Download or read book Thermionic Energy Conversion Processes and devices written by George N. Hatsopoulos and published by MIT Press (MA). This book was released on 1973 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Good,No Highlights,No Markup,all pages are intact, Slight Shelfwear,may have the corners slightly dented, may have slight color changes/slightly damaged spine.
Download or read book Thermionic Energy Conversion written by George N. Hatsopoulos and published by . This book was released on 1979-01 with total page 683 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prepared under the auspices of the U.S. Department of Energy Division of Power Systems. Volume I of Thermionic Energy Conversiondealt with processes and devices (MIT Press, 1974). Its four chapters summarized information basic to the field and not subject to substantial alteration by future developments. Volume II begins with chapter 5 and describes the scientific and engineering aspects of thermionic conversion and the experience with actual operational hardware. It summarizes the experience and analytic methods that should be useful in the development of new applications of thermionic conversion. Thermionic Energy Conversionis intended for scientists and engineers working in the field of energy conversion. With increased interest in maximizing the efficiency of present energy conversion systems, it is an important reference for scientific and engineering libraries as well. The book benefits especially from the authors' actual experience-Hatsopoulos and his firm, Thermo Electron Corporation, are leaders in this field. Gyftopoulos and his students have made basic contributions to the theory of thermionic conversion. Both authors have developed a unified quantum theory of mechanics and thermodynamics. The book covers Elements of Quantum Mechanics; Principles of Thermodynamics; Thermodynamics of Stable Equilibrium States; Thermodynamics of Steady States; Emission Phenomena; Collisionless Transport Phenomena; Analysis of Performance Characteristics of High-Pressure Diodes; Experimental Techniques; Experimental Studies and Correlations of Characteristics; Metallurgy of Electrode Materials; Design and Fabrication of Practical Convertors; and Thermionic Power System Engineering.
Download or read book Thermionic Energy Conversion Processes and devices written by George N. Hatsopoulos and published by MIT Press (MA). This book was released on 1973 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Good,No Highlights,No Markup,all pages are intact, Slight Shelfwear,may have the corners slightly dented, may have slight color changes/slightly damaged spine.
Download or read book Application of Semiconductors to Thermionic Energy Converters written by Daniel C. Riley and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermionic energy conversion (TEC) is a direct heat-to-electricity conversion technology with the potential to leapfrog state-of-the-art solid-state conversion in efficiency and power density. In a thermionic energy converter, electrons evaporate from a hot electrode, the cathode, into a vacuum gap and are collected by a cooler electrode, the anode, to generate electric current. In the 1960s-1970s numerous groups reported thermionic converters with power densities above 10 W/cm^2 and conversion efficiencies of ~15%. However most of this work was tied to the US space-nuclear program which ended in 1973, and thermionics research has never fully recovered. As a result two central challenges yet remain in thermionics: (1) High operating temperatures necessary to produce electric current result in difficult materials challenges, and (2) low operating voltages due to losses associated with space charge and high anode work functions. However, new opportunities to tackle these challenges are available as a result of the breathtaking rise of semiconductor fabrication technology. In this work I present a new physical mechanism called photon enhanced thermionic emission (PETE). This concept is an improvement on thermionic emission by using light to boost the average energy of carriers in a hot p-type semiconductor cathode. Additionally, unlike in a photovoltaic cell, the waste heat from recombination losses and sub-bandgap light absorption is utilized to heat the cathode. Thus a PETE cathode can produce efficient electron emission at lower temperatures than a thermionic cathode. I will describe theoretical calculations showing that a PETE device may exceed 40% solar power conversion efficiency, and the conversion efficiency may exceed 50% if a PETE device is used in tandem with a solar thermal backing cycle. I will also describe an experimental demonstration of the PETE effect in an ultra-high vacuum photoemission measurement. In the cathode of an energy converter based on photon-enhanced thermionic emission (PETE) photoexcited carriers may need to encounter the emissive surface numerous times before having sufficient thermal energy to escape into vacuum and therefore should be confined close to the surface. However, in a traditional planar geometry, a thin cathode results in incomplete light absorption. Nanostructuring has the potential to increase light capture and boost emission by decoupling the lengths associated with photon absorption and electron emission. Nanostructures may complicate the properties of the emissive surface; therefore, the effect of nanostructuring on emission efficiency needs to be studied. In this work I describe results from a suite of simulation tools we have developed to capture the full photoemission process: photon absorption, carrier transport within the active material, and electron ballistics following emission. I show that the theoretical efficiency of a negative electron affinity emitter may be increased with nanostructures if light absorption and electron escape ballistics are considered. I then describe measurements of the photoemission efficiency of fabricated nanostructures that were designed based on the results of the simulation suite. I will also present a fundamentally new method to increase the operating voltage of a TEC by lowering the anode work function using the surface photovoltage effect. When a semiconductor surface is illuminated, photo-excited carriers form an internal dipole, or surface photovoltage (SPV), in the band-bending region and begin to flatten the bands near the surface. This SPV is analogous to the photovoltage in a photovoltaic cell and can reduce the effective work function of the material. I will describe an experimental demonstration using the SPV effect to produce a low work function surface. I will also describe a proof-of-concept demonstration of the SPV effect applied to improve the I-V characteristics of thermionic device. This generic physical process extends across materials systems and forms a realistic path to ultra-low work functions in devices to enable efficient thermionic energy conversion.
Download or read book Renewable Technologies written by Mohammad Islam and published by LAP Lambert Academic Publishing. This book was released on 2010-06 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermionic energy converter (TEC) is a device to generate electricity from heat in a silent, vibration-free operation. Non-idealities such as negative space-charge effect and electron reflection from collector surface adversely effect output current density and device efficiency. Using a range of thin film deposition techniques such as rf plasma magnetron sputtering, electrochemical deposition and electroless process, different surface structures were developed and tested for suppression of electron reflection using Cs/O vapor plasma TECs. Principles of both vacuum and solution based synthesis of thin films, and promising device configurations for thermionic energy converters are presented. This book overviews evolution of thermionics technology in a comprehensive manner, identifies key issues and challenges to be addressed, and suggests feasible solutions based on a sensible choice of materials and processes. The contents of this book are useful for teaching at both undergraduate and postgraduate levels as well as for researchers working on thin film synthesis and characterization for applications in energy, microelectronics, and surface engineering industries.
Download or read book Direct Conversion of Energy written by William R. Corliss and published by Good Press. This book was released on 2023-11-20 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Direct Conversion of Energy" by William R. Corliss. Published by Good Press. Good Press publishes a wide range of titles that encompasses every genre. From well-known classics & literary fiction and non-fiction to forgotten−or yet undiscovered gems−of world literature, we issue the books that need to be read. Each Good Press edition has been meticulously edited and formatted to boost readability for all e-readers and devices. Our goal is to produce eBooks that are user-friendly and accessible to everyone in a high-quality digital format.
Download or read book 2019 19th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications PowerMEMS written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optimal Thermionic Energy Conversion with Established Electrodes for High temperature Topping and Process Heating written by and published by . This book was released on 1980 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research on Materials Processes and Devices Related to Energy Conversion written by MASSACHUSETTS INST OF TECH CAMBRIDGE ENERGY CONVERSION AND SEMICONDUCTOR LAB. and published by . This book was released on 1961 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research concerned: Thermal-electric materials, processes, and devices including: Graded-Gap Detector using the HgTeCdTe system, Four-Probe Correction Factors for Wedge-Shaped Geometries, and ThermalPhoto-Voltaic Energy Converter using Germanium; Refractory thermoelectric materials of the GdSe- and Ce-Se systems and high temperature thermionic materials of the systems Y + Hf, Nb, Cr, Re, and Rh; and Mo plus ThO2, IaO2, BaO; Thermionic energy converter studies of emit er materials; Superconducting Materials of NiobiumTin Alloys; Superconducting Solenoids using Niobium-Tin Materials; Fuel Cell Studies.
Download or read book Energy Conversion Systems Reference Handbook written by Electro-Optical Systems (Firm) and published by . This book was released on 1961 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research on Materials Processes and Devices Related to Energy Conversion written by and published by . This book was released on 1962 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research is reported in five major divisions: I. Subcontracting Materials and Systems, II. Electrochemical Energy Conversion Research, III. High temperature Metallurgy Research on Thermoelectric and Thermionic Materials, IV. Solid State Energy Converters, V. The Development of Thermionic Emitter Materials.
Download or read book Thermionic Energy Conversion written by George N. Hatsopoulos and published by . This book was released on 1979 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Energy Conversion written by Andrea M. Mitofsky and published by Createspace Independent Publishing Platform. This book was released on 2018-08-25 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct Energy Conversion discusses both the physics behind energy conversion processes and a wide variety of energy conversion devices. A direct energy conversion process converts one form of energy to another through a single process. The first half of this book surveys multiple devices that convert to or from electricity including piezoelectric devices, antennas, solar cells, light emitting diodes, lasers, thermoelectric devices, and batteries. In these chapters, physical effects are discussed, terminology used by engineers in the discipline is introduced, and insights into material selection is studied. The second part of this book puts concepts of energy conversion in a more abstract framework. These chapters introduce the idea of calculus of variations and illuminate relationships between energy conversion processes.This peer-reviewed book is used for a junior level electrical engineering class at Trine University. However, it is intended not just for electrical engineers. Direct energy conversion is a fascinating topic because it does not fit neatly into a single discipline. This book also should be of interest to physicists, chemists, mechanical engineers, and other researchers interested in an introduction to the energy conversion devices studied by scientists and engineers in other disciplines.
Download or read book Elements of Energy Conversion written by Charles R. Russell and published by Elsevier. This book was released on 2013-10-22 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elements of Energy Conversion brings together scattered information on the subject of energy conversion and presents it in terms of the fundamental thermodynamics that apply to energy conversion by any process. Emphasis is given to the development of the theory of heat engines because these are and will remain most important power sources. Descriptive material is then presented to provide elementary information on all important energy conversion devices. The book contains 10 chapters and opens with a discussion of forms of energy, energy sources and storage, and energy conversion. This is followed by separate chapters on thermal properties and relations, heat engines, chemical energy, electrochemical processes, and solar energy. Subsequent chapters deal with thermoelectricity, thermionic generators, radioisotope power sources, and energy storage.
Download or read book Microfabricated Thermionic Energy Converters written by Jae Hyung Lee and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermionic energy converters (TECs) are heat engines that convert heat directly to electricity at very high temperatures. This energy conversion process is based on thermionic emission--the evaporation of electrons from conductors at high temperatures. In its simplest form, the converter consists of two electrodes in the parallel plate capacitor geometry, and it uses the thermionically emitted current to drive an electrical load. This dissertation presents research on five key areas of microfabricated thermionic energy converters ([mu]-TECs). First, the numerical calculation of the emitter-collector gap that maximizes the power conversion efficiency of thermionic energy converters (TECs) is discussed. Thermionic energy converters require emitter and collector work-functions that are relatively low, to reach useful efficiencies at typical operating temperatures of 1000 - 1500 oC. The optimum arises because efficiency drops both at very large gaps, due to space-charge limitations on the TEC current, and at very small gaps, due to the increased heat loss via near-field radiative heat transfer. The numerical calculation results show that, for typical TECs made with cesiated tungsten electrodes, the optimal gaps range from 900 nm to 3 [micrometers]. I then discuss several prototypes of mechanically and thermally robust [mu]-TECs, including the stress-relieved emitter design, emitter-collector structural design, as well as a recent approach for the stand-alone (encapsulated) [mu]-TECs. Thermionic emission from the SiC emitter was demonstrated for the first time. The stress-relieved design emitters were analyzed, and the work-function of the SiC emitter was estimated at temperatures of up to 2900K. Also described are both the planar and the U-shaped suspension for microfabricated TECs ([mu]-TECs). Our initial planar [mu]-TECs achieved emitter temperatures of over 2000 K with incident optical intensity of approximately 1 W/mm2 (equivalent to 1000 Suns), remained structurally stable under thermal cycling, and maintained a temperature difference between the emitter and the collector of over 1000 K. Conformal sidewall deposition of poly-SiC on a sacrificial mold is used to fabricate stiff suspension legs with U-shaped cross sections, which increases the out-of-plane rigidity and prevents contact with the substrate during the heating of the suspended emitter. By extending the conventional technique of cesium coatings to SiC, we reduce the work-function from 4 eV to 1.65 eV at room temperature. Subsequently, we tested [mu]-TECs with both barium and barium oxide coatings. The coatings reduced the work-function of the SiC emitter to as low as ~2.14 eV and increased the thermionic current by 5-6 orders of magnitude, which is a key step toward realizing a efficient thermionic energy converter. Encapsulation of [mu]-TEC was achieved by an anodic bond between pyrex and the silicon substrate with via feedthroughs. Last, I introduce the photon-enhanced thermionic emission (PETE) concept, and show why a single crystal photo-emitter is needed. I cover my recent fabrication development of smart-cut layer transfer using Spin-on-Glass (SoG). In addition, a novel layer transfer technology that can transfer any device materials onto the glass substrate, which I call "Anything on Glass, " is briefly described. I, then, describe how the first demonstration of the photon-enhanced thermionic emission (PETE) from the microfabricated emitter was achieved. The p-type SiC emitter was used to demonstrate PETE in an uncesiated and microfabricated sample, bringing this energy conversion approach closer to practical applications.
Download or read book Ultra High Temperature Thermal Energy Storage Transfer and Conversion written by Alejandro Datas and published by Woodhead Publishing. This book was released on 2020-09-01 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra-High Temperature Thermal Energy Storage, Transfer and Conversion presents a comprehensive analysis of thermal energy storage systems operating at beyond 800°C. Editor Dr. Alejandro Datas and his team of expert contributors from a variety of regions summarize the main technological options and the most relevant materials and characterization considerations to enable the reader to make the most effective and efficient decisions.This book helps the reader to solve the very specific challenges associated with working within an ultra-high temperature energy storage setting. It condenses and summarizes the latest knowledge, covering fundamentals, device design, materials selection and applications, as well as thermodynamic cycles and solid-state devices for ultra-high temperature energy conversion.This book provides a comprehensive and multidisciplinary guide to engineers and researchers in a variety of fields including energy conversion, storage, cogeneration, thermodynamics, numerical methods, CSP, and materials engineering. It firstly provides a review of fundamental concepts before exploring numerical methods for fluid-dynamics and phase change materials, before presenting more complex elements such as heat transfer fluids, thermal insulation, thermodynamic cycles, and a variety of energy conversation methods including thermophotovoltaic, thermionic, and combined heat and power. Reviews the main technologies enabling ultra-high temperature energy storage and conversion, including both thermodynamic cycles and solid-state devices Includes the applications for ultra-high temperature energy storage systems, both in terrestrial and space environments Analyzes the thermophysical properties and relevant experimental and theoretical methods for the analysis of high-temperature materials
Download or read book Thermionics Quo Vadis written by National Research Council and published by National Academies Press. This book was released on 2001-12-18 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report evaluates the Defense Threat Reduction Agency prior and present sponsored efforts; assess the present state of the art in thermionic energy conversion systems; assess the technical challenges to the development of viable thermionic energy conversion systems for both space and terrestrial applications; and recommend a prioritized set of objectives for a future research and development program for advanced thermionic systems for space and terrestrial applications.
