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Baziotopoulos, Con, et mikewood@deakin edu au. « Utilising solar energy within conventional coal fired power stations ». Deakin University. School of Engineering and Technology, 2002. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20060817.145445.
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Although the thermodynamic advantages of using solar energy to replace the bled off steam in the regeneration system of Rankine cycle coal fired power stations has been proven theoretically, the practical techno/economic feasibility of the concept has yet to be confirmed relative to real power station applications. To investigate this concept further, computer modelling software THERMSOLV was specifically developed for this project at Deakin University, together with the support of the Victorian power industry and Australian Research Council (ARC). This newly developed software simulates the steam cycle to assess the techno/economic merit of the solar aided concept for various power station structures, locations and local electricity market conditions. Two case studies, one in Victoria Australia and one in Yunnan Province, China, have been carried out with the software. Chapter one of this thesis defines the aims and scope of this study. Chapter two details the literature search in the related areas for this study. The thermodynamic concept of solar aid power generation technology has been described in chapter three. In addition, thermodynamic analysis i.e. exergy/availability has been described in this chapter. The Thermosolv software developed in this study is detailed in chapter four with its structure, functions and operation manual included. In chapter five the outcomes of two case studies using the Thermosolv software are presented, with discussions and conclusions about the study in chapters 6 and 7 respectfully. The relevant recommendations are then made in chapter eight.
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Rowe, Scott Christian. « Pilot Plant Analysis, Experiments, and Control for the Hybridization of Transient Solar Heat with Conventional Utilities ». Thesis, University of Colorado at Boulder, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10791867.
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The direct capture of solar heat is now commercial for electrical generation at 550 °C (1000 °F), which has provoked interest in solar driven approaches to commodity and fuels production at higher temperatures. However, conventional commodity and fuels facilities often operate continuously regardless of weather and nighttime conditions. Conversely, direct sunlight is immediately lost upon shading by clouds and sunset. Beyond inconvenience, this intermittency has the potential to destroy high temperature equipment through thermal fatigue and thermal shock. To overcome interruptions in solar availability we propose the inclusion of direct sunlight in commodities and fuels production as a supplement to conventional electrical heating. Within this regime conventional utilities are ideally sourced from sustainable stored or orthogonal energy sources. Control is needed to substitute solar, which can be lost within seconds during transient weather, with electrical heat. To explore control strategies for the alternation of solar and electrical heat a new facility was constructed at the University of Colorado, Boulder. Specifically, a 45 kW 18 lamp high-flux solar simulator was erected that approximates the sunlight found in actual concentrated solar plants. Calorimetry was analyzed for the measurement of extreme radiance in this testbed. Results from calorimeter design were applied to radiation measurement from the lamps, which were capable of delivering 9.076±0.190 kW of power to a ?10 cm target with a peak flux of 12.50 MW/m2 (12,500 “suns”). During this characterization a previously unknown observer effect was seen that differentiates radiative heat from lamps and the energy delivered by sunlight in actual concentrated solar facilities. This characterization allowed confident experimentation within the lamp testbed for control studies on a 15 kW solar-electric tube furnace for commodities and fuels production. Furnace electric heat was manipulated by four different linear control strategies for the rejection weather transients reproduced by the high-flux solar simulator lamps. These included feedback, feedforward feedback, model predictive control, and model predictive control with a weather forecast. It was found that model predictive control with a forecast best maintained furnace conditions. Prior researchers have suggested that forecasts would be useful in solar control, which was shown across simulation and experiment.
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Ma, Yizheng. « PHOTOVOLTAIC ENERGY POTENTIAL FOR NON- RESIDENTIAL BUILDINGS IN VISBY ». Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448444.
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Gotland is a pilot area for Sweden to achieve carbon neutrality, which means that achieve a 100% sustainable energy supply is significant for Gotland energy development. Gotland has good sunshine conditions and solar radiation, but the development of solar energy is relatively slow. In order to prove that Visby, the largest city in Gotland, has good solar energy potential, this paper aims to investigate the PV potential for non-residential buildings in Visby by modelling the installation of roof solar panels on representative non- residential buildings (Visby Galleria, surrounding buildings in Stenhuggarvägen) through quantitative research methods. From the final result of the modelling, the solar energy potential per square meter of Visby's non-residential buildings is 121kWh, and the total solar electricity generation potential is 708 GWh. The research results show that Visby's non-residential buildings have high solar power potential, and it can be used as one of the methods to achieve a 100% sustainable energy supply.
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Rader, Thomas J. « Comparing Estimates of the Capacity Values of Photovoltaic Solar Power Plants Using Hourly and Sub-hourly Data ». The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1353966527.
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Lissau, Jonas Sandby. « Non-Coherent Photon Upconversion on Dye-Sensitized Nanostructured ZrO2 Films for Efficient Solar Light Harvesting ». Doctoral thesis, Uppsala universitet, Fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229831.
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Photon upconversion by sensitized triplet–triplet annihilation (UC-STTA) is a photophysical process that facilitates the conversion of two low-energy photons into a single high-energy photon. A low-energy photon is absorbed by a sensitizer molecule that produces a triplet excited state which is transferred to an emitter molecule. When two emitter triplet states encounter each other, TTA can take place to produce a singlet excited state which decays by emission of a high-energy (upconverted) photon. While traditional single-threshold dye-sensitized solar cells (DSSCs) have a maximum efficiency limit of ca. 30%, it has been predicted theoretically that implementation of UC-STTA in DSSCs could increase that efficiency to more than 40%. A possible way to implement UC-STTA into DSSCs, would be to replace the standard sensi- tized nanostructured TiO2 photoanodes by upconverting ones loaded with emitter molecules. Following TTA, the excited emitter molecule would be quenched by injection of a high-energy electron into the conduction band of the TiO2. To explore the practical aspects of this strategy for a highly efficient DSSC, in this thesis UC-STTA is studied in model systems based on nanostructured ZrO2 films. These ZrO2 films are a good proxy for the TiO2 films used in DSSCs, and allow for relatively easy optimization and study of UC-STTA by allowing measurements of the upconverted photons without the complications of electron injection into the film. Herein it is experimentally proven that UC-STTA is viable on nanostructured metal oxide films under non-coherent irradiation with intensities comparable to sunlight. Two different system architectures are studied, differing in the position of the molecular components involved in the UC-STTA mechanism. Both architectures have the emitter molecules adsorbed onto the ZrO2 surface, but the sensitizers are positioned either in solution around the nanostructure, or co-adsorbed with the emitters onto the ZrO2 surface. A set of challenges in the study and optimization of the UC-STTA process is identified for each type of system. Proposals are also given for how to further improve the understanding and UC-STTA optimization of these systems toward application in DSSCs to overcome the present solar energy conversion efficiency limit.
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Qandil, Hassan Darwish Hassan. « Investigations of the Fresnel Lens Based Solar Concentrator System through a Unique Statistical-Algorithmic Approach ». Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1609121/.
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This work investigates the Fresnel-lens-based solar concentrator-receiver system in a multi-perspective manner to design, test and fabricate this concentrator with high-efficiency photon and heat outputs and a minimized effect of chromatic aberrations. First, a MATLAB®-incorporated algorithm optimizes both the flat-spot and the curved lens designs via a statistical ray-tracing methodology of the incident light, considering all of its incidence parameters. The target is to maximize the solar ray intensity on the receiver's aperture, and therefore, achieve the highest possible focal flux. The algorithm outputs prismatic and dimensional geometries of the Fresnel-lens concentrator, which are simulated by COMSOL® Multiphysics to validate the design. For the second part, a novel genetically-themed hierarchical algorithm (GTHA) has been investigated to design Fresnel-lens solar concentrators that match with the distinct energy input and spatial geometry of various thermal applications. Basic heat transfer analysis of each application decides its solar energy requirement. The GTHA incorporated in MATLAB® optimizes the concentrator characteristics to secure this energy demand, balancing a minimized geometry and a maximized efficiency. Two experimental applications were selected from literature to validate the optimization process, a solar welding system for H13 steel plates and a solar Stirling engine with an aluminum-cavity receiver attached to the heater section. In each case, a flat Fresnel-lens with a spot focus was algorithmically designed to supply the desired solar heat, and then a computer simulation of the optimized lens was conducted showing great comparability to the original experimental results. Thirdly, the prismatic geometry of the Fresnel lens was further optimized through a statistical approach that incorporates laws of light refraction and trigonometry. The proposed design produces high focal irradiance that is more suitable for thermal applications. The motivation was to enhance the tolerability of a flat Fresnel-lens concentrator to tracking errors, without the use of secondary optics or sophisticated, and normally costly, meticulous tracking equipment. A comparative simulation analysis was conducted for two case studies from literature, each with a different design method. Fresnel lenses optimized by this work enhanced the concentration acceptance product (CAP) significantly, compared to that in literature. Then, this work introduced an innovative code-based, detailed, and deterministic geometrical approach, which couples the optimization of the Fresnel lens primary optical element (POE) and the dome-shaped secondary optical element (SOE). The objective was to maximize the concentration acceptance product, while using the minimum SOE and receiver geometries at a given f-number and incidence angle (also referred to as the tracking error angle). The laws of polychromatic light refraction along with trigonometry and spherical geometry were utilized to optimize the POE grooves, SOE radius, receiver size, and SOE–receiver spacing. Two literature case studies were analyzed to verify this work's optimization, and the equivalent POEs designed by this work, with optimized SOEs, showed a significant enhancement in the CAP values compared to that of literature. Lastly, four methods for prototyping the Fresnel lens were discussed and experimentally tested; 3D printing, acrylic resin casting, direct CNC machining in acrylic and hot embossing. Once tested, the methods of CNC machining and hot embossing of acrylic proved to be the most promising in terms of cost, fabrication time, and concentration effectiveness. Future work will focus on enhancing the algorithmic design and improving the quality of lens fabrication.
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Dallas, William. « Resonance ultrasonic vibrations (RUV) for crack detection in silicon wafers for solar cells ». [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001848.
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Baig, Hasan. « Enhancing performance of building integrated concentrating photovoltaic systems ». Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/17301.
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Buildings both commercial and residential are the largest consumers of electricity. Integrating Photovoltaic technology in building architecture or Building Integrated Photovoltaics (BIPV) provides an effective means for meeting this huge energy demands and provides an energy hub at the place of its immediate requirement. However, this technology is challenged with problems like low efficiency and high cost. An effective way of improving the solar cell efficiency and reducing the cost of photovoltaic systems is either by reducing solar cell manufacturing cost or illuminating the solar cells with a higher light intensity than is naturally available by the use of optical concentrators which is also known as Concentrating Photovoltaic (CPV) technology. Integrating this technology in the architecture is referred as Building integrated Concentrating Photovoltaics (BICPV). This thesis presents a detailed performance analysis of different designs used as BICPV systems and proposes further advancements necessary for improving the system design and minimizing losses. The systems under study include a Dielectric Asymmetric Compound Parabolic Concentrator (DiACPC) designed for 2.8×, a three-dimensional Cross compound parabolic concentrator (3DCCPC) designed for 3.6× and a Square Elliptical Hyperbolic (SEH) concentrator designed for 6×. A detailed analysis procedure is presented showcasing the optical, electrical, thermal and overall analysis of these systems. A particular issue for CPV technology is the non-uniformity of the incident flux which tends to cause hot spots, current mismatch and reduce the overall efficiency of the system. Emphasis is placed on modelling the effects of non-uniformity while evaluating the performance of these systems. The optical analysis of the concentrators is carried out using ray tracing and finite element methods are employed to determine electrical and thermal performance of the system. Based on the optical analysis, the outgoing flux from the concentrators is predicted for different incident angles for each of the concentrators. A finite element model for the solar cell was developed to evaluate its electrical performance using the outputs obtained from the optical analysis. The model can also be applied for the optimization of the front grid pattern of Si Solar cells. The model is further coupled within the thermal analysis of the system, where the temperature of the solar cell is predicted under operating conditions and used to evaluate the overall performance under steady state conditions. During the analysis of the DiACPC it was found that the maximum cell temperature reached was 349.5 K under an incident solar radiation of 1000 W/m2. Results from the study carried on the 3DCCPC showed that a maximum cell temperature of 332 K is reached under normal incidence, this tends to bring down the overall power production by 14.6%. In the case of the SEH based system a maximum temperature of 319 K was observed on the solar cell surface under normal incidence. An average drop of 11.7% was found making the effective power ratio of the system 3.4. The non-uniformity introduced due to the concentrator profile causes hotspots in the BICPV system. The non-uniformity was found to reduce the efficiency of the solar cell in the range of 0.5-1 % in all the three studies. The overall performance can be improved by addressing losses occurring within different components of the system. It was found that optical losses occurred at the interface region formed due to the encapsulant spillage along the edges of the concentrator. Using a reflective film along the edge of the concentrating element was found to improve the optical efficiency of the system. Case studies highlighting the improvement are presented. A reflective film was attached along the interface region of the concentrator and the encapsulant. In the case of a DiACPC, an increase of 6% could be seen in the overall power production. Similar case study was performed for a 3DCCPC and a maximum of 6.7% was seen in the power output. To further improve the system performance a new design incorporating conjugate reflective-refractive device was evaluated. The device benefits from high optical efficiency due to the reflection and greater acceptance angle due to refraction. Finally, recommendations are made for development of a new generation of designs to be used in BiCPV applications. Efforts are made towards improving the overall performance and reducing the non-uniformity of the concentrated illumination.
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Junda, Maxwell M. « Spectroscopic Ellipsometry as a Versatile, Non-Contact Probe of Optical, Electrical, and Structural Properties in Thin Films : Applications in Photovoltaics ». University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1493148258156143.
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Hibberd, Christopher J. « Development of non-vacuum and low-cost techniques for Cu(In, Ga)(Se, S)2 thin film solar cell processing ». Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/5840.
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Solar photovoltaic modules provide clean electricity from sunlight but will not be able to compete on an open market until the cost of the electricity they produce is comparable to that produced by traditional methods. At present, modules based on crystalline silicon wafer solar cells account for nearly 90% of photovoltaic production capacity. However, it is anticipated that the ultimate cost reduction achievable for crystalline silicon solar cell production will be somewhat limited and that thin film solar cells may offer a cheaper alternative in the long term. The highest energy conversion efficiencies reported for thin film solar cells have been for devices based around chalcopyrite Cu(In, Ga)(Se, S)2 photovoltaic absorbers. The most efficient Cu(In, Ga)(Se, S)2 solar cells contain absorber layers deposited by vacuum co-evaporation of the elements. However, the cost of ownership of large area vacuum evaporation technology is high and may be a limiting factor in the cost reductions achievable for Cu(In, Ga)(Se, S)2 based solar cells. Therefore, many alternative deposition methods are under investigation. Despite almost thirty companies being in the process of commercialising these technologies there is no consensus as to which deposition method will lead to the most cost effective product. Non-vacuum deposition techniques involving powders and chemical solutions potentially offer significant reductions in the cost of Cu(In, Ga)(Se, S)2 absorber layer deposition as compared to their vacuum counterparts. A wide range of such approaches has been investigated for thirty years and the gap between the world record Cu(In, Ga)(Se, S)2 solar cell and the best devices containing non-vacuum deposited absorber layers has closed significantly in recent years. Nevertheless, no one technique has demonstrated its superiority and the best results are still achieved with some of the most complex approaches. The work presented here involved the development and investigation of a new process for performing one of the stages of non-vacuum deposition of Cu(In, Ga)(Se, S)2 absorber layers. The new process incorporates copper into an initial Group III-VI precursor layer, e.g. indium gallium selenide, through an ion exchange reaction performed in solution. The ion exchange reaction requires only very simple, low-cost equipment and proceeds at temperatures over 1000°C lower than required for the evaporation of Cu under vacuum. In the new process, indium (gallium) selenide initial precursor layers are immersed in solutions containing Cu ions. During immersion an exchange reaction occurs and Cu ions from the solution exchange places with Group III ions in the layer. This leads to the formation of an intimately bonded, laterally homogeneous copper selenide – indium (gallium) selenide modified precursor layer with the same morphology as the initial precursor. These modified precursor layers were converted to single phase chalcopyrite CuInSe2 and Cu(In, Ga)Se2 by annealing with Se in a tube furnace system. Investigation of the annealing treatment revealed that a series of phase transformations, beginning at low temperature, lead to chalcopyrite formation. Control of the timing of the Se supply was demonstrated to prevent reactions that were deemed detrimental to the morphology of the resulting chalcopyrite layers. When vacuum evaporated indium (gallium) selenide layers were used as initial precursors, solar cells produced from the absorber layers exhibited energy conversion efficiencies of up to 4%. While these results are considered promising, the devices were characterised by very low open circuit voltages and parallel resistances. Rapid thermal processing was applied to the modified precursor layers in an attempt to further improve their conversion into chalcopyrite material. Despite only a small number of solar cells being fabricated using rapid thermal processing, improvements in open circuit voltage of close to 150mV were achieved. However, due to increases in series resistance and reductions in current collection only small increases in solar cell efficiency were recorded. Rapid thermal processing was also used to demonstrate synthesis of single phase CuInS2 from modified precursor layers based on non-vacuum deposited indium sulphide. Non-vacuum deposition methods provide many opportunities for the incorporation of undesirable impurities into the deposited layers. Analysis of the precursor layers developed during this work revealed that alkali atoms from the complexant used in the ion exchange baths are incorporated into the precursor layers alongside the Cu. Alkali atoms exhibit pronounced electronic and structural effects on Cu(In, Ga)Se2 layers and are beneficial in low concentrations. However, excess alkali atoms are detrimental to Cu(In, Ga)Se2 solar cell performance and the problems encountered with cells produced here are consistent with the effects reported in the literature for excess alkali incorporation. It is therefore expected that further improvements in solar cell efficiency might be achieved following reformulation of the ion exchange bath chemistry.
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Alves, Ricardo Henrique Fonseca. « Estudo de geração fotovoltaica distribuída : análise econômica e o uso de redes neurais artificiais ». Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/7563.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The main goal of this work is to propose a methodology for the selection of 51 consumers in Nova Veneza-GO connected to two transformers in the pre-Smart Grid network. The methodology consists of ten stages ranging from the grouping of consumers with the same power consumption profile using a neural network, that is, a Non Parametric Self-Organizing Map (PSOM), until the complete and optimal allocation of financial resources through of an Integer Linear Programming. We obtained 12 different groups (clusters) of consumers of the two transformers with the same power consumption profile using the network PSOM algorithm. This grouping (clustering) was considered in the dimensioning and design of Photovoltaic Systems Connected to the Grid (Grid-Tie Systems) using three different computational tools, among them, an approach based on the PVSyst software, trial version V6.39. In addition, a study of Economic Engineering was carried out to expand the R&D pilot project aiming at the implementation of Grid Tie Systems for all the consumers of Nova Veneza-GO and Goiânia-GO, considering consumption data available by Celg-D and also considering two different scenarios based on the implementation of photovoltaic systems with and without government incentive. An Economic Engineering analysis was performed considering that 1%, 5%, 10%, 20%, 30% and 100% of Consumer Units (UC) adhere to the implantation of solar systems in Goiânia-GO. Environmental results were found for the city of Nova Veneza-GO and Goiânia-GO, evidencing an expressive reduction in CO2 emissions and a great saving of water.
O principal objetivo deste trabalho é propor uma metodologia para a escolha de 51 Unidades Consumidoras (UC) em Nova Veneza-GO ligados a dois transformadores pertencentes a uma rede pré Smart Grid localizada na cidade. A metodologia consiste de dez etapas que vão desde o agrupamento de consumidores com mesmo perfil de consumo de energia elétrica utilizando uma rede neural PSOM (do inglês: Non Parametric Self-Organizing Map), incluindo a realização de alocação de recursos financeiros de forma otimizada por meio de Programação Linear Inteira. Utilizando a rede PSOM, foi possível agrupar os consumidores dos dois transformadores em 12 grupos distintos com mesmo “perfil de consumo”. Esse agrupamento foi importante para o dimensionamento de Sistemas Fotovoltaicos Conectados à Rede Elétrica (Sistemas Grid-Tie) utilizando diferentes ferramentas computacionais, dentre elas, o software PVSyst na versão trial V6.39. Adicionalmente, foi feito um estudo de Engenharia Econômica visando a implantação de Sistemas Fotovoltaicos Conectados à Rede Elétrica para todos os consumidores de Nova Veneza-GO e de Goiânia-GO, considerando dados de consumo disponibilizados pela concessionária local e também considerando dois diferentes cenários: implantação de sistemas fotovoltaicos com e sem incentivo do governo. Foi realizada ainda uma análise de Engenharia Econômica considerando uma adesão em Goiânia-GO de 1%, 5%, 10%, 20%, 30% e 100% das Unidades Consumidoras (UC). Resultados ambientais foram encontrados para a cidade de Nova Veneza-GO e Goiânia-GO, evidenciando uma redução expressiva na emissão de CO2 e uma grande economia de água.
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Joubert-Garnaud, Carole. « Les énergies renouvelables dans l’agriculture de la Charente-Maritime : l’émergence en milieu rural d’un nouveau moteur du développement économique et social non dépourvu d’incidences sur l’environnement local ». Thesis, La Rochelle, 2010. http://www.theses.fr/2010LAROF035/document.
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Cette thèse porte sur la place nouvellement attribuée aux énergies renouvelables dans un département français encore largement rural, la Charente-Maritime, alors que commence à se poser, ici comme ailleurs, la question du changement climatique et celle de l’épuisement des énergies fossiles dans un contexte privilégiant de plus en plus la mise en place de mesures de protection de l’environnement. La thèse passe en revue les différentes énergies renouvelables d’ores et déjà produites et utilisées en Charente-Maritime ou dont la mise en œuvre est envisagée (hydroélectricité, solaire, éolien, énergie issue de la biomasse). Plusieurs exemples précis d’exploitations agricoles impliquées dans la production et la consommation de ces nouvelles énergies sont longuement présentés. La thèse s’intéresse également au potentiel de développement de ces énergies, à leurs retombées sur l’environnement et à la façon dont elles sont perçues, tant par les agriculteurs que les élus locaux, les responsables d’associations ou les habitants en général. Il apparaît clairement que la politique de développement des énergies renouvelables actuellement menée en Charente-Maritime est incitative, tout particulièrement en ce qui concerne l’énergie solaire et la biomasse énergie au profit desquelles les aides régionales et départementales sont importantes (mise en œuvre d’une filière locale bois – énergie dans le pays Saintonge Romane). Par contre, l’édification de parcs éoliens est freinée par les pouvoirs publics en raison de leur trop fort impact paysager dans un département à vocation touristique affirmée. La thèse montre, en fin de compte, que le bilan environnemental que l’on peut tirer de toutes ces innovations apparaît mitigé : le recours aux énergies renouvelables réduit un peu la dépendance des campagnes charentaises à l’égard des énergies fossiles, mais l’impact environnemental direct de ces nouvelles sources d’énergie apparaît ambigu et pour le moins contrasté. L’étude, quoique conduite dans un cadre territorial relativement restreint, est néanmoins largement représentative des transformations en cours dans les campagnes françaises, voire européennes, les particularités locales et nationales ayant été clairement soulignéesThis thesis deals with the newly role given to the renewable energies in a still rural French area, The Charente Maritime, while here and there, two issues are at stake : the question of climate change as well as the dramatic decrease of fossil energy stocks, in a period more and more turning towards the implementation of environment protection measures.Our research makes a review of the different renewable energies. Firstly the ones already produced and used in Charente Maritime, secondly the ones whose implementation is planned and eventually those which are in a state of project. (hydroelectric, solar, wind and biomass energies). The thesis is also about the potential of these energies expansion, about their consequences on environment, and in the way farmers, local representatives, association leaders and inhabitants view them.As a conclusion the thesis shows that environment results that we can draw from all these innovations is mixed : while the use of renewable energies reduce a little the dependence of Charentaises countries from fossil energies, the direct environment impact of these new energy sources appears ambiguous and especially contrasted. The study has been made in a quite little geographical area. It is all the same representative of the current changes in the French as well as the European countryside, the local and national specificities having been clearly underlined
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Cabral, João Bosco Ribeiro Fernandes. « Conversor CC-CC Não isolado de elevado ganho para aplicação no processamento de energia solar fotovoltaica ». Universidade do Estado de Santa Catarina, 2013. http://tede.udesc.br/handle/handle/2075.
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Previous issue date: 2013-03-06Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This Master Thesis proposes a high gain non-isolated DC-DC converter applied on the processing of PV energy. The proposed converter is a boost converter with quadratic characteristic and with central point at its output. Basic operations and electric characteristics of a PV cell are described, including the procedures to determine its parameters. A model for numeric simulation is presented. A review of the high gain non-isolated DC-DC converters topologies is presented. Shows the converter´s transfer functions and the control strategy adopted as well as the design of control circuits. The control system is consisting of three loops, an internal loop of input current control, an external loop of total output voltage control and an additional loop of voltage unbalance control. The simulation and experimental results are shown to validate the analysis developed and demonstrate the performance of the control system adopted.
Esta Dissertação de Mestrado propõe um conversor CC-CC não isolado de elevado ganho para aplicação no processamento de energia solar fotovoltaica. O conversor proposto é um boost com característica quadrática e com ponto médio na sua saída. Descrevem-se o funcionamento básico e as características elétricas de uma célula fotovoltaica, incluindo-se o procedimento da determinação dos parâmetros e da modelagem dos módulos fotovoltaicos, apresentando-se um modelo para simulação numérica. Apresenta-se uma revisão de topologias de conversores CC-CC não isolados com elevado ganho estáticos. Apresentam-se as funções de transferência do conversor e a estratégia de controle adotada bem como o projeto dos circuitos de controle. O sistema de controle composto por três malhas de controle, uma malha interna de corrente de entrada, uma malha externa de tensão total e uma malha adicional de equalização de tensão. Resultados de simulação e experimentais são apresentados para validar as análises desenvolvidas e demonstrar o desempenho do sistema de controle adotado.
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Senevirathna, Wasana. « Azadipyrromethene-based Metal Complexes as 3D Conjugated Electron Acceptors for Organic Solar Cells ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1402062085.
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Fumo, Nelson. « COOLING, HEATING, AND POWER SYSTEMS ENERGY PERFORMANCE AND NON-CONVENTIONAL EVALUATION BASED ON ENERGY USE ». MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06062008-120919/.
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Cooling, Heating and Power (CHP) systems have been recognized as a key alternative for thermal energy and electricity generation at or near end-user sites. CHP systems can provide electricity while recovering waste heat to be used for space and water heating, and for space cooling. Although CHP technology seems to be economically feasible, because of the constant fluctuations in energy prices, CHP systems cannot always guarantee economic savings. However, a well-designed CHP system can guarantee energy savings, which makes necessary the quantification of non-conventional benefits from this technology in order to offset any economic weakness that can arise as consequence of energy prices. Some aspects that could be included in a non-conventional evaluation are: building energy rating, emission of pollutants, power reliability, power quality, fuel flexibility, brand and marketing benefits, protection from electric rate hikes, and benefits from promoting energy management practices. This study focuses on two aspects: building energy rating and emission reduction of pollutants, related to CHP system energy performance. Two methodologies have been developed in order to estimate the energy related benefits from CHP technology. To determine the energy performance, a model has been developed and implemented to simulate CHP systems in order to estimate the building-CHP system energy consumption. The developed model includes the relevant variables governing CHP systems such as: type and size of the components, individual component efficiencies, system operating mode, operational strategy, and building demand for power, heating, and cooling. The novelty of this model is the introduction of the Building Primary Energy Ratio (BPER) as a parameter to implement a primary energy operational strategy, which allows obtaining the best energy performance from the building-CHP system. Results show that the BPER operational strategy always guarantees energy savings. On the other hand, results from a cost-oriented operational strategy reveal that for critical design conditions, high economic savings can be obtained with unacceptable increment of energy consumption. For Energy Star Rating and Leadership in Energy and Environmental Design (LEED) Rating, results show that CHP systems have the ability to improve both ratings.
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FORMOZOV, ANDREY. « SEARCH FOR NON-STANDARD NEUTRINO INTERACTIONS WITH LARGE-VOLUME LIQUID SCINTILLATOR DETECTORS ». Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/646205.
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Even though electroweak part of the Standard Model passed decades of testing and precision measurements, there is still a space for the presence of new physics. In particular, the neutrino sector in the last years has been reaching the level of precision oscillometry. However, the current data are not able to exclude many possible extended scenarios, in which new interactions comparable with the standard ones are still possible. This work is dedicated to beyond-Standard-Model interactions of neutrino and electron called Non-Standard Interactions or shortly NSI. Analogously to standard electroweak interactions, NSI could be charged current (CC) and neutral current (NC) type. Usually, in analyses of experiments, NC and CC NSI are considered separately, and I follow this strategy in the course of this work. The global search for NSI involves almost all experimental approaches of neutrino physics and goes far beyond the scope of this work. Here, instead, I look at the problem through the prism of the large-scale liquid scintillator experiments and confine the investigation to the search for NC NSI with solar neutrinos. In addition, I review CC NSI with reactor neutrinos at medium baseline.
As a contribution into upcoming JUNO experiment, I investigate liquid scintillator energy response and radiopurity, which are essential for the successful realization of solar and reactor neutrino physics programs and, therefore, for NC and CC NSI search. I analyze in detail the non-linearity and energy resolution of liquid scintillator. I develop an experimental Compton coincidence technique with High Pure Germanium gamma spectrometer, provide a conservative measurement of the Birks’ ionization quenching constant kB and discuss problems related to its measurement. Throughout the study, I also formulate the optimal characteristics of the experimental apparatus for this improvement. The ultimate goal of this investigation is separating intrinsic energy resolution, which was never yet robustly measured for liquid organic scintillators. The intrinsic energy resolution may have an impact on the energy response of the new generation large liquid scintillator detectors such as JUNO and have to be carefully investigated. Applying single photon counting technique, I perform a calibration of the PMT charge scale and set apart statistical term from the total liquid scintillator energy resolution. Remaining term significantly differs from zero, indicating the presence of additional contribution associated with the intrinsic energy resolution. As an outlook, the precise estimation of the light collection should be conducted in order to ensure that its contribution is not significant to mimic the observed intrinsic resolution effect. The analysis of the radiopurity of the liquid scintillator showed that it is close to the one demanded for reactor neutrino program and CC-NSI search. Still, an improvement of purification procedure is necessary to fulfill solar neutrino program requirements for NC NSI search. Finally, I place the limits to NC NSI parameters for electron and tau neutrino with the Phase II data of Borexino experiment. The limits are quite stringent and compatible with other experiments. The best up-to-date limit to the left electron NSI-parameter is obtained. The allowed regions could be further significantly reduced by incorporating the current result in a global analysis. Besides, the same analysis approach is used to measure the squared sine of the Weinberg angle with a precision comparable with reactor neutrino experiments and place the most robust limit on the probability of ν−ν̄ conversion in the Sun for solar neutrinos with energies Eν < 1.8 MeV. I conclude with deliberation on the applicability of solar neutrino NC NSI approach for current JUNO detector configuration.
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Fernando, Juwanmandadige Roshan. « Tuning the Opto-Electronic Properties of Core-Substituted Naphthalenediimides through Imide Substitution ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1401984667.
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Shahin, Ahmed Eid Moussa. « Contribution à l’optimisation des structures de conversion DC/DC non isolées ». Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL045N/document.
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Dans ce mémoire, nous avons étudié les convertisseurs d’interface permettant l’interconnexion d’une source basse tension non linéaire et d’un bus DC moyenne tension. La source choisie, pour l’étude, était une pile à combustible de type PEM. La structure de puissance retenue correspondant à la mise en cascade d’un convertisseur entrelacé en entrée et d’un convertisseur trois niveaux en sortie. Afin de dimensionner au mieux le convertisseur global, nous avons proposé un modèle analytique permettant de connaitre l’ensemble des pertes dans le système en fonction du point de fonctionnement et de ses paramètres. Nous avons montré que l’ensemble des pertes dans le convertisseur peut être modélisé par deux résistances non linéaires dont l’estimation est possible à partir des modèles moyens du convertisseur. Une commande basée sur le concept de platitude des systèmes différentiels a été utilisée pour assurer les différentes contraintes du système tout en obtenant des propriétés dynamiques élevées en asservissement et en régulation. Dans la dernière partie du mémoire, nous nous sommes intéressés aux solutions permettant de satisfaire les contraintes sur le taux d’ondulation de courant en entrée du convertisseur. Nous avons proposé et dimensionné une nouvelle structure de convertisseur permettant de supprimer les ondulations de courant générées par le convertisseur de puissance. Ce filtre actif se connecte en parallèle avec le convertisseur de puissance. Des résultats expérimentaux ont permis de montrer que le taux d’ondulation de courant d’un convertisseur élévateur a été réduit, le taux d’ondulation de courant passant de 23.3% à 1.9%In this thesis, we studied interface converters enabling the interconnection of a low voltage nonlinear source and a medium voltage DC bus. The source selected for the study was a fuel cell PEM. The chosen power architecture corresponds to a cascaded structure constituted with an interleaved Boost converter at input stage and a three-level Boost converter at output stage. To design the converter, we proposed an analytical model to know the total losses in the system according to the operating point and its parameters. We showed that all losses in the converter can be modeled by two nonlinear resistors. An estimation of these resistors, deduced from average model of the converter, is developed. A control based on the concept of differential systems flatness has been used for the proposed converter structure. It allows taking into account the different system constraints. High dynamic properties as regard to external perturbations or parameters variations are achieved. In the last part of the thesis, we investigate solutions to respect the constraints on the rate of input current ripple. We propose a new active filtering converter connected in parallel with the power one. We have shown that the ripple current of a boost converter was reduced, the ripple current being reduced from 23.3% to 1.9%
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Lipana, Catherine H. « When incentives are not enough : a study on how the Philippine government can attract foreign investments in renewable power / ». Bergen : Norges Handelshøyskole, 2008. http://bora.nhh.no:8080/bitstream/2330/2118/1/Lipana%202008.pdf.
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De, Silva Tharukara Sudath Priyantha. « Develop strategies to increase the Non Conventional Renewable Energy power generation in Sri Lanka above 10% level by the year 2015 ». Thesis, KTH, Energi och klimatstudier, ECS, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109768.
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World’s energy needs are increasing day by day and meeting that ever increasing demand by fossil fuels is becoming difficult due to factors like scarcity of the resource, vulnerability of supply due to political unrest of fuel rich countries, and environmental implications of usage. As a result, Usage of renewable energy resources as alternatives is becoming popular and important. Sri Lanka has already committed to achieve 10% of grid connected electricity energy from Non Conventional Renewable Energy sources by the year 2015 and launched many programs to support that initiative. Under this dissertation, a broad study on present and future electricity generation and transmission network of Sri Lanka are carried out referring the most recent CEB publications like Long Term Generation Expansion Plan and Transmission Expansion plans and further using the expert opinions. Special attention is given to calculate present and future (2015) Non Conventional Renewable Energy share of power generation considering the constraints and mentioning the assumptions. Existing policies to promote NCRE power generation are reviewed while discussing the barriers. Wind has identified as the viable potential candidate as future NCRE power generation option even though the near term capacity is limited due to grid constraints and inadequate transmission and distribution network. It is recommended to the government to start an accelerated wind power harness program by addressing the issues pertaining to the technology. The strategies developed under the study are all about to achieve more than 10% target by the year 2015.
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Liu, Li. « Propriétés photo-physiques de nouveaux matériaux moléculaires pour la conversion de photons en énergie ». Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE010/document.
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Plusieurs processus photo-induits d'énergie et de transfert d'énergie ont été étudiés en solution et dans le film par spectroscopie d'absorption transitoire et de fluorescence pour deux types de cellules solaires. Combinés avec d'autres expériences et par une analyse globale, ces phénomènes ultrarapides avec leur durée de vie ont été observés et les scénarios photo-induits ont été déterminés. La compréhension approfondie des matériaux moléculaires pourrait aider les chimistes à concevoir des cellules solaires efficaces. La première étude sur l'influence des conceptions chimiques sur la formation et la séparation des charges implique différentes fractions donneuses et différents solvants et les résultats ont été expliqués par la théorie de Marcus-Jortner combinée avec le calcul quantique. La deuxième étude porte sur les complexes Fe (II) comme photosensibilisateurs pour les cellules solaires sensibilisées aux colorants. On a étudié une série de complexes de Fe (II) homo et hétérotéptiques avec des ligands de carbène et de terpyridine en solution et dans le film. La durée de vie de l'état de transfert de la charge métal-ligand du triplet d'enregistrement du complexe Fe (II) est obtenue en solution. La compréhension du film est en coursVarious photo-induced energy and energy transfer processes were investigated in solution and in the film by transient absorption and fluorescence spectroscopies for two types of solar cells. Combined with other experiments and through a global analysis, those ultrafast phenomena with their lifetimes were observed and the photo-induced scenarios were determined. The insight understanding of molecular materials could help chemists to design efficient solar cells.The first study about the influence of chemical designs on charge formation and separation involves different donor moieties and different solvents and the results were explained by Marcus-Jortner theory combined with quantum calculationThe second investigation is about Fe(II) complexes as photosensitizers for dye-sensitized solar cells. A series of homo- and heteroleptic Fe(II) complexes with carbene and terpyridine ligands have been studied in solution and in the film. The record triplet metal-to-ligand charge transfer state lifetime of Fe(II) complex is achieved in solution. The further understanding in the film is in progress
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Sehar, Fakeha. « Impact of Ice Storage on Electrical Energy Consumption in Large and Medium-sized Office Buildings in Different Climate Zones ». Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/35291.
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Cooling demand constitutes a large portion of total electrical demand for office buildings during peak hours. Deteriorating load factors, increased use of more inefficient and polluting peaking units are the aftermaths of growth in peak demand challenging energy system efficiency and grid reliability.
Ice storage technology can help shift this peak cooling demand to off-peak periods. Ice storage reduces or even eliminates chiller operation during peak periods. The objective of the research is to analyze the chiller energy consumption of conventional non-storage and ice storage cooling systems for large and medium-sized office buildings in diverse climate zones. The research also quantifies the peak energy savings as a result of ice storage systems.
To accomplish the thesis objectives the Demand Response Quick Assessment Tool (DRQAT) has been used to model and simulate large and medium-sized office buildings in diverse climate zones with non-storage and ice storage cooling systems. Demand Response Quick Assessment Tool (DRQAT) has been developed by LBNLâ s Demand Response Research Center. It is based on the most popular features and capabilities of EnergyPlus and is downloadable from [1]. The construction and weather files in DRQAT have been modified to incorporate construction standards and weather data for the cities representing the diverse climate zones. The ice storage systemâ s operating and control strategies investigated include full storage and partial storage with storage priority and chiller priority.
Research findings indicate that chiller energy consumption for non-storage and ice storage systems depends highly on climatic conditions. The climate zones with hot summers as well as small day and night temperature variations show higher chiller energy consumption. The marine climate zone has the lowest chiller energy consumption. The cold/humid climate zone has higher chiller energy consumption than the cold/dry and very cold climate zones. The cold/dry and very cold climate zones have comparable chiller energy consumption. The research findings will help utilities and building owners to quantify the benefits of installing ice storage systems in office buildings located in different climate zones.Master of Science
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Piedrafita, Francos Daniel. « Designing, testing and modelling two innovative non-conventional buckling restrained braces for seismic resistant buildings ». Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/284738.
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In this thesis two all-steel BRB have been designed, manufactured and tested, and both satisfy the testing protocols required by EU and US codes. They are composed of a steel slotted restraining unit which stabilizes the steel core. The first one, the Modular Buckling Restrained Brace (MBRB), is composed by several seriated modules which contain several dissipation units connected in parallel, which yield under shear forces. Although it has good hysteretic response and a high ductility, its core is heavy and expensive to manufacture. The second one,the Slotted Buckling Restraining Brace (SBRB), solves these two shortcomings. It yields under axial forces, like the conventional BRBs, but the usual solid core has been substituted by a perforated plate. The core is a one-piece element composed of two lateral bands, of a nearly uniform section and designed to yield, connected by stabilizing bridges, which behave elastic. The buckling prevention of the lateral bands is done by the restraining unit and the stabilizing bridges. Design expressions have been proposed to design both devices, and a numerical material model have been formulated and implemented in commercial finite element method software to numerically simulate the behavior of the braces, which will reduce the need of full scale tests for its designEn la present tesi, dos BVR totalment metàl·lics s’han dissenyat, fabricat i assajat, satisfent tots dos els requeriments dels protocols definits per les normes europees i americanes. Estan formats per un element de travat ranurat que estabilitza el nucli metàl·lic. El primer d’ells, el Braç de Vinclament Restringit Modular (BVRM), està format per diversos mòduls seriats que a la vegada contenen diverses unitats de dissipació, que plastifiquen sota esforços tallants, connectades en paral·lel. Tot i que té un bon comportament histerètic i una gran ductilitat, el nucli és pesat i difícil de fabricar. El segon braç, anomenat Braç de Vinclament Restringit Ranurat (BVRR), soluciona aquests inconvenients. Plastifica sota esforços axials, de la mateixa manera que els BVR convencionals, però el nucli massís és substituït per una platina perforada. Aquest nucli consisteix en un únic element composat per dos bandes laterals, dissenyades per a plastificar i amb una secció quasi constant, connectades per diversos ponts estabilitzadors que es mantenen sempre en el seu rang elàstic. Aquests ponts, juntament amb l’element de travat, impedeixen el vinclament de les bandes laterals. S’han proposat diverses expressions de disseny pels dos braços. S’ha formulat i implementat, en un programa d’elements finits comercial, un model de material per a simular numèricament el comportament dels braços, reduint així la dependència dels assajos a escala real durant el seu procés de disseny
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Trap, Guillaume. « Etude du trou noir massif central de la Galaxie et de son environnement ». Phd thesis, Université Paris-Diderot - Paris VII, 2011. http://tel.archives-ouvertes.fr/tel-00862003.
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Ce manuscrit rassemble une série de travaux observationnels et phénoménologiques relatifs à des objets compacts variables du centre de notre Galaxie, à savoir le trou noir supermassif central, Sagittarius A*, et des étoiles à neutrons hébergées par des sursauteurs X. La première partie traite de la source Sgr A*, sujette à des éruptions quotidiennes, dont les mécanismes déclencheurs et les processus de rayonnement sont encore inconnus. Cette activité éruptive a été sondée par l'intermédiaire de plusieurs vastes campagnes d'observations multi-longueurs d'onde (en rayons gamma, rayons X, infrarouge et submillimétrique) étalées entre 2007 et 2009. Des données recueillies simultanément par les instruments XMM-Newton/EPIC, INTEGRAL/ISGRI+JEM-X, Fermi/LAT, VLT/NACO+VISIR et APEX/LABOCA, lors de plusieurs nouvelles éruptions majeures, ont ainsi permis de caractériser en détail le comportement spectro-temporelle de ces dernières et de contraindre les modèles d'émissions non-thermiques du milieu radiatif (synchrotron, Compton inverse, plasmoïde en expansion). Dans un second temps, une vingtaine de sursauts X de type I en provenance de deux binaires X de faible masse, transitoires, du noyau Galactique, GRS 1741.9-2853 et AX J1745.6-2901, ont été examinés à travers les données de différents satellites X de basse énergie (2-30 keV). Ces observations ont été discutées dans le cadre théorique, relativement bien établi, d'explosions thermonucléaires d'un mélange hydrogène-hélium, amassé à la surface d'étoiles à neutrons accrétantes.
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Rahmani, Mustapha Amine. « Gestion de l'énergie d'une micro-centrale solaire thermodynamique ». Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT077/document.
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Cette thèse s'inscrit dans le cadre du projet collaboratif MICROSOL, mené par Schneider Electric, et qui oeuvre pour le développement de micros centrales solaires thermodynamiques destinées à la production d'électricité en sites isolés (non connectés au réseau électrique) en exploitant l'énergie thermique du soleil. Le but de cette thèse étant le développement de lois de commande innovantes et efficaces pour la gestion de l'énergie de deux types de micros centrales solaires thermodynamiques : à base de moteur à cycle de Stirling et à base de machines à Cycle de Rankine Organique (ORC). Dans une première partie, nous considérons une centrale solaire thermodynamique à base de machine à cycle de Stirling hybridée à un supercondensateur comme moyen de stockage d'énergie tampon. Dans ce cadre, nous proposons une première loi de commande validée expérimentalement, associée au système de conversion d'énergie du moteur Stirling, qui dote le système de performances quasi optimales en termes de temps de réponse ce qui permet de réduire la taille du supercondensateur utilisé. Une deuxième loi de commande qui gère explicitement les contraintes du système tout en dotant ce dernier de performances optimales en terme de temps de réponse, est également proposée. Cette dernière loi de commande est en réalité plus qu'un simple contrôleur, elle constitue une méthodologie de contrôle applicable pour une famille de systèmes de conversion de l'énergie.Dans une deuxième partie, nous considérons une centrale solaire thermodynamique à base de machine à cycle de Rankine Organique (ORC) hybridée à un banc de batteries comme moyen de stockage d'énergie tampon. Etant donné que ce système fonctionne à vitesse de rotation fixe pour la génératrice asynchrone qui est connectée à un système de conversion d'énergie commercial, nous proposons une loi de commande prédictive qui agit sur la partie thermodynamique de ce système afin de le faire passer d'un point de fonctionnement à un autre, lors des appels de puissance des charges électriques, le plus rapidement possible (pour réduire le dimensionnement des batteries) tout en respectant les contraintes physiques du système. La loi de commande prédictive développée se base sur un modèle dynamique de la machine ORC identifié expérimentalement grâce à un algorithme d'identification nonlinéaire adéquatThis Ph.D thesis was prepared in the scope of the MICROSOL project, ledby Schneider Electric, that aims at developing Off-grid solar thermodynamic micro powerplants exploiting the solar thermal energy. The aim of this thesis being the development of innovative and efficient control strategies for the energy management of two kinds of solar thermodynamic micro power plants: based on Stirling engine and based and Organic RankineCycle (ORC) machines.In a first part, we consider the Stirling based solar thermodynamic micro power planthybridized with a supercapacitor as an energy buffer. Within this framework, we propose afirst experimentally validated control strategy, associated to the energy conversion system ofthe Stirling engine, that endows the system with quasi optimal performances in term of settlingtime enabling the size reduction of the supercapacitor. A second control strategy that handlesexplicitly the system constraints while providing the system with optimal performances interm of settling time , is also proposed. This control strategy is in fact more than a simplecontroller, it is a control framework that holds for a family of energy conversion systems.In a second part, we consider the Organic Rankine Cycle (ORC) based thermodynamicmicro power plant hybridized with a battery bank as an energy buffer. Since this system worksat constant speed for the asynchronous generator electrically connected to a commercial energyconversion system, we propose a model predictive controller that acts on the thermodynamicpart of this system to move from an operating point to another, during the load power demandtransients, as fast as possible (to reduce the size of the battery banks) while respecting thephysical system constraints. The developed predictive controller is based upon a dynamicmodel, for the ORC power plant, identified experimentally thanks to an adequate nonlinearidentification algorithm
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Sakho, Moctar. « Méthodes de calcul des apports solaires par les ouvertures de bâtiments non conventionnels en environnement complexe ». Grenoble 1, 1989. http://www.theses.fr/1989GRE10082.
Texte intégralRésumé :
L'objet de ce travail est l'elaboration de programmes pour micro-ordinateurs ibm-pc et compatibles, permettant le calcul des apports solaires par les ouvertures de batiments, dans le cas d'une architecture non conventionnelle et d'un environnement complexe. Les apports par rayonnement direct sont calcules par le programme insol-b qui peut aussi servir a la determination des ombres portees. Les apports par les rayonnements reflechis et diffus sont determines par le programme insol-dr; le modele de ciel anisotrope de perez est utilise pour le rayonnement diffus
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Oliveira, Eduardo Sylvestre Lopes de. « Projeto, construção, simulação, implementação e testes de um gerador a relutância chaveada monofásico ». Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18153/tde-08082011-164853/.
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O objetivo do trabalho é apresentar o funcionamento de um gerador a relutância chaveado monofásico. Para isso, foi desenvolvido um modelo computacional em ambiente Matlab Simulink, fazendo-se a comunicação entre diferentes partes do sistema. O comportamento da dinâmica de geração é apresentado para diferentes pontos do sistema, e testes experimentais realizados em um pequeno protótipo confirmam as características funcionais desta máquina. Ensaios realizados comprovam sua funcionalidade e simplicidade de operação, tendo estabilidade de geração para ampla faixa de velocidade de funcionamento, caracterizando uma máquina promissora, robusta e eficiente para aplicações especiais.This work presents a single-phase switched reluctance machine operating as a generator. For that purpose, a computational model was developed in Matlab Simulink environment, wherein all the system components, such as voltage source, drive and machine model, and load were integrated. The current and voltage behavior for several points of operations are presented. Furthermore, experimental tests were also carried out in a simple prototype to validate its functionality and simplicity of operation, providing a stable power generation over a wide range of speed. The results showed that the single-phase switched reluctance generator can be robust, efficient, and promising for especial applications.
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Mallangi, Siva Sai Reddy. « Low-Power Policies Based on DVFS for the MUSEIC v2 System-on-Chip ». Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229443.
Texte intégralRésumé :
Multi functional health monitoring wearable devices are quite prominent these days. Usually these devices are battery-operated and consequently are limited by their battery life (from few hours to a few weeks depending on the application). Of late, it was realized that these devices, which are currently being operated at fixed voltage and frequency, are capable of operating at multiple voltages and frequencies. By switching these voltages and frequencies to lower values based upon power requirements, these devices can achieve tremendous benefits in the form of energy savings. Dynamic Voltage and Frequency Scaling (DVFS) techniques have proven to be handy in this situation for an efficient trade-off between energy and timely behavior. Within imec, wearable devices make use of the indigenously developed MUSEIC v2 (Multi Sensor Integrated circuit version 2.0). This system is optimized for efficient and accurate collection, processing, and transfer of data from multiple (health) sensors. MUSEIC v2 has limited means in controlling the voltage and frequency dynamically. In this thesis we explore how traditional DVFS techniques can be applied to the MUSEIC v2. Experiments were conducted to find out the optimum power modes to efficiently operate and also to scale up-down the supply voltage and frequency. Considering the overhead caused when switching voltage and frequency, transition analysis was also done. Real-time and non real-time benchmarks were implemented based on these techniques and their performance results were obtained and analyzed. In this process, several state of the art scheduling algorithms and scaling techniques were reviewed in identifying a suitable technique. Using our proposed scaling technique implementation, we have achieved 86.95% power reduction in average, in contrast to the conventional way of the MUSEIC v2 chip’s processor operating at a fixed voltage and frequency. Techniques that include light sleep and deep sleep mode were also studied and implemented, which tested the system’s capability in accommodating Dynamic Power Management (DPM) techniques that can achieve greater benefits. A novel approach for implementing the deep sleep mechanism was also proposed and found that it can obtain up to 71.54% power savings, when compared to a traditional way of executing deep sleep mode.Nuförtiden så har multifunktionella bärbara hälsoenheter fått en betydande roll. Dessa enheter drivs vanligtvis av batterier och är därför begränsade av batteritiden (från ett par timmar till ett par veckor beroende på tillämpningen). På senaste tiden har det framkommit att dessa enheter som används vid en fast spänning och frekvens kan användas vid flera spänningar och frekvenser. Genom att byta till lägre spänning och frekvens på grund av effektbehov så kan enheterna få enorma fördelar när det kommer till energibesparing. Dynamisk skalning av spänning och frekvens-tekniker (såkallad Dynamic Voltage and Frequency Scaling, DVFS) har visat sig vara användbara i detta sammanhang för en effektiv avvägning mellan energi och beteende. Hos Imec så använder sig bärbara enheter av den internt utvecklade MUSEIC v2 (Multi Sensor Integrated circuit version 2.0). Systemet är optimerat för effektiv och korrekt insamling, bearbetning och överföring av data från flera (hälso) sensorer. MUSEIC v2 har begränsad möjlighet att styra spänningen och frekvensen dynamiskt. I detta examensarbete undersöker vi hur traditionella DVFS-tekniker kan appliceras på MUSEIC v2. Experiment utfördes för att ta reda på de optimala effektlägena och för att effektivt kunna styra och även skala upp matningsspänningen och frekvensen. Eftersom att ”overhead” skapades vid växling av spänning och frekvens gjordes också en övergångsanalys. Realtidsoch icke-realtidskalkyler genomfördes baserat på dessa tekniker och resultaten sammanställdes och analyserades. I denna process granskades flera toppmoderna schemaläggningsalgoritmer och skalningstekniker för att hitta en lämplig teknik. Genom att använda vår föreslagna skalningsteknikimplementering har vi uppnått 86,95% effektreduktion i jämförelse med det konventionella sättet att MUSEIC v2-chipets processor arbetar med en fast spänning och frekvens. Tekniker som inkluderar lätt sömn och djupt sömnläge studerades och implementerades, vilket testade systemets förmåga att tillgodose DPM-tekniker (Dynamic Power Management) som kan uppnå ännu större fördelar. En ny metod för att genomföra den djupa sömnmekanismen föreslogs också och enligt erhållna resultat så kan den ge upp till 71,54% lägre energiförbrukning jämfört med det traditionella sättet att implementera djupt sömnläge.
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Barik, Satyanarayan. « Hybrid Solar PV and Wind-Driven PMSG System with Single DC-DC Converter and Hysteresis Inverter ». Thesis, 2016. http://ethesis.nitrkl.ac.in/9290/1/2016_MT_SBarik.pdf.
Texte intégralRésumé :
Due to shortage of fossil fuels and the bad environmental effects, a lot of research is going on renewable energy sources. By the invention of high grade PV cells and better MPPT technique PV system is largely utilised now a days. To make it more reliable PV along with wind generator is used as a hybrid system. Many techniques are used to extract the maximum power from both the sources. Here Perturb and Observe method is used with little modification.
In conventional hybrid system we use two dc-dc converter, i.e one DC-DC converter for each energy source. But here instead of two DC-DC converter, one DC-Dc converter is used. Both the sources are connected to a common Dc bus whose voltage is controlled by MPPT algorithm and Boost converter. By minimising the no of converter the loss in the circuit is reduced and hence the efficiency is increased. The energy is converted to ac by hysteresis controlled inverter and then connected to grid. The above method is modelled and simulated in Simulink/matlab and the results are verified.
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REJŠKOVÁ, Alžběta. « Non-metabolic use of solar energy in plants ». Doctoral thesis, 2009. http://www.nusl.cz/ntk/nusl-49140.
Texte intégralRésumé :
Non-metabolic use of solar energy in plants can be seen as plant thermoregulation driven directly by solar irradiance. Adaptations leading to warming up are particularly important in cold habitats. Cooling processes are needed everywhere where there is short-term or long-term excess of solar energy. Plants are of utmost importance for ecosystem and landscape functioning. Vegetation has a potential to regulate the Earth{\crq}s surface temperature and improve conditions for other living organisms. By regulating energy and water fluxes between land surface and the atmosphere vegetation is closely related to the climate system.
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Peterseim, JHM. « Enabling concentrating solar power in Australia : an investigation of the benefits and potential role of concentrating solar power and non-conventional fuel hybrid plants in Australia's transition to a low-carbon energy future ». Thesis, 2014. http://hdl.handle.net/10453/30341.
Texte intégralRésumé :
University of Technology, Sydney. Institute for Sustainable Futures.After decades of stability the Australian electricity market is undergoing changes. Current government targets aim to reduce greenhouse gas emissions by 5% and raise renewable electricity production to 45 TWh by 2020. In addition, increases to natural gas prices, aging generation assets and falling electricity demand have had an impact in recent years. Uncertainties exist around current policies, including the carbon pricing mechanism and the renewable energy target, but in light of Australian and international ambitions to lower greenhouse gas emissions the deployment of renewable energy technologies is essential. In recent years wind and photovoltaic installations have shown the highest renewable energy growth rates while concentrating solar power has struggled, despite Australia having some of the best natural resources for concentrating solar power in the world and some selected government funding. Reasons for the slow uptake include the comparatively high cost and lack of financial incentives. While technology costs are expected to decrease by up to 40% by 2020 through deployment as well as research and development, other cost reduction options have to be identified to promote short-term implementation in electricity markets such as Australia where the wholesale cost is low. To overcome the cost problem and to address other relevant implementation barriers this research analyses the hybridisation of concentrating solar power with biomass and waste feedstocks. The results of this research include: ▪ a recommendation for a categorisation system for CSP hybrid plants based on the degree of interconnection of the plant components ▪ the availability of combined resources to generate up to 33.5 TWh per year and abate 27 million tonnes CO₂ annually ▪ an analysis of the most suitable CSP technologies for hybridisation ▪ a technology comparison showing CSP cost reductions through hybridisation of up to 40% ▪ the identification of cost differences of up to 31% between different hybrid concepts ▪ an analysis showing that the current economic and policy settings are the most significant implementation barriers ▪ two case studies with different biomass and waste feedstocks requiring power purchase agreements of AU$ 100-155/MWh. Based on the various benefits of concentrating solar power hybrid plants, this research analyses the potential role of this technological pairing in Australia’s transition to a low carbon energy future. The research concludes that concentrating solar power hybrid plants, not only hybridised with biomass and waste feedstocks, can immediately enable a lower cost deployment of concentrating solar power facilities in Australia. The technology, deployment and operation of the first hybrid installations would provide market participants with valuable lessons and would have the potential to reconfigure the electricity market towards more sustainable generation. This could help promote the development of future low-cost concentrating solar power plants in Australia.
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Althobaiti, Wejdan. « Photophysics of Poly(3-hexylthiophene):Non-Fullerene Acceptor Organic Solar Cells ». Thesis, 2021. http://hdl.handle.net/10754/670709.
Texte intégralRésumé :
Insight into the relationship between the Ionization Energy (IE) offsets between donor and acceptor materials and the performance of the organic solar cells (OSC) could improve the charge generation efficiency. Charge generation can proceed through two different paths in Bulk Heterojunction (BHJ) based OSCs which are electron transfer from donor to acceptor and hole transfer from acceptor to donor. Electron transfer can be controlled by electron affinities and hole transfer can be controlled by ionization energies. In this work, large IE offsets were investigated in poly(3-hexylthiophene-2,5-diyl)(P3HT):Non Fullerene Acceptor (NFA) based OSCs by fabricating and characterizing devices, also conducting several experiments to optimize the processing conditions for the devices. These results provide an overview of the charge transfer and IE offsets dependence, also a general picture of the photophysics in P3HT:NFAs based OSCs. Moreover, using wide bandgap polymer donor which has shallow IE such as P3HT with low-bandgap NFAs may provide sufficient IE offsets between donor and acceptors enabled us to reach the inverted Marcus regime. In this regime, the electron transfer rate decreases upon decreasing the charge transfer (CT) state energy compared to the exciton energy. The decrease of the internal quantum efficiency (IQE) upon increasing the IE offset suggests that we are in that regime.
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ALLAM, MAJD. « Renewable energy in the Mediterranean sea : the economic influence ». Doctoral thesis, 2020. http://hdl.handle.net/11573/1463603.
Texte intégralRésumé :
The aim of our thesis is to study the current situation of renewable energy in the Mediterranean Sea and to examine the relationship between GDP and renewable energy consumption; by using statistical techniques as correlation tests, cluster analysis and multiple linear regression models. It is in the latter that the main contribution of this research has been made. This research has made it possible to perceive the close relationship between renewable energy and gross domestic product. Our research broadens the knowledge basics of this field in the Mediterranean countries’ context. It gives focus on the available energy sources in this region, in order to understand better the social and environmental role of renewable energy in achieving sustainable development. The results of this study will enable researchers to create a stronger theoretical and empirical basis through which future research about the economic, social and political aspects of renewable energy can be developed.
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Haque, Kazi Ashraful. « Feasible estimation of PV installation in Bangladesh through studying statistical data of lands, households, and industries ». Thesis, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448428.
Texte intégralRésumé :
This thesis aims to determine the accessible solar potential and estimation of PV installation in Bangladesh to increase solar power production concerning conventional power production in Bangladesh. The rise of renewable energy sources and especially solar energy may result in a significant contribution to the power generation system. To achieve its advantage, proper study and research are important to establish the tangible solar capacity from relevant parameters. Conventional power production depends on a variety of factors and needs to be replaced by renewable resources for the increasing demand. Solar energy is a free source of energy and Bangladesh receives a huge quantity of solar radiation due to its geographical location in the tropical zone. In this thesis, solar irradiation, PV output, and many other parameters are determined to discover the potential of solar power. After that, total land area, population, number of households from the home establishment, number of industries, untilled land area, and other related factors are thoroughly studied and calculated to establish accessible solar electricity. Economic and environmental impacts are the most important criteria of this renewable resource from the country's perspective. Cost and CO2 emission are discussed for conventional electricity production and compared to solar electricity production.
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Real, Daniel Jordan. « Renewable Electricity Generation via Solar-Powered Methanol Reforming : Hybrid Proton Exchange Membrane Fuel Cell Systems Based on Novel Non-Concentrating, Intermediate-Temperature Solar Collectors ». Diss., 2015. http://hdl.handle.net/10161/11388.
Texte intégralRésumé :
Tremendous research efforts have been conducted studying the capturing and conversion of solar energy. Solar thermal power systems offer a compelling opportunity for renewable energy utilization with high efficiencies and excellent cost-effectiveness. The goal of this work was to design a non-concentrating collector capable of reaching temperatures above 250 °C, use this collector to power methanol steam reforming, and operate a proton exchange membrane (PEM) fuel cell using the generated hydrogen. The study presents the construction and characterization of a non-concentrating, intermediate-temperature, fin-in-tube evacuated solar collector, made of copper and capable of reaching stagnation temperatures of 268.5 °C at 1000 W/m2 irradiance. The collector was used to power methanol steam reforming, including the initial heating and vaporization of liquid reactants and the final heating of the gaseous reactants. A preferential oxidation (PROX) catalyst was used to remove CO from simulated reformate gas, and this product gas was used to operate a PEM fuel cell. The results show 1) that the outlet temperature is not limited by heat transfer from the absorber coating to the heat transfer fluid, but by the amount of solar energy absorbed. This implicates a constant heat flux description of the heat transfer process and allows for the usage of materials with lower thermal conductivity than copper. 2) It is possible to operate a PEM fuel cell from reformate gas if a PROX catalyst is used to remove CO from the gas. 3) The performance of the fuel cell is only slightly decreased (~4%) by CO2 dilution present in the reformate and PROX gas. These results provide a foundation for the first renewable electricity generation via solar-powered methanol reforming through a hybrid PEM fuel cell system based on novel non-concentrating, intermediate-temperature solar collectors.
Dissertation
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Sasidharan, Sayuj. « Studies on Pressurized Solar Thermal Receiver and Thermal Energy Storage System ». Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5658.
Texte intégralRésumé :
High-efficiency power cycles for concentrating solar power (CSP) technology such as air or supercritical carbon-dioxide (s-CO2) based Brayton cycle require high-pressure high-temperature conditions at the gas turbine inlet. This requires heating of the heat transfer fluid (HTF) to those conditions (~3-35 bar, 900-1600 K for air and ~200 bar, 1000 K for s-CO2) using a solar thermal receiver. Thus, the design and analysis of the pressurized receiver system form an important part towards the development of such solarized power plants.
A coupled optical and thermal model is developed for analyzing a cavity-based pressurized receiver, with dynamic variation of solar radiation input. The optical part involves the focal region flux characterization of a fixed-focus Scheffler reflector that provides a spatially resolved heat flux to the receiver cavity surface. This is achieved using a combination of on-sun experiments and ray-tracing simulation. On the other hand, the transience in heat input to the receiver is captured by curve-fitting the measured DNI variation with time corresponding to the experimental testing period. This spatially and temporally varying heat flux is coupled to the thermal analysis of the receiver to predict the flow field and the enthalpy gain by the heat transfer fluid (HTF) along with the thermal losses from the receiver cavity. This numerical model is subsequently validated with on-sun experimental testing of a hybrid tubular and cavity receiver using a 32 m2 Scheffler dish for heat input and compressed air at 20 bar as the HTF. The numerical and experimental results are found to be in good agreement under comparable conditions, thus proving the effectiveness of the coupled optical and thermal model. To account for the transient nature of the receiver heating during the on-sun experiments, the receiver efficiency definition is modified to include the thermal inertia of the receiver material. It is observed that natural convection is the dominant heat loss mechanism that significantly reduces the overall thermal efficiency of the receiver.
In the context of cavity receivers, the rate of heat transfer to the pressurized HTF is limited by the forced convection mode. For the enhancement of heat transfer in such systems, a passive method using metallic wire meshes in the HTF flow path is explored. Firstly, a pore-scale analysis is performed on the inline stacked wire mesh geometry for determining the hydraulic and thermal characteristics of the medium. The heat transfer taking place between the wire struts and the airstream at the local level is captured by thermal analysis on a representative elementary volume (REV) defined for this mesh geometry. This yields an interstitial Nusselt number for capturing the local heat transfer between the two phases. Subsequently, a homogeneous equivalent porous medium is defined using the properties obtained from the pore-scale analysis. For modelling the heat transfer within the two phases, the local thermal non-equilibrium (LTNE) model is implemented using the obtained Nusselt number correlation. The numerical model is subsequently validated with laboratory-scale experiments performed on a channel stacked with wire mesh layers and thermal load provided using an electric heater. The model prediction shows good agreement with the experimental results. However, the LTNE effect is not that pronounced under the present thermal conditions.
Among the storage options available for such applications, sensible heat storage using ceramic material with honeycomb structure having gas flow passages has been used for the present study, because of its cost advantage and stability at high temperatures and pressures. To enhance the performance of such systems, the effect of block arrangement is analysed with respect to the rate of charging and discharging. Towards this end, two configurations are explored for the same storage material volume; a bigger cross-sectional area system with smaller HTF flow length and a smaller cross-sectional area system with a longer flow length. These systems are thermally cycled between 443 K and 300 K using compressed air at 10 bar pressure. Analytical and numerical models are developed that are validated using laboratory experiments, and the results are in good agreement with both the modelling approaches. This study reveals that the block arrangement that allows for higher flow velocity through the honeycomb channels of the ceramic block charges and discharges the system at ~1.5 times faster than the other configuration with slower air stream velocity under identical thermal conditions.
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Raiker, Gautam Anil. « Design and Development of Non-Intrusive Load Monitoring Techniques and Solar Photovoltaic-Thermoelectric Hybrid Energy Conversion Systems ». Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5731.
Texte intégralRésumé :
Standalone Solar Photovoltaic (PV) Systems are deployed where access to the conventional Electric Grid is not present. It is necessary to extract most of the available power from the Solar PV modules as the supply is limited. In such cases, the breakdown of energy demand must be monitored in real-time. Energy Disaggregation is employed to understand the components of the loads connected to the system. One of the techniques used for Energy Disaggregation is Non-Intrusive Load Monitoring (NILM). In this approach, only a single, smart energy meter upstream of the demand side is used to estimate the individual constituents of the load, removing the need for multiple sensors to monitor each load. NILM works by training a Machine Learning model through historical data or power signatures of different appliances and deducing individual components in real-time. In the thesis work, the Factorial Hidden Markov Model is applied for NILM wherein the Hidden States of the model, which are the same as the Appliance States, are estimated based on the power signal from the Smart Energy Meter. Training of the Factorial Hidden Markov model requires historical sub-metered data of each appliance which may be challenging to acquire. Significant contributions of this work are to synthetically develop training datasets based on known parameters of appliances using an Energy Demand Model. The appliance datasets are compared with the Indian Dataset for Ambient Water and Energy (iAWE). With the advent of the Internet of Things (IoT) technology, it is now possible to remotely control individual circuits. Another contribution of this work is providing a single platform to monitor and control Appliances using IoT devices. The data regarding the states of these IoT devices is fed back to the NILM algorithm to improve the accuracy and reduce computation times. The other part of the thesis work mainly consists of Solar PV systems with maximum power point tracking. The Optimum value of Voltage and Current needs to be tracked independently of the load and weather conditions. Amongst the Control Strategies, Voltage Control is most prevalent, and there was a need to investigate Current Control as literature is limited. A framework for Current Control Strategies for Boost Converters was developed and experimentally verified. The Hill-Climbing or the Perturb and Observe method was used for implementation, in which momentum based on past perturbations, was introduced which showed improved performance. Further, a domain-independent Bond Graph approach to model hybrid thermoelectric systems was established. A modular Thermoelectric System is designed, which shows potential for Improvement in the Cooling Capacity and Coefficient of Performance of the system. An Active Heating and Cooling controlled chamber with a Standalone Solar PV System including Energy Disaggregation to Monitor the demand is fabricated and installed.
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« Substring Current-Voltage Measurement of PV Strings Using a Non-Contact I-V Curve Tracer ». Master's thesis, 2020. http://hdl.handle.net/2286/R.I.57398.
Texte intégralRésumé :
abstract: In the current photovoltaic (PV) industry, the O&M (operations and maintenance) personnel in the field primarily utilize three approaches to identify the underperforming or defective modules in a string: i) EL (electroluminescence) imaging of all the modules in the string; ii) IR (infrared) thermal imaging of all the modules in the string; and, iii) current-voltage (I-V) curve tracing of all the modules in the string. In the first and second approaches, the EL images are used to detect the modules with broken cells, and the IR images are used to detect the modules with hotspot cells, respectively. These two methods may identify the modules with defective cells only semi-qualitatively, but not accurately and quantitatively. The third method, I-V curve tracing, is a quantitative method to identify the underperforming modules in a string, but it is an extremely time consuming, labor-intensive, and highly ambient conditions dependent method. Since the I-V curves of individual modules in a string are obtained by disconnecting them individually at different irradiance levels, module operating temperatures, angle of incidences (AOI) and air-masses/spectra, all these measured curves are required to be translated to a single reporting condition (SRC) of a single irradiance, single temperature, single AOI and single spectrum. These translations are not only time consuming but are also prone to inaccuracy due to inherent issues in the translation models. Therefore, the current challenges in using the traditional I-V tracers are related to: i) obtaining I-V curves simultaneously of all the modules and substrings in a string at a single irradiance, operating temperature, irradiance spectrum and angle of incidence due to changing weather parameters and sun positions during the measurements, ii) safety of field personnel when disconnecting and reconnecting of cables in high voltage systems (especially field aged connectors), and iii) enormous time and hardship for the test personnel in harsh outdoor climatic conditions. In this thesis work, a non-contact I-V (NCIV) curve tracing tool has been integrated and implemented to address the above mentioned three challenges of the traditional I-V tracers.
This work compares I-V curves obtained using a traditional I-V curve tracer with the I-V curves obtained using a NCIV curve tracer for the string, substring and individual modules of crystalline silicon (c-Si) and cadmium telluride (CdTe) technologies. The NCIV curve tracer equipment used in this study was integrated using three commercially available components: non-contact voltmeters (NCV) with voltage probes to measure the voltages of substrings/modules in a string, a hall sensor to measure the string current and a DAS (data acquisition system) for simultaneous collection of the voltage data obtained from the NCVs and the current data obtained from the hall sensor. This study demonstrates the concept and accuracy of the NCIV curve tracer by comparing the I-V curves obtained using a traditional capacitor-based tracer and the NCIV curve tracer in a three-module string of c-Si modules and of CdTe modules under natural sunlight with uniform light conditions on all the modules in the string and with partially shading one or more of the modules in the string to simulate and quantitatively detect the underperforming module(s) in a string.Dissertation/Thesis
Masters Thesis Engineering 2020
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Deshpande, Devyani S. « Exploring the feasibility of passive cooling technology in the non-residential building sector over various climatic regions in the United States ». 2010. http://liblink.bsu.edu/uhtbin/catkey/1629783.
Texte intégralRésumé :
The thesis presents a comprehensive overview of the context and significance of ventilation cooling techniques and their feasibility in the United States. Passive cooling is one of the more architecturally interesting ways by which architects could make buildings energy efficient. There is great interest in passive systems since they can lead to a huge reduction of energy costs and support more sustainable building solutions. A number of ventilation system options are available to fill the need for a lower cost alternative to active [conventional] systems. It is the non-residential sector where energy consumption is of most concern and integrating passive natural ventilation in new non-residential buildings is receiving a lot of attention internationally and the U.S. building industry. Interest in improving air quality by passive ventilation is also increasing.Department of Architecture
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Singh, Naval. « Non-Conventional Energy Sources ». Thesis, 2009. http://ethesis.nitrkl.ac.in/218/1/Thesis.pdf.
Texte intégralRésumé :
While fossil fuels will be the main fuels for thermal power, there is fear that they will get exhausted eventually in this century. Therefore other systems based on non-conventional and renewable sources are being tried by many countries. These are solar, wind, sea, geothermal and biomass. After making a detailed preliminary analysis of biomass energy, geothermal energy, ocean thermal energy, tidal energy and wind energy, I focused mainly on Wind power for 7th semester. In wind power, I have studied mechanical design of various types of wind turbines, their merits, demerits and applications, isolated and grid-connected wind energy systems with special attention to power quality. In the end I wrote, compiled and successfully executed a MATLAB program to assess the impact of a wind farm on the power system.
Solar radiation represents the earth’s most abundant energy source. This energy resource has a number of characteristics that make it a very desirable option for utilization. The perennial source of solar energy provides unlimited supply, has no negative impact on the environment, is distributed everywhere, and is available freely. In India, the annual solar radiation is about 5 kWh/m2 per day; with about 2300-3200 sunshine hours per year.
Solar energy can be exploited for meeting the ever-increasing requirement of energy in our country. Its suitability for decentralized applications and its environment-friendly nature make it an attractive option to supplement the energy supply from other sources. In 8th Semester, I have made an attempt to study the ways through which solar energy can be harnessed and stored. I have also written MATLAB program to evaluate performance of fuel cell.
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Joshi, Mahendra Chandra. « Control & ; Energy Management of Battery/Ultracapacitor Based Hybrid Energy Storage System ». Thesis, 2019. http://ethesis.nitrkl.ac.in/10118/1/2019_PhD_MCJoshi_513EE1013_Control.pdf.
Texte intégralRésumé :
The present research work deals with the control & energy management of battery & Ultracapacitor (UC) based Hybrid Energy Storage System (HESS). The proposed con-trol and energy management algorithms improve the system response and the HESS utilization. The efficiency, durability, and health of the HESS depend on control-ling the power flow of the HESS components subjected to their specified operational constraints. It is achieved by the Energy Management Algorithm (EMA). Power allo-cation is done by frequency sharing algorithm by allotting high-frequency components of load demand to UC and low-frequency components to the battery. An improved frequency sharing algorithm for battery/UC HESS in the presence of delay has been proposed in this work. The presence of the delay due to the digital implementation has been included in inner current control transfer functions for designing the PI con-troller. Initially, the PI controller parameters have been designed with phase margin and bandwidth specifications. The total time delay in the system varies and depends on the controller speed, and computational complexity and also, due to the presence of the unmodeled dynamics of the system, the stability and the performance of the system might be affected. Hence, to ensure system stability in the presence of de-lay, initially, the complete stabilizing set for inner PI controllers have been derived. Furthermore, the stabilizing set satisfying the specified frequency domain specifica-tions, i.e., phase margin and gain margin, have also been analytically derived and experimentally verified. As stated above, apart from frequency share-based power allocation, the EMA should also ensure proper operational constraints of the HESS components. In conventional EMAs, UC voltage is maintained at a nominal value by the UC voltage regulation loop, which reduces energy supplied by UC to the load during transients. This research proposes a filter based UC voltage control loop which eliminates the high-frequency components of UC charging current and hence reduces the conflict with DC-link voltage regulation loop. However, in UC voltage control loop based EMA’s, the UC operation remains restricted to a reference voltage to prevent it from overcharging/undercharging. This leads to a very narrow utilization of the UC voltage range. Since UC voltage can safely be varied from zero to its maximum rated voltage, therefore, rather than employing a UC voltage control loop, a time-share based approach has been proposed for UC charging/discharging. The proposed EMA operation depends on the defined UC voltage band instead of a UC reference voltage, which increases its power delivery capacity by approximately 2-4 times than the conventional EMAs. An experimental prototype of the system is designed, and the proposed control algorithm and EMA have been tested in the different operating regions for validation. The major contributions of the thesis can be summarized as: 1. Improved frequency sharing algorithm in the presence of delay.
2. The complete stabilizing set satisfying the desired phase margin and gain margin has been derived.
3. Filter based UC voltage control has been proposed.
4. Time-share based EMA has been proposed that improves UC utilization.
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Tiwari, Pusyakant, Dhananjaya Swain et Anil Kumar Koppuravuri. « Study of Wind Energy System with Induction Generators ». Thesis, 2011. http://ethesis.nitrkl.ac.in/2283/1/THESIS.pdf.
Texte intégralRésumé :
Wind energy, as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean, and produces no greenhouse gas emissions during operation. The world has enormous resources of wind power. It has been estimated that even if 10% of raw wind potential could be put to use, all the electricity needs of the world would be met. A phased programme to develop wind energy in India started as early as 1985, and today the total installed capacity has reached 1650 MW, saving about 935,000 metric tonnes of coal.
Wind electrical generation systems are the most cost-competitive of all the environmentally clean and safe renewable energy sources in the world. They are also competitive with fossil fuel generated power and much cheaper than nuclear power.
Traditionally, wind generation systems used variable pitch constant speed wind turbines (horizontal or vertical axis) that were coupled to squirrel cage induction generators or wound-field synchronous generators and fed power to utility grids or autonomous loads.
The recent evolution of power semiconductors and variable frequency drives technology has aided the acceptance of variable speed generation systems. Such systems can yield 20-30% more power than constant-speed generation systems.
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« Giving light and hope in rural Afghanistan : the impact of Norwegian Church Aid's barefoot approach on women beneficiaries / ». Oslo : Institute of Sociology and Human Geography, Universitetet i Oslo, 2008. http://www.duo.uio.no/publ/iss/2008/76872/Master_Karina_Standal.pdf.
Texte intégral
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Sethi, Aditya Kumar, et Vijay Ravichandran. « Pitch Control of Horizontal Axis Wind Turbine ». Thesis, 2011. http://ethesis.nitrkl.ac.in/2430/1/Pitch_Control_of_Horizontal_Axis_Wind_Turbine.pdf.
Texte intégralRésumé :
Wind energy is fast becoming the most preferable alternative to conventional sources of electric power. Owing to the perennial availability of wind and the considerable range of power control, wind turbines are now coming up in almost all parts of the world. In the early days of development, wind turbines were designed to rotate at constant speed through pitch control or stall control. The modern wind turbines implement pitch control in order to tap maximum energy at wind speeds lower than rated wind speed.
In this project, three different models of pitch actuator system have been studied and a discrete time adaptive PID model has been proposed where the gains of the PID controller are modified based on the time response parameters of the previous time cycle. It is expected to offer better control over a wide range of wind speeds.
Keywords: Pitch control, renewable energy, adaptive PID Control, Wind Energy Conversion Systems
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Dhanuka, Raghav. « Modelling of doubly fed induction generator based wind turbine ». Thesis, 2013. http://ethesis.nitrkl.ac.in/5343/1/109EE0268.pdf.
Texte intégralRésumé :
There has been a constant rise in the use of renewable energy resources. Global wind energy capacity soared by a fifth to 238GW at the end of 2011. India being the 5th largest player globally, accounted for 16GW. Wind energy is an important form of renewable energy as there is no greenhousE gas emission compared to non-renewable fossil fuels. There has been a rising demand for wind energy ever since its first implementation. This project work studies the power-speed characteristics and the torque-speed characteristics and the fundamentals of wind electrical systems along with the modeling of the various wind turbine features and simulation of the same using MATLAB-SIMULINK. It deals with the vector control and modeling of the Doubly-Fed Induction Generator, which can be used to transmit power to the network through both the stator and the converters connected to the rotor. The turbine current, voltage, power and other characteristics are studied on variation of the grid parameters.
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Deori, Anupam. « Grid Integration Issues of Distributed Generations ». Thesis, 2015. http://ethesis.nitrkl.ac.in/7820/1/2015_Grid_Deori.pdf.
Texte intégralRésumé :
Paucity in the energy scenario had made conservation of energy an essential issue. Usage of Renewable energy sources (RES) is increasing in the present era, which calls for green and clean energy sources. RES includes various forms viz., solar energy, wind energy, geothermal energy etc. but the most favored are the solar and wind energy. Most RES are intermittent in nature. To integrate RES to a utility grid is a quite challenging task, to track the maximum power point (MPP) of a consistently irradiated PV system is important and is yet another challenge. Of all the available methods in the MPPT context the Perturb and observe (P & O) method and incremental conductance method are the widely used techniques. In this project the P & O method is implemented for tracking the MPP. The tracking system conventionally is supplied the PV array voltage and current to track the MPP. In this thesis instead of having a sensor for measurement of the solar array current, it is estimated or observed with a sliding mode observer. The observer is based on sliding-mode and is constructed from the dynamic equations of the considered system viz. a single phase grid connected Photovoltaic system that has a Photovoltaic module and a single-phase H-bridge inverter. The solar array current is observed by the known values or measured values of the array voltage and inductor current. The current estimation is governed by the sliding mode observer gain, as we increase the value of the gain chattering problems come into being. The estimated value almost follows the original current and hence, is used to track the MPP. In this thesis at first the methodology of grid integration of distributed Photovoltaic systems are studied and simulated. And then an observer based on sliding-mode theory, the MPPT control was developed.
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Tarai, Rakesh Kumar. « Evaluation and Analysis of the Photovoltaic Potential for Odisha ». Thesis, 2016. http://ethesis.nitrkl.ac.in/8297/1/2016-MT-214EE5495-Photovoltaic_Potential_for_Odisha.pdf.
Texte intégralRésumé :
Solar energy is a potential resource for the various renewable energy options which is clean, inexhaustible and eco-friendly. The development of usage and installation of PV system needs a relevant solar policy making plan through proper assessment of solar PV Energy potential. The study uses the estimate of the PV potential of an area under consideration using the PVGIS online software. The study divides the total geographic area of into a grid of „mxn‟. The PVGIS evaluated the value of incident solar radiation and generated PV energy at central coordinate of each grid. The evaluation of energy potential for four cases (based on mounting and tracking) uses two critical parameters: annual incident Global radiation and annual PV Energy production. A methodology is presented to plot the rasterized maps of the solar energy potential. The study further discusses a case study of Odisha to show the usefulness of the proposed methodology to develop a district wise strategy for promoting the installation of grid-connected PV system. The decision to install a PV plant depends on three major factors: the climatic and environment conditions of the location, the viability of commercial operations, and the government policies. Considering uncertain nature of geographical parameters development of a reliable model to predict the energy output of a plant-to-be installed becomes essential. The study proposes models that consider only two meteorological variables collected from 1195 locations of Odisha: total annual incident global radiation on the PV module and annual average air temperature. The thesis focuses on simplification at every stage of the development while validating the preciseness of the model. A case study of NIT Rourkela is considered to apply a various methods for the evaluation of PV potential. Again the current solar policy framework of India is reviewed along with the challenges the nation has to face for achieving the targets.
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Kumar, Ranjeet, et S. R. Sagiraju. « Harnessing of Wave Power from Horizontal Flow Dynamics of Shallow Waves ». Thesis, 2009. http://ethesis.nitrkl.ac.in/300/1/PROJECT__RK_Sundar_final.pdf.
Texte intégralRésumé :
Harnessing Ocean Wave power is a potential source of renewable form of energy. Our project was aimed at finding the constraints and proposing a suitable solution to utilize this form of energy. Ocean Wave Power is the most predictable, periodic and concentrated source among all renewable sources, but the constraints imposed on its harnessing are a result of its Ocean environment. Ocean wave dissipates energy in several strata of circular oscillation. But with depth induced water pressure these circular oscillation are squished into ellipse that approximates to back & forth motion. Statistically the horizontal oscillation shares the 68% of energy spectrum of wave energy. But due to irregular flow and variable pressure conventional hydropower harnessing techniques become improbable. In our project we have proposed a simple solution that takes the direct advantage of utilizing this energetic horizontal momentum of ocean waves, without in between conversion.
Our project works in parallel and in tandem with another group working on this project but deals with a different aspect of the problem. Our project has worked on finding the depth induced variation of distribution of ocean energy and maximum optimum depth for harnessing. The suitable components required for conversion from mechanical to electrical energy were analyzed. The slow rpm speed output needed attention for its conversion and Axial/Transverse Flux Permanent seemed to be the solution for our scenario.
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Gupta, Saurabh, et Rahul Shrivastava. « Study and Design of a Zero Voltage Switched Boost Converter ». Thesis, 2009. http://ethesis.nitrkl.ac.in/1026/1/Project.pdf.
Texte intégralRésumé :
We study theoretical circuit operation of zero voltage switching over the basic premise of boost converters (step-up dc chopper circuits). Zero-voltage switching technique is studied which, in contrast to zero-current switching, eliminates the switching loss and dv/dt noise due to the discharging of junction capacitances and the reverse recovery of diodes Zero Voltage Switching (ZVS) including various switching techniques in resonant converters is studied. Also a working model of a Zero Voltage Switched Boost Converter is constructed in the laboratory and its working and waveforms observed.
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Ghosh, S., et A. B. Swer. « Modelling of the Breakdown Voltage of Solid Insulating Materials using Soft Computing Techniques ». Thesis, 2010. http://ethesis.nitrkl.ac.in/1972/1/btech_project_online.pdf.
Texte intégralRésumé :
The aim of the project is to use Soft Computing Techniques (SCT) in order to model the breakdown voltage of solid insulating materials. Since the breakdown voltage behaviour is non-linear, it can be best modeled using SCT such as Artificial Neural Network (ANN), Radial Basis Function (RBF) Network, Fuzzy Logic (FL) Techniques etc. In order to obtain the experimental data on the breakdown voltage, experiments are conducted under AC and DC conditions and then all the SCT model are applied on it.
The prediction of the breakdown voltage of solid insulating materials is indeed a challenging task. Hence the best way to go about it is by resorting to SCT in order to model and predict the breakdown voltage.