CN117489454A - Novel thermoelectric generator and thermoelectric semiconductor width calculation method in thermoelectric module of novel thermoelectric generator - Google Patents

Novel thermoelectric generator and thermoelectric semiconductor width calculation method in thermoelectric module of novel thermoelectric generator Download PDF

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CN117489454A
CN117489454A CN202311210575.1A CN202311210575A CN117489454A CN 117489454 A CN117489454 A CN 117489454A CN 202311210575 A CN202311210575 A CN 202311210575A CN 117489454 A CN117489454 A CN 117489454A
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thermoelectric
thermoelectric module
module
semiconductor
exhaust pipe
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罗丁
张浩慷
杨学林
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China Three Gorges University CTGU
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China Three Gorges University CTGU
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • F01N5/025—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat the device being thermoelectric generators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B21/00—Machines, plants or systems, using electric or magnetic effects
    • F25B21/02—Machines, plants or systems, using electric or magnetic effects using Peltier effect; using Nernst-Ettinghausen effect
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/30—Circuit design
    • G06F30/39—Circuit design at the physical level
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N11/00—Generators or motors not provided for elsewhere; Alleged perpetua mobilia obtained by electric or magnetic means
    • H02N11/002—Generators
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/08—Thermal analysis or thermal optimisation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Evolutionary Computation (AREA)
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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Thermal Sciences (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

The novel thermoelectric generator and the thermoelectric semiconductor width calculation method in the thermoelectric module thereof mainly comprise a thermoelectric generator, wherein the thermoelectric generator consists of a heat exchanger, a thermoelectric module and an S-shaped liquid cooling long plate; the inner side of the heat exchanger is attached to the exhaust pipe, the outer side of the heat exchanger is provided with a plurality of surfaces, and a plurality of thermoelectric modules are distributed on each surface of the heat exchanger along the length direction; the area of each thermoelectric module on each face is increased along the heat flow direction of the exhaust pipe. According to the novel thermoelectric generator and the thermoelectric semiconductor width calculation method in the thermoelectric modules, the thermoelectric modules with different thermoelectric semiconductor widths are adopted along the heat flow direction, and the widths are continuously increased along the heat flow direction, so that the influence of heat flow temperature reduction in the downstream direction of the exhaust pipe is counteracted, uniform output of the thermoelectric modules is realized, and the overall output performance of the thermoelectric generator is effectively improved.

Description

Novel thermoelectric generator and thermoelectric semiconductor width calculation method in thermoelectric module of novel thermoelectric generator
Technical Field
The invention relates to the field of thermoelectricity, in particular to a novel thermoelectric generator and a thermoelectric semiconductor width calculation method in a thermoelectric module of the novel thermoelectric generator.
Background
In recent years, thermoelectric generators have been attracting attention because they can directly convert waste heat into electric energy, and have many advantages of no moving parts, no pollution, silent operation, and the like. Considering that about 30% of the heat energy generated by combustion of fossil fuel by an internal combustion engine is released into the air in the form of exhaust gas, the thermoelectric generator clearly has a wide application prospect in the field of waste heat recovery of automobile exhaust.
Thermoelectric generators are typically composed of a heat exchanger, a thermoelectric module, and a heat sink. In order to recover the waste heat contained in the fluid, the heat is absorbed by the heat exchanger and then transferred to the thermoelectric module, and the heat sink is disposed at the cold end of the thermoelectric module, so that a temperature difference occurs in the thermoelectric module, and the thermoelectric generator outputs current due to the seebeck effect.
However, when the thermoelectric generator system is used for recovering the waste heat contained in the automobile exhaust, the overall output power is affected by the temperature drop along the heat flow direction, the overall output current is limited by the minimum output current in the thermoelectric module when connected in series, and the overall output voltage is limited by the minimum output voltage when connected in parallel, so that the waste of electric energy is caused.
Disclosure of Invention
The invention aims to solve the technical problem of providing a novel thermoelectric generator and a thermoelectric semiconductor width calculation method in the thermoelectric generator module, wherein thermoelectric modules with different thermoelectric semiconductor widths are adopted along the heat flow direction, and the widths are continuously increased along the heat flow direction, so that the influence of heat flow temperature reduction in the downstream direction of an exhaust pipe is counteracted, uniform output of the thermoelectric modules is realized, and the overall output performance of the thermoelectric generator is effectively improved.
In order to solve the technical problems, the invention adopts the following technical scheme:
a novel thermoelectric generator, wherein the area of a thermoelectric module is continuously increased along the heat flow direction; the novel thermoelectric generator consists of a heat exchanger, a thermoelectric module and an S-shaped liquid cooling long plate.
The outside of the cross section of the heat exchanger is designed to be equal to a hexagon, the inside of the cross section is designed to be a circle, and the inside and the outside are concentric.
The thermoelectric module consists of a ceramic plate, copper electrodes, a P-type thermoelectric semiconductor and an N-type thermoelectric semiconductor, wherein the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor are connected in series through the copper electrodes and are clamped between the upper ceramic plate and the lower ceramic plate.
The surface of the S-shaped liquid cooling long plate is attached to the upper end surface of the thermoelectric module, and the internal flow passage is designed into an S-shaped cylinder.
As shown in fig. 1, the lengths of the heat exchanger and the S-type liquid cooling long plate are the same, and are L, and the distance from the thermoelectric module to two ports of the exhaust pipe and the distance between the two thermoelectric modules are t.
As shown in FIG. 2, the inside diameter of the exhaust pipe is R 1 The diameter of the circular section of the heat exchanger is R 2 The side length of the hexagonal section of the heat exchanger is L 1 。
As shown in fig. 3, each thermoelectric module comprises thermoelectric semiconductors in b rows and b columns, the geometrical parameters of the P-type thermoelectric semiconductors and the N-type thermoelectric semiconductors in the same thermoelectric module are the same, the numbers of the P-type thermoelectric semiconductors and the N-type thermoelectric semiconductors in each thermoelectric module are the same, N is n=1, 2,3, … …, and the numbers of copper electrodes are 2N, 2n=b 2 -2。
As shown in FIG. 4, in all thermoelectric modules, the thickness of the ceramic plate is H 1 The thickness of the copper electrode is H 2 The length and thickness of the P/N type thermoelectric semiconductor are L respectively 2 And H 3 The row spacing of the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor is the same, and the row spacing of the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor is a.
As shown in fig. 5, the thickness of the S-type liquid cooling long plate is H, two round holes are formed in the side surface of the S-type liquid cooling long plate, the inlet and the outlet of the fluid are respectively formed, and the diameter of the S-type liquid cooling long plate pipe is d.
In the technical proposal, the device is replacedThe inner side of the heat exchanger is attached to an automobile exhaust pipe, M thermoelectric modules are respectively distributed on the six surfaces of the heat exchanger, the thermoelectric modules are axially distributed at equal intervals along the heat flow direction, the thermoelectric modules and the heat radiator on each surface have the same distribution rule, and on the same heat exchanger surface, the 1 st thermoelectric module is close to the heat flow inlet, and the M th thermoelectric module is close to the heat flow outlet; the width of the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor in the ith thermoelectric module is W i The column spacing between the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor isi is an integer, and i is more than or equal to 1 and less than or equal to M.
Thermoelectric semiconductor width W of ith thermoelectric module in the novel thermoelectric generator i Comprises the following steps:
s1: assume that the difference between the width of the i+1th thermoelectric module P/N type thermoelectric semiconductor and the width of the i th thermoelectric module P/N type thermoelectric semiconductor is Δw, i.e., Δw=w i+1 -W i Wherein Δw satisfies the relationship:W 1 are known.
S2: building a thermal resistance model to let T w For the temperature of the contact surface between the exhaust pipe segment and the heat flow corresponding to the thermoelectric module, T h_i For the hot end average temperature of the ith thermoelectric module, the thermal resistance of the exhaust pipe to the hot end of the thermoelectric module
Wherein: u (u) 1 For the thickness of the exhaust pipe H 3 Is the thickness of the P/N type thermoelectric semiconductor, u 2 Lambda is the average thickness of the heat exchanger 1 Lambda is the thermal conductivity of the exhaust pipe 2 Lambda is the heat conductivity of the heat exchanger 3 For the thermal conductivity of the ceramic plate, A 1 For the surface area of the contact surface of the heat exchanger and the heat flow, A 2 For the surface area of the contact surface of the heat exchanger and the radiator, A 3 Is the surface area of the contact surface of the ceramic plate and the heat exchanger.
S3: by the equation of heat absorptionCalculating to obtain heat Q absorbed by thermoelectric module h ；
Wherein: c is the specific heat capacity of the heat flow,is the mass flow of the heat flow, delta T is the temperature difference between two ends of the exhaust pipe section, L 3 For the width of the ceramic plate of the thermoelectric module, L represents the length of the exhaust pipe.
S4: by passing throughThe convective heat transfer coefficient h is calculated, and the average Nusselt number of air and water is expressed as +.>f＝(1.82lgRe-1.64) -2 Reynolds number->Planty ++>
Wherein: λ represents thermal conductivity, D represents hydraulic diameter; hydraulic diameter d=2r 1 ，R 1 Is the inner diameter of the exhaust pipe.
S5: by the equation of heat absorptionCalculating to obtain the hot end average temperature of the ith thermoelectric module +.>
Wherein: a is the cross-sectional area of the interior of the pipeline, h is the convective heat transfer coefficient,representing the average temperature, T, of heat flow of the exhaust pipe section corresponding to the ith thermoelectric module h Indicating the temperature of the hot end of the thermoelectric module, R h Representing the thermal resistance of the exhaust pipe to the hot end of the thermoelectric module, Q h Representing the amount of heat absorbed by the thermoelectric module.
S6: by equation ofCalculating to obtain the internal resistance of the ith thermoelectric module:
wherein ρ is P Representing the resistivity, ρ, of a P-type thermoelectric semiconductor N The resistivity of the N-type thermoelectric semiconductor is represented, N represents the number of P-type thermoelectric semiconductors or N-type thermoelectric semiconductors of each thermoelectric module, ρ Copper (Cu) The resistivity of the copper electrode is shown.
S7: output current of ith thermoelectric module
Wherein N represents the number of P-type thermoelectric semiconductors or N-type thermoelectric semiconductors of each thermoelectric module, alpha represents the Seebeck coefficient, T h_i For the hot side average temperature, T, of the ith thermoelectric module c Indicating the cool side temperature of the thermoelectric module.
S8: let the output current of the i-th thermoelectric module be equal to the output current of the i+1th thermoelectric module, namely:calculating to obtain the temperature relation between the thermoelectric semiconductor width of the ith thermoelectric module and the thermoelectric semiconductor width of the (i+1) th thermoelectric module, namely, satisfying the equation: (T) h_i -T c )W i ＝(T h_i+1 -T c )W i+1 。
S9: calculate the ithThe thermoelectric modules correspond to the heat flow average temperature of the exhaust pipe sectionsThe temperature average value of the boundary of the ith thermoelectric module along the two ends of the heat flow direction is equal to the equation:
wherein T is in And T out The temperature of the hot-fluid inlet and the hot-fluid outlet are respectively, t is the distance from the thermoelectric module to two ports of the exhaust pipe and the distance between the two thermoelectric modules, L 3 Is the width of the ceramic plate of the thermoelectric module and is a known condition.
S10: determining the magnitude relationship between Δw and heat flow temperature, such that i=1 in S9, i.e
Wherein DeltaW represents the difference between the width of the (i+1) th thermoelectric module P/N type thermoelectric semiconductor and the width of the (i) th thermoelectric module P/N type thermoelectric semiconductor,obtained from S9->
S11: calculating the thermoelectric semiconductor width of each thermoelectric module in the heat flow direction, i.e. wi=w+ (i-1) Δw
The invention discloses a novel thermoelectric generator and a thermoelectric semiconductor width calculation method in a thermoelectric module thereof, which have the following technical effects:
1) According to the thermoelectric generator, thermoelectric modules with different thermoelectric semiconductor widths are adopted along the heat flow direction, the widths of the thermoelectric modules are continuously increased along the heat flow direction, the width of each thermoelectric module can be calculated by solving the tolerance of the widths of the thermoelectric modules according to the working temperature of each thermoelectric module, the uniform output of the different thermoelectric modules is finally realized, and the overall output performance of thermoelectric power generation is improved.
2) The invention is different from the existing hexagonal thermoelectric generator in that: the thermoelectric modules with different thermoelectric semiconductor widths are adopted, and the widths of the thermoelectric modules are gradually increased along the heat flow direction, so that the influence of heat flow temperature reduction in the downstream direction of an automobile exhaust pipe is counteracted, and the recycling rate of automobile exhaust waste heat is greatly improved.
3) The area of the thermoelectric module is increased by increasing the width of the thermoelectric semiconductor of the thermoelectric module in the tail gas downlink direction, so that the output currents of the thermoelectric module are equal, the difficulty of current limitation is overcome, and the overall output performance of the thermoelectric generator is improved.
4) According to the invention, the tolerance expression of the thermoelectric semiconductor width change in the thermoelectric module is obtained by calculating by establishing the thermal resistance model of the thermoelectric generator, and the width of the thermoelectric semiconductor in the thermoelectric module can be determined by the heat flow and the related parameters of the thermoelectric generator, so that the calculation is convenient and quick.
5) In view of the problems mentioned in the background section, some researchers have adopted a variable-area annular thermoelectric device in which thermoelectric semiconductors have a cross-sectional area that is increasing in the direction of heat flow, and have been structured to overcome this problem. The single thermoelectric module structure designed by the invention adopts thermoelectric semiconductors with different sizes, the structure is complex, and the single thermoelectric module of the invention adopts thermoelectric semiconductors with the same size, thereby being more easy for mass production and application.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
fig. 1 is a schematic structural view of the present invention.
Fig. 2 is a schematic side view of the present invention.
Fig. 3 is a schematic structural view of a thermoelectric module according to the present invention.
Fig. 4 is a schematic side view of a thermoelectric module according to the present invention.
FIG. 5 is a schematic view of a flow channel structure of an S-type liquid-cooled long plate according to the present invention.
FIG. 6 is a flowchart of ΔW calculation in the present invention.
In the figure: the heat exchanger comprises an exhaust pipe 1, a heat exchanger 2, a thermoelectric module 3, an S-type liquid cooling long plate 4, a fluid inlet 5, a fluid outlet 6, a ceramic plate 3.1, a copper electrode 3.2, a P-type thermoelectric semiconductor 3.3 and an N-type thermoelectric semiconductor 3.4.
Detailed Description
As shown in fig. 1, the novel thermoelectric generator consists of a heat exchanger 2, a thermoelectric module 3 and an S-type liquid cooling long plate 4. The heat exchanger 2, the thermoelectric module 3 and the S-shaped liquid cooling long plate 4 are sequentially arranged on the exhaust pipe 1 from inside to outside, and the diameter of the inner side of the exhaust pipe 1 is R 1 . The length of the exhaust pipe 1, the length of the heat exchanger 2 and the length of the S-shaped liquid cooling long plate 4 are the same, and the lengths are L. The thermoelectric modules 3 are arranged in groups along the axial direction of the exhaust pipe 1, and the area of the thermoelectric modules is continuously increased along the heat flow direction.
As shown in fig. 1-2, specifically, the heat exchanger 2 is designed to have an isosceles shape on the outer side of the cross section, a circular shape on the inner side of the cross section, and concentric inner and outer sides. The inner side round surface of the heat exchanger 2 is attached to the exhaust pipe 1, and M thermoelectric modules 3 are distributed on six surfaces of the outer side of the heat exchanger 2.
As shown in fig. 2, the diameter of the circular section of the heat exchanger 2 is R 2 The side length of the equal hexagonal section of the heat exchanger 2 is L 1 。
As shown in fig. 1, the thermoelectric modules 3 are distributed axially at equal intervals along the heat flow direction, and the thermoelectric modules 3 on each surface of the heat exchanger 2 have the same distribution rule. On each surface of the heat exchanger 2, the distance from the thermoelectric module 3 to both ports of the exhaust pipe 1 and the interval between the two thermoelectric modules 3 are both t.
As shown in fig. 3, each thermoelectric module 3 is composed of a ceramic plate 3.1, copper electrodes 3.2, P-type thermoelectric semiconductors 3.3 and N-type thermoelectric semiconductors 3.4, and the P-type thermoelectric semiconductors 3.3 and N-type thermoelectric semiconductors 3.4 are connected in series through the copper electrodes 3.2 and sandwiched between the upper and lower ceramic plates 3.1.
Each thermoelectric module 3 comprises thermoelectric semiconductors in b rows and b columns, the geometric parameters of the P-type thermoelectric semiconductors 3.3 and the N-type thermoelectric semiconductors 3.4 positioned on the same thermoelectric module 3 are the same, and the numbers of the P-type thermoelectric semiconductors 3.3 and the N-type thermoelectric semiconductors 3.4 on each thermoelectric module 3 are the sameN, n=1, 2,3, … …, the number of copper electrodes is 2n, 2n=b 2 -2。
As shown in fig. 4, in all thermoelectric modules 3, the thickness of the ceramic plate 3.1 is H 1 The thickness of the copper electrode 3.2 is H 2 The lengths of the P-type thermoelectric semiconductor 3.3 and the N-type thermoelectric semiconductor 3.4 are L 2 The thickness of the P-type thermoelectric semiconductor 3.3 and the N-type thermoelectric semiconductor 3.4 is H 3 The row spacing of the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor is the same, and the row spacing of the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor is a.
As shown in fig. 5, the surface of the S-shaped liquid cooling long plate 4 is attached to the upper end surface of the thermoelectric module 3, and the internal flow passage is designed as an S-shaped cylinder. The thickness of the S-shaped liquid cooling long plate 4 is H, two round holes are formed in the side face of the S-shaped liquid cooling long plate 4, the two round holes are respectively an inlet 4.1 and an outlet 4.2 of fluid, and the diameter of a pipeline in the S-shaped liquid cooling long plate 4 is d.
As shown in fig. 5, on the same surface of the heat exchanger 2, the 1 st thermoelectric module 3 is near the inlet 4.1 of the heat flow, and the M-th thermoelectric module 3 is near the outlet 4.2 of the heat flow.
The width of the P-type thermoelectric semiconductor 3.3 and the N-type thermoelectric semiconductor 3.4 in the ith thermoelectric module 3 is W i ，L 3 The width of the ceramic plate of the thermoelectric module; the column spacing between the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor isi is an integer, and i is more than or equal to 1 and less than or equal to M.
The i-th thermoelectric module thermoelectric semiconductor width W i Comprises the following steps:
s1: assume that the difference between the width of the i+1th thermoelectric module P/N type thermoelectric semiconductor and the width of the i th thermoelectric module P/N type thermoelectric semiconductor is Δw, i.e., Δw=w i+1 -W i Wherein Δw satisfies the relationship:W 1 are known.
S2: building a thermal resistance model to let T w For the temperature of the contact surface between the exhaust pipe segment and the heat flow corresponding to the thermoelectric module, T h_i For the hot end average temperature of the ith thermoelectric module, the thermal resistance of the exhaust pipe to the hot end of the thermoelectric module
Wherein: u (u) 1 For the thickness of the exhaust pipe H 3 Is the thickness of the P/N type thermoelectric semiconductor, u 2 Lambda is the average thickness of the heat exchanger 1 Lambda is the thermal conductivity of the exhaust pipe 2 Lambda is the heat conductivity of the heat exchanger 3 For the thermal conductivity of the ceramic plate, A 1 For the surface area of the contact surface of the heat exchanger and the heat flow, A 2 For the surface area of the contact surface of the heat exchanger and the radiator, A 3 Is the surface area of the contact surface of the ceramic plate and the heat exchanger.
S3: by the equation of heat absorptionCalculating to obtain heat Q absorbed by thermoelectric module h ；
Wherein: c is the specific heat capacity of the heat flow,is the mass flow of the heat flow, delta T is the temperature difference between two ends of the exhaust pipe section, L 3 For the width of the ceramic plate of the thermoelectric module, L represents the length of the exhaust pipe 1.
S4: by passing throughThe convective heat transfer coefficient h is calculated, and the average Nusselt number of air and water is expressed as +.>f＝(1.821gRe-1.64) -2 Reynolds number->Planty ++>
Wherein: λ represents thermal conductivity, D represents hydraulic diameter; hydraulic diameter d=2r 1 ，R 1 Is the inner diameter of the exhaust pipe.
S5: by the equation of heat absorptionCalculating to obtain the hot end average temperature of the ith thermoelectric module +.>
Wherein: a is the cross-sectional area of the interior of the pipeline, h is the convective heat transfer coefficient,representing the average temperature, T, of heat flow of the exhaust pipe section corresponding to the ith thermoelectric module h Indicating the temperature of the hot end of the thermoelectric module, R h Representing the thermal resistance of the exhaust pipe to the hot end of the thermoelectric module, Q h Representing the amount of heat absorbed by the thermoelectric module.
S6: by equation ofCalculating to obtain the internal resistance of the ith thermoelectric module:
wherein ρ is P Representing the resistivity, ρ, of a P-type thermoelectric semiconductor N The resistivity of the N-type thermoelectric semiconductor is represented, N represents the number of P-type thermoelectric semiconductors or N-type thermoelectric semiconductors of each thermoelectric module, ρ Copper (Cu) The resistivity of the copper electrode is shown.
S7: output current of ith thermoelectric module
Wherein N represents the number of P-type thermoelectric semiconductors or N-type thermoelectric semiconductors of each thermoelectric module, alpha represents the Seebeck coefficient, T h_i For the hot side average temperature, T, of the ith thermoelectric module c Indicating the cool side temperature of the thermoelectric module.
S8: let the output current of the i-th thermoelectric module be equal to the output current of the i+1th thermoelectric module, namely:calculating to obtain the temperature relation between the thermoelectric semiconductor width of the ith thermoelectric module and the thermoelectric semiconductor width of the (i+1) th thermoelectric module, namely, satisfying the equation: (T) h_i -T c )W i ＝(T h_i+1 -T c )W i+1 。
S9: calculating the heat flow average temperature of the exhaust pipe section corresponding to the ith thermoelectric moduleThe temperature average value of the boundary of the ith thermoelectric module along the two ends of the heat flow direction is equal to the equation:
wherein T is in And T out The temperature of the hot-fluid inlet and the hot-fluid outlet are respectively, t is the distance from the thermoelectric module to two ports of the exhaust pipe and the distance between the two thermoelectric modules, L 3 Is the width of the ceramic plate of the thermoelectric module and is a known condition.
S10: determining the magnitude relationship between Δw and heat flow temperature, such that i=1 in S9, i.e
Wherein ΔW represents the difference between the width of the i+1th thermoelectric module P/N type thermoelectric semiconductor and the width of the i thermoelectric module P/N type thermoelectric semiconductor;obtained from S9->
S11: calculating the thermoelectric semiconductor width of each thermoelectric module in the direction of heat flow, i.e. W i ＝W 1 +(i-1)ΔW。
The known parameters of the hexagonal thermoelectric generator of this example are listed in table 1, and the other relevant parameters are listed in table 2.
Table 1 geometrical parameters of thermoelectric generators
TABLE 2 other relevant parameters
Calculated, Δw=0.3 mm, satisfies the condition:thus, according to formula W i ＝W 1 And (3) delta W of (i-1), and sequentially obtaining the widths of M thermoelectric semiconductors of the thermoelectric modules.

Claims (9)

1. The novel thermoelectric generator consists of a heat exchanger (2), a thermoelectric module (3) and an S-shaped liquid cooling long plate (4); the method is characterized in that: the inner side of the heat exchanger (2) is attached to the exhaust pipe (1), the outer side of the heat exchanger is provided with a plurality of surfaces, and a plurality of thermoelectric modules (3) are distributed on each surface of the heat exchanger (2) along the length direction; the area of each thermoelectric module (3) on each surface along the heat flow direction of the exhaust pipe (1) is increased continuously.
2. The novel thermoelectric generator of claim 1 wherein: the length of the exhaust pipe (1) and the length of the heat exchanger (2) are the same as those of the S-shaped liquid cooling long plate (4), and the lengths of the exhaust pipe and the heat exchanger are L.
3. The novel thermoelectric generator of claim 2 wherein: the outside of the section of the heat exchanger (2) is designed to be an equal hexagon, M thermoelectric modules (3) are respectively distributed on six surfaces, the thermoelectric modules (3) are axially distributed at equal intervals along the heat flow direction, the distance from each thermoelectric module (3) to two ports of the exhaust pipe (1) and the interval between the two thermoelectric modules (3) are t, and the thermoelectric modules (3) and the heat exchanger (2) on each surface have the same distribution rule.
4. The novel thermoelectric generator of claim 3 wherein: each thermoelectric module (3) consists of a ceramic plate (3.1), copper electrodes (3.2), a P-type thermoelectric semiconductor (3.3) and an N-type thermoelectric semiconductor (3.4), wherein the P-type thermoelectric semiconductor (3.3) and the N-type thermoelectric semiconductor (3.4) are connected in series through the copper electrodes (3.2) and are clamped between the upper ceramic plate (3.1) and the lower ceramic plate (3.1).
5. The novel thermoelectric generator of claim 4 wherein: each thermoelectric module (3) comprises thermoelectric semiconductors in b rows and b columns, the geometric parameters of the P-type thermoelectric semiconductors (3.3) and the N-type thermoelectric semiconductors (3.4) which are positioned in the same thermoelectric module (3) are the same, the numbers of the P-type thermoelectric semiconductors (3.3) and the N-type thermoelectric semiconductors (3.4) of each thermoelectric module (3) are the same, N is equal to n=1, 2,3, … …, and the numbers of copper electrodes are equal to 2N, 2n=b 2 -2。
6. The novel thermoelectric generator of claim 4 wherein: in all thermoelectric modules (3), the thickness of the ceramic plate (3.1) is H 1 The thickness of the copper electrode (3.2) is H 2 The lengths of the P-type thermoelectric semiconductor (3.3) and the N-type thermoelectric semiconductor (3.4) are L 2 The thickness of the P-type thermoelectric semiconductor (3.3) and the N-type thermoelectric semiconductor (3.4) are H 3 The row spacing of the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor is the same, and the row spacing of the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor is a.
7. The novel thermoelectric generator of claim 5 wherein: the surface of the S-shaped liquid cooling long plate (4) is attached to the upper end surface of the thermoelectric module (3), the inner flow passage is designed into an S-shaped cylinder, two round holes are formed in the side face of the S-shaped liquid cooling long plate (4), and the two round holes are respectively an inlet (4.1) and an outlet (4.2) of the S-shaped cylinder.
8. The novel thermoelectric generator of claim 7 wherein: on the surface of the same heat exchanger (2), the 1 st thermoelectric module (3) is close to the inlet (4.1) of the heat flow, and the M th thermoelectric module (3) is close to the outlet (4.2) of the heat flow; the width W of the P-type thermoelectric semiconductor (3.3) and the N-type thermoelectric semiconductor (3.4) in the ith thermoelectric module (3) i ，L 3 The width of the ceramic plate of the thermoelectric module; the column spacing between the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor isi is an integer, and i is more than or equal to 1 and less than or equal to M.
9. The thermoelectric semiconductor width W of the ith thermoelectric module in the novel thermoelectric generator of claim 8 i Comprises the following steps:
s1: assume that the difference between the width of the i+1th thermoelectric module P/N type thermoelectric semiconductor and the width of the i th thermoelectric module P/N type thermoelectric semiconductor is Δw, i.e., Δw=w i+1 -W i Wherein Δw satisfies the relationship:W 1 are known.
S2: building a thermal resistance model to let T w For the temperature of the contact surface between the exhaust pipe segment and the heat flow corresponding to the thermoelectric module, T h_i For the hot end average temperature of the ith thermoelectric module, the thermal resistance of the exhaust pipe to the hot end of the thermoelectric module
Wherein: u (u) 1 For the thickness of the exhaust pipe H 3 Is the thickness of the P/N type thermoelectric semiconductor, u 2 Lambda is the average thickness of the heat exchanger 1 Lambda is the thermal conductivity of the exhaust pipe 2 Lambda is the heat conductivity of the heat exchanger 3 For the thermal conductivity of the ceramic plate, A 1 Is a heat exchanger and heatSurface area of flow contact surface, A 2 For the surface area of the contact surface of the heat exchanger and the radiator, A 3 Is the surface area of the contact surface of the ceramic plate and the heat exchanger.
S3: by the equation of heat absorptionCalculating to obtain heat Q absorbed by thermoelectric module h ；
Wherein: c is the specific heat capacity of the heat flow,is the mass flow of the heat flow, delta T is the temperature difference between two ends of the exhaust pipe section, L 3 For the width of the ceramic plate of the thermoelectric module, L represents the length of the exhaust pipe.
S4: by passing throughThe convective heat transfer coefficient h is calculated, and the average Nusselt number of air and water is expressed as +.>f＝(1.82lgRe-1.64) -2 Reynolds number->Planty ++>
Wherein: λ represents thermal conductivity, D represents hydraulic diameter; hydraulic diameter d=2r 1 ，R 1 Is the inner diameter of the exhaust pipe, and f is the frictional resistance.
S5: by the equation of heat absorptionCalculating to obtain the hot end average temperature of the ith thermoelectric module +.>
Wherein: a is the cross-sectional area of the interior of the pipeline, h is the convective heat transfer coefficient,representing the average temperature, T, of heat flow of the exhaust pipe section corresponding to the ith thermoelectric module h Indicating the temperature of the hot end of the thermoelectric module, R h Representing the thermal resistance of the exhaust pipe to the hot end of the thermoelectric module, Q h And X is simply a formula for representing the heat absorbed by the thermoelectric module.
S6: by equation ofCalculating to obtain the internal resistance of the ith thermoelectric module:
wherein ρ is P Representing the resistivity, ρ, of a P-type thermoelectric semiconductor N The resistivity of the N-type thermoelectric semiconductor is represented, N represents the number of P-type thermoelectric semiconductors or N-type thermoelectric semiconductors of each thermoelectric module, ρ Copper (Cu) The resistivity of the copper electrode is shown.
S7: output current of ith thermoelectric module
Wherein N represents the number of P-type thermoelectric semiconductors or N-type thermoelectric semiconductors of each thermoelectric module, alpha represents the Seebeck coefficient, T h_i For the hot side average temperature, T, of the ith thermoelectric module c Indicating the cool side temperature of the thermoelectric module.
S8: let the output current of the i-th thermoelectric module be equal to the output current of the i+1th thermoelectric module, namely:calculating to obtain the temperature relation between the thermoelectric semiconductor width of the ith thermoelectric module and the thermoelectric semiconductor width of the (i+1) th thermoelectric module, namely, satisfying the equation: (T) h_i -T c )W i ＝(T h_i+1 -T c )W i+1 。
S9: calculating the heat flow average temperature T of the exhaust pipe section corresponding to the ith thermoelectric module i It is equal to the average temperature of the boundary of the ith thermoelectric module along the two ends of the heat flow direction, namely, the equation is satisfied:
wherein T is in And T out The temperature of the hot-fluid inlet and the hot-fluid outlet are respectively, t is the distance from the thermoelectric module to two ports of the exhaust pipe and the distance between the two thermoelectric modules, L 3 Is the width of the ceramic plate of the thermoelectric module and is a known condition.
S10: determining the magnitude relationship between Δw and heat flow temperature, such that i=1 in S9, i.e
Wherein DeltaW represents the difference between the width of the (i+1) th thermoelectric module P/N type thermoelectric semiconductor and the width of the (i) th thermoelectric module P/N type thermoelectric semiconductor,obtained from S9->
S11: calculating the thermoelectric semiconductor width of each thermoelectric module in the direction of heat flow, i.e. W i ＝W 1 +(i-1)ΔW。
CN202311210575.1A 2023-09-19 2023-09-19 Novel thermoelectric generator and thermoelectric semiconductor width calculation method in thermoelectric module of novel thermoelectric generator Pending CN117489454A (en)

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