Performance Optimization Method and Device for a Ring-Shaped Thermoelectric Generator with a Needle Fin Structure

Abstract

The present invention discloses a method and device for optimizing the performance of a ring-shaped thermoelectric generator with a needle-shaped fin structure. The method includes: identifying variable factors affecting the output performance of the ring-shaped thermoelectric generator, and obtaining orthogonal array experimental combinations corresponding to the variable factors; establishing a three-dimensional numerical model of the ring-shaped thermoelectric generator device with a needle-shaped fin structure, performing fluid field-thermal field-electric field simulation coupling on the orthogonal array experimental combinations, solving the control equations of the fluid field, thermal field, and electric field, and obtaining the net power and conversion efficiency corresponding to each variable factor; respectively simulating the signal-to-noise ratio of the net power or the signal-to-noise ratio of the conversion efficiency corresponding to each variable factor, and calculating the average signal-to-noise ratio of the net power or the average signal-to-noise ratio of the conversion efficiency corresponding to the same variable factor and the same initial data. The present invention can fit a cylindrical heat source, enhance fluid heat transfer, and determine the optimal parameter combination affecting the output performance of the ring-shaped thermoelectric generator through signal-to-noise ratio analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery, and particularly to a method and device for optimizing the performance of an annular thermoelectric generator with a pin fin structure. Background Art

[0002] Due to the excessive use of fossil energy, carbon dioxide emissions and energy shortages have become global problems. Researchers have been committed to exploring and developing alternative green energy technologies to reduce emissions and the use of fossil fuels. As one of the alternative energy technologies, a thermoelectric generator can directly recover waste heat and convert it into electrical energy, and has the advantages of direct conversion, no noise, no vibration, and long service life.

[0003] Chinese Patent CN110024145A provides a thermoelectric generator with two substrates. A plurality of thermoelectric elements are arranged between the two flat substrates to connect the electrodes on the substrates. However, the structure of the flat thermoelectric generator has the following defects: for a cylindrical heat source such as an automobile exhaust pipe, the flat plate cannot fit the pipe, reducing the energy utilization. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention proposes a method and device for optimizing the performance of an annular thermoelectric generator with a pin fin structure. The device can fit a cylindrical heat source. By arranging a cross-shaped pin fin structure inside the annular heat exchanger, the fluid heat transfer is strengthened. The optimization method performs fluid field-thermal field-electric field simulation coupling on the established three-dimensional numerical model of the annular thermoelectric generator device. Through signal-to-noise ratio analysis, the sensitivity of each variable factor to the output performance of the thermoelectric generator is obtained, and the optimal parameter combination affecting the output performance of the annular thermoelectric generator is determined.

[0005] To achieve the above object, a method for optimizing the performance of an annular thermoelectric generator with a pin fin structure designed by the present invention is used to measure and optimize the influence of the pin fin structure on the output performance of the annular thermoelectric generator. The special feature is that it includes:

[0006] Step 1: Identify X variable factors that affect the output performance of the annular thermoelectric generator. The variable factors include the characteristics of hot air and the pin fin structure. Determine Y initial data corresponding to each variable factor. Use the Taguchi method to perform orthogonal array experiment combinations on all the initial data to obtain several groups of orthogonal array experiment combinations corresponding to the X variable factors.

[0007] Step 2: Establish a three-dimensional numerical model of the annular thermoelectric generator device with a pin fin structure, mesh the three-dimensional numerical model, and perform fluid field-thermal field-electric field simulation coupling on several groups of orthogonal array experimental combinations to solve the control equations of the fluid field, thermal field, and electric field. Specifically: Perform fluid field simulation coupling on the hot air in the hot air channel (1) and the cooling water in the cooling water channel (3) in the heat exchanger unit; perform thermal field simulation coupling on the pin fins (2), hot air channel (1), thermocouples (5), and cooling water channel (3) in the thermoelectric module unit; perform electric field simulation coupling on the thermocouples (5) in the thermoelectric module unit and the load resistors connected in series in the thermoelectric generator.

[0008] Step 3: Propose using net power and conversion efficiency as two indicators to measure the output performance of the thermoelectric generator, determine the mathematical equations for the net power and conversion efficiency of the thermoelectric generator, and obtain several net powers and several conversion efficiencies corresponding to each variable factor.

[0009] Step 4: Introduce a signal-to-noise ratio parameter expressed in terms of net power or conversion efficiency, respectively simulate several net power signal-to-noise ratios or several conversion efficiency signal-to-noise ratios corresponding to each variable factor, calculate the average net power signal-to-noise ratio or average conversion efficiency signal-to-noise ratio corresponding to the same variable factor and the same initial data, determine the maximum average net power signal-to-noise ratio or maximum average conversion efficiency signal-to-noise ratio corresponding to the same variable factor, and use the initial data corresponding to the maximum average net power signal-to-noise ratio or maximum average conversion efficiency signal-to-noise ratio as the optimal initial data for the variable factor. Finally, use the optimal initial data corresponding to each of the X variable factors as the optimal parameter combination affecting the output performance of the annular thermoelectric generator.

[0010] Further, in Step 1, the X variable factors are hot air temperature, hot air mass flow rate, pin fin height, pin fin diameter, and number of pin fins.

[0011] Further, in Step 2, establish a three-dimensional numerical model of the annular thermoelectric generator device with a pin fin structure through Ansys / Spaceclaim software, perform fluid field simulation coupling on several groups of orthogonal array experimental combinations through Ansys / Fluent software, and perform thermal field-electric field simulation coupling on several groups of orthogonal array experimental combinations through Ansys / thermal-electric software.

[0012] Even further, in Step 2, the renormalization group k-ε turbulence model is used for the hot air in the hot air channel (1) and the cooling water in the cooling water channel (3), and the control equation of the fluid field is

[0013]

[0014]

[0015]

[0016]

[0017]

[0018] In the formula,

[0019] v represents the hot air fluid velocity,

[0020] P represents the hot air pressure,

[0021] μ represents the dynamic viscosity of hot air,

[0022] λ represents the thermal conductivity,

[0023] T represents the hot air temperature,

[0024] ρ represents the hot air density,

[0025] k represents the turbulent kinetic energy,

[0026] c represents the specific heat capacity,

[0027] u i represents the velocity in the X i direction,

[0028] α k represents the inverse effective Prandtl number of k,

[0029] μ eff represents the effective dynamic viscosity,

[0030] G k represents the turbulent kinetic energy generated by the average velocity gradient,

[0031] G b represents the turbulent kinetic energy generated by buoyancy,

[0032] ε represents the friction loss coefficient,

[0033] Y M represents the contribution of pulsating expansion,

[0034] α ε represents the inverse effective Prandtl number of ε,

[0035] C 1ε represents an empirical constant with a value of 1.44,

[0036] C 2ε represents an empirical constant with a value of 1.92,

[0037] C 3εIt is a coefficient related to buoyancy in compressible flow calculations. When the mainstream is parallel to the gravity direction, C 3ε = 1.0; when the mainstream is perpendicular to the gravity direction, C 3ε = 0,

[0038] R ε is user-defined.

[0039] Furthermore, in step two, the control equation of the thermal field is

[0040]

[0041]

[0042]

[0043]

[0044] In the formula,

[0045] λ p represents the thermal conductivity of the p-type semiconductor leg,

[0046] T p represents the hot air temperature of the p-type semiconductor leg,

[0047] ρ p represents the density of the p-type semiconductor leg,

[0048] represents the current density vector,

[0049] S p represents the Seebeck coefficient of the p-leg,

[0050] λ n represents the thermal conductivity of the n-type semiconductor leg,

[0051] T n represents the hot air temperature of the n-type semiconductor leg,

[0052] ρ n represents the density of the n-type semiconductor leg,

[0053] S n represents the Seebeck coefficient of the n-leg,

[0054] λ co represents the thermal conductivity of the copper sheet,

[0055] ρ co represents the density of the copper sheet,

[0056] λ ce represents the thermal conductivity of the ceramic sheet.

[0057] Furthermore, in step two, the control equation of the electric field is

[0058]

[0059]

[0060]

[0061] In the formula,

[0062] represents the electric potential,

[0063] represents the electric field density vector,

[0064] α represents the Seebeck coefficient,

[0065] represents the current density vector,

[0066] σ represents the electrical conductivity.

[0067] Furthermore, in step three, the mathematical equations for the net power and conversion efficiency are

[0068] P net = P out - P loss

[0069]

[0070]

[0071]

[0072] In the formula,

[0073] P net is the net power of the thermoelectric generator,

[0074] P out is the total output power of the thermoelectric generator,

[0075] P loss is the pressure drop loss of the thermoelectric generator caused by adding the pin fin structure,

[0076] U is the voltage of the series load resistor in the thermoelectric generator,

[0077] R L is the resistance value of the series load resistor in the thermoelectric generator,

[0078] P1 is the total pressure of the hot air flowing into the surface of the pin fin structure,

[0079] P2 is the total surface pressure of the hot air flowing out of the pin fin structure,

[0080] m f is the mass flow rate of the hot air,

[0081] ρ is the density of the hot air,

[0082] η is the conversion efficiency of the thermoelectric generator,

[0083] Q h is the heat absorbed by the pin fin structure from the hot air.

[0084] Further, in step four, the signal-to-noise ratio expressed in terms of net power or conversion efficiency is

[0085]

[0086] wherein,

[0087] S / N is the signal-to-noise ratio,

[0088] y is the net power or conversion efficiency output by the ring-shaped thermoelectric generator.

[0089] The present invention also designs a ring-shaped thermoelectric generator device with a pin fin structure. The performance optimization method of the above ring-shaped thermoelectric generator with a pin fin structure includes:

[0090] A heat exchanger unit, including a cylindrical hot air channel sleeved on the outer periphery of the automobile exhaust pipe. A plurality of pin fins for enhancing heat transfer and arranged in a staggered manner are fixedly provided on the inner wall of the hot air channel, and each pin fin extends towards the automobile exhaust pipe; a ring-shaped cooling water channel is arranged outside the hot air channel;

[0091] A thermoelectric module unit, including N thermoelectric rings arranged in electrical series between the hot air channel and the cooling water channel. Each thermoelectric ring is internally provided with M pairs of thermocouples distributed in a circumferential manner. Each pair of thermocouples includes a p-type semiconductor leg and an n-type semiconductor leg. A conductive copper sheet and a ceramic sheet are sequentially attached to the outside and inside of the p-type semiconductor leg, and a conductive copper sheet and a ceramic sheet are sequentially attached to the outside and inside of the n-type semiconductor leg.

[0092] Further, N is 12, M is 24, the height h of each pair of thermocouples is 6.6 mm, and the angle θ of each p-type semiconductor leg p is 6°, the angle θ of each n-type semiconductor leg n is 6°, and the angle θ between the p-type semiconductor leg and the n-type semiconductor leg in is 1.5°.

[0093] The advantages of the present invention are:

[0094] 1. The present invention strengthens fluid heat transfer and improves the heat transfer at the hot end of the annular thermoelectric generator and its output performance by arranging pin fins in a cross pattern inside the annular heat exchanger.

[0095] 2. The present invention analyzes the influence of various variable factors on the output performance of the annular thermoelectric generator by using the Taguchi method, establishes an orthogonal array experimental combination of the initial data corresponding to each variable factor, then establishes a three-dimensional numerical model of the annular thermoelectric generator device with a pin fin structure, performs fluid field-thermal field-electric field simulation coupling on the orthogonal array experimental combination, obtains the sensitivity of each variable factor to the output performance of the thermoelectric generator, and determines the optimal parameter combination affecting the output performance of the annular thermoelectric generator; the Taguchi method greatly reduces the number of simulation experiments and shortens the calculation time; the simulation coupling of multiple physical fields of fluid field-thermal field-electric field obtains the sensitivity of each variable factor to the output performance of the thermoelectric generator, and determines the optimal parameter combination affecting the output performance of the annular thermoelectric generator.

[0096] The present invention relates to a method and device for optimizing the performance of an annular thermoelectric generator with a pin fin structure. The device can fit a cylindrical heat source, strengthens fluid heat transfer by arranging pin fins in a cross pattern inside the annular heat exchanger. The optimization method performs fluid field-thermal field-electric field simulation coupling on the established three-dimensional numerical model of the annular thermoelectric generator device, and determines the optimal parameter combination affecting the output performance of the annular thermoelectric generator through signal-to-noise ratio analysis. Description of the Drawings

[0097] Figure 1 is a three-dimensional structural schematic diagram of the annular thermoelectric generator device with a pin fin structure in the present invention;

[0098] Figure 2 is Figure 1 a cross-sectional structural schematic diagram;

[0099] Figure 3 is Figure 1 a structural schematic diagram of the thermocouple in

[0100] Figure 4 is a flowchart of the method for optimizing the performance of the annular thermoelectric generator with a pin fin structure in the present invention;

[0101] Figure 5 is a schematic diagram of the effect of Ansys modeling on fluid field-thermal field-electric field simulation coupling;

[0102] Figure 6 is the average net power signal-to-noise ratio curve corresponding to each variable factor in the embodiment under different initial data;

[0103] Figure 7The average conversion efficiency signal-to-noise ratio curves corresponding to various variable factors in the embodiments under different initial data;

[0104] In the figure: hot air channel 1, pin fin 2, cooling water channel 3, thermoelectric ring 4, thermocouple 5;

[0105] The thermocouple 5 includes: p-type semiconductor leg 5-1, n-type semiconductor leg 5-2, conductive copper sheet 5-3, ceramic sheet 5-4;

[0106] Thermocouple height h, p-type semiconductor leg angle θ p and n-type semiconductor leg angle θ n and the angle θ between the p-type semiconductor leg and the n-type semiconductor leg in . Detailed implementation manners

[0107] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0108] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and 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, and therefore should not be construed as a limitation of the invention.

[0109] As Figures 1 to 3 shown, the annular thermoelectric generator device with a pin fin structure of the present invention includes:

[0110] A heat exchanger unit, including a cylindrical hot air channel 1 sleeved on the outer periphery of the automobile exhaust pipe, and the hot air channel 1 is used to carry hot air. A plurality of pin fins 2 for strengthening heat transfer and arranged in a staggered manner are fixedly provided on the inner wall of the hot air channel 1, and each pin fin 2 extends towards the automobile exhaust pipe, and the pin fins 2 are used to achieve the purpose of optimizing the performance of the thermoelectric generator. A circular cooling water channel 3 is arranged outside the hot air channel 1.

[0111] A thermoelectric module unit, including N thermoelectric rings 4 arranged in electrical series between the hot air channel 1 and the cooling water channel 3, and the interval between adjacent thermoelectric rings 4 is 1 mm.

[0112] Each of the thermoelectric rings 4 is internally provided with M pairs of thermocouples 5 distributed in a circumferential manner. Each pair of thermocouples 5 includes a p-type semiconductor leg 5-1 and an n-type semiconductor leg 5-2. A conductive copper sheet 5-3 and a ceramic sheet 5-4 are successively attached to the outer and inner sides of the p-type semiconductor leg 5-1, respectively. A conductive copper sheet 5-3 and a ceramic sheet 5-4 are successively attached to the outer and inner sides of the n-type semiconductor leg 5-2, respectively.

[0113] The M pairs of thermocouples 5 are connected in a form of thermal parallel connection and electrical series connection.

[0114] Preferably, N is 12, M is 24, the height h of each pair of thermocouples 5 is 6.6 mm, and the angle θ of each p-type semiconductor leg 5-1 p is 6°, the angle θ of each n-type semiconductor leg 5-2 n is 6°, and the angle θ between the p-type semiconductor leg 5-1 and the n-type semiconductor leg 5-2 in is 1.5°.

[0115] By arranging a pin fin structure in a crosswise manner inside the annular heat exchanger, the present invention strengthens the heat transfer of the fluid, improves the heat transfer at the hot end of the annular thermoelectric generator, and improves the output performance of the annular thermoelectric generator.

[0116] As Figure 4 shown, the method for optimizing the performance of the annular thermoelectric generator with a pin fin structure according to the present invention is used to measure and optimize the influence of the pin fin structure on the output performance of the annular thermoelectric generator, and includes the following steps:

[0117] Step 1: Identify X variable factors that affect the output performance of the annular thermoelectric generator. The variable factors include the characteristics of hot air and the pin fin structure. Determine Y initial data corresponding to each variable factor, and perform an orthogonal array experiment combination on all the initial data by using the Taguchi method to obtain several groups of orthogonal array experiment combinations corresponding to the X variable factors.

[0118] Specifically, X is 5 and Y is 5. The 5 variable factors are the hot air temperature, the hot air mass flow rate, the pin fin height, the pin fin diameter, and the number of pin fins.

[0119] The 5 initial data corresponding to each of the above 5 variable factors are shown in Table 1 below.

[0120] Table 1 Variable factors and corresponding initial data

[0121]

[0122]

[0123] Use the Taguchi method to conduct orthogonal array experiments on the above 5 variable factors, and obtain the corresponding 25 groups of orthogonal array experiment combinations as shown in Table 2 below.

[0124] Table 2 Orthogonal array experiment combinations

[0125]

[0126] Step 2: Establish a three-dimensional numerical model of the annular thermoelectric generator device with a pin-fin structure, divide the mesh of the three-dimensional numerical model, and perform fluid field-thermal field-electric field simulation coupling on several groups of orthogonal array experiment combinations, and solve the control equations of the fluid field, thermal field, and electric field. Specifically: Perform fluid field simulation coupling on the hot air in the hot air channel (1) and the cooling water in the cooling water channel (3) in the heat exchanger unit; perform thermal field simulation coupling on the pin fins (2), hot air channel (1), thermocouples (5), and cooling water channel (3) in the thermoelectric module unit; perform electric field simulation coupling on the thermocouples (5) in the thermoelectric module unit and the series-connected load resistors in the thermoelectric generator.

[0127] Specifically, establish a three-dimensional numerical model of the annular thermoelectric generator device with a pin-fin structure through Ansys / Spaceclaim software.

[0128] Perform fluid field simulation coupling on 25 groups of orthogonal array experiment combinations through Ansys / Fluent software. Set the k-ε turbulence model in Fluent, define the fluid material, fluid velocity and temperature, and set the coupling surface.

[0129] Perform thermal field-electric field simulation coupling on 25 groups of orthogonal array experiment combinations through Ansys / thermal-electric software. Define the solid material, divide the mesh, and set the ground boundary, voltage coupling boundary, and fluid-solid coupling interface.

[0130] Set the number of iteration steps in Ansys / system coupling. The relationships and energy conversions between various physical fields in Ansys are as Figure 5 shown. Modify the specific solver for multi-physical fields and start the calculation.

[0131] Specifically, the hot air in the hot air channel (1) and the cooling water in the cooling water channel (3) adopt the renormalization group (RNG) k-ε turbulence model, and the control equation of the fluid field is

[0132]

[0133]

[0134]

[0135]

[0136]

[0137] In the formula,

[0138] v represents the velocity of the hot air fluid,

[0139] P represents the hot air pressure,

[0140] μ represents the dynamic viscosity of the hot air,

[0141] λ represents the thermal conductivity,

[0142] T represents the hot air temperature,

[0143] ρ represents the hot air density,

[0144] k represents the turbulent kinetic energy,

[0145] c represents the specific heat capacity,

[0146] u i represents the velocity in the X i direction,

[0147] α k represents the inverse effective Prandtl number of k,

[0148] μ eff represents the effective dynamic viscosity,

[0149] G k represents the turbulent kinetic energy generated by the mean velocity gradient,

[0150] G b represents the turbulent kinetic energy generated by buoyancy,

[0151] ε represents the friction loss coefficient,

[0152] Y M represents the contribution of pulsating dilation,

[0153] α ε represents the inverse effective Prandtl number of ε,

[0154] C 1ε represents an empirical constant with a value of 1.44,

[0155] C 2ε represents an empirical constant with a value of 1.92,

[0156] C 3ε is a coefficient related to buoyancy in the calculation of compressible flow. When the mainstream is parallel to the gravity direction, C 3ε = 1.0; when the mainstream is perpendicular to the gravity direction, C 3ε= 0,

[0157] R ε is user-defined.

[0158] Specifically, the control equation of the thermal field is

[0159]

[0160]

[0161]

[0162]

[0163] In the formula,

[0164] λ p represents the thermal conductivity of the p-type semiconductor leg,

[0165] T p represents the hot air temperature of the p-type semiconductor leg,

[0166] ρ p represents the density of the p-type semiconductor leg,

[0167] represents the current density vector,

[0168] S p represents the Seebeck coefficient of the p-leg,

[0169] λ n represents the thermal conductivity of the n-type semiconductor leg,

[0170] T n represents the hot air temperature of the n-type semiconductor leg,

[0171] ρ n represents the density of the n-type semiconductor leg,

[0172] S n represents the Seebeck coefficient of the n-leg,

[0173] λ co represents the thermal conductivity of the copper sheet,

[0174] ρ co represents the density of the copper sheet,

[0175] λ ce represents the thermal conductivity of the ceramic sheet.

[0176] Specifically, the control equation of the electric field is

[0177]

[0178]

[0179]

[0180] In the formula,

[0181] represents the electric potential,

[0182] represents the electric field density vector,

[0183] α represents the Seebeck coefficient,

[0184] represents the current density vector,

[0185] σ represents the conductivity.

[0186] Step 3: Propose using the net power and conversion efficiency as two indicators to measure the output performance of the thermoelectric generator, and determine the mathematical equations for the net power and conversion efficiency of the thermoelectric generator, and obtain several net powers and several conversion efficiencies corresponding to each variable factor.

[0187] The pin fins 2 increase the thermal measurement temperature of the thermoelectric module while also increasing the frictional resistance, that is, increasing the output efficiency while also increasing the pressure drop loss. In order to measure the impact of the heat transfer enhancement measures on the output performance of the annular thermoelectric generator, it is necessary to comprehensively consider the total output power P out and the pressure drop loss P loss , and propose using the net power P net and the conversion efficiency η as two indicators to measure the thermoelectric performance.

[0188] Specifically, the mathematical equations for the net power and conversion efficiency are

[0189] P net = P out - P loss

[0190]

[0191]

[0192]

[0193] In the formula,

[0194] P net is the net power of the thermoelectric generator,

[0195] P out is the total output power of the thermoelectric generator,

[0196] P lossThe addition of the pin fin structure results in a pressure drop loss in the thermoelectric generator.

[0197] U is the voltage across the series load resistor in the thermoelectric generator.

[0198] R L is the resistance value of the series load resistor in the thermoelectric generator.

[0199] P1 is the total pressure on the surface where hot air flows into the pin fin structure.

[0200] P2 is the total pressure on the surface where hot air flows out of the pin fin structure.

[0201] m f is the mass flow rate of hot air.

[0202] ρ is the density of hot air.

[0203] η is the conversion efficiency of the thermoelectric generator.

[0204] Q h is the heat absorbed by the pin fin structure from hot air.

[0205] Read the total pressure P1 of the hot air flowing in after integration, the total pressure P2 of the hot air flowing out, and the heat Q absorbed by the hot air in Ansys / Fluent. h . Read the voltage U of the series load resistor in Ansys / thermal-electric.

[0206] Step 4: Introduce the signal-to-noise ratio parameter expressed in net power or conversion efficiency. Respectively simulate a number of net power signal-to-noise ratios or a number of conversion efficiency signal-to-noise ratios corresponding to each variable factor. Calculate the average net power signal-to-noise ratio or the average conversion efficiency signal-to-noise ratio corresponding to the same variable factor and the same initial data. Determine the maximum average net power signal-to-noise ratio or the maximum average conversion efficiency signal-to-noise ratio corresponding to the same variable factor. And use the initial data corresponding to the maximum average net power signal-to-noise ratio or the maximum average conversion efficiency signal-to-noise ratio as the optimal initial data for this variable factor. Finally, use the optimal initial data corresponding to each of the X variable factors as the optimal parameter combination affecting the output performance of the annular thermoelectric generator.

[0207] Specifically, the signal-to-noise ratio expressed in net power P net , or conversion efficiency η is

[0208]

[0209] In the formula,

[0210] S / N is the signal-to-noise ratio,

[0211] y is the net power output or the conversion efficiency of the annular thermoelectric generator.

[0212] The signal-to-noise ratios of the 25 groups of simulation experiment results expressed in net power or conversion efficiency are calculated. The numerical simulation results of the orthogonal sequence of the above variable factor A are shown in Table 3 below.

[0213] Table 3 Numerical simulation results of the orthogonal sequence of variable factor A

[0214]

[0215] According to the net power P shown in Table 3 obtained from the finite element simulation net and the predicted values of the conversion efficiency η, the average net power signal-to-noise ratio or the average conversion efficiency signal-to-noise ratio of each variable factor under each initial data can be obtained. For example, in terms of the net power, the average net power signal-to-noise ratio of variable factor A is equal to (0.784 + 8.049 + 12.956 + 11.833 + 10.037) / 5 = 8.73171574.

[0216] The average net power signal-to-noise ratio or the average conversion efficiency signal-to-noise ratio of other variable factors under each initial data is calculated in a similar manner. Figure 6 This is the average net power signal-to-noise ratio curve corresponding to different initial data under each variable factor in this embodiment; Figure 7 This is the average conversion efficiency signal-to-noise ratio curve corresponding to different initial data of each variable factor in this embodiment.

[0217] It can be seen from Figures 6 to 7 that when the average net power signal-to-noise ratio or the average conversion efficiency signal-to-noise ratio reaches the maximum value, the optimal combination of each variable factor is A5B3C3D5E5, that is, the hot-end gas temperature is 673K, the hot-end gas mass flow rate is 30g / s, the fin height is 20mm, the fin diameter is 3mm, and the number of fins is 480.

[0218] In addition, the influence ranking of X variable factors on the net power or the conversion efficiency can also be obtained through the average net power signal-to-noise ratio or the average conversion efficiency signal-to-noise ratio corresponding to the same variable factor and the same initial data. The specific method is as follows:

[0219] The difference between the maximum average net power signal-to-noise ratio and the minimum average net power signal-to-noise ratio corresponding to the same variable parameter and the same initial data is taken as the influence of the variable parameter on the net power output of the thermoelectric generator. The larger the difference, the greater the influence of the variable parameter on the net power output of the thermoelectric generator; the smaller the difference, the smaller the influence of the variable parameter on the net power output of the thermoelectric generator. The difference between the maximum average conversion efficiency signal-to-noise ratio and the minimum average conversion efficiency signal-to-noise ratio corresponding to the same variable parameter and the same initial data is taken as the influence of the variable parameter on the conversion efficiency output of the thermoelectric generator. The larger the difference, the greater the influence of the variable parameter on the conversion efficiency output of the thermoelectric generator; the smaller the difference, the smaller the influence of the variable parameter on the conversion efficiency output of the thermoelectric generator.

[0220] It can be seen from Figures 6 to 7 the results that:

[0221] I. The influence order of the 5 variable factors on the net power output P net of the annular thermoelectric generator is: Factor A > Factor D > Factor C > Factor E > Factor B. The difference of Factor B is the smallest, indicating that changing the hot air mass flow has almost no influence on the net power output of the annular thermoelectric generator.

[0222] II. The influence order of the 5 variable factors on the conversion efficiency η output of the annular thermoelectric generator is: Factor A > Factor D > Factor C > Factor E > Factor B. Similarly, the difference of Factor B is the smallest, indicating that changing the hot air mass flow has almost no influence on the conversion efficiency output of the annular thermoelectric generator.

[0223] In the present invention, the Taguchi method is used to analyze the influence of each variable factor on the output performance of the annular thermoelectric generator, an orthogonal array experimental combination corresponding to the initial data of each variable factor is established, and then a three-dimensional numerical model of the annular thermoelectric generator device with a pin-fin structure is established. The fluid field-thermal field-electric field simulation coupling is carried out on the orthogonal array experimental combination to obtain the sensitivity of each variable factor to the output performance of the thermoelectric generator, and the optimal parameter combination affecting the output performance of the annular thermoelectric generator is determined; the Taguchi method greatly reduces the number of simulation experiments and shortens the calculation time; the simulation coupling of multiple physical fields of the fluid field-thermal field-electric field obtains the sensitivity of each variable factor to the output performance of the thermoelectric generator, and the optimal parameter combination affecting the output performance of the annular thermoelectric generator is determined.

[0224] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A performance optimization method for a ring-shaped thermoelectric generator with a needle-shaped fin structure, which is used to measure and optimize the influence of the needle-shaped fin structure on the output performance of the ring-shaped thermoelectric generator, is characterized in that Including: Step 1: Identify X variable factors that affect the output performance of the annular thermoelectric generator. The variable factors include the characteristics of hot air and the structure of pin fins. Determine Y initial data corresponding to each variable factor, and use the Taguchi method to conduct orthogonal array experiments on all the initial data to obtain several groups of orthogonal array experiment combinations corresponding to the X variable factors. Step 2: Establish a three-dimensional numerical model of the annular thermoelectric generator device with a pin fin structure. Mesh the three-dimensional numerical model, and perform fluid field-thermal field-electric field simulation coupling on several groups of orthogonal array experiment combinations. Solve the control equations of the fluid field, thermal field, and electric field, specifically: perform fluid field simulation coupling on the hot air in the hot air channel (1) and the cooling water in the cooling water channel (3) in the heat exchanger unit; perform thermal field simulation coupling on the pin fins (2), hot air channel (1), thermocouples (5), and cooling water channel (3) in the thermoelectric module unit; perform electric field simulation coupling on the thermocouples (5) in the thermoelectric module unit and the series-connected load resistors in the thermoelectric generator. Step 3: Propose using net power and conversion efficiency as two indicators to measure the output performance of the thermoelectric generator, and determine the mathematical equations for the net power and conversion efficiency of the thermoelectric generator to obtain several net powers and several conversion efficiencies corresponding to each variable factor. Step 4: Introduce the signal-to-noise ratio parameter expressed by net power or conversion efficiency, respectively simulate several net power signal-to-noise ratios or several conversion efficiency signal-to-noise ratios corresponding to each variable factor, calculate the average net power signal-to-noise ratio or average conversion efficiency signal-to-noise ratio corresponding to the same variable factor and the same initial data, determine the maximum average net power signal-to-noise ratio or maximum average conversion efficiency signal-to-noise ratio corresponding to the same variable factor, and use the initial data corresponding to the maximum average net power signal-to-noise ratio or maximum average conversion efficiency signal-to-noise ratio as the optimal initial data for the variable factor. Finally, use the optimal initial data corresponding to each of the X variable factors as the optimal parameter combination affecting the output performance of the annular thermoelectric generator.

2. The performance optimization method of the annular thermoelectric generator with a needle-shaped fin structure according to claim 1, characterized in that: In Step 1, the X variable factors are hot air temperature, hot air mass flow rate, pin fin height, pin fin diameter, and the number of pin fins.

3. The performance optimization method of the annular thermoelectric generator with a needle-shaped fin structure according to claim 1, characterized in that: In Step 2, establish a three-dimensional numerical model of the annular thermoelectric generator device with a pin fin structure through Ansys / Spaceclaim software, perform fluid field simulation coupling on several groups of orthogonal array experiment combinations through Ansys / Fluent software, and perform thermal field-electric field simulation coupling on several groups of orthogonal array experiment combinations through Ansys / thermal-electric software.

4. The performance optimization method of the annular thermoelectric generator with a needle-shaped fin structure according to claim 3, characterized in that: In Step 2, the renormalization group k-ε turbulence model is used for the hot air in the hot air channel (1) and the cooling water in the cooling water channel (3), and the control equation of the fluid field is In the formula, v represents the hot air fluid velocity, P represents the hot air pressure, μ represents the dynamic viscosity of hot air, λ represents the thermal conductivity, T represents the hot air temperature, ρ represents the hot air density, k represents the turbulent kinetic energy, c represents the specific heat capacity, u i represents the velocity in the X i direction, α k represents the inverse effective Prandtl number of k, μ eff represents the effective dynamic viscosity G k represents the turbulent kinetic energy generated by the average velocity gradient G b represents the turbulent kinetic energy generated by buoyancy ε represents the friction loss coefficient, Y M represents the contribution of pulsating expansion, α ε represents the inverse effective Prandtl number of ε C 1ε represents an empirical constant with a value of 1.44, C 2ε represents an empirical constant with a value of 1.92 C 3ε is the coefficient related to buoyancy in compressible flow calculations. When the main flow is parallel to the direction of gravity, C 3ε = 1.0; when the main flow is perpendicular to the direction of gravity, C 3ε = 0, R ε For customization.

5. The performance optimization method of the annular thermoelectric generator with a needle-shaped fin structure according to claim 4, characterized in that: In Step 2, the control equation of the thermal field is where λ p represents the thermal conductivity of the p-type semiconductor leg T p Indicates the hot air temperature of the p-type semiconductor leg ρ p represents the density of p-type semiconductor legs represents the current density vector, S p represents the Seebeck coefficient of the p legs, λ n represents the thermal conductivity of the n-type semiconductor leg T n Represents the hot air temperature of the n-type semiconductor leg ρ n represents the density of n-type semiconductor legs S n represents the Seebeck coefficient of n legs λ co represents the thermal conductivity of the copper sheet ρ co represents the density of the copper sheet λ ce represents the thermal conductivity of the ceramic chip.

6. The performance optimization method of the annular thermoelectric generator with a needle-shaped fin structure according to claim 5, characterized in that: In Step 2, the control equation of the electric field is where represents the electric potential, represents the electric field density vector, α represents the Seebeck coefficient, represents the current density vector, σ represents the electrical conductivity.

7. The performance optimization method of the annular thermoelectric generator with a needle-shaped fin structure according to claim 6, characterized in that: In Step 3, the mathematical equations of the net power and conversion efficiency are P net = P out -P loss where P net is the net power of the thermoelectric generator P out is the total output power of the thermoelectric generator P loss The addition of the pin fin structure results in a pressure drop loss of the thermoelectric generator. U is the voltage of the series load resistor in the thermoelectric generator, R L is the resistance value of the series load resistor in the thermoelectric generator, P1 is the total pressure of the hot air flowing into the surface of the pin fin structure, P2 is the total pressure of the hot air flowing out of the surface of the pin fin structure, m f is the thermal air mass flow rate, ρ is the density of the hot air, η is the conversion efficiency of the thermoelectric generator, Q h Absorb the heat of the hot air with a pin fin structure.

8. The performance optimization method of the annular thermoelectric generator with a needle-shaped fin structure according to claim 1, characterized in that In Step 4, the signal-to-noise ratio expressed in terms of the net power or conversion efficiency is where S / N is the signal-to-noise ratio, y is the net power or conversion efficiency output by the annular thermoelectric generator.

9. A ring-shaped thermoelectric generator device with a needle-shaped fin structure, applicable to the performance optimization method of the ring-shaped thermoelectric generator with a needle-shaped fin structure according to any one of claims 1 to 8, characterized in that, It includes: A heat exchanger unit, including a cylindrical hot air channel (1) sleeved on the outer periphery of the automobile exhaust pipe. A plurality of staggered pin fins (2) for enhancing heat transfer are fixedly arranged on the inner wall of the hot air channel (1), and each of the pin fins (2) extends towards the automobile exhaust pipe; an annular cooling water channel (3) is arranged outside the hot air channel (1); A thermoelectric module unit, including N thermoelectric rings (4) arranged in electrical series between the hot air channel (1) and the cooling water channel (3). M pairs of thermocouples (5) are circumferentially distributed in each of the thermoelectric rings (4). Each pair of the thermocouples (5) includes a p-type semiconductor leg (5-1) and an n-type semiconductor leg (5-2). A conductive copper sheet (5-3) and a ceramic sheet (5-4) are sequentially attached to the outer and inner sides of the p-type semiconductor leg (5-1), and a conductive copper sheet (5-3) and a ceramic sheet (5-4) are sequentially attached to the outer and inner sides of the n-type semiconductor leg (5-2).

10. The annular thermoelectric generator device with a needle-shaped fin structure according to claim 9, characterized in that: N is 12, M is 24, the height h of each pair of the thermocouples (5) is 6.6 mm, and the angle θ of each p-type semiconductor leg (5-1) p is 6°, and the angle θ of each n-type semiconductor leg (5-2) n is 6°. The angle θ between the p-type semiconductor leg (5-1) and the n-type semiconductor leg (5-2) in is 1.5°.

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