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Akdogan, Volkan. "Thermoelectric power generator for automotive applications." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37702/.
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A thermoelectric generator (TEG) converts thermal energy into electrical energy corresponding to temperature gradient across both hot and cold surfaces with a conversion efficiency of approximately 5%. In spite of the conversion efficiency, TEGs can be implemented effectively for waste heat recovery systems within the power rating of kilowatts. The insufficiency of natural resources, frequently increasing oil costs and emission regulations have become an incentive factor of the recent increased interest in TEG applications. This thesis introduces a practical implementation of the thermoelectric generator for an automotive exhaust system which has a rapid transient response to produce electrical energy from the waste heat which flows through the exhaust pipe. In addition to automotive TE power generator implementation, an H-Bridge DC-DC converter within the operation of maximum power point tracking method is introduced in this thesis to obtain the maximum power transfer between the thermoelectric power generator and the load. This thesis presents a transient solution to the two-dimensional heat transfer equation with variant ambient temperature that determines heat transfer and electrical potential across the thermoelectric pellet. This equation is applied into a designed two-dimensional heat transfer MATLAB model and a comparison of simulation and experimental results approves the accuracy of the designed model. In addition to heat transfer simulation, a dynamic large scale thermoelectric power generator simulation program is introduced in this thesis to provide data analysis of actual implementation.
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Smith, Kevin D. "An investigation into the viability of heat sources for thermoelectric power generation systems /." Online version of thesis, 2009. http://hdl.handle.net/1850/8266.
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Twaha, Ssennoga. "Regulation of power generated from thermoelectric generators." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49544/.
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In recent years, the efficiency of thermoelectric devices has improved greatly due thermoelectric material and device geometrical improvements. However, the efficiency of TEG is still low, being a subject of further research for more improvement. Hence, the main objective of the research carried out in this thesis is to analyse the performance of dc-dc converters with or without MPPT in conditioning the power generated from TEG. In light of this objective, the following case studies have been carried out. The initial study has analysed the performance of a TEG/dc-dc boost converter system. Results indicate that the converter is able to stabilise and boost the voltage and higher efficiencies are achieved at different hot side temperatures. The next study proposes the use of MPPT algorithm to harvest maximum power from TEG system. Hence, the analysis of the performance of TEG/dc-dc converter with MPPT enabled by Incremental conductance (IC) method is done. The results indicate that the IC based MPPT approach is able to track the maximum power point but with relatively lower efficiencies than the Perturb and Observe (P&O) based MPPT method. method. Another study has analysed the parameters for the performance of TEG/dc-dc converter system in different modes with a variable load. The TEG system is subjected to different hot side temperatures, including increasing step, increasing random and constant cold side temperature profiles. The study has demonstrated how the proper selection of converter components is a necessity to avoid converter losses as well interferences on the load connected to TEG/dc-dc converter system. Furthermore, another study compares the performance of extremum seeking control (ESC) and P&O MPPT algorithms applied to TEG system. The TEG model is validated with results from multiphysics (COMSOL) modelling software. To assess the effect of temperature dependency of TEG parameters, two TEG materials have been chosen; bismuth telluride (Bi2Te3) with temperature dependent Seebeck effect (S), electrical conductivity (σ) and thermal conductivity (k); and lead telluride (PbTe) with non-temperature dependent S, σ and k. Results indicate that ESC MPPT method outperforms the P&O technique in terms extracting maximum power and the simulation speed. Results also indicate that ESC outperforms the IC technique in terms of extracting maximum power and the speed of computation. ESC method is faster than the IC method. In the final study, the application of the concept and the design of a distributed dc-dc converter architecture (DCA) on TEG system is deliberated. The distributed or cascaded converter architecture involves the use of non-isolated per-TEG dc-dc converter connected to the load. Alternatively, for some specific loads, especially in automotive applications, soft-switched, isolated bi-directional dc-dc converters can be used instead of non-isolated converters because these integrated converters enable bi-directional power flow control capability. Simulations and experimental studies have been carried out to demonstrate and prove the necessity of the DCA design application on TEG systems. In addition, some of the factors affecting the performance of TEG systems are correspondingly analysed.
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Rutberg, Michael J. (Michael Jacob). "Modeling water use at thermoelectric power plants." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74674.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student submitted PDF version of thesis.<br>Includes bibliographical references (p. 74-77).<br>The withdrawal and consumption of water at thermoelectric power plants affects regional ecology and supply security of both water and electricity. The existing field data on US power plant water use, however, is of limited granularity and poor quality, hampering efforts to track industry trends and project future scenarios. Furthermore, there is a need for a common quantitative framework on which to evaluate the effects of various technologies on water use at power plants. To address these deficiencies, Part 1 of this thesis develops an analytical system-level generic model (SGEM) of water use at power plants. The S-GEM applies to fossil, nuclear, geothermal and solar thermal plants, using either steam or combined cycles, and outputs water withdrawal and consumption intensity, in liters per megawatt-hour. Two validations of the S-GEM are presented, one against data from the literature for a variety of generation types, the other against field data from coal plants in South Africa. Part 2 of the thesis then focuses on cooling systems, by far the largest consumers of water in most power plants. The water consumption of different cooling systems is placed on a common quantitative basis, enabling direct comparison of water consumption between cooling system types, and examination of the factors that affect water consumption within each cooling system type. The various cost, performance, and environmental impact tradeoffs associated with once-through, pond, wet tower, dry, and hybrid cooling technologies are qualitatively reviewed. Part 3 examines cooling of concentrating solar power (CSP) plants, which presents particular problems: the plants generate high waste heat loads, are usually located in water-scarce areas, and are typically on the margin of economic viability. A case study is conducted to explore the use of indirect dry cooling with cold-side thermal energy storage, in which cooling water is chilled and stored at night, when ambient temperatures are lower and the plant is inactive, and then used the following day. This approach is shown to hold promise for reducing the capital, operational, and performance costs of dry cooling for CSP.<br>by Michael J. Rutberg.<br>S.M.
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Montecucco, Andrea. "Efficiently maximising power generation from thermoelectric generators." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5213/.
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Thermoelectric generators (TEGs) convert the thermal energy flowing through them into DC electrical energy in a quantity dependant on the temperature difference across them and the electrical load applied, with a conversion efficiency of typically 5%. Nonetheless, they can be successfully employed to recover energy from waste heat and their use has increased rapidly in recent years, with applications ranging from microwatts to kilowatts, due to energy policy legislations and increasing energy cost determined by climate change, environmental issues and availability of energy sources. The performance of TEGs, subject to thermal and electrical effects, can vary considerably depending on the operating conditions, therefore it is necessary to measure and characterise their performance, and to understand their dynamic behaviour and interaction with the other parts of the system. Based on this knowledge it is then desired to develop an effective electronic system able to control these devices so as to maximise the power generated and increase the overall efficiency of the system. Several TEGs can be electrically connected in series and/or parallel (forming an array) to provide the required voltage and/or current. However, TEGs are usually employed in environments with time-varying temperatures, thermal powers and electrical loads. As a consequence in most TEG systems the individual thermoelectric devices can be subject to temperature mismatch due to operating conditions. Therefore it is of relevant importance to accurately simulate the evolution of thermoelectric systems during thermal and electrical transients. At the same time accurate experimental performance data are necessary to permit precise simulations. Unfortunately, there is still no standardised method to test the electrical and thermal performance of TEGs. This thesis tackles these key challenges and contributes to the pool of existing knowledge about TEGs dealing with four main topics: testing of thermoelectric generators, simulation of thermoelectric generating systems, design and production of power electronic converters for thermoelectric generators, and physical applications of thermoelectric generators. After an introduction to the physical phenomena underlying the operation of TEGs, this thesis describes the innovative test system built at the University of Glasgow to assess the performance of TEG devices in the ”real-world”. The fixture allows a single TEG device to be tested with thermal input power up to 1 kW and hot temperature up to 800◦C with minimal thermal losses and thermal shock; the mechanical clamping force can be adjusted up to 5 kN, and the temperatures are sensed by thermocouples placed directly on the TEGs surfaces. A computer program controls all the instruments in order to minimise errors and to aid accurate measurement and test repeatability. The test rig can measure four TEGs simultaneously, each one individually controlled and heated. This allows testing the performance of TEG arrays under mismatched conditions, e.g., dimensions, clamping force, temperature, etc. Under these circumstances experimental results and a mathematical analysis show that when in operation each TEG in the array will have a different electrical operating point at which maximum energy can be extracted and problems of decreased power output arise. This thesis provides the transient solution to the one-dimensional heat conduction equation with internal heat generation that describes the transfer and generation of heat throughout a thermoelectric device with dynamic exchange of heat through the hot and cold sides. This solution is then included in a model in which the Peltier effect, the thermal masses and the electrical behaviour of the system are also considered. The resulting model is created in Simulink and the comparison with experimental results from a TEG system confirms the accuracy of the simulation tool to predict the evolution of the thermoelectric system both in steady-state and during thermal or electrical transients. This thesis presents an investigation of the optimum electrical operating load to maximise the power produced by a TEG. Both fixed temperature difference and fixed thermal input power conditions are considered. Power electronic converters controlled by a Maximum Power Point Tracking (MPPT) algorithm are used to maximise the power transfer from the TEG to the load. The MPPT method based on the open-circuit voltage is arguably the most suitable for the almost linear electrical characteristic of TEGs. An innovative way to perform the open-circuit voltage measurement during the pseudo-normal operation of the power converter is presented. This MPPT technique is supported by theoretical analysis and used to control an efficient synchronous Buck-Boost converter capable of interfacing TEGs over a wide range of temperatures. The prototype MPPT converter is controlled by an inexpensive microcontroller, and a lead-acid battery is used to accumulate the harvested energy. Experimental results using commercial TEG devices demonstrate the ability of the MPPT converter to accurately track the maximum power point during steady-state and thermal transients. This thesis also presents two practical applications of TEGs. The first application exploits the thermal energy generated by a stove to concurrently produce electrical energy and heat water, while the second application recovers the heat energy rejected to ambient by a car’s exhaust gas system to generate electrical energy for battery charging.
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Naylor, Andrew J. "Towards highly-efficient thermoelectric power harvesting generators." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366984/.
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Power harvesting from thermoelectric generators is considered as a viable route towards sustainable energy generation by the conversion of thermal gradients occuring naturally or from waste heat sources into useful electrical energy. This thesis investigates the electrodeposition of n-type binary, ternary and doped thermoelectric materials, with the aim of demonstrating that electrodeposition can be used as a cost-effective and simple technique to fabricate highly-efficient thermoelectric materials. In order to achieve this, the thermoelectric and electrical properties of such materials must be related to their microstructural properties. Therefore, a detailed and systematic study of their microstructural properties, including morphology, crystal structure, composition and crystallite size, is undertaken whilst also measuring the electrical and thermoelectric properties. It is found that the potential of the working electrode, employed as the substrate during the electrodeposition of bismuth telluride, is one of the most effective variables in the fabrication process. More anodic potentials such as 0 V vs. SCE offer the best microstructural and thermoelectric properties. The addition of a surfactant, sodium lignosulphonate, to the electrolyte further improves the microstructural properties of bismuth telluride thin films, by levelling the deposits and inducing greater crystallographic orientation in growth planes perpendicular to the substrate. This is believed to be preferential for improving thermoelectric properties. The electrodeposition of the ternary thermoelectric material bismuth tellurium selenide shows that the microstructural and hence the thermoelectric and electrical properties of the thin films can be optimised by use of more positive electrode potentials. The thin films fabricated exhibit a thermoelectric efficiency of up to two orders of magnitude greater than similar materials prepared by electrodeposition previously and equal efficiency to those prepared by methods which are more costly and difficult to undertake. Doping these materials with copper, by electrochemical means, further improves the thermoelectric efficiency by over another order of magnitude.
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Hu, Shih-Yung. "Heat transfer enhancement in thermoelectric power generation." [Ames, Iowa : Iowa State University], 2009.
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Omer, Siddig Adam. "Solar thermoelectric system for small scale power generation." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/7440.
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This thesis is concerned with the design and evaluation of a small scale solarthermoelectric power generation system. The system is intended for electricity generation and thermal energy supply to small scale applications in developing countries of the sunny equatorial regions. Detailed design methodologies and evaluations of both the thermoelectric device and the solar energy collector, which are parts of the combined system, are presented. In addition to experimental evaluations, three theoretical models are presented which allow the design and evaluation of both the thermoelectric module and the solar energy collector. One of the models (a unified thermoelectric device model) concerns the geometrical optimization and performance prediction of a thermoelectric module in power generation mode. The model is unified in the sense that it accounts for the effect of all the parameters that contribute to the performance of the thermoelectric module, a number of which are ignored by the available design models. The unified model is used for a comparative evaluation of five thermoelectric modules. One of these is commercially available and the others are assumed to have optimum geometry but with different design parameters (thermal and electrical contact layer properties). The model has been validated using data from an experimental investigation undertaken to evaluate the commercial thermoelectric module in power generation mode. Results showed that though the commercially available thermoelectric cooling devices can be used for electricity generation, it is appropriate to have modules optimized specifically for power generation, and to improve the contact layers of thermoelement accordingly. Attempts have also been made to produce and evaluate thermoelectric materials using a simple melt-qucnching technique which produces materials with properties similar to those of the more expensive crystalline materials.
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Jovovic, Vladimir. "Engineering of Thermoelectric Materials for Power Generation Applications." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1248125874.
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Kamata, Masahiro. "Engineering Considerations on Thermoelectric Power in Electrochemical Systems." Kyoto University, 1988. http://hdl.handle.net/2433/74722.
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Thompson, Megan Elizabeth Dove. "Fabrication and Testing of a Heat Exchanger Module for Thermoelectric Power Generation in an Automobile Exhaust System." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/19233.
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Thermoelectric generators (TEGs) are currently a topic of interest in the field of energy harvesting for automobiles. In applying TEGs to the outside of the exhaust tailpipe of a vehicle, the difference in temperature between the hot exhaust gases and the automobile coolant can be used to generate a small amount of electrical power to be used in the vehicle. The amount of power is anticipated to be a few hundred watts based on the temperatures expected and the properties of the materials for the TEG. <br />This study focuses on developing efficient heat exchanger modules for the cold side of the TEG through the analysis of experimental data. The experimental set up mimics conditions that were previously used in a computational fluid dynamics (CFD) model. This model tested several different geometries of cold side sections for the heat exchanger at standard coolant and exhaust temperatures for a typical car. The test section uses the same temperatures as the CFD model, but the geometry is a 1/5th scaled down model compared to an full-size engine and was fabricated using a metal-based rapid prototyping process. The temperatures from the CFD model are validated through thermocouple measurements, which provide the distribution of the temperatures across the TEG. All of these measurements are compared to the CFD model for trends and temperatures to ensure that the model is accurate. Two cold side geometries, a baseline geometry and an impingement geometry, are compared to determine which will produce the greater temperature gradient across the TEG.<br>Master of Science
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Sandoz-Rosado, Emil Jose. "Investigation and development of advanced models of thermoelectric generators for power generation applications /." Online version of thesis, 2009. http://hdl.handle.net/1850/10795.
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Engelke, Kylan Wynn. "Novel thermoelectric generator for stationary power waste heat recovery." Thesis, Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/engelke/EngelkeK0510.pdf.
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Internal combustion engines produce much excess heat that is vented to the atmosphere through the exhaust fluid. Use of solid-state thermoelectric (TE) energy conversion technology is a promising technique to recapture some of the energy lost. The TE effect, discovered in 1821 by Thomas Seebeck, is essentially the solid-state conversion of a temperature gradient into an electric potential. The scope of this work was the design, testing and evaluation of a novel and robust TE generator that is amendable to use in a vast array of convective thermal processes. Seebeck testing of TE elements was combined with thermal/hydraulic and thermoelectric modeling to develop the design of a working prototype system. A proof-of-concept small-scale prototype (SSP) TE generator was built to evaluate concepts intended for the construction of a fully-functional field demonstration prototype (FDP). The SSP was used to evaluate electrical contact integrity, thermal characteristics, various TE materials and the feasibility of using compression-based TE contacts. The SSP featured 9 P/N TE pairs and has thus far produced a maximum open-circuit voltage of 380mV and a maximum electrical power of 1.47W. Knowledge gained from the SSP construction and testing was utilized in the design and fabrication of the FDP. A liquid-cooled Honda ES6500 6.0kW genset was procured to provide a test-bed for the FDP. The primary goal was to power the electric radiator fan with the heat energy contained in its exhaust, thus decreasing the genset's fuel consumption rate. The FDP contained 256 P/N pairs and thus far has produced an open-circuit voltage of 5.5VDC and a maximum power of 8.49W. Replacing the stock muffler reduced fuel consumption by 11.6% whereas removing the fan load reduced it an additional 1.64%. Through the recovery and conversion of wasted thermal energy, the genset's fuel consumption rate was successfully lowered, therefore validating the benefits of secondary TE power systems. The radiator fan of the Honda ES6500 consumes approximately 1% of the overall power output of the genset. Radiator fans in larger gensets can draw as much as 12-16% of their peak output. By recuperating waste heat, substantially higher fuel savings could be achieved.
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Lowe, Adam John. "Thermoelectric power and photoemission studies in high temperature superconductors." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305550.
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Kraemer, Daniel Ph D. Massachusetts Institute of Technology. "Solar thermoelectric power conversion : materials characterization to device demonstration." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103490.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 268-289).<br>Meeting the ever growing global energy demand with mostly fossil fuel based energy technologies is not sustainable, pollutes the environment and is the main cause of climate change threatening our planet as we know it. Solar energy technologies are a promising, sustainable and clean alternative due to the vast abundance of sunlight. Thus far, photovoltaic solar cells and concentrated solar power are considered to be the most promising approaches. Solar cells directly convert sunlight into electricity by photon induced electron-hole pair generation. Concentrated solar power captures the sunlight in form of heat which is then converted to electricity by means of a traditional mechanical power block. In this thesis, we explore solar thermoelectric generators (STEGs) as an alternative way to convert sunlight to electricity. Similar to concentrated solar power STEGs capture the sunlight in form of heat. However, the captured heat is directly converted to electricity by means of a thermoelectric generator. This solid-state direct heat-to-electricity conversion significantly simplifies the system, reduces cost and maintenance and enables transient operation and system scalability without affecting the performance. Therefore, STEGs have the potential to be deployed as small scale solar power converters in remote areas and on rooftops and as large scale concentrated solar power plants. While the concept of solar thermoelectric power conversion has been proposed over a century ago, most successful experimental efforts reported in, the literature have been limited to below 1 % for STEGs without optical concentration and to approximately 3 - 5 % with optical concentration. Theoretical STEG performances as modeled and discussed in this thesis predict significantly higher efficiencies. A detailed STEG model is introduced to theoretically investigate various parasitic losses and how to minimize their effect to obtain highest and most realistic performance predictions. Additionally, a methodology to optimize a photovoltaic-thermoelectric hybrid system based on spectral splitting is introduced. The optimization and performance prediction of a STEG is only accurate if the relevant material properties are known with high accuracy. However, typical spectroscopy techniques to determine the optical properties, namely the solar absorptance and infrared emittance, of a solar absorber have shortcomings which can lead to significant errors. Similarly, typical commercial equipment to measure the properties of thermoelectric materials including the Seebeck coefficient, the electrical resistivity and the thermal conductivity are prone to large errors. Therefore, we introduce in this thesis novel experimental techniques to measure all relevant properties with improved accuracies in particular the techniques to measure the total hemispherical emittance of a surface and a material's thermal conductivity. A record-low total hemispherical emittance of 0.13 at 500 °C is demonstrated for an Yttria-stabilized-Zirconia-based cermet solar absorber with solar absorptance of 0.91 and thermal stability up to 600 °C. Furthermore, a method was developed to directly measure the efficiency of a thermoelectric leg. Using this method a record-high thermoelectric efficiency of 8.5 % is demonstrated at a relatively small temperature difference of 225 °C for a novel MgAgSb-based compound with hot-pressed silver contact pads. By increasing the temperature difference to a material's compatible 275 °C a thermoelectric efficiency of 10 % is achievable which, thus far, has only been achieve at almost twice the temperature difference. The third main contribution of this thesis is the experimental demonstration of solar thermoelectric power conversion. A record-high STEG efficiency of 4.6 % is demonstrated at AM1.5G (1 kW/m 2) conditions which is 7 times higher than previously reported best values. The performance improvement is achieved by using a STEG with nano-structured bulk thermoelectric materials, a spectrally-selective solar absorber and taking advantage of large thermal concentrations under a vacuum. Despite the vacuum environment and the use of a low-temperature spectrally-selective solar absorber the optimal hot-junction operating temperature is limited to approximately 200 °C due to increasing thermal radiation heat loss. In order to substantially increase the operating temperature difference and STEG efficiency, larger incident solar power densities are required. Furthermore, the STEG requires segmented thermoelectric legs and a high-temperature stable solar absorber. The optimized STEGs are fabricated and tested at moderate and high optical solar concentration. Efficiencies of close to 8 % at 38 suns and close to 10 % at 211 suns, measured based on the solar flux at the absorber, are demonstrated for a STEG with a spectrally-selective solar absorber. The maximum demonstrated solar-to-electricity CSTEG efficiency is 7.5 %. Furthermore, the performance of a STEG at moderate optical concentration with a high-temperature stable black paint solar absorber and a directionally-selective solar receiver cavity is demonstrated to be comparable to a STEG with a spectrally-selective surface at similar insolation.<br>by Daniel Kraemer.<br>Ph. D.
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Mayer, Peter (Peter Matthew) 1978. "High-density thermoelectric power generation and nanoscale thermal metrology." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40503.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.<br>Includes bibliographical references (p. 299-305).<br>Thermoelectric power generation has been around for over 50 years but has seen very little large scale implementation due to the inherently low efficiencies and powers available from known materials. Recent material advances appear to have improved the technology's prospects. In this work we show that significantly increased generated power densities are possible even for established material technologies provided that parasitic losses are controlled and effective strategies are found for handling the large resulting heat fluxes. We optimize the performance of a thermoelectric generator in this regime, and discuss fundamental performance limits in this context. We present a design of a thermoelectric generator using conventional material and a microchannel heat sink that we predict can generate many times the power of a conventional thermoelectric, at a comparable efficiency. A high temperature vacuum test station is used to characterize the power generation, efficiency, and material properties of thermoelectric materials and generators. The results of a series of studies on various bulk and thin-film materials are presented, as well as packaged generator performance. The method of CCD thermoreflectance imaging is pursued in this thesis as a quantitative means for making noncontact temperature measurements on solid-state samples at the micro- and nano-scale. We develop and test a theory of the instrument and the measurement process to rigorously characterize the accuracy and precision of the resulting thermal images. We experimentally demonstrate sub-micron spatial resolution and sub-20 mK temperature resolution with this tool. High-resolution thermal images of thermoelectric elements, polysilicon-gate field effect transistors, and other integrated electronic devices are presented.<br>by Peter M. Mayer.<br>Ph.D.
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Song, Yang M. Eng Massachusetts Institute of Technology. "Oxide based thermoelectric materials for large scale power generation." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45358.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.<br>Includes bibliographical references (leaves 63-65).<br>The thermoelectric (TE) devices are based on the Seebeck and Peltier effects, which describe the conversion between temperature gradient and electricity. The effectiveness of the material performance can be described by its figure of merit, ZT, which is defined as ZT = [alpha]²[sigma]T / [kappa] , where a is the Seebeck coefficient of the material, a is the electrical conductivity and [kappa] is the total thermal conductivity, and T is the temperature. In the past, TE power generation has been confined to niche applications. It has been technically and economically more efficient to produce electricity using traditional generators rather than a thermoelectric generator. However, recent significant advances in the scientific understanding of quantum well and nanostructure effects on TE materials properties and modem thin layer and nanoscale manufacturing technologies have combined to create advanced TE materials with high figure of merit (>3). An engineering analysis performed in this study identified large scale waste heat recovery opportunities that are suitable for advanced TE power generation systems.<br>by Yang Song.<br>M.Eng.
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Raja, Santosh. "Advanced thermoelectric power measurements using deployable three-point electrodes." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310893.
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Rahman, Mahmudur. "The application of thermoelectric generators as remote power sources." Thesis, University of Manchester, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.645193.
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Fransson, Erik, and Daniel Olsson. "Thermoelectric Generators : A comparison of electrical power outputs depending on temperature." Thesis, Högskolan Dalarna, Institutionen för information och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:du-38031.
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Today many processes generate a lot of waste heat, for example industries or cars. One way to make this thermal energy useful is to transform it into electrical energy with a thermoelectric generator (TEG) or thermoelectric cooler (TEC). This technology is not used in any large scale today, but a lot of research is being done on the subject. The technology is based on the Seebeck effect and uses a temperature difference between two sides of an element to generate an electrical current. The reason that the research has gained more attention in recent years is because of the increasing electricity prices and the diminishing natural resources. Other benefits are that they run quietly and do not demand much maintenance.Another area where this technology could be useful is in off-grid cabins where it is easy to generate a lot of thermal energy by burning wood, but electrical energy is in high demand.In this thesis two different types of TEGs and one type of TEC are tested to investigate how much power they generate at different temperature differences, how well they meet the specified values in their respective data sheet and what their power per euro value is. For this, an experimental setup was made with:- An induction plate to increase the temperature on the hot side.- A CPU-fan, to reduce the temperature on the cold side.- Two temperature sensors (one for measuring the hot temperature and one for the cold one).- An electric circuit featuring a voltmeter, an amperemeter and an adjustable resistor (rheostat).The results show that, for this experiment the highest received power (6,38 W) comes from the medium-priced element but the highest power per euro comes from the lowest priced element (1,16 W/€). A quality problem for the lowest priced element was that parts of the solder melted when the temperature exceeded 225 °C. Another problem was that the induction plate was unable to provide enough heat for the most expensive of the elements to reach the temperature for which the retailer supplies their measured data.
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Prabhakar, Radhika. "Scalable Carbon Nanotube Networks Embedded in Elastomers and their use in Transverse Thermoelectric Power Generation." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1572879766382909.
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Sullivan, Owen A. "Embedded thermoelectric devices for on-chip cooling and power generation." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45867.
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Thermoelectric devices are capable of providing both localized active cooling and waste heat power generation. This work will explore the possibility of embedding thermoelectric devices within electronic packaging in order to achieve better system performance. Intel and Nextreme, Inc. have produced thin-film superlattice thermoelectric devices that have above average performance for thermoelectrics and are much thinner than most devices on the market currently. This allows them to be packaged inside of the electronic package where the thermoelectric devices can take advantage of the increased temperatures and decreased thermal lag as compared to the devices being planted on the outside of the package. This work uses the numerical CFD solver FLUENT and the analog electronic circuit simulator SPICE to simulate activity of thermoelectric devices within an electronics package.
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Thiel, Philipp [Verfasser]. "Calcium Manganese(IV) Oxides for Thermoelectric Power Conversion / Philipp Thiel." München : Verlag Dr. Hut, 2015. http://d-nb.info/1080754431/34.
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Chang, Lieh-Jeng. "Neutron diffraction studies of the magnetic structures of R-Ni-B-C compounds." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245934.
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Nishino, Y., Y. Sandaiji, S. Yagi, M. Kato, S. Harada, and K. Soda. "Origin of large thermoelectric power in off-stoichiometric Fe2VAl-based alloys." IOP Publishing, 2011. http://hdl.handle.net/2237/20775.
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Burton, Matthew Richard. "Soft-templating of nanostructured materials for thermoelectric power harvesting and catalysis." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/418157/.
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The ever increasing demand for energy along with climate change has stimulated much research in the field of green energy technology. Thermoelectric generators are one form of green energy technology that generates electrical power from waste heat harvesting. Current fabrication techniques for thermoelectric materials are costly and the efficiency of materials is low. This work uses electrodeposition as a cheap fabrication that allows for control of a large number of variables to optimise materials. In the literature the doping of bismuth tellurium selenide has shown improvements in thermoelectric performance. Bismuth telluride and bismuth tellurium selenide have been electrodeposited before, but the electrochemical doping of bismuth tellurium selenide has not received much interest in the literature. In Chapter 3 bismuth tellurium selenide was doped with Cu to higher levels than ever reported before, by the addition of Cu(NO3)2 into the electrolyte. The level of Cu doping was shown to be linear with increasing Cu(NO3)2 concentration in the electrolyte, as determined by EDX. Cu doping was shown to exponentially decay the electrical conductivity, whilst concentrations between 1.25 mM and 1.75 mM Cu(NO3)2 were shown to increase the magnitude of the Seebeck coefficient, from -55 μV K-1 in the absence of Cu to a peak value of -390 μV K-1 when using an electrolyte concentration of 1.50 mM Cu(NO3)2. Whilst a slight improvement in power factor was seen for one sample made with 1.50 mM Cu(NO3)2 present in the electrolyte, this was not reproducible and on average Cu doping was not shown to improve thermoelectric performance. The electrochemical doping of bismuth tellurium selenide with Ag is reported for the first time and was shown to be linear with increasing Ag(NO3) concentration in the electrolyte. The addition of 0.25 mM Ag(NO3) in the electrolyte was shown to lower electrical conductivity to 296 S cm-1 from 564 S cm-1 in the absence of Ag(NO3). Further addition of Ag(NO3) into the electrolyte was shown to not diminish the electrical conductivity further. Ag doping also diminished the magnitude of the Seebeck coefficient. The most striking observation was the use of a SMSE reference electrode instead of a SCE reference electrode yielded the greatest improvement in thermoelectric performance of bismuth tellurium selenide films, producing a power factor of 0.33 mW m-1 K-1, compared to a value of 0.13 mW m-1 K-1 when using an SCE reference. The effect of different reference electrodes on the electrodeposition of bismuth telluride based materials has not been reported in the literature. The improvement in power factor is believed to be caused by the removal of Cl- ions, which may have been causing a detrimental effect on the electrodeposition of bismuth tellurium selenide films for thermoelectric applications. Reduced dimensionality offers a strategy for increasing the efficiency of thermoelectric materials primarily by lowering lattice thermal conductivity. In Chapter 4 a lyotropic liquid crystal is used for the first time to template bismuth telluride. The use of a phytantriol template during bismuth telluride electrodeposition was shown to produce a disordered nanostructure containing nanowires with diameters as low as 6 nm. Prior to this work the smallest bismuth telluride nanowires reported in the literature were 15 nm. The composition of these nanowires was controlled by altering the composition of the electrolyte. A Seebeck coefficient of -88 μV K-1 was measured. The films were seen to oxidise, with oxygen content of 60 atomic % measured by EDX. This oxidation resulted in a low electrical conductivity of 19 S cm-1 being measured. Whilst bismuth telluride is the best performing room temperature thermoelectric material, the rarity and toxicity of tellurium restricts the commercial viability of thermoelectric generators manufactured with bismuth telluride. Sulphur is an earth abundant element that is considered non-toxic and like tellurium sulphur is a group 16 element. This makes bismuth sulphide a potential alternative to bismuth telluride. In Chapter 5 planar bismuth sulphide films were successfully electrodeposited at a potential of -0.4 V vs SCE form an electrolyte created using 100 mM Bi(NO3)3, 100 mM Na2S2O3 and 200 mM EDTA in deionised water. A room temperature Seebeck coefficient of -29.8 μV K-1 was recorded. The use of a phytantriol template resulted in the production of a single diamond nanostructure with a lattice parameter of 139.6 (± 3.2) Å, as shown by SAXS and TEM. The electrodeposit was the first ever single diamond phytantriol templated semiconductor material. A lower Seebeck coefficient of -12.3 μV K-1 was recorded for the nanostructure. Fuel cells are promising technologies for transport and portable power generation due their ability to continually generate electricity when supplied with fuel. Current fuel cells are electrocatalysed by expensive Pt based materials. Pd is a more earth abundant and cheaper material with the potential to be used instead of Pt for the electrocatalyst in fuel cells. In Chapter 6 a phytantriol template was used for the first time to electrodeposit Pd with a high surface area per mass of 30.8 m2 g-1, and a high surface area per volume of 3.66 × 106 cm2 cm-3. The large surface area was due to a single diamond nanostructure being formed with a lattice parameter of 140.0 (± 4.6) Å, as determined by SAXS. This high surface area Pd nanostructure allowed for greater electrooxidation of methanol, ethanol and glycerol per gram of Pd when compared to Pd black and a film deposited in the absence of phytantriol.
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Bekera, Behailu Belamo. "Stochastic Drought Risk Analysis and Projection Methods For Thermoelectric Power Systems." Thesis, The George Washington University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3725243.
Full textAbstract:
<p> Combined effects of socio-economic, environmental, technological and political factors impact fresh cooling water availability, which is among the most important elements of thermoelectric power plant site selection and evaluation criteria. With increased variability and changes in hydrologic statistical stationarity, one concern is the increased occurrence of extreme drought events that may be attributable to climatic changes. As hydrological systems are altered, operators of thermoelectric power plants need to ensure a reliable supply of water for cooling and generation requirements. The effects of climate change are expected to influence hydrological systems at multiple scales, possibly leading to reduced efficiency of thermoelectric power plants. This study models and analyzes drought characteristics from a thermoelectric systems operational and regulation perspective. A systematic approach to characterize a stream environment in relation to extreme drought occurrence, duration and deficit-volume is proposed and demonstrated. More specifically, the objective of this research is to propose a stochastic water supply risk analysis and projection methods from thermoelectric power systems operation and management perspectives. The study defines thermoelectric drought as a shortage of cooling water due to stressed supply or beyond operable water temperature limits for an extended period of time requiring power plants to reduce production or completely shut down. It presents a thermoelectric drought risk characterization framework that considers heat content and water quantity facets of adequate water availability for uninterrupted operation of such plants and safety of its surroundings. In addition, it outlines mechanisms to identify rate of occurrences of the said droughts and stochastically quantify subsequent potential losses to the sector. This mechanism is enabled through a model based on compound Nonhomogeneous Poisson Process. This study also demonstrates how the systematic approach can be used for better understanding of pertinent vulnerabilities by providing risk-based information to stakeholders in the power sector.</p><p> Vulnerabilities as well as our understanding of their extent and likelihood change over time. Keeping up with the changes and making informed decisions demands a time-dependent method that incorporates new evidence into risk assessment framework. This study presents a statistical time-dependent risk analysis approach, which allows for life cycle drought risk assessment of thermoelectric power systems. Also, a Bayesian Belief Network (BBN) extension to the proposed framework is developed. The BBN allows for incorporating new evidence, such as observing power curtailments due to extreme heat or lowflow situations, and updating our knowledge and understanding of the pertinent risk. In sum, the proposed approach can help improve adaptive capacity of the electric power infrastructure, thereby enhancing its resilience to events potentially threatening grid reliability and economic stability.</p><p> The proposed drought characterization methodology is applied on a daily streamflow series obtained from three United States Geological Survey (USGS) water gauges on the Tennessee River basin. The stochastic water supply risk assessment and projection methods are demonstrated for two power plants on the White River, Indiana: Frank E. Ratts and Petersburg, using water temperature and streamflow time series data obtained from a nearby USGS gauge. </p>
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Fauzan, Miftah Yama. "Thermoelectric Generator Modeling and Power Maximization in Non-Uniform Heat Distribution." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/85454.
Full textAbstract:
Thermoelectric generation (TEG) has become a promising alternative energy whose source comes from abundant thermal. The conversion method is environmentally friendly, since it is based on a physical process allowing direct conversion from thermal to electricity. Other advantages of the system include silent operation, no moving parts, long lifetime, and supporting the sustainability motto of “reduce, reuse, recycle”. This thesis provides a study of maximizing the power generation of thermoelectric generator considering non-uniform heat distribution.
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Palu, Ivo. "Impact of wind parks on power system containing thermal power plants = Tuuleparkide mõju soojuselektrijaamadega energiasüsteemile /." Tallinn : TUI Press, 2009. http://digi.lib.ttu.ee/i/?443.
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Brogan, Quinn Lynn. "Low Power IC Design with Regulated Output Voltage and Maximum Power Point Tracking for Body Heat Energy Harvesting." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/81549.
Full textAbstract:
As wearable technology and wireless sensor nodes become more and more ubiquitous, the batteries required to power them have become more and more unappealing as they limit lifetime and scalability. Energy harvesting from body heat provides a solution to these limitations. Energy can be harvested from body heat using thermoelectric generators, or TEGs. TEGs provide a continuous, scalable, solid-state energy source ideal for wearable and wireless electronics and sensors. Unfortunately, current TEG technology produces low power (< 1 mW) at a very low voltage (20-90 mV) and require the load to be matched to the TEG internal resistance for maximum power transfer to occur. This thesis research proposes a power management integrated circuit (PMIC) that steps up ultralow voltages generated by TEGs to a regulated 3 V, while matching the internal resistance.
The proposed boost converter aims to harvest energy from body heat as efficiently and flexibly as possible by providing a regulated 3 V output that can be used by a variable load. A comparator-based burst mode operation affords the converter a high conversion ratio at high efficiency, while fractional open circuit voltage maximum power point tracking ensures that the controller can be used with a variety of TEGs and TEG setups. This control allows the converter to boost input voltages as low as 50 mV, while matching a range of TEG internal source resistances in one stage.
The controller was implemented in 0.25 µm CMOS and taped out in February 2016. Since these fabricated chips will not be completed and delivered until May 2016, functionality has only been verified through simulation. Simulation results are promising and indicate that the peak overall efficiency is 81% and peak low voltage, low power efficiency is 73%. These results demonstrate the the proposed converter can achieve overall efficiencies comparable to current literature and low power efficiencies better than similar wide range converters in literature.<br>Master of Science
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Berger, Brian Lee. "Development of a Protective Coating for TAGS-85 Thermoelectric Material." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1375129912.
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De, Silva Pinnaduwage Sisira Indika Pujitha Nanda. "The normal state thermoelectric power and Hall effect of high temperature superconductors." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263528.
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Singh, Tanuj. "Development of a premixed burner integrated thermoelectric power generator for insect control." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/68407/.
Full textAbstract:
Electrical power generation using hydrocarbons presents a huge potential owing to their higher power densities and environmental factors associated with lithium ion batteries. Small scale combustors have been widely developed and tested for power generation purpose employing Thermoelectrics and Thermophotovoltaic conversion of combustion heat into electricity. This thesis is concerned with development and investigation of a novel non-catalytic meso scale self-aspirating premixed burner integrated thermoelectric generator for a CO2 Generator device having its application in the insect control industry. Flame stabilisation has been one of the main issues in small scale combustion systems due to higher surface to volume ratio associated with small size of the combustor. Previous research has shown that catalytic combustion is one way of improving flame stabilisation, however employing a catalyst into the system increases the manufacturing cost which can be a significant downside. This research work studies flame stabilisation mechanisms in meso-scale burner which mainly focuses on Backward Facing Step or Sudden Expansion Step and secondary air addition into the combustion chamber. A 250 W premixed burner was developed which was classified as a meso scale burner whose operating parameters were in a range of micro-combustors whereas the size was comparatively bigger due to its integration with standard size thermoelectric modules. The first phase of the research was concerned with development of the burner which included optimisation of the design to achieve a stable enclosed premixed flame as per the design and operational requirements. It was found that flame blowoff can be prevented by addition of secondary air into the combustion chamber downstream of the step. The second phase of the research focused on the integration of the burner with thermoelectric power generators. This involved investigation of various configurations to optimise the electrical power output. The burner integrated thermoelectric unit was then tested in the actual field to validate the concept of integrating combustion and thermoelectrics for small scale power generation applications. The final phase of the research involved a study on the effect of secondary air addition on flame stabilisation in burners employing backward facing step. The minimum secondary air requirement for burner with different step heights was determined. The addition of secondary air cross-stream into the combustion chamber creates stable recirculation zone which reduces the local stream velocity and hence prevents flame blowoff.
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Badr, Lamya. "A Comparative Study of Cooling System Parameters in U.S. Thermoelectric Power Plants." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/72990.
Full textAbstract:
As the importance of water use in the power generation sector increases across the nation, the ability to obtain and analyze real power plant data is pivotal in understanding the water energy nexus. The Navajo Generating Station in Arizona and the Browns Ferry Nuclear Plant in Alabama are examples of where water shortages have threatened the operation of power generators. The availability of freshwater in the United States is beginning to dictate how and where new power plants are constructed. The purpose of this study is to provide and analyze cooling system parameters using 2008 data provided by the Energy Information Administration. Additionally, the cost of water saved among different categories of power plants is calculated. In general, the conditions which cause cooling systems to withdraw less water are not necessarily the more expensive conditions, and vice versa. While not all the variability in the cost of cooling systems is being accounted for, the results from this study prove that nameplate capacity, capacity factor, age of power plant, and region affect the costs of installed cooling systems. This study also indicates that it would be most cost effective for once-through cooling systems to be replaced with recirculating- pond instead of recirculating- tower systems. The implications of this study are that as power plant owner's struggle in balancing cost with water dependence, several parameters must first be considered in the decision-making process.<br>Master of Science
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Banerjee, D., P. Dhara, K. Chatterjee, K. Kargupta, and S. Ganguly. "Thermoelectric Characterization of Nanostructures of Bismuth Prepared by Solvothermal Approach." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35251.
Full textAbstract:
Nanostructured thermoelectric materials being an emerging area of research bismuth (Bi) nanostructures
have been developed by solvothermal approach with a change of solvent. Structural characterization
revealed that nanorods and nanospheres like structures were generated in the process when the solvent
used were only ethylene glycol (EG) and ethylene glycol with absolute ethanol (AE) in the ratio of 1:1 respectively.
Electrical properties viz. conductivity (σ) and thermoelectric power(S) have been measured in
the temperature range 300K to 400K. From the observed value of σ and S power factor P has been calculated.
The property improved for nanosphere like structures.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35251
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Farmer, Justin Ryan. "A comparison of power harvesting techniques and related energy storage issues." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33072.
Full textAbstract:
Power harvesting, energy harvesting, power scavenging, and energy scavenging are four terms commonly used to describe the process of extracting useful electrical energy from other ambient energy sources using special materials called transducers that have the ability to convert one form of energy into another. While the words power and energy have vastly different definitions, the terms â power harvestingâ and â energy harvestingâ are used interchangeably throughout much of the literature to describe the same process of extracting electrical energy from ambient sources. Even though most of the energy coupling materials currently available have been around for decades, their use for the specific purpose of power harvesting has not been thoroughly examined until recently, when the power requirements of many electronic devices has reduced drastically.
The overall objective of this research is to typify the power source characteristics of various transducer devices in order to find some basic way to compare the relative energy densities of each type of device and, where possible, the comparative energy densities within subcategories of harvesting techniques. Included in this research is also a comparison of power storage techniques, which is often neglected in other literature sources.
An initial analysis of power storage devices explores the background of secondary (rechargeable) batteries and supercapacitors, the advantages and disadvantages of each, as well as the promising characteristics of recent supercapacitor technology developments. Also explored is research into the effectiveness of piezoelectric energy harvesting for the purpose of battery charging, with particular focus on the current output of piezoelectric harvesters.
The first objective involved presenting and verifying a model for a cantilever piezoelectric bimorph. Next, an investigation into new active fiber composite materials and macro fiber composite devices utilizing the d31 coefficient is performed in comparison to a monolithic piezoelectric bimorph. The information gathered here was used to design a two bimorph device termed the mobile energy harvester (MEH). Worn by a human being at the waste level, the MEH harvests energy from each footfall during walking or running.
The next objective involved characterizing small temperature gradient (less than 200 oC) thermoelectric generators (TEGs). Four TEGs were linked in series and joined with a specially made aluminum base and fin heat sink. This device was then mounted to the exhaust system of an automobile and proved capable of recharging both an 80 and a 300 milliamp-hour battery. A switching circuit concept to step up the output voltage is also presented. However, the circuit proves somewhat difficult to implement, so an alternative DC/DC device is proposed as a possible solution. With the advent of highly efficient, low voltage DC to DC converters, it is shown that their high current, low voltage output can be converted to a higher voltage source that is suitable for many electronic and recharging applications.
As extensive literature exists on the capabilities of photovoltaic and electromagnetic energy harvesting, no original experimentation is presented. Instead, only a brief overview of the pertinent technological advances is provided in this document for the purpose of comparison to piezoelectric and thermoelectric energy harvesting. The main research focus, as described above, is dedicated to designing and performing original experiments to characterize cutting edge piezoelectric and thermoelectric transducer materials. To conclude and unify the document, the final section compares the power harvesting techniques with one another and introduces methods of combining them to produce a hybrid, multiple energy domain harvesting device. A piezoelectric-electromagnetic harvesting combination device is presented and scrutinized, revealing that such a device could improve the amount of energy extracted from a single harvesting unit.
The research presented here not only expands on the present understanding of these materials, but also proposes a new method of creating a hybrid power harvesting device utilizing two of the energy coupling domains, electromechanical and piezoelectric. The goal is to maximize the harvested energy by tapping into as many ambient sources as are available and practical.<br>Master of Science
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Takeuchi, Tsunehiro, Takeshi Kondo, Tsuyoshi Takami, Hirofumi Takahashi, Hiroshi Ikuta, Uichiro Mizutani, Kazuo Soda, et al. "Contribution of electronic structure to the large thermoelectric power in layered cobalt oxides." The American Physical Society, 2004. http://hdl.handle.net/2237/7117.
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Mueller, Kyle Thomas. "Super-adiabatic combustion in porous media with catalytic enhancement for thermoelectric power conversion." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4809.
Full textAbstract:
The combustion of ultra-lean fuel to air mixtures provides an efficient way to convert the chemical energy of hydrocarbons into useful power. Conventional burning techniques of a mixture have defined flammability limits beyond which a flame cannot self-propagate due to heat losses. Matrix stabilized porous medium combustion is an advanced technique in which a solid porous matrix within the combustion chamber accumulates heat from the hot gaseous products and preheats incoming reactants. This heat recirculation extends the standard flammability limits and allows the burning of ultra-lean fuel mixtures, conserving energy resources, or the burning of gases of low calorific value, utilizing otherwise wasted resources. The heat generated by the porous burner can be harvested with thermoelectric devices for a reliable method of generating electricity for portable electronic devices by the burning of otherwise noncombustible mixtures. The design of the porous media burner, its assembly and testing are presented. Highly porous (~80% porosity) alumina foam was used as the central media and alumina honeycomb structure was used as an inlet for fuel and an outlet for products of the methane-air combustion. The upstream and downstream honeycomb structures were designed with pore sizes smaller than the flame quenching distance, preventing the flame from propagating outside of the central section. Experimental results include measurements from thermocouples distributed throughout the burner and on each side of the thermoelectric module along with associated current, voltage and power outputs. Measurements of the burner with catalytic coating were obtained for stoichiometric and lean mixtures and compared to the results obtained from the catalytically inert matrix, showing the effect on overall efficiency for the combustion of fuel-lean mixtures.<br>ID: 030646196; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.A.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 105-119).<br>M.S.A.E.<br>Masters<br>Mechanical and Aerospace Engineering<br>Engineering and Computer Science<br>Aerospace Engineering; Thermofluid Aerodynamic Systems Track
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Marton, Christopher Henry. "An air-breathing, portable thermoelectric power generator based on a microfabricated silicon combustor." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62615.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2011.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>"February 2011." Cataloged from student submitted PDF version of thesis.<br>Includes bibliographical references (p. 224-237).<br>The global consumer demand for portable electronic devices is increasing. The emphasis on reducing size and weight has put increased pressure on the power density of available power storage and generation options, which have been dominated by batteries. The energy densities of many hydrocarbon fuels exceed those of conventional batteries by several orders of magnitude, and this gap motivates research efforts into alternative portable power generation devices based on hydrocarbon fuels. Combustion-based power generation strategies have the potential to achieve significant advances in the energy density of a generator, and thermoelectric power generation is particularly attractive due to the moderate temperatures which are required. In this work, a portable-scale thermoelectric power generator was designed, fabricated, and tested. The basis of the system was a mesoscale silicon reactor for the combustion of butane over an alumina-supported platinum catalyst. The system was integrated with commercial bismuth telluride thermoelectric modules to produce 5.8 W of electrical power with a chemical-to-electrical conversion efficiency of 2.5% (based on lower heating value). The energy and power densities of the demonstrated system were 321 Wh/kg and 17 W/kg, respectively. The pressure drop through the system was 258 Pa for a flow of 15 liters per minute of air, and so the parasitic power requirement for air-pressurization was very low. The demonstration represents an order-of-magnitude improvement in portable-scale electrical power from thermoelectrics and hydrocarbon fuels, and a notable increase in the conversion efficiency compared with other published works. The system was also integrated with thermoelectric-mimicking heat sinks, which imitated the performance of high-heat-flux modules. The combustor provided a heat source of 206 to 362 W to the heat sinks at conditions suitable for a portable, air-breathing TE power generator. The combustor efficiency when integrated with the heat sinks was as high as 76%. Assuming a TE power conversion efficiency of 5%, the design point operation would result in thermoelectric power generation of 14 W, with an overall chemical-to-electrical conversion efficiency of 3.8%.<br>by Christopher Henry Marton.<br>Ph.D.
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Shoaei, Parisa Daghigh. "Technoeconomic Analysis of Textured Surfaces for Improved Condenser Performance in Thermoelectric Power Plants." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101966.
Full textAbstract:
Nonwetting surfaces including superhydrophobic (SHS) and liquid infused surfaces
(SLIPS) exhibit diverse exceptional characteristics promoting numerous application
opportunities. Engineered textured surfaces demonstrate multiple features including drag
reduction, fouling reduction, corrosion resistance, anti-fogging, anti-icing, and
condensation enhancement. Integrating these properties, nonwetting surfaces have shown
significant potential in improving the efficiency of energy applications. The first part of
the thesis work aims at developing a fundamental mathematical understanding of the
wetting process on the solid surface followed by presenting fabrication methodologies
specifically focused on metallic substrates. The second part of this thesis presents an
exhaustive survey on recent advancements and researches about features of nonwetting
surfaces that could be implemented in major industrial applications.
To establish how realistically these features could enhance the real-life applications,
the third part of this work investigates the dynamic performance and economic benefits
of using textured surfaces fabricated using an electrodeposition process for condenser
tubes in thermoelectric power plants. The textured surfaces are expected to provide
enhanced performance by deterring fouling and promoting dropwise condensation of the
steam on the shell side. Using a thermal resistance network of a shell and tube condenser,
detailed parametric studies are carried out to investigate the effect of various design
parameters on the annual condenser performance measured in terms of its electric energy
output of a representative 550 MW coal-fired power plant. A cost modeling tool and a
new Levelized cost of condenser (LCOC) metric have been developed to evaluate the
economic and performance benefits of enhanced condenser designs. The LCOC is
defined as the ratio of the lifetime cost of the condenser (and associated costs such as
coating, operation and maintenance) to the total electric energy produced by the
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thermoelectric power plant. The physical model is coupled with a numerical optimization
method to identify the optimal design and operating parameters of the textured tubes that
minimizes LCOC. Altogether, the study presents the first effort to construct and analyze
enhanced condenser design with textured tube surfaces on annual thermoelectric power
plant performance and compares it against the baseline condenser design with plain
tubes.<br>Master of Science<br>Liquid repellant surfaces have attracted lots of attention due to their numerous
promising characteristics including promoting condensation, drag reduction, prohibiting
fouling/deposition, corrosion, and fog/dew harvesting. These attributes have the potential
to inspire a variety of applications for these surfaces in power plants, automotive and
aviation industries, oils/organic solvents clean-up, fuel cells, solar panels, membrane
distillation, stone/concrete protection, surgical fabrics, and biological applications, to
name a few. Some of these applications have reached their potential for real-life
implementation and more are still at the research phase needing more experimental and
fundamental studies to get them ready.
The first part of this study presents the fundamentals of the wetting process. Next,
fabrication methods for metallic surfaces have been explored to identify the most scalable
and cost-effective approaches which could be administered in large scale industrial
applications.
A comprehensive review of recent publications on features of nonwetting surfaces has
been carried out and presented in the second part of this thesis. To establish how
realistically these features could enhance the real-life applications of a thermo-economic
a performance model is developed for a powerplant condenser in the third section. Through
a simple and cost-effective electrodeposition process, the common condenser tubes are
modified to achieve textured tubes with superhydrophobic properties. The influence of
using textured tubes on the plant's performance and its economic benefits are
investigated to predict the potential promises of nonwetting surfaces.
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Erturun, Ugur. "Effect of Leg Geometries, Configurations, and Dimensions on Thermo-mechanical and Power-generation Performance of Thermoelectric Devices." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3561.
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Environmental challenges, such as global warming, growing demand on energy, and diminishing oil sources have accelerated research on alternative energy conversion methods. Thermoelectric power generation is a promising method to convert wasted heat energy into useful electrical energy form. A temperature gradient imposed on a thermoelectric device produces a Seebeck potential. However, this temperature gradient causes thermal stresses due to differential thermal expansions and mismatching of the bonded components of the device. Thermal stresses are critical for thermoelectric devices since they can generate failures, including dislocations, cracks, fatigue fractures, and even breakdown of the entire device. Decreases in power-generation performance and operation lifetime are major consequences of these failures. In order to minimize thermal stresses in the legs without affecting power-generation capabilities, this study concentrates on structural solutions. Thermoelectric devices with non-segmented and segmented legs were modeled. Specifically, the possible effect of various leg geometries, configurations, and dimensions were evaluated using finite-element and statistical methods. Significant changes in the magnitudes and distributions of thermal stresses occurred. Specifically, the maximum equivalent stresses in the rectangular-prism and cylindrical legs were 49.9 MPa and 43.3 MPa, respectively for the temperature gradient of 100ºC. By using cylindrical legs with modified dimensions, decreases in the maximum stresses in legs reached 21.2% without affecting power-generation performance. Moreover, the effect of leg dimensions and coaxial-leg configurations on power generation was significant; in contrast, various leg geometries and rotated-leg configurations had very limited affect. In particular, it was possible to increase power output from 20 mW to 65 mW by simply modifying leg widths and heights within the defined range. It should be noted, however, this modification also increased stress levels. It is concluded that leg geometries, configurations, and dimensions can be redesigned for improved durability and overall performance of thermoelectric devices.
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Brázdil, Marian. "Termoelektrické moduly pro mikrokogenerační zdroje." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399217.
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Small domestic hot water boilers burning solid fuels represent a significant source of air pollu-tion. It is therefore an effort to increase their combustion efficiency and to reduce the produc-tion of harmful emissions. For this reason, the operation of older and currently unsatisfactory types of household boilers has been legally restricted. Preferred types of boilers are low-emission boilers, especially automatic or gasification boilers. Most of them, however, in compar-ison with previous types of boilers, also require connection to the electricity grid. If there is a long-term failure in electricity grid, the operation of newer boiler types is limited. Wood and coal gasification boilers are currently available on the market and can be operated even in the event of a power failure, but only in heating systems with natural water circulation. In heating systems with forced water circulation, these boilers, fireplaces or fireplace inserts with hot-water heat exchangers cannot be operated without external battery supply in the event of a power failure. The dissertation thesis therefore deals with the question of whether it would be possible by thermoelectric conversion of waste heat of flue gases of small-scale low-emission combustion hot water domestic boilers to obtain sufficient electricity, to power supply their circulation pumps and to ensure operation in systems with forced water circulation independently of elec-tricity supply from the grid. In order to answer this question, a simulation tool predicting the power parameters of ther-moelectric generators was created. Compared to previously published works, the calculations and simulations include the influence of the generator on the boiler flue gas functionality. To verify the simulation tool, an experimental thermoelectric generator was built using the waste heat of the flue gas of an automatic hot water boiler for wood pellets. In addition to this genera-tor, there was also created an experimental thermoelectric fireplace insert and other equipment related to these experiments.
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Denker, Reha. "Quantification Of Thermoelectric Energy Scavenging Opportunity In Notebook Computers." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614629/index.pdf.
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Thermoelectric (TE) module integration into a notebook computer is experimentally investigated in this thesis for its energy harvesting opportunities. A detailed Finite Element (FE) model was constructed first for thermal simulations. The model outputs were then correlated with the thermal validation results of the selected system. In parallel, a commercial TE micro-module was experimentally characterized to quantify maximum power generation opportunity from the combined system and component data set. Next, suitable &ldquo<br>warm spots&rdquo<br>were identified within the mobile computer to extract TE power with minimum or no notable impact to system performance, as measured by thermal changes in the system, in order to avoid unacceptable performance degradation. The prediction was validated by integrating a TE micro-module to the mobile system under test. Measured TE power generation power density in the carefully selected vicinity of the heat pipe was around 1.26 mW/cm3 with high CPU load. The generated power scales down with lower CPU activity and scales up in proportion to the utilized opportunistic space within the system. The technical feasibility of TE energy harvesting in mobile computers was hence experimentally shown for the first time in this thesis.
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Smith, Mark John. "Low temperature phonon-drag thermoelectric power calculations in GaAs/GaAlAs heterojunctions and Si MOSFETs." Thesis, University of Warwick, 1989. http://wrap.warwick.ac.uk/4163/.
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The effect on the electron transport of the confinement of the electrons to a narrow channel in GaAs/GaAlAs heterojunctions and Si MOSFETs is reflected in quantities like the thermopower (S) which is sensitive to the transport of both heat and charge. The calculations described here confirm that in these systems S is dominated by phonondrag (Sg) at temperatures (T) around 1-10K and reveals more sensitivity than previously imagined. Simple models and the Boltzmann transport formalism have been investigated. The formalism enhances the predictions of the simple models and reproduces the simple S. formulae in appropriate limits. Amplification of S9 in quasi-2D arises from the loss of the momentum conservation constraint across the channel at small widths b. Earlier calculations were numerically inaccurate and greatly overestimate -S9 by ignoring screening. An effective multi-subband screening dielectric function is defined which reduces to the single subband approximation at small b and low electron density (n). Nondegeneracy has also been included. It is an important consideration despite the low temperatures of most of the data. The treatment of electron confinement has been improved and the temperature dependence of the polarizability investigated. It is unimportant in the current experimental systems but significant at lower n and higher T. The piezoelectric scattering mechanism has been introduced and dominates S. in the heterojunction for T <1K. A dominant 2D wavevector component has been defined for the phonon population at given T which is very helpful in understanding S9. A correction for the energy dependence of the electron relaxation-time is necessary and demonstrates the dependence of S. upon the dominant electron scattering mechanism. The calculations of S. in the quantum-limit and boundary scattering regime now explain the measured S in heterojunctions and peaks in -Sg/T3 in the MOSFET up to an accuracy better than 10% without adjustable parameters.
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Sadler, Zachary James. "Design and Analysis of Compressed Air Power Harvesting Systems." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/7052.
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Procedure for site discovery, system design, and optimization of power harvesting systems is developed with an emphasis on application to air compressors. Limitations for the usage of infrared pyrometers is evaluated. A system of governing equations for thermoelectric generators is developed. A solution method for solving the system of equations is created in order to predict power output from the device. Payback analysis is proposed for determining economic viability. A genetic algorithm is used to optimize the power harvesting system payback with changing quantities and varieties of thermoelectric generators, as well as the back work put into cooling the thermoelectric generators. Experimental data is taken for laboratory simulation of a power harvesting system under varying resistive load and thermal conductances in order to confirm the working model. A power harvester is designed for and installed on a consumer grade portable air compressor. Experimental data is compared against the model's prediction. As a case study, a system is designed for a water-cooled power harvesting system. Thermoelectric generator power harvesters are found to be economically infeasible for typical installations at current energy prices. Changes in parameters which would increase economic feasibility of the power harvesting system are discussed.
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Jahanbakhsh, David. "Implementation of DC-DC converter with maximum power point tracking control for thermoelectric generator applications." Thesis, KTH, Elektrisk energiomvandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109705.
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A heavy duty vehicle looses approximately 30-40 % of the energy in the fuel as waste heat through the exhaust system. Recovering this waste heat would make the vehicle meet the legislative and market demands of emissions and fuel consumption easier. This recovery is possible by transforming the waste heat to electric power using a thermoelectric generator. However, the thermoelectric generator electric characteristics makes direct usage of it unprotable, thus an electric power conditioner is necessary. First a study of dierent DC-DC converters is presented, based on that the most suitable converter for thermoelectric application is determined. In order to maximize the harvested power, maximum power point tracking algorithms have been studied and analyzed. After the investigation, the single ended primary inductor converter was simulated and implemented with a perturb and observe algorithm, and the incremental conductance algorithm. The converter was tested with a 20 W thermoelectric generator, and evaluated.The results show that the incremental conductance is more robust and stable compared to the perturb and observe algorithm. Further on, the incremental conductance also has a higher average eciency during real implementation.
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Edvinsson, Nils. "Energy harvesting power supply for wireless sensor networks : Investigation of piezo- and thermoelectric micro generators." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-210429.
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Computers and their constituent electronics continue to shrink. The same amount of work can be done with increasingly smaller and cheaper components that need less power to function than before. In wireless sensor networks, the energy needed by one sensor node borders the amount that is already present in its immediate surroundings. Equipping the electronics with a micro generator or energy harvester gives the possibility that it can become self-sufficient in energy. In this thesis two kinds of energy harvesters are investigated. One absorbs vibrations and converts them into electricity by means of piezo-electricity. The other converts heat flow through a semiconductor to electricity, utilizing a thermoelectric effect. Principles governing the performance, actual performance of off-the-shelf components and design considerations of the energy harvester have been treated. The thermoelectric micro generator has been measured to output power at 2.7 mW and 20°C with a load of 10 W. The piezoelectric micro generator has been measured to output power at 2.3 mW at 56.1 Hz, with a mechanical trim weight and a load of 565 W. In these conditions the power density of the generators lies between 2-3 W/m2.
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Oda, Yutaka. "Characteristics of thermoelectric power generation with rectangular-fin elements and its applicability in micro systems." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144913.
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Chen, Jie. "Design and analysis of a thermoelectric energy harvesting system for powering sensing nodes in nuclear power plant." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/64792.
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In this work, a thermoelectric energy harvester system aimed at harvesting energy for locally powering sensor nodes in nuclear power plant coolant loops has been designed, fabricated and tested. Different mathematical modeling methods have been validated by comparing with experimental results. The model developed by this work has the best accuracy in low temperature range and can be adapted and used with any heat sink, heat pipe, or thermoelectric system, and have proven to provide results closely matching experimental data. Using the models, an optimization of the thermoelectric energy harvesting system has been performed which is applicable to any energy harvester of this variety.
With experimental validation, the system is capable of generating sufficient energy to power all the sensors and electronical circuits designed for this application. The effect of gamma radiation on this thermoelectric harvester has also been proved to be small enough through radiation experiment.<br>Master of Science
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Langham, Ryan C. "Feasibility study and system architecture of radioisotope thermoelectric generation power systems for usmc forward operating bases." Monterey California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34695.
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Approved for public release; distribution is unlimited<br>This study sought to identify the feasibility of utilizing a radioisotope thermal (thermoelectric/stirling) generator to provide power to a deployed USMC Expeditionary Force. The conceptual system architecture was constructed through use of the systems engineering process, identifying necessary subsystems and integration boundaries. Radioisotope comparison was then performed, utilizing weighted design factors. It was determined that Sr-90, Cs-137, and Cm-244 would be the most effective fuel sources for this mission area. By analyzing current thermoelectric technology, it was determined that maximum system efficiency is limited to 1015 percent when utilizing available lead telluride thermoelectrics. Barriers to development of identified physical subsystem components were then identified, including health and environmental hazards of potential isotopes, as well as shielding criteria. The system development was found to be feasible and additional design work and development work is proposed.