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 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advantages of thermionic energy conversion (TEC) have been counted and are recounted with emphasis on high-temperature service in coal-combustion products. Efficient, economical, nonpolluting utilization of coal here and now is a critically important national goal. And TEC can augment this capability not only by the often proposed topping of steam power plants but also by higher-temperature topping and process heating. For these applications, applied-research-and-technology (ART) work reveals that optimal TEC with approx. 1000-to approx. 1100 K collectors is possible using well-established tungsten electrodes. Such TEC with 1800 K emitters could approach 26.6% efficiency at 27.4 W/cm2 with approx. 1000 K collectors and 21.7% at 22.6 W/cm2 with approx. 1100 K collectors. These performances require 1.5- and 1.7-eV collector work functions (not the 1-eV ultimate) with nearly negligible interelectrode losses. Such collectors correspond to tungsten electrode systems in approx. 0.9-to approx. 6-torr cesium pressures with 1600-to-1900 K emitters. Because higher heat-rejection temperatures for TEC allow greater collector work functions, interelectrode-loss reduction becomes an increasingly important target for applications aimed at elevated temperatures. Studies of intragap modifications and new electrodes that will allow better electron emission and collection with lower cesium pressures are among the TEC-ART approaches to reduced interelectrode losses. These solutions will provide very effective TEC to serve directly in coal-combustion products for high-temperature topping and process heating. In turn this will help to use coal-and to use it well.
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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1981 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book High temperature High power density Thermionic Energy Conversion for Space written by James F. Morris and published by . This book was released on 1977 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Energy Research Abstracts written by and published by . This book was released on 1993 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy a Continuing Bibliography with Indexes written by and published by . This book was released on 1981 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Science and Technology of Coal and Coal Utilization written by Bernard Cooper and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filling the need for new and improved energy sources is an area where societal effects of science and technology will surely increase. The editors and authors have attempted in this volume to present the most current work on the science and technology of coal and coal utilization. Serious disagreement exists on several key issues such as carbon dioxide release and acid rain. At the same time, however, coal is the world's most abundant fossil fuel and will have to be used to supply the world's energy needs for the next several decades. The 1979 National Research Council Report, "En ergy in Transition: 1985-2010," has estimated that the United States alone may go from a 1979 coal consumption of 14 QUADS per annum (approximately 750 million tons per year) to approximately 40-50 QUADS per annum (approximately 2 billion tons per year) by the year 2010. If this scale of coal utilization is to become a reality, a significant level of research and development will be necessary to establish advanced process technologies and to improve related areas such as materials and instrumentation. The editors hope that this volume will allow a technically educated person to become aware of the several aspects of coal utilization, from characterization of coal itself to the processes of coal utilization. B. R. Cooper and W. A. Ellingson March, 1983 vii Contents 1. THE SCIENCE AND TECHNOLOGY OF COAL AND COAL UTILIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Bernard R. Cooper and William A. Ellingson 2. COAL CHARACTERIZATION. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Download or read book Proceedings of the Intersociety Energy Conversion Engineering Conference written by and published by . This book was released on 1989 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1981 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes all works deriving from DOE, other related government-sponsored information and foreign nonnuclear information.
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 Government Reports Announcements Index written by and published by . This book was released on 1981 with total page 1052 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spacecraft Radiative Transfer and Temperature Control written by Thomas E. Horton and published by . This book was released on 1982 with total page 560 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 Synerjy written by and published by . This book was released on 1981 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1981 with total page 1316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Download or read book 1979 Department of Energy Authorization written by United States. Congress. House. Committee on Science and Technology and published by . This book was released on 1978 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:
