Download or read book Toward High Efficiency Radioisotope Thermophotovoltaic System by Spectral Control written by Xiawa Wang and published by . This book was released on 2017 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the design, modeling, and measurement results of a radioisotope thermophotovoltaic system (RTPV) using a two-dimensional photonic crystal emitter and low bandgap thermophotovoltaic (TPV) cell to realize spectral control. The RTPV generator aims to use the decay heat released by plutonium-238 fuel to heat up the emitter to incandescence and convert the infrared radiation to electricity in the TPV cell. With spectral control, high energy photons above the cell bandgap ([lambda] 2.25 [mu]m for InGaAsSb cell) are emitted to produce more electrical power while low energy photons ([lambda] 2.25 [mu]m) in far infrared are suppressed to reduce waste heat. We validated a system simulation using the measurements of a prototype system powered by an electrical heater equivalent to one plutonium fuel pellet. The thermal insulation design used multilayer insulation, which was found to be both efficient and chemically compatible with the photonic crystal emitter. We compared the system performance using a photonic crystal emitter to the one using a polished flat tantalum emitter and found that spectral control with the photonic crystal was four times more efficient. Based on the simulation, we further extended the design and performance estimates to real life RTPV generators optimized for both space and terrestrial applications. With the experimentally tested InGaAsSb TPV cell, the system efficiency can potentially reach above 8% with a specific power of 7.5 W/kg. With more advanced InGaAs monolithic-integrated-modules, the system efficiency can reach around 20% with a specific power above 17 W//kg.
Download or read book Thermophotovoltaics written by Thomas Bauer and published by Springer Science & Business Media. This book was released on 2011-06-17 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermophotovoltaics is the science and technology associated with the direct generation of electricity from high temperature heat. Potential applications include combined heat and power, portable and auxiliary power, radioisotope space power, industrial waste heat recovery and concentrated solar power. This book aims at serving as an introduction to the underlying theory, overview of present day components and system arrangements, and update of the latest developments in the field. The emphasis is placed on the understanding of the critical aspects of efficient thermophotovoltaic system design. The aim is to assist researchers in the field.
Download or read book High Efficiency Direct Thermal to Electric Energy Conversion from Radioisotope Decay Using Selective Emitters and Spectrally Tuned Solar Cells written by Donald L. Chubb and published by . This book was released on 1993 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photovoltaics for Space written by Sheila G. Bailey and published by Elsevier. This book was released on 2022-10-26 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: PV has traditionally been used for electric power in space. Solar panels on spacecraft are usually the sole source of power to run the sensors, active heating and cooling, and communications. Photovoltaics for Space: Key Issues, Missions and Alternative Technologies provides an overview of the challenges to efficiently produce solar power in near-Earth space and beyond: the materials and device architectures that have been developed to surmount these environmental and mission-specific barriers. The book is organized in four sections consisting of detailed introductory and background content as well as a collection of in-depth space environment, materials processing, technology, and mission overviews by international experts. This book will detail how to design and optimize a space power system’s performance for power-to-weight ratio, effectiveness at end of operational life (EOL) compared to beginning of operational life (BOL), and specific mission objectives and goals. This book outlines the knowledge required for practitioners and advanced students interested in learning about the background, materials, devices, environmental challenges, missions, and future for photovoltaics for space exploration. Provides an update to state-of-the-art and emerging solar cell technologies Features comprehensive coverage of solar cells for space exploration and materials/device technology options available Explains the extreme conditions and mission challenges to overcome when using photovoltaics in space
Download or read book Fabrication and Testing of an Infrared Spectral Control Component for Thermophotovoltaic Power Conversion Applications written by Francis Martin O'Sullivan and published by . This book was released on 2004 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermophotovoltaic (TPV) power conversion is the direct conversion of thermal radiation to electricity. Conceptually, TPV power conversion is a very elegant means of energy conversion. A thermal source emits a radiative spectrum, which is incident upon a photovoltaic (PV) diode. The PV diode then converts some of the incident photons to electricity. The photons which are converted to electricity have energies greater than the electronic bandgap of the material from which the PV diode is fabricated. Unfortunately the thermal sources used in TPV systems are typically broadband, meaning that a significant amount of the emitted radiation cannot be converted to electricity because the photons are not energetic enough to produce electron-hole pairs in the PV diode. This unconvertible radiation is dissipated as heat in the PV diode and represents a very large loss in a TPV system's conversion efficiency. This thesis describes the development of a spectral control component which can be used to filter the radiation emitted from a TPV system's thermal source, such that only convertible radiation is incident upon the PV diode. The theoretical analysis of filter designs based on a Si/SiO2 dielectric stack is described in this text. The methods and processes used to fabricate physical samples of the spectral control component are discussed. The results of the spectral analysis of the physical samples are documented and a comparison between the predicted performance of the filter designs and the measured performance of the fabricated filter samples is made.
Download or read book Development and Modelling of a Thermophotovoltaic System written by Giovanni Mattarolo and published by kassel university press GmbH. This book was released on 2007 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectral Engineering for Solar thermal and Thermal radiative Systems written by Yi Huang (Ph. D.) and published by . This book was released on 2020 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing energy efficiency for power generation and reduction of energy consumption are two important venues to address the energy supply and global warming challenges we face today. Radiation from the sun and terrestrial heat sources can be harvested for power generation. It is also an important heat transfer channel, with which one can control in order to regulate the temperature of objects. In this thesis, we focus on strategies to harvest and control solar and thermal radiation, with the goals (1) to improve power generation efficiency using solar and thermal photovoltaics and (2) to reduce the energy consumption used to maintain human comfort in built environments. Solar radiation, as one of the most abundant energy sources on Earth, is now harvested by photovoltaics around the world. While solar photovoltaics already has reached considerable efficiencies, there is still room for improvement. One fundamental limit in solar photovoltaics is the discard of photons with energy smaller than the material bandgap. Another challenge for solar PVs, due to the intermittent nature of solar power, is the lack of low-cost electricity storage systems that provide electricity on-demand. Solar thermal systems, on the other hand, can dispatch energy on-demand due to low-cost of thermal storage systems. Hybrid systems that combine solar PV and solar thermal systems can potentially harvest solar energy at higher efficiency and provide more dispatchable sources of energy. In the first part of my thesis, we designed and experimentally tested a spectral-selective, thermally-conductive component to be used in such hybrid solar-PV thermal system. The component can direct part of the solar spectrum to the photovoltaics and to absorb the rest of the spectrum for use in a thermal system, thereby harvesting the entire solar spectrum with an energy conversion efficiency close to 23%, and with over 40% dispatchable electricity generated from thermal energy. The photovoltaic energy conversion efficiency can also improve by recycling photons with energy smaller than the material bandgap. In a thermo-photovoltaic system, low-energy photons can be designed to reflect back to the radiation source, and therefore energy carried by these photons can be re-used. Thermo-photovoltaic devices also showed great potential to provide low-cost, dispatachable electricity when combined with high-temperature thermal storage systems and concentrated solar power. In the second part of my thesis, we have designed and optimized a practical, crystalline-Si based thermo-photovoltaic cell to be fabricated on double-side polished wafers. The Si-based TPV cell, combined with a 2300K gray radiator, can potentially reach 40% energy conversion efficiency. We have evaluated and optimized the Si-TPV performance with comprehensive considerations of components in the photovoltaic cell, including doping and junction depth, front and back surface field, passivation layer, back reflector, front metallization, as well as tolerance to roughness introduced in fabrication. Experimental tests have been conducted on doped Si samples with back reflectors, and identified potential pathways to further reduce optical and electrical losses. The maturity of the Si PV technologies and its relatively low cost points to great promise of high-efficiency thermo-photovoltaic devices for high-temperature thermal energy storage. Thermal radiation is also integral to the regulation of heat balance and temperatures of human body. Spaces in built environments are typically kept at near-ambient temperatures for human thermal comfort. However, heating and cooling of spaces consume 40% of the total energy used in the US. Instead of regulating temperature in vast spaces, local regulation of heat near human bodies can potentially save large amounts of energy. In the third part of my thesis, we study the use of fabrics to regulate skin temperatures of the human body by controlling the input and output radiation channels of the human skin, an important yet largely under-studied channel for body temperature regulation. We then propose desired spectral properties of fabrics for both heating and cooling purposes, and in both indoor and outdoor environments. Finally, we investigate via both simulation and experiments, how morphology and material of polymer-based fabrics can be used to achieve the desired spectral properties.
Download or read book Thermophotovoltaic Generation of Electricity written by Carlos Algora and published by American Institute of Physics. This book was released on 2007-03-09 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book features peer-reviewed papers that were presented at the Seventh World Conference on Thermophotovoltaic Generation of Electricity. Thermophotovoltaic technology is a promising new means for the direct conversion of thermal to electric energy. Its potential applications range from military power, to space propulsion, to commercial products for market niches.
Download or read book Tuning Energy Transport in Solar Thermal Systems Using Nanostructured Materials written by Andrej Lenert and published by . This book was released on 2014 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar thermal energy conversion can harness the entire solar spectrum and theoretically achieve very high efficiencies while interfacing with thermal storage or back-up systems for dispatchable power generation. Nanostructured materials allow us to tune the spectral properties and heat transfer behavior to enable such systems. However, under high temperature conditions, thermal management, system optimization and minimization of parasitic losses are necessary to achieve competitive solar power generation. This thesis seeks to achieve spectral control and thermal management through manipulation of nanostructured materials. First, this thesis presents the design and development of a nanophotonic solar thermophotovoltaic (STPV) that harnesses the full spectrum of the sun, in a solid-state and scalable way. Through device optimization and control over spectral properties at high temperatures (~1300 K), a device that is 3 times more efficient than previous STPVs is demonstrated. To achieve this result, a framework was developed to identify which parts of the spectrum are critical and to guide the design of nanostructured absorbers and emitters for STPVs. The work elucidated the relative importance of spectral properties depending on the operating regime and device geometry. Carbon nanotubes and a silicon/silicon dioxide photonic crystal were used to target critical properties in the high solar concentration regime; and two-dimensional metallic photonic crystals were used to target critical properties in the low solar concentration regime. A versatile experimental platform was developed to interchangeably test different STPV components without sacrificing experimental control. In addition to demonstrating significant improvements in STPV efficiency, an experimental procedure to quantify the energy conversion and loss mechanisms helped improve and validate STPV models. Using these validated models, this thesis presents a scaled-up device that can achieve 20% efficiencies in the near term. With potential integration of thermal-based storage, such a technology can supply power efficiently and on-demand, which will have significant implications for adoption of STPVs. Second, the thesis shifts focus away from solid-state systems to thermal-fluid systems. A new figure of merit was proposed to capture the thermal storage, heat transfer and pumping power requirements for a heat transfer fluid is a solar thermal system. Existing and emerging fluids were evaluated based on the new metric as well as practical issues. Finally, sub-micron phase change material (PCM) suspensions are investigated for simultaneous enhancement of local heat transfer and thermal storage capacity in solar thermal systems. A physical model was developed to explain the local heat transfer characteristics of a flowing PCM suspension undergoing melting. A mechanism for enhancement of heat transfer through.control over the distribution of PCM particles inside a channel was discovered and explained. Together, this thesis makes significant contributions towards improving our understanding of the role and the effective use of nanostructured materials in solar thermal systems.
Download or read book Advanced Thermophotovoltaic Cells Modeling Optimized for Use in Radioisotope Thermoelectric Generators RTGs for Mars and Deep Space Missions written by Bradley P. Davenport and published by . This book was released on 2004-06-01 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: To accommodate the need for power on deep space missions, satellites must carry a source capable of providing adequate power for the life of the mission. This is currently done using radioisotope thermoelectric generators (RTGs). Current RTGs consist of a heat source, Pu-238, and a thermocouple that inefficiently converts heat into electricity. To improve the overall efficiency of RTGs, a better thermoelectric converter is needed to replace the thermocouple. This thesis examines the possible use of thermophotovoltaic (TPV) cells in RTGs. Two cells were developed and optimized for the spectrum from a 1300K blackbody that simulates the spectrum of an RTG heat source. Current TPV cells are built and tested with different thicknesses and doping levels to the most efficient design, an expensive and time-consuming method. This thesis presents a model that can predict the output of a cell under various spectra. The model can easily be changed to simulate different cell thicknesses and doping levels, and it can be changed to simulate cells of different materials. The models presented in this thesis were built using the Silvaco Virtual Wafer Fabrication software package. To prove the capabilities of this software package in designing TPV models, an initial cell was designed using a well-documented material: gallium arsenide (GaAs). Voltage-current characteristics and frequency response data were recorded from this model and compared with experimental data from a similar cell. Once the model was verified, more exotic materials could be examined: gallium antimonide (GaSb) and indium gallium arsenide (InGaAs). As with the GaAs cell model, the GaSb and InGaAs models were first optimized for the AM0 spectrum and compared to experimental results. Programs were written using Matlab to run iterations of Silvaco to change layer thicknesses and doping levels. Other programs also were used to help determine the most efficient TPV cell design. (41 figures, 48 refs.)
Download or read book Next Generation Photovoltaics written by A. Martí and published by CRC Press. This book was released on 2003-09-01 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although photovoltaics are regarded by many as the most likely candidate for long term sustainable energy production, their implementation has been restricted by the high costs involved. Nevertheless, the theoretical limit on photovoltaic energy conversion efficiency-above 85%-suggests that there is room for substantial improvement of current commercially available solar cells, both silicon and thin-film based. Current research efforts are focused on implementing novel concepts to produce a new generation of low-cost, high-performance photovoltaics that make improved use of the solar spectrum. Featuring contributions from pioneers of next generation photovoltaic research, Next Generation Photovoltaics: High Efficiency through Full Spectrum Utilization presents a comprehensive account of the current state-of-the-art in all aspects of the field. The book first discusses topics, such as multi-junction solar cells (the method closest to commercialization), quantum dot solar cells, hot carrier solar cells, multiple quantum well solar cells, and thermophotovoltaics. The final two chapters of the book consider the materials, fabrication methods, and concentrator optics used for advanced photovoltaic cells. This book will be an essential reference for graduate students and researchers working with solar cell technology.
Download or read book Spectral Control for Thermophotovoltaic Energy Conversion written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Where Solar Thermal Meets Photovoltaic for High efficiency Power Conversion written by David Matthew Bierman and published by . This book was released on 2014 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: To develop disruptive techniques which generate power from the Sun, one must understand the aspects of existing technologies that limit performance. Solar thermal and solar photovoltaic schemes dominate today's solar market but both bring intrinsic and practical constraints. What will tomorrow's solar market look like? Third generation solar power generation techniques to utilize a larger portion of the solar spectrum are a promising path for high efficiency power generation, but experimental demonstrations remain limited. In this work, the components of a solar thermophotovoltaic power converter are introduced and discussed. While solar thermophotovoltaic devices have the potential to convert sunlight into electricity at astronomically high efficiencies, there are a number of practical challenges that must first be addressed. Novel photonic materials, design concepts, and both intrinsic and practical limitations of solar thermophotovoltaic conversion are explored in this thesis. The conversion mechanisms as well as a number of experimental implementations are presented. Finally, the device performance is characterized and both geometrical and spectral improvements are discussed.
Download or read book Thermophotovoltaic Arrays for Electrical Power Generation written by Sarnoff Corporation and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sarnoff has designed an integrated array of thermophotovoltaic (TPV) cells based on the In(Al)GaAsSb/GaSb materials system. These arrays will be used in a system to generate electrical power from a radioisotope heat source that radiates at temperatures from 700 to 1000 C. Two arrays sandwich the slab heat source and will be connected in series to build voltage. Between the arrays and the heat source is a spectral control filter that transmits above-bandgap radiation and reflects below-bandgap radiation. The goal is to generate 5 mW of electrical power at 3 V from a 700 C radiant source. Sarnoff is a leader in antimonide-based TPV cell development. InGaAsSb cells with a bandgap of 0.53 eV have operated at system conversion efficiencies greater than 17%. The system included a front-surface filter, and a 905 C radiation source. The cells were grown via organo-metallic vapor-phase epitaxy. Sarnoff will bring this experience to bear on the proposed project. The authors first describe array and cell architecture. They then present calculated results showing that about 80 mW of power can be obtained from a 700 C radiator. Using a conservative array design, a 5-V output is possible.
Download or read book Directory of Solar Energy Research Activities in the United States written by and published by . This book was released on 1980 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1997 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
