Technology & Engineering
Thermoelectric Effect
The thermoelectric effect is the phenomenon where a temperature difference in a material leads to the generation of an electric voltage. This effect is utilized in thermoelectric devices, which can convert heat directly into electricity. It has applications in power generation, waste heat recovery, and cooling systems, making it a promising technology for energy efficiency and sustainability.
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11 Key excerpts on "Thermoelectric Effect"
eBook - PDF- Lidong Chen, Ruiheng Liu, Xui Shi(Authors)
- 2020(Publication Date)
- Elsevier(Publisher)
C H A P T E R 1 General principles of thermoelectric technology 1.1 Introduction The first Thermoelectric Effect, namely the Seebeck effect, was discov-ered in 1821, which describes the electromotive force generated by the temperature difference. In the following thirty years or more, Peltier effect and Thomson effect were successively discovered. These effects are the three main physical effects in thermoelectric technology that describe the direct conversion between thermal and electrical energies [1 3] . Although the discoveries of both Seebeck and Peltier effects were made using a circuit composed of two different conductors and the effects were only observed at the junctions between dissimilar conduc-tors, they are actually the bulk properties of the materials involved, not the interfacial phenomena. Solid state physics developed in the follow-ing century reveals that all the three Thermoelectric Effects originate from the energy difference of carriers in different materials and/or in the different parts of materials under different temperatures. Thomson built the relationship among the three effects, and devel-oped the basic thermodynamic theories for Thermoelectric Effects [3] . Thomson’s work showed that a circuit composed of two conductors with positive and negative Seebeck coefficients (usually called the ther-mocouple) is a type of heat engine. Such heat engine can generate elec-trical power by virtue of the temperature difference, or pump heat to realize refrigeration. However, since the reversible Thermoelectric Effects are always accompanied by the irreversible Joule heat and heat conduc-tion, its energy conversion efficiency is principally low. Thermoelectric Effects have been widely used for temperature calibrations as thermo-couples, but they had no practical application as heat engine, and there 1 Thermoelectric Materials and Devices DOI: https://doi.org/10.1016/B978-0-12-818413-4.00001-6 Copyright © 2021 China Science Publishing & Media Ltd.
eBook - PDF- Diana Enescu(Author)
- 2019(Publication Date)
- IntechOpen(Publisher)
• When the electrical energy is converted into thermal energy, the phenomenon is known as the Peltier effect , with applications in cooling and heating. The device used in such applications is called thermoelectric cooler (TEC) [11 – 13]. In this case, thermoelectric modules are efficient temperature controllers [14]. Figure 2. Electrical energy recovered from waste heat. 3 Thermoelectric Energy Harvesting: Basic Principles and Applications DOI: http://dx.doi.org/10.5772/intechopen.83495 • When the thermal energy is converted into electrical energy, the phenomenon is known as the Seebeck effect , with applications for power generation. The device used in such applications is called thermoelectric generator (TEG) [15, 16]. The Seebeck effect occurs when a temperature difference across a conductor pro-vides a voltage at the conductor ends. Two distinct conductors A and B are linked together to compose the junctions of a circuit ( Figure 3 ). These conductors are connected electrically in series and thermally in parallel. One junction has the hot temperature T h and another one has the cold temperature T c , with T h bigger than T c . The Seebeck effect appears due to the thermal diffusion which provokes the motion of the charge carriers (electrons or holes) across (or against) temperature difference in the conductors. The Seebeck voltage at the circuit junctions can be written as: V ¼ α A � α B |fflfflfflffl{zfflfflfflffl} α AB 0 @ 1 A � T h � T c |fflfflfflffl{zfflfflfflffl} Δ T 0 @ 1 A (1) where α A and α B are the Seebeck coefficients for the conductors A and B, in V � K � 1 . The Seebeck coefficient of a thermoelectric material or thermopower α AB is the connection parameter between the input temperature difference and the output voltage difference. The Seebeck coefficient of a thermoelectric material depends on temperature, as well as on other two physical transport properties (thermal con-ductivity, electric conductivity).
eBook - PDF- Patricia Aranguren(Author)
- 2018(Publication Date)
- IntechOpen(Publisher)
Keywords: refrigeration, thermoelectric unit, energy indicators, cooling capacity, coefficient of performance, temperature control, renewable sources 1. Introduction The Thermoelectric Effect represents direct conversion of the temperature difference into volt-age and vice versa and refers to phenomena with which the current flows through the thermo-elements or legs of a thermoelectric module. The Thermoelectric Effect is formed due to free motion of the charge carriers (free electrons e À considered as negative charge carriers and holes h + considered as positive charge carriers) in metals and semiconductors while carrying energy and electric charge. In this case, the electric effects are accompanied by thermal effects and vice versa [1]. The Thermoelectric Effects are Peltier effect, Thomson effect and Seebeck effect. The Peltier effect is the phenomenon that converts current to temperature and occurs when an © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. electric current flows through a thermoelectric device. The Peltier effect is a reversible phe-nomenon, because the Peltier heat depends directly on the direction of the carrier flow or electrical current [2]. There is interdependence between the sense of the electric current and the temperature differ-ence at the hot and cold ends of a thermoelectric device. In other words, if the current flow is changed, the temperature at the hot and cold ends is changed as well.
eBook - PDFThermal Design
Heat Sinks, Thermoelectrics, Heat Pipes, Compact Heat Exchangers, and Solar Cells
- HoSung Lee(Author)
- 2022(Publication Date)
- Wiley(Publisher)
5 Thermoelectric Design 5.1 INTRODUCTION Thermoelectrics is literally associated with thermal and electrical phenomena. Thermoelectric processes can directly convert thermal energy into electrical energy or vice versa. A thermocouple uses the electrical potential (electromotive force) generated between two dissimilar wires to measure temperature. Basically, there are two devices: thermoelectric generators (TEGs) and thermoelectric coolers (TECs). These devices have no moving parts and require no maintenance. TEGs s have great potential for waste heat recovery from power plants and automotive vehicles. Such devices can also provide reliable power in remote areas such as in deep space and mountaintop telecommunication sites. TECs provide refrigeration and temperature control in electronic packages and medical instruments. Thermoelectrics have become increasingly important with numerous applications. Since thermoelectricity was discovered in the early nineteenth century, there has not been much improvement in efficiency or materials until the recent development of nanotechnology, which has led to a remarkable improve- ment in performance. It is thus very important to understand the fundamentals of thermoelectrics for development and thermal design. We start with a brief history of thermoelectricity. In 1821, Thomas J. Seebeck discovered that an electromotive force or a poten- tial difference could be produced by a circuit made from two dissimilar wires when one of the junctions was heated. This is called Seebeck effect. Thirteen years later in 1834, Jean Peltier discovered the reverse process that the passage of an electric current through a thermocouple produces heating or cooling depending on its direction.
- Peter Spies, Markus Pollak, Loreto Mateu, Peter Spies, Markus Pollak, Loreto Mateu(Authors)
- 2015(Publication Date)
- Jenny Stanford Publishing(Publisher)
Chapter 6 Thermoelectric Generators Robert Hahn a and Jan D. K¨ onig b a Fraunhofer Institute Reliability and Microintegration, Gustav-Meyer-Allee 25, 13355 Berlin, Germany b Fraunhofer IPM, Heidenhofstrasse 8, 79110 Freiburg, Germany [email protected], [email protected] 6.1 Physical Principles The discovery of thermoelectricity was done a long ago. In 1821, Thomas J. Seebeck observed that the needle of a compass was deflected in the vicinity of two metallic conductors connected to one another when different temperatures prevailed at the joints. The degree of deflection here was proportional to the temperature difference. The reason for the movement of the compass needle was an electrical field that had apparently been created by the difference in temperature between the conductors. The effect observed by Seebeck also functions in the opposite direction and was first described by Jean C. A. Peltier in 1834: If electricity is applied to the two connected conductors, a temperature gradient occurs at the contact points. Heat energy is transported from one connection point to the other, leading to a cooling effect. Handbook of Energy Harvesting Power Supplies and Applications Edited by Peter Spies, Loreto Mateu, and Markus Pollak Copyright c 2015 Pan Stanford Publishing Pte. Ltd. ISBN 978-981-4241-86-1 (Hardcover), 978-981-4303-06-4 (eBook) www.panstanford.com 218 Thermoelectric Generators 6.1.1 The Seebeck Effect The Seebeck effect is the phenomenon underlying the conversion of heat energy into electrical power. Its physical significance can be appreciated by considering the effect of imposing a temperature gradient along a finite conductor. Without temperature gradient, the carriers in the conductor have a distribution according to the thermal equilibrium Fermi–Dirac distribution.
eBook - PDFICT - Energy - Concepts Towards Zero
Power Information and Communication Technology
- Giorgos Fagas, Luca Gammaitoni, Douglas Paul, Gabriel Abadal Berini, Giorgos Fagas, Luca Gammaitoni, Douglas Paul, Gabriel Abadal Berini(Authors)
- 2014(Publication Date)
- IntechOpen(Publisher)
Chapter 4 Thermoelectric Energy Harvesting Douglas Paul Additional information is available at the end of the chapter http://dx.doi.org/10.5772/57092 1. Introduction The generation of electrical energy from thermal energy was originally discovered by Thomas Johann Seebeck in 1822 when he first demonstrated that a thermoelectric voltage was produced after providing a temperature difference across two materials. Jean Charles Athanase Peltier then demonstrated in 1834 that the application of a current could be used to pump heat, an effect with great potential for refrigeration. It was not until the 1850s that Lord Kelvin worked out the physics of the Seebeck and Peltier effects attributing the reversible heat flow discovered by Peltier must have an entropy associated with it and the Seebeck coefficient was a measure of the entropy associated with the electric current. Further developments in the theoretical understanding of thermoelectrics required quantum mechanics. The efficiency of the thermoelectric generation process was derived in 1911 by Edmund Altenkirch. 2. Fundamental physics Before describing and deriving the main thermodynamic properties and equations, it is worthwhile having a brief review of the key parts of physics required for thermoelectrics. One of the first effects that will be used to derive the thermoelectric efficiency is Joule’s law of heating. Joule was the first to demonstrate that any current passing through a resistor produces an amount of heat (Fig. 1(a)). Specifically the heat, Q (as a power i.e. energy / time) generated by passing a current, I though a resistance, R is given by Joule’s first law Q = I 2 R (1) It should be clear that thermoelectrics have heat being transported through a range of materials and some understanding of the transport of that heat is required. The heat generated by any process will be transported through a material driven by any temperature © 2014 Paul; licensee InTech.
eBook - PDFLow-Grade Heat Harvesting
Materials, Devices, and Technologies
- Xiaogang Zhang(Author)
- 2023(Publication Date)
- Wiley-VCH(Publisher)
2.1.1.1 Seebeck Effect The Seebeck effect is a phenomenon that can convert heat energy into electric energy. The basic principle can be shown in Figure 2.2a. Two different conductor materials A and B are joined to form a circuit. If the temperature of the two joint ends is maintained at T 1 and T 2 , respectively. Assuming that there is a certain temperature difference ΔT between the two ends, this will drive the carrier to move Low-Grade Heat Harvesting: Materials, Devices, and Technologies, First Edition. Xiaogang Zhang. © 2024 WILEY-VCH GmbH. Published 2024 by WILEY-VCH GmbH. 22 2 Conventional Thermoelectric Devices for Low-Grade Heat Harvesting 3.6 3.2 2.8 2.4 ZT max ZT 2.0 1.6 1.2 0.8 Clathrates GeTe Bi 2–x Sb x Te 3 SnTe PbTe Thermoelectric system Clathrates GeTe Zintls 1.8 2.6 1.7 2.8 1.5 1.6 1.8 1.9 2.6 2.8 ZT max 2.6 1.5 1.8 2.4 904 780 Cost (US$ kg –1 ) Cost-Effectiveness 420 153 138 121 100 65 53 19 2.6 Skutterudites BiCuSeO Cu 2–x Se Sn 1–x Se PbTe SnTe Bi 2–x Sb x Te 3 Half-Heuslers Sn 1–x Se Cu 2–x Se BiCuSeO Skutterudites Half Heuslers 3.5 (a) (b) 3.0 2.0 2.5 1.5 1.0 0.5 0.0 2010 2012 2014 Year 2016 2018 2020 0.10 1000 750 Cost (US$ kg –1 ) 500 250 0 0.08 0.06 0.04 0.02 0.00 Cost-effectiveness (ZT max / cost) Figure 2.1 ZT values for state-of-the-art thermoelectric materials in the last 10 years. (a) Reported maximum ZT values (ZT max ) with error bars, calculated cost, and calculated cost-effectiveness (ZT max /cost), and (b) timeline for the state-of-the-art thermoelectric materials (bulks). Source: Shi et al. [1]/American Chemical Society. in a direction, generate current, and form a thermoelectric electromotive force V in the circuit. Therefore, the Seebeck coefficient is defined as: S = dV dT where S is the Seebeck coefficient, unit: μV K −1 , the value can be positive or negative according to the thermal conductivity property of different materials. 2.1.1.2 Peltier Effect The Peltier effect is the inverse effect of the Seebeck effect.
eBook - PDF- Charles R. Russell(Author)
- 2013(Publication Date)
- Pergamon(Publisher)
Electrochemical pre-parations of some elements were accomplished with the minute currents produced in this way. The only use of thermoelectricity over the next century was for temperature measurements. Even in this application the important advantages of Seebeck's mineral semiconductors were overlooked. The next step in the history of thermoelectricity came in 1834 when Peltier, a French watchmaker, observed that a thermal effect is produced by an electric current flowing through a junc-tion of dissimilar conductors. However, Peltier also failed to comprehend the fundamental nature of his observation. He concluded only that Ohm's law might not apply for very weak currents. A revival of interest in thermoelectric power came with the development after 1939 of synthetic semiconductor materials hav-ing Thermoelectric Effects orders of magnitude greater than those THERMOELECTRICITY 275 in metals. The application of these new materials to thermoelectric systems was recognized by Maria Telka who made a generator of some 5 percent efficiency using zinc antimonide and lead sulfide. THERMOELECTRIC PHENOMENA The flow of heat and the flow of electrons through a material are related. The flow of electrons transports some thermal energy and the flow of heat transports some electricity. In addition are the irreversible conversion of electrical energy into heat by electri-cal resistance, designated as Joule or PR heating, and the irrever-sible flow of heat by thermal conduction. A thermoelectric generator is illustrated in Fig. 7-2. Two dissim-ilar materials, n and p, are connected by metal conductors mak-ing good thermal and electrical contact at the hot and cold junctions. The electrical energy generated from thermal energy does work in an external circuit; the remainder of the thermal energy is rejected from the cold junction at 0 . The potential depends upon both the temperature difference and the properties of the materials.
eBook - PDF- Kenichi Takahata(Author)
- 2009(Publication Date)
- IntechOpen(Publisher)
Practical thermoelectric devices emerged in the 1960’s and have developed significantly since then with a number of manufacturers now marketing thermoelectric modules for cooling, heating and power generation applications. Thermoelectric power generation is mainly influenced by the Seebeck effect, with thermoelectric cooling and heating influenced predominantly by the Peltier effect. The Thomson effect does not have a major influence although it should always be included in detailed calculations (Rowe, 2006). For power generation applications, a small amount of electrical power, typically in the μW or mW range, can be generated by a thermoelectric module if a temperature difference is maintained between two terminals of a thermoelectric module. Alternatively, a thermoelectric module can operate as a heat pump, providing Micro Electronic and Mechanical Systems 16 heating or cooling of an object connected to one side of a thermoelectric module if a DC current is applied to the module’s input terminals. The technology has achieved commercial success in mini-refrigeration, cooling and space-craft power applications, with the consumer market for mini-refrigerators and coolers currently the most successful commercial application (Hachiuma and Fukuda, 2007). Future developments in thermoelectric technology will include the need to reduce the size, and improve the performance, of current thermoelectric devices in order to address thermal problems in microelectronics, and create localised low-power energy sources for electronic systems. 2.2 Standard thermoelectric module construction Standard thermoelectric modules are constructed from P-type and N-type thermo-elements, often referred to as thermoelectric couples, connected electrically in series and thermally in parallel. Each couple is constructed from two ‘pellets’ of semiconductor material usually made from Bismuth Telluride.
eBook - PDF- Alina Adriana Minea(Author)
- 2012(Publication Date)
- CRC Press(Publisher)
269 8 Heat Transfer in Thermoelectricity Myriam Lazard 8.1 Introduction When. a. temperature. difference. exists,. a. potential. for. power. production. ensues:.it.is.the.principle.of.thermoelectricity . .It.could.provide.an.unconven-tional.energy.source.for.a.wide.range.of.applications.even.if.the.efficiency. of.the.thermoelements.is.rather.low . .Even.if.the.basis.and.the.principle.of. thermoelectric.effects.have.been.clearly.and.widely.described.these.last.cen-turies,.a.significant.part.of.research.and.development.effort.is.still.devoted. to.thermoelectricity.in.order.to.make.it.emerge.as.renewable.energy.and.to. promote.an.understanding.of.the.role.thermoelectric.technology.may.play. in.environmental.impact . .Many.significant.advances.have.been.made.con-cerning.the.discovery.and.the.elaboration.of.thermoelectric.materials.with.a. high.figure.of.merit.(the.good.candidates.are.among.materials.with.low.ther-mal.conductivity.but.high.electrical.conductivity),.but.the.need.of.thermal. CONTENTS 8.1 . Introduction. ................................................................................................ 269 8.2 . Modelling.of.a.Thermoelectric.LEG. ........................................................ 272 8.2.1 . Governing.Equation. ...................................................................... 272 8.2.2 . Analytical.Modelling. .................................................................... 273 8.2.3 . Numerical.Modelling. .................................................................... 274 8.2.4 . Analogical.Modelling.with.Thermal.Capacitances. and.Resistances. .............................................................................. 275 8.2.5 . Thermoelectric.Quadrupole. ......................................................... 280 8.3 . Applications. ................................................................................................ 284 8.3.1 . Potential.Use.of.Thermoelectricity.for.the.
eBook - PDFRefrigerators, Heat Pumps and Reverse Cycle Engines
Principles, State of the Art and Trends
- Jocelyn Bonjour(Author)
- 2023(Publication Date)
- Wiley-ISTE(Publisher)
This chapter offers a current and pedagogical overview of thermoelectricity and is structured into two main parts oriented to the use in heat pump mode. In the first part (section 6.1), the physical mechanisms behind Thermoelectric Effects are discussed with the aim of providing a basic understanding of the challenges and strategies of current research. In the second part (section 6.2), the implementation and performance of TE systems in heat pump mode are discussed in order to identify the prospects for improvement according to their integration. A summary of the main applications is given at the end of the chapter in order to illustrate the wide field of application of this technology. References to recent specialized articles and books are offered to the reader in order to deepen knowledge on the topics discussed. The following books comprehensively cover the subject ranging from physical effects, development of materials and devices (Nolas et al. 2001; Lee 2016; Skipidarov and Nikitin 2016; Dávila et al. 2017; Rowe 2018). Thermoelectric Systems as an Alternative to Reverse Cycle Engines 211 Figure 6.1. The two ways of using a thermoelectric (TE) module NOTES ON FIGURE 6.1.– a) Photograph of a TE module, Model ET-241-14-15 (P=105 W, 6 A, 29.8 V (dc)) from Adaptive Thermal Management, optimized for a temperature gradient of approximately 76°C with a dimension of 5 cm by 5 cm. Schematic representations of a cross-section of a TE module in b) heat pump and c) generator operating modes. A TE module is made up of “p”- and “n”-type semiconductor material segments that are interconnected in series in an alternating manner by metal electrodes (thick black lines) supported by ceramic insulating substrates (white rectangles). The color gradient indicates a temperature gradient (hot in red and cold in blue). b) Heat pump mode (refrigerator/heater): an electric power is applied to the input of the TE module, which is then crossed by an electrical current (Ohm’s law).
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