation software to calculate the thermoelectric units (4) with different shapes obtained by rotating or folding different strip functions; then use the thermal resistance calculation formula to perform integral solution to obtain the thermal resistance θ of the thermoelectric unit (4). pillar The interfacial thermal resistance θ between the human body surface and the thermoelectric unit (4) pillar-skin and the interfacial thermal resistance θ between the thermoelectric unit (4) and the environment pillar-air And check whether the thermal resistance of the thermoelectric unit (4) matches the thermal resistance of the two interfaces; if they match, the shape of the thermoelectric unit (4) is the optimal shape. Step 2: Based on the optimal shape of the thermoelectric unit (4) obtained in Step 1, use finite element analysis software to simulate the influence of different thermal resistance fabric structures, thermoelectric unit shape and size and different filling rates on the built-in temperature difference and output power of the thermoelectric fabric, and select the thermoelectric fabric with the largest output power. Step 3: Based on the thermoelectric fabric with the highest output power obtained in Step 2, weave the corresponding fabric (3) and process it into P-type thermoelectric units (4) and N-type thermoelectric units (4) with optimal geometric shapes; then arrange the P-type thermoelectric units (4) and N-type thermoelectric units (4) with optimal geometric shapes alternately in the holes of the fabric (3); Step 4: Print the welding material onto the top of the thermoelectric unit (4); then sew the conductive wire into the fabric (3) and pass through the top of the thermoelectric unit (4) to form an electrode; then heat the material to melt it, so that the conductive wire and the welding material form a welding surface (1) on the top of the thermoelectric unit (4) to complete the circuit welding on the top of the thermoelectric fabric. Similarly, the welding material is printed onto the bottom of the thermoelectric unit (4); then the conductive wire is sewn into the fabric (3) and passes through the bottom of the thermoelectric unit (4) to form an electrode; then the welding material is heated to melt, so that the conductive wire and the welding material form a welding surface (1) at the bottom of the thermoelectric unit (4) to complete the circuit welding at the bottom of the thermoelectric fabric. Step 5: Connect the P-type thermoelectric unit (4) and the N-type thermoelectric unit (4) in a π-shaped series connection in the fabric thickness direction to form a conductive path, and obtain a thermoelectric fabric based on the variable cross-section thermoelectric unit.

2. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 1, the numerical calculation software used is Matlab; In step 1, the spline function is a linear function or a nonlinear function; the nonlinear function is a quadratic function, an exponential function, a hyperbolic tangent function, or a trigonometric function.

3. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 1, the thermal resistance θ of the thermoelectric unit (4) is checked. pillar The formula for determining whether the thermal resistances of the two interfaces are matched is: In the formula, ZT is the thermoelectric figure of merit of the thermoelectric unit (4) at the average temperature of the hot and cold ends.

4. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 2, the finite element analysis software used is ANSYS; In step 2, the fabric structure is weft-knitted fabric, warp-knitted fabric, or spaced fabric.

5. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 3, the fabric (3) is a fabric with an array of holes; In step 3, the thermoelectric unit (4) is formed by processing the thermoelectric crystal rod; the material of the thermoelectric crystal rod is bismuth telluride, lead telluride, selenium-silver sulfide solid solution or silver selenium-silver sulfide-silver telluride solid solution; the processing method is: machine tool, wire cutting, hot stretching and mold shaping.

6. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 3, the alternating arrangement is as follows: each P-type thermoelectric unit (4) is adjacent to at least one N-type thermoelectric unit (4), and each N-type thermoelectric unit (4) is adjacent to at least one P-type thermoelectric unit (4).

7. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 4, solder paste is used as the soldering material; In step 4, screen printing is used for printing.

8. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 4, the conductive wire is sewn into the fabric (3) in an S-shape, spring shape or lining shape to form an S-shaped electrode (2), a spring-shaped electrode or a lining electrode (5); In step 4, the conductive wire is made of a flexible material with high electrical conductivity.

9. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1 or 8, characterized in that, The conductive wire is made of gold, silver, copper, carbon nanotubes, or graphene.

10. The method for preparing thermoelectric fabric based on variable cross-section thermoelectric units according to claim 1, characterized in that, In step 4, the heating temperature is the melting temperature of the welding material, and the heating time is 1 to 5 minutes.

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