Thermoelectric generator with built-in convergent heat exchanger and key parameter acquisition method

Abstract

The invention relates to the field of thermoelectricity, in particular to a thermoelectric generator with a built-in convergent heat exchanger and a key parameter acquisition method. Comprising an airflow pipeline, the airflow pipeline comprises a middle airflow pipeline and front and rear airflow pipelines, the middle airflow pipeline is arranged in a heat exchanger and connected with the heat exchanger in an attached mode, the hole diameter of the middle airflow pipeline is continuously increased in the heat flow flowing direction, and the front end and the rear end of the middle airflow pipeline are connected with the front and rear airflow pipelines; by introducing the convergence angle, the middle airflow pipeline extends along the convergence angle, the hole diameter is gradually increased in the extending process, and in the hole diameter changing process, the heat energy loss caused by the heat flow temperature gradient can be effectively reduced, the output current is improved, and more uniform and efficient convergence and conduction of heat energy in the heat exchanger are achieved.

Description

Technical Field

[0001] The present invention relates to the field of thermoelectricity, and in particular to a thermoelectric generator with a built-in converging heat exchanger and a method for acquiring key parameters. Background Art

[0002] The thermoelectric generator with integrated heat exchanger can realize the conversion of waste heat stored in the fin and heat pipe system into electrical energy, which not only realizes energy recycling but also promotes the development of clean energy technology.

[0003] During the operation of the heat exchanger, its internal air flow channel often maintains a fixed aperture design. This static structure will encounter the problem of uneven heat absorption when facing the continuous backward flow of air: a large amount of heat energy carried by the front airflow is quickly absorbed by the tube wall and converted into heat energy storage or initial utilization. As the airflow goes deeper, the remaining heat it carries is reduced due to absorption in the front section, resulting in a decrease in the waste heat resources available in the rear section of the heat exchanger, and then the electrical energy generated by the Seebeck effect (i.e., thermoelectric effect) is also weakened, limiting the improvement of the overall energy conversion efficiency. Summary of the invention

[0004] In view of the problems mentioned in the prior art, the present invention proposes a thermoelectric generator with a built-in converging heat exchanger and a method for obtaining key parameters. By continuously increasing the aperture of the airflow duct, the heat exchange between the exhaust gas and the heat exchanger can be greatly enhanced, and the optimal output of the thermoelectric semiconductor as a whole can be achieved, which effectively improves the power transmission performance of the thermoelectric generator.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a thermoelectric generator with a built-in converging heat exchanger, comprising:

[0007] The airflow duct includes a central airflow duct and front and rear airflow ducts, the central airflow duct is arranged in the heat exchanger and is closely connected to the heat exchanger, the aperture of the central airflow duct increases along the flow direction of the heat flow, and the front and rear ends of the central airflow duct are connected to the front and rear airflow ducts;

[0008] Thermoelectric module, each surface of the heat exchanger is provided with at least one thermoelectric module along the length direction;

[0009] A liquid cooling plate is bonded and connected to the thermoelectric module.

[0010] As a further improvement of the present invention, the radius of the inlet side of the central airflow duct is r1, and the radius of the outlet side of the central airflow duct is r2, wherein r2 satisfies the following relationship:

[0011]

[0012] Where: l is the width of the heat exchanger side; m is the thickness of the outermost fin of the heat exchanger;

[0013] Where r1 satisfies the following relationship:

[0014]

[0015] As a further improvement of the present invention, the aperture of the central airflow duct is θ along the heat flow direction. i Uniformly increase, where θ i The following relationship is satisfied:

[0016] θ i =θ0+iΔθ

[0017] Where θ0 is the initial size of the convergence angle, and Δθ is the change step size of the convergence angle;

[0018] Where Δθ satisfies the following relationship:

[0019]

[0020] The radius of the inlet side of the central airflow duct is r1, the radius of the outlet side is r2, and the convergence angle θ i The following relationship is satisfied:

[0021] r2=r1+q tanθ i

[0022] Where: q is the length of the heat exchanger.

[0023] As a further improvement of the present invention, the thickness of the inner fin of the heat exchanger is t i , the distance between adjacent inner fins is d i , the thickness of the outermost fin is m;

[0024] The number of fins distributed on each side of the heat exchanger is equal, which is n1, where n1 = 1, 2, 3, ...;

[0025] The width of each side of the heat exchanger is l, and l satisfies the following relationship:

[0026] l=n1(t i +d i )

[0027] As a further improvement of the present invention, the thickness of the inner fin satisfies the following relationship:

[0028] t i =t0±iΔt

[0029] Where: t0 is the initial thickness of the inner fin, Δt is the step length of the inner fin thickness change,

[0030] The spacing between adjacent inner fins satisfies the following relational expression:

[0031]

[0032] In the formula: d0 is the initial spacing of the inner fins, and Δd is the step size of the change in the inner fin spacing, where

[0033] As a further improvement of the present invention, the initial thickness of the inner fins and the initial spacing between adjacent inner fins satisfy the following relational expression:

[0034]

[0035] When i changes, it satisfies t i +d i = t0 + d0.

[0036] As a further improvement of the present invention, the thermoelectric module includes a ceramic plate, a copper sheet, a P-type semiconductor, and an N-type semiconductor; the P-type semiconductor and the N-type semiconductor are connected by a copper sheet, and the upper and lower ends of the copper sheet are attached to the ceramic plate;

[0037] The length of the thermoelectric module is p, where p < q, and q is the length of the heat exchanger.

[0038] As a further improvement of the present invention, the same number of thermoelectric modules are distributed on each surface of the heat exchanger, and the number of each is n2, where n2 = 1, 2, 3,...;

[0039] The same number of thermoelectric modules are evenly distributed, and the spacing is k, and k satisfies the following relational expression:

[0040] q = n2p + (n2 + 1)k

[0041] As a further improvement of the present invention, the parameters of the thermoelectric modules in the three directions of the X-axis, Y-axis, and Z-axis are as follows:

[0042] The number of P-type semiconductors and N-type semiconductors in the X-axis direction is equal. The thickness of the P-type semiconductor in the i-th column is L i , and the thickness of the N-type semiconductor in the (i + 1)-th column is L i+1 , where L i = L i+1 ;

[0043] The spacing between adjacent P-type semiconductors and N-type semiconductors is D;

[0044] The lengths of the ceramic plate, P-type semiconductor, N-type semiconductor, and copper sheet in the Y-axis direction are all W;

[0045] The height of the ceramic plate in the Z-axis direction is H1, the height of the copper sheet is H2, and the heights of the P-type semiconductor and N-type semiconductor are both H3.

[0046] A method for obtaining key parameters of a thermoelectric generator with a built-in converging heat exchanger comprises the following steps:

[0047] S1: Set boundary conditions: The bottom surface of the lower ceramic plate is set to the high temperature boundary T h , the top surface of the upper ceramic plate is set as the low temperature boundary T c ;

[0048] Satisfy I i =I i+1 , where: I i is the current flowing through the P-type semiconductor in the i-th column, I i+1 Current flows through the N-type semiconductor in the i+1th column;

[0049] S2: Calculate the voltage U of the P-type semiconductor in the i-th column caused by the temperature difference i,P , the calculation formula is as follows:

[0050] U i,P =|α P |(T h,i -T c )

[0051] Where: α P is the Seebeck coefficient of the P-type semiconductor, T h,i is the hot end temperature of the P-type semiconductor;

[0052] S3: Calculate the voltage U of the N-type semiconductor in the i+1th column caused by the temperature difference i+1,N , the calculation formula is as follows:

[0053] U i+1,N =|α N |(T h,i+1 -T c )

[0054] Where: α N is the Seebeck coefficient of N-type semiconductor; T h,i+1 is the hot end temperature of the N-type semiconductor;

[0055] S4: Calculate the resistance R of the N-type semiconductor in the i+1th column caused by the temperature difference i+1,N and the resistance R of the P-type semiconductor in the i-th column i,P , the calculation formula is as follows:

[0056]

[0057] Where: N is the resistivity of N-type semiconductor; A is the cross-sectional area H3*W between N-type semiconductor and P-type semiconductor;

[0058]

[0059] In the formula, ρ P is the resistivity of the P-type semiconductor; A is the cross-sectional area H3*W between the N-type semiconductor and the P-type semiconductor;

[0060] S5: Calculate the current I of the N-type semiconductor i+1,N and the current I of the P-type semiconductor i,P , the calculation formula is as follows:

[0061]

[0062] According to the boundary conditions in step S1, T h,i+1 =T h,i , get the convergence angle θ i Optimal value;

[0063] S6: According to the convergence angle θ i Optimal value, select the inner fin thickness t i Distance between adjacent inner fins d i The output power of a single thermoelectric module is calculated by the voltage and internal resistance of the P-type semiconductor in the i-th column and the N-type semiconductor in the i+1th column. The calculation formula is as follows:

[0064]

[0065] Iterate to get the maximum output power and obtain the inner fin thickness t i Distance between adjacent inner fins d i Optimal value.

[0066] Compared with the prior art, the present invention has achieved the following technical effects:

[0067] The present invention introduces a convergence angle so that the central airflow duct extends along the convergence angle. During the extension process, the aperture gradually increases. During the aperture change process, the heat energy loss caused by the heat flow temperature gradient can be effectively reduced, the output current can be increased, and the heat energy can be more evenly and efficiently converged and conducted inside the heat exchanger.

[0068] The key parameter acquisition method in the present invention adjusts the fin thickness and spacing according to the output power, which can maximize the utilization of the heat exchange area and optimize the heat transfer efficiency; it not only enhances the heat exchange capacity of the heat exchanger, but also further improves the overall output performance of the thermoelectric generator, thereby improving the energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0070] Figure 2 This is a schematic diagram of the structure of the centrally placed airflow duct of the present invention;

[0071] Figure 3 Another schematic diagram of the centrally-placed airflow duct structure of the present invention;

[0072] Figure 4 It is a schematic diagram of the front and rear airflow ducts and the rear airflow duct of the present invention;

[0073] Figure 5 It is a schematic diagram of the liquid cooling plate of the present invention;

[0074] Figure 6 Schematic diagram of the heat exchanger of the present invention;

[0075] Figure 7 Another structural schematic diagram of the heat exchanger of the present invention;

[0076] Figure 8 It is a schematic diagram of parameters of the heat exchanger of the present invention;

[0077] Fig. 9 This is a schematic diagram of a thermoelectric module of the present invention;

[0078] Fig.10 Another schematic diagram of the thermoelectric module of the present invention;

[0079] Fig.11 This is a schematic diagram of the parameters of the thermoelectric module of the present invention;

[0080] Fig.12 It is a schematic diagram of the iterative process of the present invention;

[0081] Fig.13 Schematic diagram for comparing experimental results of the present invention.

[0082] Figure numerals: 1. thermoelectric module; 2. central airflow duct; 3. front and rear airflow ducts; 4. heat exchanger; 5. liquid cooling duct; 6. liquid cooling plate; 7. ceramic plate; 8. P-type semiconductor; 9. N-type semiconductor; 10. copper sheet. DETAILED DESCRIPTION

[0083] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limiting the present application. On the contrary, the embodiments of the present application include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0084] The examples of the present application are described in detail below, and the examples of the examples are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The examples described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0085] Example 1

[0086] like Figure 1 As shown, the present invention is a thermoelectric generator with a built-in converging heat exchanger 4, comprising: an airflow duct, the airflow duct comprising a central airflow duct 2 and front and rear airflow ducts 3, the central airflow duct 2 is arranged in the heat exchanger 4 and is closely connected to the heat exchanger 4, the aperture of the central airflow duct 2 increases continuously along the flow direction of the heat flow, and the front and rear ends of the central airflow duct 2 are connected to the front and rear airflow ducts 3; a thermoelectric module 1, each surface of the heat exchanger 4 is closely connected with at least one thermoelectric module 1 along the length direction; and a liquid cooling plate 6, the liquid cooling plate 6 is closely connected to the thermoelectric module 1.

[0087] The structure of the central airflow duct 2 in the embodiment is as follows: Figure 2 The structure shown is a cylindrical structure. The heat exchanger 4 uses a thin metal plate with a hexagonal corrugated surface as a heat transfer element. Specifically, the outer side of the shell cross-section of the heat exchanger 4 is designed to be an equihexagon, and the inner side of the cross-section is designed to be circular. The outer side of the cross-section is concentrically arranged with the inner side of the cross-section, and fins are arranged between the outer side of the cross-section and the inner side of the cross-section. The central airflow duct 2 is arranged in the heat exchanger 4 and is closely connected to the heat exchanger 4. Since the aperture of the central airflow duct 2 is variable, the circular part on the inner side of the heat exchanger 4 matches the size of the central airflow duct 2. The inlet of the heat exchanger 4 and the inlet side of the central airflow duct 2 have the same radius r1, and the outlet of the heat exchanger 4 and the outlet side of the central airflow duct 2 have the same radius r2.

[0088] like Figure 4 The figure shows a schematic diagram of the front and rear airflow ducts 3 in the embodiment. The shapes of the front and rear airflow ducts 3 are the same as the shape of the heat exchanger 4, both of which are hexagonal structures. After the middle airflow duct 2 is connected to the heat exchanger 4, the two front and rear airflow ducts 3 are respectively connected to the front end and the rear end of the middle airflow duct 2.

[0089] like Figure 5 As shown, in the embodiment, a plurality of liquid cooling plates 6 are arranged evenly distributed along each surface of the hexagonal heat exchanger 4, wherein the length and width of the liquid cooling plates 6 are the same as the width l and the length q of the heat exchanger 4; wherein a liquid cooling pipe 5 is arranged in the liquid cooling plate 6, and the liquid cooling pipe 5 is an S-shaped liquid cooling pipe 5, and the S-shaped channel can extend the passing time of the cooling medium and further improve the cooling effect; in the embodiment, for example Figure 5In the figure, a channel inlet and a channel outlet are respectively provided at the left and right ends of the same side of the liquid cooling plate 6, wherein the channel inlet is connected to the inlet of the liquid cooling pipe 5, and the channel outlet is connected to the outlet of the liquid cooling pipe 5, to ensure that the cooling medium in the liquid cooling pipe 5 can pass smoothly. The cooling medium in this embodiment is preferably cooling water.

[0090] Implementation example Figure 3 As shown, the inlet radius of the central airflow duct 2 is r1, and the outlet radius of the central airflow duct 2 is r2, wherein the inlet radius r1 gradually increases along the length direction to the outlet radius r2, wherein r2 satisfies the following relationship:

[0091]

[0092] l is the width of the heat exchanger side; m is the thickness of the outermost fin of the heat exchanger;

[0093] Where r1 satisfies the following relationship:

[0094]

[0095] like Figure 3 As shown, the aperture of the central airflow duct is θ along the direction of the heat flow. i Uniformly increase, where θ i The following relationship is satisfied:

[0096] θ i =θ0+iΔθ

[0097] Where θ0 is the initial size of the convergence angle, and Δθ is the change step size of the convergence angle;

[0098] Where Δθ satisfies the following relationship:

[0099]

[0100] The radius of the inlet side of the central airflow duct is r1, the radius of the outlet side is r2, and the convergence angle θ i The following relationship is satisfied:

[0101] r2=r1+q tanθ i

[0102] Where: q is the length of the heat exchanger.

[0103] Implementation example Figure 6 , Figure 7 as well as Figure 8 The heat exchanger schematic is shown in FIG. Figure 7 The thickness of the inner fin of the heat exchanger is t i , the distance between adjacent inner fins is d i, the thickness of the outermost fin is m; the number of fins in each side of the hexagonal heat exchanger is the same, and the width of each side of the heat exchanger is l, which satisfies the following relationship:

[0104] l=n1(t i +d i )

[0105] Figure 7 As shown, the inner fin thickness satisfies the following relationship:

[0106] t i =t0±iΔt

[0107] Where: t0 is the initial thickness of the inner fin, Δt is the step length of the inner fin thickness change,

[0108] The spacing between adjacent inner fins satisfies the following relationship:

[0109]

[0110] Where: d0 is the initial spacing of the inner fins, Δd is the step size of the inner fin spacing change,

[0111] The initial thickness of the inner fin and the initial spacing between adjacent inner fins satisfy the following relationship:

[0112]

[0113] When i changes, satisfying t i +d i =t0+d0, specifically, the total value of the initial thickness t0 of the inner fin and the initial spacing d0 of the adjacent inner fins is fixed, and no matter how i changes, t i +d i =t0+d0.

[0114] like Fig. 9 , Fig.10 as well as Fig.11 As shown, in the embodiment, the thermoelectric modules are arranged on each surface of the hexagonal heat exchanger and connected to the liquid cooling plate. Each surface may be provided with multiple thermoelectric modules. In the embodiment, five thermoelectric modules are preferably provided, wherein the five thermoelectric modules are connected in series, and the spacing between each thermoelectric module is k, and k satisfies the following relationship:

[0115] q=n2p+(n2+1)k

[0116] It can be seen that the spacing k is related to the length p of the thermoelectric module 1 , the length q of the heat exchanger 4 and the number of the thermoelectric modules 1 .

[0117] In the embodiment, the thermoelectric module 1 is a square structure as a whole, wherein the length p of the thermoelectric module 1 is less than the length q of the heat exchanger 4 , and the length of the heat exchanger 4 should have a margin and cover the thermoelectric module 1 together with the liquid cooling plate 6 .

[0118] In the embodiment, the thermoelectric module 1 includes a ceramic plate 7, a copper sheet 10, a P-type semiconductor 8 and an N-type semiconductor 9; the P-type semiconductor 8 and the N-type semiconductor 9 are connected by the copper sheet 10, wherein the upper and lower ends of the copper sheet 10 are bonded and connected to the ceramic plate 7, such as Fig.11 As shown, the thermoelectric module 1 is observed along the X-axis, Y-axis and Z-axis directions respectively, and its parameters are:

[0119] The number of P-type semiconductors 8 and N-type semiconductors 9 in the X-axis direction is equal, and the thickness of the P-type semiconductor 8 in the i-th column is L i , the thickness of the N-type semiconductor 9 in the i+1th column is L i+1 , where L i =L i+1 ;

[0120] The distance between adjacent P-type semiconductors 8 and N-type semiconductors 9 is D;

[0121] The lengths of the ceramic plate 7, the P-type semiconductor 8, the N-type semiconductor 9 and the copper sheet 10 in the Y-axis direction are all W;

[0122] The height of the ceramic plate 7 in the Z-axis direction is H1, the height of the copper sheet 10 is H2, and the heights of the P-type semiconductor 8 and the N-type semiconductor 9 are both H3.

[0123] Example 2

[0124] This embodiment is basically the same as the first embodiment, except that this embodiment provides a method for obtaining key parameters of a thermoelectric generator with a built-in converging heat exchanger, which is characterized by comprising the following steps:

[0125] S1: Set boundary conditions: The bottom surface of the lower ceramic plate is set to the high temperature boundary T h , the top surface of the upper ceramic plate is set as the low temperature boundary T c ;

[0126] Satisfy I i =I i+1 , where: I i is the current flowing through the P-type semiconductor in the i-th column, I i+1 Current flows through the N-type semiconductor in the i+1th column;

[0127] S2: Calculate the voltage U of the P-type semiconductor in the i-th column caused by the temperature difference i,P , the calculation formula is as follows:

[0128] U i,P =|αP |(T h,i -T c )

[0129] Where: α P is the Seebeck coefficient of the P-type semiconductor, T h,i is the hot end temperature of the P-type semiconductor;

[0130] S3: Calculate the voltage U of the N-type semiconductor in the i+1th column caused by the temperature difference i+1,N , the calculation formula is as follows:

[0131] U i+1,N =|α N |(T h,i+1 -T c )

[0132] Where: α N is the Seebeck coefficient of N-type semiconductor; T h,i+1 is the hot end temperature of the N-type semiconductor;

[0133] S4: Calculate the resistance R of the N-type semiconductor in the i+1th column caused by the temperature difference i+1,N and the resistance R of the P-type semiconductor in the i-th column i,P , the calculation formula is as follows:

[0134]

[0135] Where: N is the resistivity of N-type semiconductor; A is the cross-sectional area H3*W between N-type semiconductor and P-type semiconductor;

[0136]

[0137] In the formula, ρ P is the resistivity of the P-type semiconductor; A is the cross-sectional area H3*W between the N-type semiconductor and the P-type semiconductor;

[0138] S5: Calculate the current I of the N-type semiconductor i+1,N and the current I of the P-type semiconductor i,P , the calculation formula is as follows:

[0139]

[0140] According to the boundary conditions in step S1, T h,i+1 =T h,i , get the convergence angle θ i Optimal value;

[0141] S6: According to the convergence angle θ i Optimal value, select the inner fin thickness t i Distance between adjacent inner fins di The output power of a single thermoelectric module is calculated by the voltage and internal resistance of the P-type semiconductor in the i-th column and the N-type semiconductor in the i+1th column. The calculation formula is as follows:

[0142]

[0143] Iterate to get the maximum output power and obtain the inner fin thickness t u Distance between adjacent inner fins d u Optimal value.

[0144] The iterative process in step S6 of the embodiment is as follows: Fig.12 As shown, the inner fin thickness t is obtained i Distance between adjacent inner fins d i Optimal value.

[0145] In this embodiment, θ0=3° and θ0=0° are selected for performance comparison, and the output power is improved compared with the traditional structure. When the intake temperature is 500K, the improvement can reach 6.3%, and the improvement effect is further improved with the increase of intake temperature. Fig.13 shown.

[0146] The thermoelectric materials of the P-type semiconductor and the N-type semiconductor used in this example are bismuth telluride-based thermoelectric materials. The parameters of the P-type and N-type semiconductors and other materials are shown in Table 1.

[0147] Table 1 Material parameters of bismuth telluride-based thermoelectric devices

[0148]

[0149] Other parameters of the device in the embodiment are shown in Table 2:

[0150] Table 2 Specific parameters

[0151]

[0152]

[0153] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0154] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0155] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0156] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A thermoelectric generator with a built-in converging heat exchanger, characterized in that: Comprising: An air flow duct, the air flow duct including a middle air flow duct and front and rear air flow ducts, the middle air flow duct being disposed within the heat exchanger and adhesively connected to the heat exchanger, the aperture of the middle air flow duct continuously increasing along the heat flow direction, and the front and rear ends of the middle air flow duct being connected to the front and rear air flow ducts; Thermoelectric modules, at least one thermoelectric module being adhesively disposed along the length direction on each surface of the heat exchanger; A liquid cooling plate, the liquid cooling plate being adhesively connected to the thermoelectric modules.

2. A thermoelectric generator with a built-in converging heat exchanger according to claim 1, characterized in that: The radius of the inlet side of the middle air flow duct is r1, and the radius of the outlet side of the middle air flow duct is r2, where r2 satisfies the following relational expression: In the formula: l is the width of the side of the heat exchanger; m is the thickness of the outermost fin of the heat exchanger; Where r1 satisfies the following relational expression:

3. A thermoelectric generator with a built-in converging heat exchanger according to claim 2, characterized in that: The aperture of the central airflow duct is θ along the heat flow direction. i Uniformly increase, where θ i The following relationship is satisfied: i i =θ0+iΔθ In the formula, θ0 is the initial size of the convergence angle, and Δθ is the change step of the convergence angle; Where Δθ satisfies the following relational expression: The radius of the inlet side of the central airflow duct is r1, the radius of the outlet side is r2, and the convergence angle θ i The following relationship is satisfied: r2=r1+qtanθ i In the formula: q is the length of the heat exchanger.

4. The thermoelectric generator with a built-in converging heat exchanger according to claim 1, characterized in that: The thickness of the inner fin of the heat exchanger is t i , the distance between adjacent inner fins is d i , the thickness of the outermost fin is m; The number of fins distributed on each side of the heat exchanger is equal, all being n1, where n1 = 1, 2, 3,...; The width of each side of the heat exchanger is l, and l satisfies the following relational expression: l=n1(t i +d i )。 5. A thermoelectric generator with a built-in converging heat exchanger according to claim 4, characterized in that: The thickness of the inner fins satisfies the following relational expression: t i =t0±iΔt Where: t0 is the initial thickness of the inner fin, Δt is the step length of the inner fin thickness change, The spacing between adjacent inner fins satisfies the following relational expression: Where: d0 is the initial spacing of the inner fins, Δd is the step size of the inner fin spacing change, 6. A thermoelectric generator with a built-in converging heat exchanger according to claim 5, characterized in that: The initial thickness of the inner fins and the initial spacing between adjacent inner fins satisfy the following relational expression: When i changes, satisfying t i +d i =t0+d0.

7. The thermoelectric generator with a built-in converging heat exchanger according to claim 1, characterized in that: The thermoelectric module includes a ceramic plate, a copper sheet, a P-type semiconductor, and an N-type semiconductor; the P-type semiconductor and the N-type semiconductor are connected by the copper sheet, and the upper and lower ends of the copper sheet are adhesively connected to the ceramic plate; Where the length of the thermoelectric module is p, where p < q, and q is the length of the heat exchanger.

8. The thermoelectric generator with a built-in converging heat exchanger according to claim 7, characterized in that: The same number of thermoelectric modules are distributed on each surface of the heat exchanger, and the number of each is n2, where n2 = 1, 2, 3,...; The same number of thermoelectric modules are equally spaced, and the spacing is k, and k satisfies the following relational expression: q = n2p + (n2 + 1)k.

9. The thermoelectric generator with a built-in converging heat exchanger according to claim 7, characterized in that: The parameters of the thermoelectric modules in the three directions of the X-axis, Y-axis, and Z-axis are as follows: The number of P-type semiconductors and N-type semiconductors in the X-axis direction is equal, and the thickness of the P-type semiconductor in the i-th column is L i , the thickness of the N-type semiconductor in the i+1th column is L i+1 , where L i =L i+1 ; The spacing between adjacent P-type semiconductors and N-type semiconductors is D; The lengths of the ceramic plate, P-type semiconductor, N-type semiconductor, and copper sheet in the Y-axis direction are all W; The height of the ceramic plate in the Z-axis direction is H1, the height of the copper sheet is H2, and the heights of the P-type semiconductor and the N-type semiconductor are both H3.

10. The method for obtaining key parameters of a thermoelectric generator with a built-in converging heat exchanger according to any one of claims 1 to 9, characterized in that: Including the following steps: S1: Set boundary conditions: The bottom surface of the lower ceramic plate is set to the high temperature boundary T h , the top surface of the upper ceramic plate is set as the low temperature boundary T c ; Satisfy I i =I i+1 , where: I i is the current flowing through the P-type semiconductor in the i-th column, I i+1 Current flows through the N-type semiconductor in the i+1th column; S2: Calculate the voltage U of the P-type semiconductor in the i-th column caused by the temperature difference i,P , the calculation formula is as follows: U i,P =|α P |(T h,i -T c ) Where: α P is the Seebeck coefficient of the P-type semiconductor, T h,i is the hot end temperature of the P-type semiconductor; S3: Calculate the voltage U of the N-type semiconductor in the i+1th column caused by the temperature difference i+1,N , the calculation formula is as follows: U i+1,N =|α N |(T h,i+1 -T c ) Where: α N is the Seebeck coefficient of N-type semiconductor; T h,i+1 is the hot end temperature of the N-type semiconductor; S4: Calculate the resistance R of the N-type semiconductor in the i+1th column caused by the temperature difference i+1,N and the resistance R of the P-type semiconductor in the i-th column i,P , the calculation formula is as follows: Where: N is the resistivity of N-type semiconductor; A is the cross-sectional area H3*W between N-type semiconductor and P-type semiconductor; In the formula, ρ P is the resistivity of the P-type semiconductor; A is the cross-sectional area H3*W between the N-type semiconductor and the P-type semiconductor; S5: Calculate the current I of the N-type semiconductor i+1,N and the current I of the P-type semiconductor i,P , the calculation formula is as follows: According to the boundary conditions in step S1, T h,i+1 =T h,i , get the convergence angle θ i Optimal value; S6: According to the convergence angle θ i Optimal value, select the inner fin thickness t i Distance d between adjacent inner fins i The output power of a single thermoelectric module is calculated from the voltage and internal resistance of the P-type semiconductor in the i-th column and the N-type semiconductor in the i+1th column. The calculation formula is as follows: Iterate to get the maximum output power and obtain the inner fin thickness t i Distance d between adjacent inner fins i Optimal value.

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