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1
Xu, Bin. "Si/SiGe thermoelectric generator." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/25750.
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This PhD thesis researches thermoelectric generator (TEG) which transfers wasted heat into electricity by thermoelectric materials. As a parameter used to characterize thermoelectric materials, figure-of-merit (ZT) models of Si bulk, Si/Si_(1-x) Ge_x bulk and Si bulk/nanowires (NWs) are built via building their models of Seebeck coefficient, electrical conductivity and thermal conductivity in this thesis. ZT of Si bulk is increased by 18% by applying a 3μm thick Si_0.8 Ge_0.2 bulk layer, and it is increased by 1000% by applying 35μm long Si NWs. TEG’s output power model which takes account of the effects of thermoelectric material, as well as all parasitic effects that affect TEG’s output power. TEG’s output power model demonstrates the output power depends on thermoelectric material’s characteristics and the contact interface quality between thermoelectric material and metal probe. Thermoelectric material’s characteristics are improved by Si NWs, Si_(1-x) Ge_x bulk, Si_(1-x) Ge_x NWs and spin-on-doping (SOD). SOD also improves the contact interface quality between thermoelectric material and metal probe, which also can be improved by sputter coating a layer of metal on thermoelectric material’s surface. Finally, TEG’s output power is increased by an order of 3 by these techniques.
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Schaevitz, Samuel B. (Samuel Benjamin) 1978. "A MEMS thermoelectric generator." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/28253.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 153-163).
The demand for portable power is large and expanding. Technologies currently available to meet this demand include batteries, fuel cells, thermophotovoltaic (TPV) generators and thermoelectric (TE) generators. Fuel cells and generators offer significantly improved performance over batteries, but issues of fuel processing and miniaturization remain. Microfabrication has the potential to address this miniaturization. Here I present work towards a thermoelectric generator based on micro-electro-mechanical system (MEMS) fabrication technologies. This thesis includes an examination of the current state of the portable power field, followed by an explanation of the thermoelectric effects and the operation of thermoelectric generators. A new analysis of the efficiency of thermoelectric devices, including parasitic losses, is included, with a detailed derivation in an appendix. The design of a prototype MEMS thermoelectric generator is presented, analyzed and fabricated. Testing shows the device performs as expected thermally. However, mechanical fragility causes very low yield during fabrication and limits the high temperature operation. Poor electrical contacts are also observed and characterized. Directions for future work are suggested to improve the efficiency and mechanical strength of the device.
by Samuel B. Schaevitz.
M.Eng.
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Odia, Ameze. "Ge/SiGe-based thermoelectric generator." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8174/.
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This thesis summarizes the milestones achieved in building a thermoelectric generator (TEG) device using a novel p- and n- type 2-D thermoelectric material called Ge/SiGe superlattice; which was grown by low energy plasma- enhanced chemical vapour deposition (LEPECVD). It begins by describing in a nutshell the advances made in the area of thermoelectrics since its inception in 1821, to the present application of nanotechnology to develop state-of-the-art thermoelectric materials of which the aforementioned material is one. Next, characterisation of the Ge/SiGe superlattice using a combination of experiment and Finite Element (FE) modelling is explained and the results obtained are discussed in comparison with published experimental results. Thereafter, experimental and FE results of the application of the Ge/SiGe superlattice to fabricate a TEG device are presented and discussed. The experimental results on the fabrication of Ge/SiGe TEG device is the first major success at achieving practically feasible voltage output of up to 2.16 mV. For ease of comparison with other published work, an effective Seebeck coefficient of 471.9V/K was estimated. At impedance matched loads of 15 and temperature difference measured across the device of 5.6 K, a power density of 0.111 W/cm2 and thermal efficiency factor of 0.0035 Wcm-2 K-2 were also estimated. The results though comparable to a few published works, still required further improvements. The limitations of the TEG that resulted to the low aforementioned performances were discussed; some of which include the restriction of the TEG to a unicouple, having only one p- and n-leg. This limitation is related to the development of the p-type Ge/SiGe material which was identified during the course of this research work. Another major limitation is that the improvised design of the unicoupled TEG, makes use of indium bonding to connect the p- and n- legs electrically in series and thermally in parallel. Indium has a low melting temperature of about 120ºC. Hence increasing the heat source above this temperature will dislocate the legs. The consequence of this is that the attainment of a significant temperature difference across the TEG that will eventually result to a high Seebeck voltage, based on the Seebeck effect principle, is limited. Ways to address these problems were therefore discussed as recommendations for future research work.
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Sivapurapu, Sai Vinay Kumar. "Preliminary design of a cryogenic thermoelectric generator." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3612/.
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A cryogenic thermoelectric generator is proposed to increase the efficiency of a vehicle propulsion system that uses liquid nitrogen as its fuel. The proposed design captures some of the heat required for vaporizing or initial heating of the liquid nitrogen to produce electricity. The thermoelectric generator uses pressurized liquid nitrogen as its cold reservoir and ambient air as the high-temperature reservoir to generate power. This study concentrated on the selection of thermoelectric materials whose properties would result in the highest efficiency over the operating temperature range and on estimating the initial size of the generator. The preliminary selection of materials is based upon their figure of merit at the operating temperatures. The results of this preliminary design investigation of the cryogenic thermoelectric generator indicate that sufficient additional energy can be used to increase overall efficiency of the thermodynamic cycle of a vehicle propulsion system.
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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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Sivapurapu, Sai Vinay Kumar Plummer Mitty Charles. "Preliminary design of a cryogenic thermoelectric generator." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3612.
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Rocha, Carlos Miguel Oliveira. "Characterization and application of a thermoelectric generator." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/19111.
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Mestrado em Engenharia MecânicaThis work is dedicated to the characterization of thermoelectric materials, as well as the simulation of their application and optimization by using a mathematical model. Thermoelectric generators are commonly used in space exploration for many decades, however their application can be extended to the recovery of exhaust gases in automobiles and industrial processes as well as the powering of different types of remote sensors. In this work, the BaGd2NiO5 material and its doping states with Ca were studied for the first time in terms of their thermoelectric properties such as Seebeck coefficient, thermal conductivity and electrical conductivity. A mathematical model was also developed to simulate the application performance of any thermoelectric material for various working conditions. After the experimental validation of the model it was used to simulate the performance of Ca0.15BaGd1.85NiO5 compound, which presented the best thermoelectric properties. The numerical simulations showed that the performance of a thermoelectric generator with this material would be as better as larger is the temperature difference that the module is subjected and as greater is the heat transfer from hot and cold sources to the thermoelectric generator. The electrical conductivity of Ca0.15BaGd1.85NiO5 is the main reason for its low viability since the conversion efficiency was much lower than 1% and the power output was also reduced. This work revealed that the doping of BaGd2NiO5 with Ca can improve its thermoelectric properties, such as the increasing of the electrical conductivity and the reduction of the thermal conductivity. Moreover, the optimization of the application showed to be important in terms of increasing the performance and reducing the material. The mathematical model permitted to conclude that the optimum thickness of the thermoelements will be as smaller as larger is the heat transfer coefficient by convection of the hot and cold fluids. The simulations with the mathematical were also useful to conclude that a generator with thermoelectric properties of Ca0.15BaGd1.85NiO5 could have a wide applicability if its electrical conductivity could be a hundred times greater than the current value.
Este trabalho é dedicado à caracterização de materiais termoeléctricos, bem como a simulação da sua aplicação e otimização utilizando um modelo matemático. Os geradores termoeléctricos são utilizados com frequência na exploração espacial à várias décadas, no entanto a sua aplicação pode ser alargada à recuperação de gases de escape em automóveis e processos industriais, bem como na alimentação de diferentes tipos de sensores remotos. No presente trabalho, o material BaGd2NiO5 e seus estados de dopagem com Ca foram estudados pela primeira vez a nível das suas propriedades termoeléctricas tais como coeficiente de Seebeck, condutividade térmica e condutividade eléctrica. Um modelo matemático foi desenvolvido de forma a simular o desempenho da aplicação de um determinado material termoeléctrico para várias condições de trabalho. Após a validação experimental do modelo, o mesmo foi utilizado para simular o desempenho do composto Ca0.15BaGd1.85NiO5, o qual apresentou as melhores propriedades termoeléctricas. As simulações numéricas permitiram concluir que o desempenho de um gerador termoeléctrico com este tipo de material seria tanto melhor quanto maior for a diferença de temperaturas a que está sujeito e quanto maior for o coeficiente de transferência de calor por convecção das fontes quente e fria. A baixa condutividade eléctrica do material Ca0.15BaGd1.85NiO5 fez com que a viabilidade da sua utilização apresente algumas dificuldades uma vez que a sua eficiência será inferior a 1%, sendo a potência produzida igualmente reduzida. Este trabalho permitiu concluir que a dopagem do material BaGd2NiO5 com Ca poderá melhorar as suas propriedades termoeléctricas, nomeadamente com o aumento da condutividade eléctrica e com a redução da condutividade térmica. Por outro lado, a otimização da aplicação mostrou ser relevante em termos de aumento do desempenho e redução de material. O modelo matemático permitiu concluir que a espessura ótima dos elementos termoeléctricos será tanto menor quanto maior for o coeficiente de transferência de calor por convecção dos fluídos quente e frio. A partir do modelo matemático foi ainda possível concluir que um gerador com as propriedades de Ca0.15BaGd1.85NiO5 poderia ter uma grande aplicabilidade e se a sua condutividade eléctrica fosse cem vezes superior ao valor atual.
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Ang, Yang Adrian. "Prediction and analytics of operating parameters on thermoelectric generator energy generation." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3872.
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The efficient use of energy at all stages along the energy supply chain and the utilization of renewable energies are very important elements of a sustainable energy supply system, specially at the conversion from thermal to electrical energy. Converting the low-grade waste heat into electrical power would be useful and effective for several primary and secondary applications. One of the viable means to convert the low-grade waste heat into electrical energy is the use of thermoelectric power conversion. The performance of thermoelectric generators, subjected to thermal effects, can vary considerably depending on the operating conditions, therefore it is necessary to measure and have a better understanding of the characteristics and performance of the thermoelectric generator. It is important to understand the thermoelectric generator’s dynamic behavior and interaction with its operating environmental parameters. Based on this knowledge, it is then significant to develop an effective mathematical model that can provide the user with the most probable outcome of the output voltage. This will contribute to its reliability and calculation to increase the overall efficiency of the system. This thesis provides the transient solution to the three-dimensional heat transfer equation with internal heat generation. It goes on to describes the transfer and generation of heat across the thermoelectric generator with dynamic exchange of heat. This solution is then included in a model in which the thermal masses and the operating environmental parameters of the thermoelectric generator are factored in. The resulting model is created in MATLAB. The comparison with experimental results from a thermoelectric generator system confirms the accuracy of the artificial neural network model. This thesis also presents two practical applications, the prediction of the input parameters with a given output voltage, and sensitivity analysis designed for the model. This is to enable users to customize the thermoelectric generator for their requirements. This allows for better usage of resources eventually.
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MacBride, Douglas Martin. "Investigations of a potential high-efficiency thermoelectric generator." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10688.
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Glatz, Wulf. "Development of flexible micro thermoelectric generators." Tönning Lübeck Marburg Der Andere Verl, 2008. http://d-nb.info/989530639/04.
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Li, Xinjie. "Concentrated Solar Thermoelectric Generators Based on V-shaped Metallic Couples." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613752123514427.
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Christian, Corey D. (Corey Dwight). "Breaking the thermo-mechanical coupling of thermoelectric materials : determining the viability of a thermoelectric generator." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121790.
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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-70).
Thermoelectric power generators (TEGs) convert a temperature difference into electricity. This temperature difference can be created from waste heat. Since up to 50% [1] of US industrial energy input is lost as waste heat, an economical means of recovering waste heat and converting it into useful electricity could represent significant energy savings. Coupled with our integrative system design which involves creating application specific thermoelectric arrays, this technology can also help enable low power generation for off-grid needs in the developing world. Although conversion efficiencies as high as 20.9% [2] (heat to electrical energy) have been predicted from simulations of TEGs systems, in practice the efficiencies are typically only a few percent. Moreover, conventional systems often require expensive components to manage heat flow through the system.
As a result of the low efficiency and high system cost, electricity generated by thermoelectric energy harvesting from waste heat is currently not competitive with conventional electricity generation on a dollars-per-watt basis. This realization has led researchers to not only focus on increasing TEG device efficiency limits but to devise cheaper manufacturing processes and methods. A system design constraint that has not been fully investigated is the coupling of thermal and mechanical properties in thermoelectric materials. The extent to which this coupling affects the performance of the TEGs will be studied. This thesis develops an approach for decoupling the thermal and mechanical properties and tests it through a variety of simulations. We propose a mechanically compliant attachment strategy which could be integrated in various waste heat recovery applications.
The strategy involves breaking the thermal and mechanical bond formed by the brittle thermoelectric elements and its substrate. Copper wire, which is more pliable, is then used to connect the thermoelectric element to the substrate. A system analysis was performed for waste heat recovery from a vehicles exhaust pipe. We found that utilizing the proposed strategy should not only lead to increased mechanical compliance but can also lead to cost savings on a dollars-per-watt basis. We found that 84% power retention could be obtained when up to 16x less material is used under most apparent conditions¹.
by Corey D. Christian.
S.M. in Engineering and Management
S.M.inEngineeringandManagement Massachusetts Institute of Technology, System Design and Management Program
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Kang, Han-Byul. "Half-Heusler Thermoelectric Materials and Modules." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102413.
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High temperature waste heat recovery has been gaining attention in recent years as it forms one of the largest sources of available energy. A rapid development of thermoelectric (TE) materials that can directly convert heat into electricity through the Seebeck effect, opens promising pathway for harvesting the thermal energy from the surroundings. In order to harvest the high-quality waste heat at elevated temperature, excellent thermal and mechanical stability of the TE materials is critical for a sustainable energy harvesting. In this respect, half-Heusler (hH) alloys are one of the promising high-temperature TE materials due to their high dimensionless thermoelectric figure of merit (zT) along with excellent mechanical and thermal stability. This dissertation demonstrates novel hH compositions and microstructures for the waste heat recovery systems. Focus in the thesis is on development of high performance hH TE materials with excellent in-air thermal stability at high temperatures (>700K). This will allow manufacturing of high efficiency and durable high temperature thermoelectric generators (TEGs).
In chapter 3 and 4, a comprehensive optimization of n-type MNiSn and p-type MCoSb (M = Hf, Zr, and Ti) compounds is investigated through systematic control of processing parameters during melting and sintering. The synthesis conditions were controlled to achieve the phase purity, desired microstructure and the enhanced charge-carrier transport. Optimized n-type and p-type compositions are found to exhibit zTmax ~ 1 at 773 K.
Chapter 5 describes breakthrough in decoupling of TE parameters in n-type half-Heusler (hH) alloys through multi-scale nanocomposite architecture with tungsten nanoinclusions. The tungsten nanoparticles not only assist electron injection, thereby improving electrical conductivity, but also enhance the Seebeck coefficient through energy filtering effect. The microstructure comprises of disordered phases with feature sizes at multiple length scales, which assists in effective scattering of heat-carrying phonons over diverse mean-free-path ranges. Cumulatively, these effects are shown to result in outstanding thermoelectric performance of zTmax ~ 1.4 at 773 K and zTavg ~ 0.93 between 300 and 973 K.
In order to deploy TE materials into a thermal energy conversion device, it is essential to understand the transformation behavior under thermal cycling at high temperatures. In-air thermal stability of the hH compositions is demonstrated in chapter 6. All the optimized compositions are found to be stable below 673 K in-air condition. The n-type MNiSn and p-type NbFeSb compounds were found to show good thermal stability even at higher temperatures (>773K), whereas MCoSb compounds did not exhibit similar level of stability.
Building upon the improved material performance and thermal stability, uni-coupled TE generators are demonstrated that exhibit high power density of 13.81 W⸱cm-2 and conversion efficiency of 10.9 % under a temperature difference of 674 K. The uni-couple TEG device shows stable performance for more than 150 hours at 873 K in air. These results are very promising for deployment of TE materials in waste heat recovery systems.Doctor of Philosophy
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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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Willfahrt, Andreas. "Screen Printed Thermoelectric Devices." Licentiate thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-106006.
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Thermoelectric generators (TEG) directly convert heat energy into electrical energy. The impediments as to why this technology has not yet found extensive application are the low conversion efficiency and high costs per watt. On the one hand, the manufacturing process is a cost factor. On the other, the high-‐priced thermoelectric (TE) materials have an enormous impact on the costs per watt. In this thesis both factors will be examined: the production process and the selection of TE materials. Technical screen printing is a possible way of production, because this method is very versatile with respect to the usable materials, substrates as well as printing inks. The organic conductor PEDOT:PSS offers reasonable thermoelectric properties and can be processed very well in screen printing. It was demonstrated by prototypes of fully printed TEGs that so-‐called vertical printed TEGs are feasible using standard graphic arts industry processes. In addition, the problems that occur with print production of TEGs are identified. Finally, approaches to solve these problems are discussed.
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Cooke, Daniel Benjamin. "Design and Optimization of a Self-powered Thermoelectric Car Seat Cooler." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83374.
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It is well known that the seats in a parked vehicle become very hot and uncomfortable on warm days. A new self-powered thermoelectric car seat cooler is presented to solve this problem. This study details the design and optimization of such a device. The design relates to the high level layout of the major components and their relation to each other in typical operation. Optimization is achieved through the use of the ideal thermoelectric equations to determine the best compromise between power generation and cooling performance. This design is novel in that the same thermoelectric device is utilized for both power generation and for cooling. The first step is to construct a conceptual layout of the self-powered seat cooler. Using the ideal thermoelectric equations, an analytical model of the system is developed. The model is validated against experimental data and shows good correlation. Through a non-dimensional approach, the geometric sizing of the various components is optimized. With the optimal design found, the performance is evaluated using both the ideal equations and though use of the simulation software ANSYS. The final design consists of a flat absorber plate embedded into the car seat with a thermoelectric attached to the back. A finned heat sink is used to cool the thermoelectric. The device is shown to generate enough power to provide a reasonable temperature drop in the seat.Master of Science
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Li, Molan. "Thermoelectric-Generator-Based DC-DC Conversion Network for Automotive Applications." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-42358.
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As waste heat recovering techniques, especially thermoelectric generator (TEG technologies, develop during recent years，its utilization in automotive industry is attempted from many aspects. Previous research shows that TEG as a waste heat harvesting method is feasible. Even though efficiencies for TEGs are as low as 3-5% with existing technology, useful electricity generation is possible due to the great amount of waste heat emitted from the internal combustion engine operation. This thesis proposes the innovative concept of thermoelectric-generator-based DC-DC conversion network. The proposed structure is a distributed multi-section multi-stage network. The target is to tackle problems facing the traditional single-stage system and to advance TEG application in automotive settings. The objectives of the project consists of providing optimal solution for the DC-DC converter utilized in the network, as well as developing a systematic and bottom-up design approach for the proposed network. The main problems of the DC-DC converters utilized in the TEG system are presented and analyzed, with solution to dynamic impedance matching suggested. First, theoretically-possible approaches to balance the large TEG internal resistance and small converter input resistance are discussed, and their limitations are presented. Then, a maximum power point tracking (MPPT) regulation model is developed to address the temperature-sensitive issue of converters. The model is integrated into a TEG-converter system and simulated under Simulink/Simscape environment, verifying the merits of MPPT regulation mechanism. With the developed model, MPPT matching efficiency over 99% is achieved within the hot side temperature range of 200°C ~300°C. A design flow is suggested for the proposed network. Analysis is conducted regarding aspects of the design flow. Several state-of-the-art thermoelectric materials are analyzed for the purpose of power generation at each waste heat harvesting location on a vehicle. Optimal materials and TE couple configurations are suggested. Besides, a comparison of prevailing DC-DC conversion techniques was made with respect to applications at each conversion level within the network. Furthermore, higher level design considerations are discussed according to system specifications. Finally, a case study is performed comparing the performances of the proposed network and traditional single-stage system. The results show that the proposed network enhances the system conversion efficiency by up to 400% in the context of the studied case.
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Lan, Song. "The role of thermoelectric generator in the efficient operation of vehicles." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/36309.
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In the face of the internationally tightened requirements and regulations for CO2 emissions from the transportation sector, waste heat recovery using a thermoelectric generator (TEG) has become the most significant research interest. A vehicular TEG, converting otherwise wasted thermal energy from engines to electricity directly for use in the vehicle systems, is a promising approach for vehicle original equipment manufacturers (OEMs) to reduce fuel consumption and lower CO2 emissions. This thesis aims to explore the main challenges to be faced in the commercialization of TEGs. Based on a review of the literature, four research gaps have been identified, which are respectively: * Translating the material improvements into TEG Performance, * Transient behaviors of vehicular TEGs under driving cycles, * Fuel saving percentage and cost-benefit estimation of TEG, * Bidirectional characteristic of TEM and bifunctional vehicular TEG. To directly address these research gaps, a quasi-static TEM model, a dynamic TEG model, a semi-empirical vehicular TEG model, and a dual-model TEM model have been respectively developed and validated through experiments on both TEM test rigs and TEG engine test benches. These developed models are used as tools to investigate the performance of TEG, parameters sensitivity, and integration effects. Model-based TEG control, TEG cost benefit ratio and feasibility of a bifunctional TEG are also explored based on the developed models. The simulation results show that TEG power generation is highly sensitive to the heat transfer coefficient of hot side heat exchanger and thermal contact resistance. The TEG installation position is identified as the most important integration effect. It has been found by the simulation result that the fuel saving with TEG installed upstream of the three-way catalyst (TWC) is 50% higher than the fuel saving with TEG installed downstream of the TWC. The fuel saving percentage for a skutterudite vehicular TEG, which can generate around 400-600W in constant speed 120km/h, is 0.5-3.6% depending on the integration position in the exhaust line. A 3-minute faster warm-up effect of engine oil can be obtained when the bifunctional TEG works in engine warm-up mode with electrical current applied.
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Adinolfi, Borea Riccardo. "Experimental investigation on working parameters of a Thermoelectric Generator-based system." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25506/.
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In the text, the investigastion and optimization of a Thermoelectric generator-based system, under different conditions, has been studied. The investigation aim is to obtain the characteristic parameters of the system: the Seebeck coeff.(α), the Thomson coeff. (τ), the Heat transferred to the Thermoelectric generators (Qh) and the electrical conversion (η). The system is built using four resistive elements as heating system, fed by a controllable generator, and forced circulating air as heat sink. The heat flow, from the source to the sink, passes through a hot heat exchanger, the thermoelectric generators, and the cold heat exchanger. The two heat exchangers are designed in order to have the best heat exchange at each surface; this is obtained by creating a planar and compact are where the heat flow is primarly conduction-type, and providing a finned and wide surface where the heat flow is primarly convection-type. The circulation of air at the heat sink is obtained through the utilization of two fans.
Utilizing the open-circuit data, the Seebeck coefficient, the Peltier coefficient, and the Thomson coefficient have been calculated, obtaining values of 187.7 μV/K,0.065 W/A,-0.043 V/K, respectively, at an average temperature of 345.731 K and temperature difference of 72.486 K. It’s been shown that the temperature range, explored with the system built, does cover the point in which the Seebeck effect has its max-value and, following, that such point does not match with the max efficiency point.
Utilizing the controllable load-test data, macroscopic thermoelectric parameters as heat flows, electrical otuput power and electrical conversion efficiency, have been calculated. In the best condition occured, results as 144.538 W, 1.829 W,1.265 % have been measured for Qh, Pout, η, respectively, at an average temperature of 367.078 K and temperature difference of 103.418 K.
All graphs show that the results are in strong agreement with the reported literature.
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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.
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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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Singh, Tanuj. "Development of a premixed burner integrated thermoelectric power generator for insect control." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/68407/.
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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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Zhou, Yu. "Energy Harvesting Using a Thermoelectric Generator and Generic Rule-based Energy Management." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1196802707.
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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.
Full textAbstract:
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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Zhou, Yu. "Energy harevsting [sic] using a thermoelectric generator and generic rule-based energy management." online version, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1196802707.
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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.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
"February 2011." Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 224-237).
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%.
by Christopher Henry Marton.
Ph.D.
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Rosa, Olívia Carolina da. "Designing a thermoelectric energy generator for waste heat recovery in heavy-duty diesel engines." reponame:Repositório Institucional da UFSC, 2017. https://repositorio.ufsc.br/xmlui/handle/123456789/182599.
Full textAbstract:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2017.Made available in DSpace on 2018-01-09T03:22:44Z (GMT). No. of bitstreams: 1 348531.pdf: 4713684 bytes, checksum: 34bc24fd45de049c399b6872963cdfdf (MD5) Previous issue date: 2017
A quantidade de energia térmica rejeitada nos gases de exaustão durante a operação de um motor diesel é aproximadamente 30 % da energia fornecida a partir do combustível. Uma alternativa para recuperar essa energia é a utilização de um gerador termoelétrico, o qual pode ser usado como energia para os sistemas auxiliares ou como energia suplementar, no caso de veículos elétricos híbridos. Este estudo tem como objetivo conceber um gerador termoelétrico e um trocador de calor acoplado à exaustão de um motor diesel, limitados por critérios de mínima eficiência térmica e máxima perda de carga no tubo de escape. O motor, o trocador de calor, e o gerador termoelétrico foram simulados em regimes permanente e transiente, usando um modelo zero dimensional para o motor e um modelo de uma dimensão para o trocador de calor/ gerador termoelétrico com propriedades em função da temperatura. O modelo de regime permanente e propriedades constantes foi usado para otimização através de duas estratégias, uma buscando a máxima potência e outra a máxima eficiência de conversão. A configuração otimizada consiste de um trocador de calor de 9 tubos, com diâmetro de 0,022 m e comprimento 0,414 m, operando com o fluido de arrefecimento do motor como fluido frio, utilizando silício-germânio como material das células termoelétricas. Quando em regime transiente, a configuração para máxima potência com 562 células termoelétricas por tubo atingiu um pico de 3500 W no início da operação e potência média de 811 W durante o transiente periódico, com eficiência termoelétrica igual a 4.27 % . A configuração para máxima eficiência de conversão contou com 150 células termoelétricas por tubo e foi capaz de gerar 1100 W no início de operação e obter potência média igual a 550 W durante o transiente periódico, com eficiência termoelétrica igual a 10.4 % . O modelo em regime transiente e com propriedades variáveis revelou o potencial de obter maior potência durante transientes curtos. Quando comparados com as realizações atuais, os resultados indicam a viabilidade do projeto para veículos de tamanho médio e pesados.
Abstract : The amount of heat energy wasted in the exhaust gas flow during operation of a diesel engine is grossly 30 % of the input energy from the fuel. An alternative to recover the heat lost through the exhaust in diesel engines is the use of thermoelectric generators, which could be used as source of power to propel auxiliary systems or as a supplement power source in case of hybrid electric vehicles. This study aims at developing and optimizing a thermoelectric generator and a heat exchanger adapted to the exhaust system, close-coupled to a diesel engine, restricted by criteria of minimum overall efficiency and maximum exhaust back-pressure. The engine, heat exchanger, and thermoelectric generator were evaluated in the steady-state and transient regime using a zero dimensional model for the engine and a one-dimensional model for the heat exchanger/thermoelectric generator with temperature dependent properties. The steady-state, constant property model was used for the optimization using two strategies, one aiming at maximum power and the other at maximum efficiency. The optimized configuration consisted of a heat exchanger with 9 tubes, with diameter of 0.022 m and length of 0.414 m, operating with engine coolant as cold fluid, using silicon germanium thermoelectric junctions. When simulated in transient regime, the configuration for maximum power with 562 thermoelectric junctions per tube was able to generate peak power at start-up of 3500 W, average power at periodic steady-state of 811 W, with 4.27 % thermoelectric efficiency. The configuration for maximum conversion efficiency had 150 thermoelectric junctions per tube, achieved peak power of 1100 W at start-up, average power at periodic steady-state of 550 W, and 10.4 % thermoelectric efficiency. The transient, variable properties simulation revealed the potential for higher power during short transients. When compared to current realizations, the results indicate the feasibility of the design for medium size and heavy-duty vehicles.
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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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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.Master of Science
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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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Headings, Leon Mark. "Modeling and Development of Thermoelectric Device Technologies for Novel Mechanical Systems." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1325258051.
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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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Börner, Floriana-Dana, Max Schreier, Bing Feng, Wolfgang Lippmann, Hans-Peter Martin, Alexander Michaelis, and Antonio Hurtado. "Development of laser-based joining technology for the fabrication of ceramic thermoelectric modules." Cambridge University Press, 2014. https://tud.qucosa.de/id/qucosa%3A39033.
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The process of laser-induced brazing constitutes a potential option for connecting several ceramic components (n- and p-type ceramic bars and ceramic substrate) of a thermoelectric generator (TEG) unit. For the construction of the TEGs, TiOₓ and BₓC were used as thermoelectric bars and AlN was used as substrate material. The required process time for joining is well below that of conventional furnace brazing processes and, furthermore, establishes the possibility of using a uniform filler system for all contacting points within the thermoelectric unit. In the work reported here, the application-specific optimization of the laser-joining process is presented as well as the adapted design of the thermoelectric modules. The properties of the produced bonding were characterized by using fatigue strength and microstructural investigations. Furthermore, the operational reliability of the modules was verified.
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Dreßler, Christian. "Herstellung, Simulation und Charakterisierung thermoelektrischer Generatoren auf Basis anisotroper Oxidmaterialien." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2017. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-227665.
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Die thermoelektrische Energiekonversion auf der Basis des Seebeck-Effekts ist eine Methode zur direkten Erzeugung elektrischer Energie aus thermischer Energie. Für die wesentlichen anwendungsrelevanten Parameter Temperaturbereich, elektrische Leistung und Herstellungskosten sind Materialauswahl und Aufbau der TEG entscheidend. In der vorliegenden Arbeit wurden erstmalig thermoelektrische Oxidkeramiken in monolithischen TEG verwendet, die auf der Grundlage des transversalen thermoelektrischen Effekts arbeiten. Die TEG wurden mit industriell skalierbaren Keramiktechnologien hergestellt, untersucht und hinsichtlich ihrer Parameter detailliert theoretisch und experimentell bewertet.
Als Modellsystem für die Materialien wurde La1-xSrxCuO4 in Kombination mit Ag bzw. Ag6Pd1 verwendet. Es konnte belegt werden, dass diese monolithischen TEG im Bereich kleiner elektrischer Leistungen eine vorteilhafte Alternative zu herkömmlichen
longitudinalen thermoelektrischen Generatoren sein können.
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Alves, Lucas Máximo. "Estudo da solidificação e do processamento cerâmico de ligas de silicio-germânio para aplicações termoelétricas." Universidade de São Paulo, 1995. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-19092013-111258/.
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Os materiais cerâmicos termoelétricos preparados a partir de ligas de SiGe, são utilizados em Geradores de Potência a Radioisótopos (GTR), na conversão de energia por efeitos termoelétricos. Neste trabalho de pesquisa foram estudadas as condições de preparação destas cerâmicas a partir de ligas de Silício-Germânio. Visou-se, portanto obter a melhor eficiência, pela otimização da \"Fator de Mérito\" (ou Número de loffe) , através dos processos de preparação e tratamentos térmicos da liga, e também na dopagem das cerâmicas. As ligas de silício-germânio (Si80Ge20) foram obtidas pela técnica de crescimento Czochralski, com campo elétrico aplicado (ECZ) e também por outras técnicas de fusão e solidificação, para comparação. Amostras com homogeneidade satisfatória foram quebradas e moídas para processamento cerâmico. E em seguida o pó da liga foi então dopado, misturando-se este com pó de boro amorfo e depois prensado, a fim de se obter elementos cerâmicos semicondutores tipo-p, com propriedades termoelétricas para altas temperaturas (≈ 1000°C). A sinterização foi feita por três técnicas diferentes: pela técnica dos Pós Discretos ou PIES (Pulverized and Intermixed Elements of Sintering), pelo procedimento cerâmico convencional, e pela Prensagem a Quente (HotPressing), sendo esta última usada como padrão de comparação. As amostras obtidas foram analisadas e caracterizadas por técnicas convencionais de caracterização cerâmica tais como: medidas da densidade, dos tamanhos dos grãos, porosidade, área superficial, etc. e também por medidas de alguns dos parâmetros físicos que influenciam diretamente na eficiência termoelétrica tais como: coeficiente Seebeck, calor específico e parâmetro de rede, para ligas de composição nominal Si80Ge20 sem e com dopantes para semicondutores tipo-p. Uma amostra preparada pela General Electric usando a técnica de Prensagem a Quente (Hot-Pressing), foi usada como padrão de comparação. A liga obtida pela técnica ECZ apresentou boa homogeneidade. Foi encontrado que a qualidade microestrutural das cerâmicas tais como: densidade, a regularidade e a composição química dos grãos das cerâmicas depende muito da técnica de processamento. Estes elementos cerâmicos termoelétricos poderão ser usados como fonte de energia em Geradores de Potência Termoelétrica a Radioisótopos (GTR) mais especificamente na alimentação de satélites brasileiros fabricados pelo Centro Técnico Aeroespacial (CTA) junto com o Instituto de Estudos Avançados (IEAv) através da Divisão de Energia Nuclear (IEAvENU) deste Instituto, ou entre outras aplicações para fins militares e civilDoped ceramics elements, prepared from Si-Ge alloy are used in Radioisotopic Thermoelectric Generators (GTR) for energy conversion by thermoelectrical effects. In this research the experimentais conditions to prepare thermoeletric ceramics from Silicon-Germanium alloys have been determined. The purpose was to get the best efficiency, by optimization of the \"Merit Figure\" (or \"loffe Number\'), using different preparation methods and thermal treatments of alloys, as well as the doping of these ceramics. Silicon-Gemanium alloys (Si80Ge20) have been grown by the Czochralski technique under applied eletric field (ECZ) , as well as by others fusion techniques for comparison. Afier the fusion of the alloy, samples with satisfactory homogeneity have been smashed and milled for ceramic processing. Powder of Si-Ge alloy was then heavely doped by mixing with amorphous boron powder and pressed to get type-P semiconductor thermoelectrical ceramics elements, at high temperatures (≈ 1000 °C). The sintering was made by three differents techniques: PIES method (Pulverized and Intermixed Elements of Sintering), convencional ceramic processing, and Hot-Pressing sintering, for comparison. The samples have been analyzed and characterized by conventional ceramics technique such as: determination of density, grain size, porosity, surface area, etc. and measuring toa some physical parameters that affect directly the thermoelectrical efficiency such as: Seebeck coefficient, specific heat and lattice parameter to Silicon-Germanium alloys with nominal composition Si80Ge20 with or without dopings to type-P semiconductors. A sample prepared by General Electric Company using the Hot-Pressing technique was used as standard. The alloy grown by ECZ technique showed a good homogeneity. It was found that the microstructural quality of the ceramics such as: density, grains regularity and chemical composition of the ceramics depend of the ceramic processing technique. These thermoelectrical elements can be used as power supply for the Brazilian satellites made by the Centro Técnico Aeroespacial (CTA) together with the Instituto de Estudos Avançados (IEAv) through the Divisão de Engenharia Nuclear (ENU) , and among other applications for military and civil purposes
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Song, Hyun-Cheol. "Piezoelectric-based Multi-Scale Multi-Environment Energy Harvesting." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/87400.
Full textAbstract:
Energy harvesting is a technology for generating electrical power from ambient or wasted energy. It has been investigated extensively as a means of powering small electronic devices. The recent proliferation of devices with ultra-low power consumption - devices such as RF transmitters, sensors, and integrated chipsets - has created new opportunities for energy harvesters. There is a variety of ambient energies such as vibration, thermal, solar, stray current, etc. Depending on energy sources, different kinds of energy conversion mechanism should be employed. For energy harvesters to become practical, their energy conversion efficiency must improve. This efficiency depends upon advances in two areas: the system or structural design of the energy harvester, and the properties of the materials employed in energy conversion. This dissertation explores developments in both areas. In the first area, the role of nano-, micro-, and bulk structure of the energy conversion materials were investigated. In the second area, piezoelectric energy harvesters and a magneto-thermoelectric generator are treated from the perspective of system design.
In the area of materials development, PbTiO3 (PTO) nanostructures consisting of nanofibers and three-dimensional (3-D) nanostructure arrays were hydrothermally synthesized. The growth mechanism of the PTO nanofibers and 3-D nanostructures were investigated experimentally and theoretically. The PTO nanostructures were composed of oriented PTO crystals with high tetragonality; these arrays could be promising candidates for nanogenerators.
Different designs for energy harvesters were explored as a means of improving energy conversion efficiency. Piezoelectric energy harvesters were designed and constructed for applications with a low frequency vibrational energy and for applications with a broadband energy spectrum. A spiral MEMS piezoelectric energy harvester design was fabricated using a silicon MEMS process and demonstrated to extract high power density at ultra-low resonance frequencies and low acceleration conditions. For a broadband energy harvester, a magnetically-coupled array of oscillators was designed and built that broadened the harvester's effective resonance frequency with considerably improved output power.
A new design concept for thermal energy harvesting that employs a magneto-thermoelectric generator (MTG) design was proposed. The MTG exploits a thermally-induced second order phase transition in a soft magnetic material near the Curie temperature. The MTG harvested electric power from oscillations of the soft magnet between hot and cold sources. For the MTG design, suitable soft magnetic materials were selected and developed using La0.85Sr0.15MnO3-Ni0.6Cu0.2Zn0.2Fe2O4 magnetic composites. The MTG was fabricated from a PVDF cantilever and a gadolinium (Gd) soft magnetic material. The feasibility of the design for harvesting energy from the waste heat was demonstrated by attaching an MTG array to a computer CPU.PHD
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Mustaffa, Muhammad Ubaidah Syafiq. "Alternative Uses of CZTS Thin Films for Energy Harvesting." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/315176.
Full textAbstract:
The search for renewable energy resources and ways to harvest them has become a global mainstream topic among researchers nowadays, with solar cells and thermoelectric generators among the energy
harvesting technologies currently being researched in vast. CZTS (Cu2ZnSnS4), a p-type semiconducting material initially researched to replace copper indium gallium selenide (CIGS) as the light absorbing
layer in thin film solar cells, was studied in this doctoral work for alternative uses in energy harvesting. This work aims to systemically investigate the prospects of CZTS to be used as hole transport layers
and thermoelectric generators. CZTS thin film was successfully fabricated using a versatile approach involving hot-injection synthesis of CZTS nanoparticles ink followed by spin coating and thermal treatment. Results obtained revealed the possibility to fine control CZTS thin film fabrication based on ink concentration and spin. Besides that, thermal treatment temperature was found to affect the film’s overall properties, where an increase in thermal treatment temperature improved the degree of crystallinity and electrical properties. In addition, a phase change going from less stable cubic and wurtzite structures to a more stable tetragonal structure was also observed. Furthermore, CZTS was found to be a good candidate to replace the commonly used organic hole transport layer in perovskite solar cells, with potentials in improving performance and stability. In addition, CZTS also possessed good transport properties to be a potential p-type material in a thermoelectric generator, with the preliminary performance of fabricated CZTS/AZO thermoelectric generator showing a maximum power output of ~350 nW at ~170 KΔT. These findings provide new perspectives for CZTS in energy harvesting applications, despite the struggle in its development as the absorber layer in thin film solar cells. Besides providing a deeper understanding of CZTS and its vast possibilities in energy harvesting applications, promising future research stemming from this work is also limitless, reinventing ways in material studies, in search of alternative applications which may be of benefit.
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Mustaffa, Muhammad Ubaidah Syafiq. "Alternative Uses of CZTS Thin Films for Energy Harvesting." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/315176.
Full textAbstract:
The search for renewable energy resources and ways to harvest them
has become a global mainstream topic among researchers nowadays,
with solar cells and thermoelectric generators among the energy
harvesting technologies currently being researched in vast. CZTS
(Cu2ZnSnS4), a p-type semiconducting material initially researched to
replace copper indium gallium selenide (CIGS) as the light absorbing
layer in thin film solar cells, was studied in this doctoral work for
alternative uses in energy harvesting. This work aims to systemically
investigate the prospects of CZTS to be used as hole transport layers
and thermoelectric generators.
CZTS thin film was successfully fabricated using a versatile
approach involving hot-injection synthesis of CZTS nanoparticles ink
followed by spin coating and thermal treatment. Results obtained
revealed the possibility to fine control CZTS thin film fabrication based
on ink concentration and spin. Besides that, thermal treatment
temperature was found to affect the film’s overall properties, where an
increase in thermal treatment temperature improved the degree of
crystallinity and electrical properties. In addition, a phase change going
from less stable cubic and wurtzite structures to a more stable tetragonal
structure was also observed. Furthermore, CZTS was found to be a good
candidate to replace the commonly used organic hole transport layer in
perovskite solar cells, with potentials in improving performance and
stability. In addition, CZTS also possessed good transport properties to
be a potential p-type material in a thermoelectric generator, with the
preliminary performance of fabricated CZTS/AZO thermoelectric
generator showing a maximum power output of ~350 nW at ~170 K
ΔT.
These findings provide new perspectives for CZTS in energy harvesting
applications, despite the struggle in its development as the absorber
layer in thin film solar cells. Besides providing a deeper understanding
of CZTS and its vast possibilities in energy harvesting applications,
promising future research stemming from this work is also limitless,
reinventing ways in material studies, in search of alternative
applications which may be of benefit.
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Ančík, Zdeněk. "Mechatronic Design and Verification of Autonomic Thermoelectric Energy Source for Aircraft Application." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-234600.
Full textAbstract:
Předložená disertační práce řeší komplexní mechatronický návrh autonomního termoelektrického zdroje energie pro letecké aplikace. Na základě dostupných zdrojů a literatury práce popisuje současný stav problematiky. V práci jsou prezentovány simulační modely MEMS termoelektrických článků, které jsou ověřeny experimentálním testováním a hodnotami dostupnými od výrobce. Na základě metodiky model-besed design byly navrženy a vyrobeny tři demonstrátory. Jejich vlastnosti byly testovány v reálných podmínkách na letecké pohonné jednotce.
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Pandit, Jaideep. "Numerical and Experimental Design of High Performance Heat Exchanger System for A Thermoelectric Power Generator for Implementation in Automobile Exhaust Gas Waste Heat Recovery." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/47919.
Full textAbstract:
The effects of greenhouse gases have seen a significant rise in recent years due to the use of fossil fuels like gasoline and diesel. Conversion of the energy stored in these fossil fuels to mechanical work is an extremely inefficient process which results in a high amount of energy rejected in the form of waste heat. Thermoelectric materials are able to harness this waste heat energy and convert it to electrical power.
Thermoelectric devices work on the principle of the Seebeck effect, which states that if two junctions of dissimilar materials are at different temperatures, an electrical potential is developed across them. Even though these devices have small efficiencies, they are still an extremely effective way of converting low grade waste heat to usable electrical power. These devices have the added advantage of having no moving parts (solid state) which contributes to a long life of the device without needing much maintenance. The performance of thermoelectric generators is dependent on a non-dimensional figure of merit, ZT. Extensive research, both past and ongoing, is focused on improving the thermoelectric generator's (TEG's) performance by improving this figure of merit, ZT, by way of controlling the material properties. This research is usually incremental and the high performance materials developed can be cost prohibitive.
The focus of this study has been to improve the performance of thermoelectric generator by way of improving the heat transfer from the exhaust gases to the TEG and also the heat transfer from TEG to the coolant. Apart from the figure of merit ZT, the performance of the TEG is also a function of the temperature difference across it, By improving the heat transfer between the TEG and the working fluid, a higher temperature gradient can be achieved across it, resulting in higher heat flux and improved efficiency from the system. This area has been largely neglected as a source of improvement in past research and has immense potential to be a low cost performance enhancer in such systems. Improvements made through this avenue, also have the advantage of being applicable regardless of the material in the system. Thus these high performance heat exchangers can be coupled with high performance materials to supplement the gains made by improved figure of merits.
The heat exchanger designs developed and studied in this work have taken into account several considerations, like pressure drop, varying engine speeds, location of the system along the fuel path, system stability etc. A comprehensive treatment is presented here which includes 3D conjugate heat transfer modeling with RANS based turbulence models on such a system. Various heat transfer enhancement features are implemented in the system and studied numerically as well as experimentally. The entire system is also studied experimentally in a scaled down setup which provided data for validation of numerical studies. With the help of measured and calculated data like temperature, ZT etc, predictions are also presented about key metrics of system performance.Ph. D.
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Jimenez, Aispuro Jesús Ernesto. "Ingénierie des générateurs thermoélectriques en régime instationnaire." Thesis, Pau, 2018. http://www.theses.fr/2018PAUU3028.
Full textAbstract:
Les générateurs thermoélectriques (TEG), associant des modules thermoélectriques à des échangeurs de chaleur adaptés, permettent de produire de l’électricité à partir d’une source chaude et d’une source froide. Leur utilisation, réservée actuellement à des applications de niche, va s’avérer judicieuse pour différentes applications industrielles ou domestiques en raison de la disponibilité imminente de nouveaux matériaux thermoélectriques permettant des rendements améliorés et des coûts moindres. Pour rendre plus attractive l’utilisation des TEG et améliorer le rendement global des futures installations, une conception et une utilisation optimisées sont indispensables.La conception de TEG performants nécessite le développement de modèles numériques intégrant tous les éléments de la chaîne énergétique (source chaude, source froide, échangeurs, convertisseurs électriques). L’objectif de la thèse est de créer un outil de simulation du fonctionnement des générateurs sur l’ensemble du cycle de production de chaleur et donc sur des fonctionnements réels dépendant du temps. Le modèle développé en 3D pour les transferts de chaleur prend en compte la dépendance à la température des propriétés des matériaux et l’effet Thomson pour le modèle thermoélectrique.La validation de cet outil de simulation a nécessité la comparaison des prédictions du modèle à des résultats expérimentaux. Un dispositif expérimental a été complété et amélioré afin de mieux répondre aux attentes des études en régime instationnaire. Ce banc d'essai permet d'effectuer des tests avec différentes configurations de générateur thermoélectrique et différentes conditions de fonctionnement. Le modèle a montré une estimation correcte des températures du système et de la production électrique du TEG. Le modèle numérique est validé et peut être utilisé pour la prédiction du fonctionnement d’un TEG dans diverses conditionsThermoelectric generators (TEG), combine thermoelectric modules with heat exchangers, making it possible to produce electricity from a hot source and a cold source. Their use, which is currently reserved for niche applications, will prove useful for various industrial or domestic applications due to the imminent availability of new thermoelectric materials allowing improved yields and lower costs. To make the use of TEGs more attractive and to improve the overall efficiency of future installations, optimized design and use are essential.The high-performance TEG design requires the development of numerical models integrating all the elements of the energy chain (hot source, cold source, exchangers, electric converters).The aim of the thesis is to create a tool for simulating the operation of generators over the entire heat production cycle and thus on real time-dependent operations. The model developed in 3D for heat transfer takes into account the temperature dependence of the properties of the materials and the Thomson effect for the thermoelectric model.The validation of this simulation tool required the comparison of model predictions with experimental results. An experimental device has been completed and improved to match better the expectations of unsteady studies. This test bench allows testing with different thermoelectric generator configurations and different operating conditions.The model showed a correct estimation of system temperatures and electrical output of TEG. The numerical model is validated and can be used to predict the operation of a TEG under various conditions
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Heghmanns, Alexander, and Michael Beitelschmidt. "Mehrkriterielle Parameteroptimierung eines Thermoelektrischen Generators." Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-142372.
Full textAbstract:
Aufgrund von steigenden Energiekosten und einer sukzessive steigenden öffentlichen sowie politischen Forderung nach Umweltbewusstsein und Nachhaltigkeit, ist die Effizienzsteigerung von Gesamtsystemen einer der treibenden Kräfte für innovative, technologische Neuheiten geworden. Besonders bei der Entwicklung von verbrennungsmotorisch angetriebenen Fahrzeugen wurden z.B. durch die Hybridisierung von Antriebssträngen, die die Rekuperation von kinetischer Energie ermöglichen, Technologien zur Energieeinsparung etabliert. Da bei Verbrennungsmotoren ein hoher Anteil der im Kraftstoff gespeicherten Energie technologiebedingt als Abwärme im Abgas verloren geht, bietet die Wärmerekuperation ein weiteres hohes Potential für weitere Einsparungen. Diese ist z.B. mit Hilfe von thermoelektrischen Generatoren (TEG) möglich, die einen Wärmestrom direkt in elektrische Energie umwandeln.
Zur effizienten TEG-Systemgestaltung ist ein hoher Temperaturgradient über dem thermoelektrisch aktivem Material notwendig, der wiederum zu kritischen thermomechanischen Spannungen im Bauteil führen kann. Diese werden zum einen durch die unterschiedlichen Temperaturausdehnungskoeffizienten der verschiedenen Materialien und zum anderen durch die mechanische Anbindung auf der heißen und kalten Seite des TEG verursacht. Somit liegt ein Zielkonflikt zwischen dem thermoelektrischen Systemwirkungsgrad und der mechanischen Festigkeit des Bauteils vor.
In dieser Arbeit wird mit Hilfe einer mehrkriteriellen Parameteroptimierung eines vollparametrisierten FE-Modells des TEG in ANSYS WORKBENCH eine Methode vorgestellt, den thermoelektrischen Wirkungsgrad bei gleichzeitiger Reduktion der thermomechanischen Spannungen zu optimieren. Zur Optimierung kommt dabei ein genetischer Algorithmus der MATLAB GLOBAL OPTIMIZATION TOOLBOX zum Einsatz. Der Modellaufbau wird in ANSYS WORKBENCH mit der Makro-Programmiersprache JSCRIPT realisiert. Als Ziel- und Bewertungsfunktionen wird die mechanische Belastung jedes Bauteils im TEG ausgewertet und dessen elektrische Leistungsdichte berechnet. Die Ergebnisse zeigen, dass mit Hilfe der vorgestellten Methodik eine paretooptimale Lösung gefunden werden kann, die den gestellten Anforderungen entspricht.
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Mativo, John M. "System Design of Composite Thermoelectrics for Aircraft Energy Harvesting." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1607959975788155.
Full text
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Carvalho, Carlos Alfredo Rodrigues de. "Estudo de viabilidade do aproveitamento do calor de escape para geração energia elétrica em automóveis." Universidade de Taubaté, 2012. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=573.
Full textAbstract:
Atualmente um dos grandes responsáveis pela emissão de CO2 (Dióxido de Carbono) são os veículos movidos a motor de combustão interna, em sua maioria os automóveis. Pesquisas recentes têm mostrado maneiras de aumentar a eficiência dos automóveis por meio do aproveitamento do calor de exaustão para geração de energia elétrica, com consequente redução no consumo de combustível. Esta dissertação tem por objetivo apresentar um estudo de viabilidade técnica de um gerador termoelétrico aproveitando o calor residual dos gases de exaustão de um motor de combustão interna para geração de energia elétrica. O trabalho apresenta o modelamento matemático e a implementação de um protótipo para realização dos ensaios para a obtenção de resultados experimentais. O protótipo foi montado utilizando módulos termolétricos cujo princípio de funcionamento é baseado nos efeitos Seebeck e Peltier, que devido ao conceito de reversibilidade podem funcionar como geradores elétricos, aquecedores ou refrigeradores. Por meio das equações teóricas e dos resultados dos ensaios experimentais foi possível avaliar o desempenho do sistema de geração de energia elétrica, determinar o comportamento dos principais parâmetros envolvidos e finalmente concluir sobre a exequibilidade e viabilidade do projeto.Currently one of the most responsible for CO2 (Carbon Dioxide) emissions are vehicles powered by internal combustion engine, in their majority the automobiles. Recent research has shown ways to improve the efficiency of automobiles through the use of exhaust heat to generate electric power, with consequent reduction in fuel consumption. This paper aims to present a technical feasibility study of a thermoelectric generator using the residual heat from exhaust gases of an internal combustion engine to generate electric power. The paper presents the mathematical modeling and implementation of a prototype for tests to obtaining experimental results. The prototype was assembled using thermoelectric modules whose operating principle is based on the phenomena called Seebeck and Peltier Effects, which due to the concept of reversibility can act as electric generators, heaters or coolers. Through the theoretical equations and experimental results it was possible to evaluate the performance of electric power generation system, determine the behavior of the main parameters and finally conclude on the feasibility and viability of the project.
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Kwan, Trevor Hocksun. "A Comprehensive Study and Optimization of Solar and TEG based Power Systems for Outer Space Applications." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/16963.
Full textAbstract:
The ongoing increase in the usage of non-renewable energy sources to meet the world demands has caused a massive increase in world pollution, leading to various issues such as global warming and climate change. This has motivated researchers and engineers to undertake intensive research into renewable energy sources which are clean, noise free and can be used in the long term. This thesis introduces design concepts that are aimed to aid designers in optimizing the design of renewable energy power source systems. The PV and TEG have been selected as the key examples to be studied. First, the thermodynamic modelling of the PV/TEG system and its application to outer space systems is examined where the output energy of the PV/TEG can be determined. Moreover, the model is also used as a basis for a genetic algorithm based optimization of the PV/TEG system in terms of maximizing power generation and minimizing mass. The next aspect that is covered in this thesis is the design of the associated DC/DC converter which is important for controlling or maximizing the energy that is acquired from the renewable energy source. Specifically, this thesis introduces an improved method of deriving the transfer functions that relate the inputs to the states of the DC-DC converter. Finally, two novel maximum power point tracking algorithms (MPPT) are introduced and applied to maximize the power extracted from the solar panel and the thermoelectric generator (TEG). These algorithms are known as the “Lock-On Mechanism” and a modified fuzzy logic control based MPPT algorithm. The novel MPPT algorithms are shown to track the MPP quicker and more accurately than that of conventional and previously proposed counterparts.
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Favarel, Camille Benjamin. "Optimisation de générateurs thermoélectriques pour la production d’électricité." Thesis, Pau, 2014. http://www.theses.fr/2014PAUU3010/document.
Full textAbstract:
Une des préoccupations majeures de la recherche dans le domaine de l’énergie est la diminution de la production des gaz à effet de serre et la réduction de notre empreinte écologique. Les générateurs thermoélectriques participent à une démarche globale d’efficacité énergétique en convertissant directement une partie de l’énergie thermique qui les traverse en énergie électrique. Ces derniers sont encore peu utilisés et rares sont les travaux qui traitent de leur optimisation. Ce travail a permis d’explorer les stratégies d’intégration des modules thermoélectriques dans les ensembles définis par les utilisateurs finaux en utilisant une méthodologie basée sur une modélisation complète des systèmes du flux de chaleur à la production électrique. Un code numérique couplant les équations de la thermique, de la thermoélectricité et de l’électricité a été développé et permet d’observer l’influence de plusieurs paramètres sur la production d’électricité (débit et température de la source chaude, débit et température de la source froide, type de modules thermoélectriques, emplacement des modules,…). La validation de ce modèle a nécessité la réalisation et l’instrumentation de plusieurs prototypes expérimentaux dont le plus conséquent est une boucle d’air à haute température alimentant un prototype de générateur thermoélectrique modulable. La conception et la réalisation de convertisseurs électriques dédiés, à recherche du point de fonctionnement maximal (MPPT), a permis de tester ces prototypes au point d’adaptation optimale. Enfin, une méthode d’optimisation appliquée au modèle nous délivre le nombre de modules ainsi que leur emplacement pour une production électrique maximale. Un outil de dimensionnement et d’optimisation de générateurs thermoélectriques est maintenant disponible. Il nous a permis tout d’abord d’étudier la faisabilité d’une production d’électricité en zones isolées au travers d’un prototype de cuisinière à bois thermoélectrique. Puis nous avons analysé la faisabilité dans le domaine de l’automobile en se plaçant à un point de fonctionnement précis correspondant au gaz d’échappementA major concern of research in the field of energy is the decrease in the production of greenhouse gas emissions and reducing our ecological footprint. Thermoelectric generators participate in a comprehensive approach to energy efficiency by directly converting a part of the thermal energy that flows through in electricity. This work explore strategies for integrating thermoelectric modules in sets defined by end users using a methodology based on a complete systems modelling from heat flow to power generation. A numerical code coupling equations of heat transfers and thermoelectricity was developed and used to observe the influence of several parameters on the production of electricity (flow and temperature of the hot source, flow and temperature of the cold source, type of thermoelectric modules, module location...). The validation of this model has necessitated the construction and the instrumentation of several experimental prototypes which for the most important is a hot air loop supplying a prototype flexible thermoelectric generator. The design and the realization of dedicated electrical converters to research the maximum operating point (MPPT) was performed to test these prototypes optimal adaptation issue. Finally, an optimization method applied to the model delivers us the number of modules and their location for maximum power production. A tool for design and optimization of thermoelectric generators is now available. It has allowed us to study the feasibility of an integrated thermoelectric generation in a variety of systems such as the automobile using exhaust gas or a specific cook stove for developing countries
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Klein, Jackson Alexander. "Energy Harvesting Opportunities Throughout the Nuclear Power Cycle for Self-Powered Wireless Sensor Nodes." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78031.
Full textAbstract:
Dedicated sensors are widely used throughout many industries to monitor everyday operations, maintain safety, and report performance characteristics. In order to adopt a more sustainable solution, much research is being applied to self-powered sensing, implementing solutions which harvest wasted ambient energy sources to power these dedicated sensors. The adoption of not only wireless sensor nodes, but also self-powered capabilities in the nuclear energy process is critical as it can address issues in the overall safety and longevity of nuclear power. The removal of wires for data and power transmission can greatly reduce the cost of both installation and upkeep of power plants, while self-powered capabilities can further reduce effort and money spent in replacing batteries, and importantly may enable sensors to work even in losses to power across the plant, increasing plant safety. This thesis outlines three harvesting opportunities in the nuclear energy process from: thermal, vibration, and radiation sources in the main structure of the power plant, and from thermal and radiation energy from spent fuel in dry cask storage. Thermal energy harvesters for the primary and secondary coolant loops are outlined, and experimental analysis done on their longevity in high-radiation environments is discussed. A vibrational energy harvester for large rotating plant machine vibration is designed, prototyped, and tested, and a model is produced to describe its motion and energy output. Finally, an introduction to the design of a gamma radiation and thermal energy harvester for spent nuclear fuel canisters is discussed, and further research steps are suggested.Master of Science
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Twaha, Ssennoga. "Regulation of power generated from thermoelectric generators." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49544/.
Full textAbstract:
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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Yu, Chih-Jung, and 余智融. "A Novel Photo-Thermoelectric Generator Integrating DSSCs with Thermoelectric Modules." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/kh262x.
Full textAbstract:
碩士國立臺北科技大學
機電整合研究所
98
This study self-develops a novel type of photoelectric conversion modules, adopting pre-prepared dye-sensitized solar cells (DSSCs) and combing with nano-Cu thermoelectric thin film to cover on the sides of the thermoelectric generator (TEG) to absorb outside light to generate electricity and use recycled waste heat to re-generate electricity. And then, the close-loop pulsating heat pipe of filling nano-CuO fluid is prepared on the cooling-side to increase cooling effects and enhance whole power generation efficiency. Thus, this study focuses on the application of elevating efficiency of the thermoelectric modules. For the preparation of the thermoelectric modules, commercial nano-Cu powder is firstly used and the doctor blade is adopted to fabricate nano-Cu heat-transfer film, serving as the media of thermal conductivity and coated on the TEG to promote the output of heat flux and energy. Secondly, submerged arc nanoparticle synthesis system (SNASS) is used to fabricate the nano-CuO fluid and the filling close-loop pulsating heat pipe is applied to the cold side to employ the variation of gas and liquid to increase cooling effects. For the fabrication of photoelectric conversion modules, this study adopts DSSCs with multi-layer TiO2 nano-film to combine with two systems to assemble the photo-thermoelectric modules. For the test of photo-thermoelectric modules, I-V measuring system and heating platform are used to deal with the output effects and electrical storage loop system and nickel-metal hydride batteries are used to test electrical storage time of photo-thermoelectric modules. Finally, the temperature measurement device is employed to analyze the performance output and conversion efficiency of photo-thermoelectric modules by simulated light and practical light. Results shows when the heat source of photo-thermoelectric modules attains 90 ℃, 85.7% power output can be elevated. The temperature difference of cold and hot sides of TEG can reach 7oC shone by simulated light of photo-thermoelectric modules and thermoelectric conversion efficiency can achieve 2.17% and produce 11.32mW/cm2 power output, enhancing 1.4% compared to singly adopting DSSCs.
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Chuang, Hsing-Jung, and 莊幸蓉. "Design and analysis of thermoelectric cooler and thermoelectric power generator." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/23933887876070559701.
Full textAbstract:
碩士國立清華大學
微機電工程研究所
93
Thermal dissipation problem has become an issue as the size of products shrunk down. In the limited space, the performance of signal transmission in high density circuitry can be improved under current development. However, more and more heat was generated by itself, and which becomes a bottleneck to make technology going down. Traditional cooling methods, such as heat sinks or fans, can’t keep such electrical elements at stable temperature. Therefore, thermoelectric cooler is a good candidate not only on upholding a stable temperature but also removing the heat generated from chips. The energy, such as petroleum, coal, coal gas, etc., will exhaust one day. The thermoelectric power generator has the advantages of environmental protection and energy technology. It can generate electric energy from the useless heat by thermoelectric effect. This paper mainly relies on the thermoelectric legs design with different geometry and size to analyze the performance of thermoelectric element.
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Liou, Meng-Chaou, and 劉孟樵. "Waste Heat Recovery using Thermoelectric Generator." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/33008569812287808625.
Full textAbstract:
碩士國立成功大學
航空太空工程學系碩博士班
97
The paper will introduce the application thermo-element transforms of waste heat available electrical energy in research, the thermo-element“HZ-20”which the company provides by “HZ”, his interior becomes by 71 pair of thermocouple series, when It has temperature difference in the high and low temperature, have the voltage output, in the experimental process, builds a platform, uses the heater to simulate the cause of waste heat , component and cooling system to achieve the condition and environment for experiment then to test thermo-element characteristic. The four group of thermo element are all test for efficiency whether because of condition and environment difference, to discover the best three efficienct ways to increase output then use the data acquisition card which “NI” company provide to coordinate the Labview windows software program to display the data which we need, is an important part of the experiment if you inflict pressure to thermo element therefore in the pressure test, use “SLICON” company provides the C8051F040 microcontroller coordinates the “KEIL” software to measure, penetrates these experiments to appraise the feasible thermoelectric electricity generation.