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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Determinação da eficiência de um coletor solar plano com aletas de vidro /

Bentivenha, Luiz Carlos, 1953- January 2005 (has links)
Orientador: José Roberto Corrêa Saglietti / Banca: Angelo Cataneo / Banca: Alessandro Torres Campos / Resumo: Os coletores solares comumente utilizados no aquecimento de água, para o consumo doméstico, possuem a placa de aquecimento solar plana do tipo chapa - tubo. Devido à crescente utilização desses equipamentos, buscou-se, através deste trabalho, modificar um equipamento convencional, o qual recebeu, na placa solar, aletas de vidro, instaladas no plano vertical em relação à tampa de vidro, dividindo a mesma em diversas áreas, propiciando um aumento, tanto da reflexão dos raios infravermelhos em seu interior, quanto do efeito estufa. O objetivo do ensaio foi estudar o comportamento térmico desse equipamento, trabalhando a determinada vazão e obtendo as temperaturas com o emprego de termopares instalados em vários pontos do sistema, buscando a determinação da eficiência térmica da placa solar modificada. Para a determinação da eficiência, foram considerados o calor útil, o calor absorvido e as perdas de calor. As equações empregadas na determinação da eficiência térmica foram trabalhadas no programa Excel.Verificou-se que o equipamento apresentou um bom rendimento, atendendo as especificações definidas pelo INMETRO. A temperatura média de saída da água do equipamento apresentou valor superior a de equipamento similar, o mesmo não ocorreu com seu rendimento, embora as diferenças registradas tenham sido pequenas. A eficiência do equipamento não depende apenas dos parâmetros do projeto, mas também de outros fatores que levam a perda de energia. / Abstract: The solar collectors commonly used in the water heating for domestic consumption possess the flat plate solar heating of plate type - tube. Due to increasing applications of those equipments the purpose was to modify the conventional, which received glass fins in the solar plate, installed in the vertical plan in relation to the glass cover, dividing the same in several areas, enabling reflection increase of the infrared rays in its interior as well as greenhouse effect. The thermal performance of the equipment has been studied analyzing the certain flow and obtaining the temperatures with the thermopairs installed in several points of the system and determining the thermal efficiency of the modified solar plate. The useful heat, the absorbed heat and the losses of heat were considered. The equations of the thermal efficiency were obtained in the Excel program. The equipment presented a good performance according to INMETRO specifications. The medium temperature of the water exit presented superior value when compared to a similar equipment. The same didn't occur with its performance, although the registered differences have been small. The efficiency of the equipment doesn't depend only on the parameters of the project, but also on other factors which lead to energy loss. / Mestre
42

Etude d'un capteur solaire hybride avec concentrateur holographique du rayonnement solaire / Study of a hybrid solar collector with holographic concentrator of solar radiation

Iurevych, Olena 07 July 2015 (has links)
Les besoins énergétiques du monde entier augmentent de plus en plus et parmi les sources en énergie renouvelable, l'énergie solaire connaît actuellement un très fort développement. Une des voies en énergie solaire est la filière utilisant des panneaux solaires hybrides qui produisent à la fois de l'électricité et de la chaleur. Le marché des capteurs hybrides en présence ou non de concentrateur et leurs caractéristiques sont présentés. Dans la thèse, on a étudié un capteur hybride associé avec un concentrateur holographique du rayonnement solaire. Ce concentrateur permet de séparer la partie visible utilisée par les cellules photovoltaïques de celle infrarouge, absorbée par l'échangeur thermique. Les différents éléments du capteur et leur fonctionnement sont décrits. Les caractéristiques du capteur et son efficacité dépendent des paramètres optiques et thermiques de ses éléments. Ces paramètres (facteurs de transmission, de réflexion, d'absorption, émissivité) ont été déterminés expérimentalement (CERTES IUT Sénart, CEMHTI Orléans, Université Blaise Pascal Clermont-Ferrand). Les résultats obtenus ont été utilisés dans une modélisation stationnaire et monodimensionnelle des échanges thermiques pour deux configurations différents (avec deux plaques en polycarbonate et avec une plaque en polycarbonate et une lame d'air). La modélisation introduit les effets radiatifs, conductifs et l'absorption du rayonnement en volume. Les profils thermiques et les rendements électriques et thermiques obtenus montrent l'efficacité d'un capteur solaire hybride avec concentrateur holographique. / The energy requirements worldwide are increasing more and among renewable energy sources, solar energy is exhibiting a very strong growth. Solar hybrid panels that produce both electricity and heat is currently a very promising way. The market for hybrid solar panel with and without concentrator and their characteristics are presented. In the thesis, a hybrid solar panel associated with a holographic concentrator solar radiation is studied. This concentrator separates the visible range used in the photovoltaic cells of the infrared range absorbed by the heat exchanger. The elements of the panel are described. The sensor characteristics and effectiveness depend on the optical and thermal parameters of its elements. These parameters (transmission factors, reflection, absorption, emissivity) were determined experimentally (CERTES IUT Sénart, CEMHTI Orleans, University Blaise Pascal Clermont-Ferrand). The results were obtained in a stationary and dimensional modelling heat exchanges for two different configurations (with two polycarbonate plates with a polycarbonate plate and an air). The model introduces radiative effects, conduction and radiation absorption by volume. The thermal profiles, and electrical and thermal efficiencies obtained show the effectiveness of a hybrid solar collector with holographic concentrator.
43

Carteras de cuero vegetal de shiringa – Vert Clair / Vert Clair - Shiringa's leder's hand bag

Bazan Guzman, Rudy Alejandro, Burgos Cruzado, Aracelly Giovana, Chavez Podesta, Diane Maite, Flores Reynoso, Nataly Maria Jesus, Salleres Capellino, Mario Carlos 21 July 2020 (has links)
En la actualidad, los consumidores en el sector de manufactura en cuero para diferentes productos van revolucionando la moda, creando productos sostenibles con procesos y materiales alternativos como el cuero vegetal en reemplazo del cuero natural o bovino. Ante ello, nace la idea de presentar un modelo de negocio sobre carteras a base de cuero vegetal, el cual será obtenido por la Asociación de productores de Shiringa ubicada en Condorcanqui - Amazonas. Asimismo, se incorpora un cargador solar como valor adicional que va acorde a la iniciativa de realizar un proyecto amigable con el ambiente. Esta propuesta, lleva como nombre Vert Clair y considera como grupo objetivo a mujeres modernas y sofisticadas entre 18 y 40 años que gustan estar a la moda. Por ende, para probar la aceptación de este proyecto se ha realizado diversas investigaciones y experimentos que permitan dar validez a este modelo de negocio, para así presentar los planes de acción en las áreas pertinente, con la finalidad de obtener una aliciente rentabilidad y a la vez también, dar a conocer al mercado e industria peruana una nueva alternativa que transforme la moda. / Nowadays, consumers in the leather manufacturing sector for different products are revolutionizing fashion, creating sustainable products with alternative processes and materials such as vegetable leather to replace natural or bovine leather. Given this, the idea was born to present a business model on wallets based on vegetable leather, which will be obtained by the Association of producers of Shiringa located in Condorcanqui - Amazonas. Also, a solar panel is incorporated as additional value that goes according with the initiative to make an environmentally friendly project. This proposal is named Vert Clair and considers as a target group modern and sophisticated woman between 18 and 40 years old who like to be fashionable. Therefore, to test the acceptance of this project, various investigations and experiments have been carried out to validate this business model, to present the action plans in the relevant areas, in order to obtain an attractive profitability and at the same time also, to make known to the Peruvian market and industry a new alternative that transforms fashion. / Trabajo de investigación
44

PUERTO RICO POWER SYSTEM TRANSITION TO RENEWABLE ENERGY

Sofia Paola Espinell Gonzalez (9970334) 14 January 2021 (has links)
<div> <div> <div> <p>Puerto Rico’s lack of effective and affordable energy substitutes after Hurricane Maria resulted in a mortality increase of 4,970 residents (Verma, Murray, and Mamdani, 2018). Puerto Rico’s Island dependency on electric power and no energy substitutes available have provoked a risk to human life after catastrophic events. The problem was measured by comparing Puerto Rico’s reliance on fossil fuels with accessible and economical renewable energy options. Solar photovoltaic (PV) technologies are the optimum alternative to transition from fossil fuel usage to renewable energy. Previous research has demonstrated the impact of using solar panels instead of an electric grid due to the constant solar radiation throughout the year. The analyzed data and projections showed a reduction in fossil fuels and carbon dioxide emissions by implementing solar photovoltaic technologies. The installation of PV systems in landfills, household roofs and transitioning to solar public lighting positively impacts the atmosphere carbon dioxide emissions. </p> </div> </div> </div>
45

Polohové řízení solárního panelu s optimalizací energetické účinnosti / Positioner for Solar Panel with Power Efficiency Optimizing

Kreysa, Karel January 2011 (has links)
This thesis is focused on design and prototyping of solar panel position control system for an obtaining of the maxima renewable energy from sun. In this thesis, various ways of solar panel positioning are considered and analyzed. Consequently, a construction arrangement of the positioner is presented. It is mechanically adapted to obtain the maximum efficiency in typical environment corresponding with the Central European geographical latitude. Different methods of sun monitoring are considered and analyzed. On the basis of this analysis, a proper prototype of sun monitor for exact positioning with disturbance filtering has been constructed. Following part of work is devoted to stable, fully automated, control subsystem for reliable functionality of solar system. A suitable microprocessor with a robust firmware has been implemented to this control unit. Finally, system parameters measurement and closing analysis of gained renewable energy and backflow computation is presented in the end of this diploma thesis.
46

Cargador Portátil Ecológico MAX - E / MAX -E Eco Friendly Portable Charger

Acosta Valverde, Melanie Araceli, Andrade Mariños, Joan Ayrton, Linares Castillos, Diego Alonso, Ortiz Chamochumbi, Renzo, Vásquez Calderón, John Erick 31 July 2020 (has links)
El presente proyecto es un cargador solar ecológico que puede ser transportado en todo momento debido a su tamaño compacto y su poco peso de 150 gramos. Además, almacena la energía del sol y la luz led para luego cargar tu dispositivo en cualquier momento. Se desarrolla su viabilidad en base a una investigación realizada a hombres y mujeres de 18 a 39 años de los niveles socioeconómicos A, B y C. Por lo tanto, el análisis permite identificar a un grupo de personas que necesitan cargar su celular en momentos importantes durante el día pero que no encuentran lugar donde conectarlo o no tienen un cargador. Para validar la solución se utilizó un prototipo del producto el cual fue presentado al público y especialistas para que salga al mercado. Por último, se realizó un concierge para calcular la intención de compra del producto y proyectar sus estados financieros, los cuales, están respaldados por pertinentes desarrollos estratégicos que llevan a cabo un plan de negocio.
47

Simulations of energy efficient windows in a historical building located in mid-Sweden

Medrano Eraso, Iñigo January 2023 (has links)
Amorphous silicon photovoltaic windows intend to not only improve thethermal bridge that windows represent but also to collect energy from theradiation incident on the windows themselves. This kind of windows can beapplied anywhere, however to maximize the benefit these can bring it isrecommended for sun-oriented façades. This research aims to investigate theimpacts that this type of windows can have on the energy performance andthermal comfort of a three-story historical stone building in the cold climateof Sweden using the simulation software IDA ICE. The model used for thesimulations had previously been developed and tested in other researches thatinvolved this same building. This research shows that the yearly energyconsumption for the townhall can be reduced down to 280000 kWh,representing a reduction of 5000 kWh compared to the base model, if theHigh transparency windows are applied, representing a reduction of 1,7%.The use of any of the four proposed windows has shown to increase thepercentage of best comfort hours by at least 5% and lowers the percentage ofunacceptable comfort hours at least by a 10%, even having cases with 0 hoursat this comfort level. The upper level of the South façade would be able toprovide the building with 800 kWh yearly, being the level with the highestenergy collection due to having more windows. Approximately every windowcould collect around 90 kWh yearly, which represents 20% of what a solarpanel of the same area correctly oriented could obtain in the same period oftime. Thus, the amorphous silicon photovoltaic windows do not seem to bethe best change despite offering a very promising thermal comfort. Theeconomical viability of this project is what prevents it from being feasiblesince the energy saving/obtaining characteristics are not of great magnitude.
48

<b>Social Identities and Environmental Decision Making</b>

Nathanael Johnson (8797193) 05 June 2024 (has links)
<p dir="ltr">Appealing to individuals’ social identity is a powerful form of social influence, capable of changing the way people process information, the information they think about, and how they evaluate other people. This form of social influence can function through perceptions of normal behavior within a social group, in which members of a group interpret ambiguous information through the lens of what is considered to be normal in their ingroup. The Social Identity Decision Process hypothesis, based on Social Identity Theory and Probabilistic Persuasion Theory, suggests that group norms associated with a decider's social identity can alter the perceived importance of attributes or cues in a decision environment and the strategies that are used to make choices in situations in which the group identity is salient. Taking the U.S. political landscape as a context and examining Republican and Democrat social identities, norms from these political groups were expected to impact the attributes and strategies partisans use when choosing whether to have solar panels on a house. Two studies are reported that examined these effects through multi-attribute decision making, in which predefined decision process models assessed participant behavior to analyze which attributes best describe participants’ decision making.</p>
49

Análise da viabilidade de um sistema de produção de energia limpa a partir da fonte primária solar convertida em energia química: o hidrogênio / Analysis of the viability of a clean energy production system from the solar primary source converted into chemical energy: hydrogen

Garcia Neto, José dos Santos 30 May 2019 (has links)
Frente a um panorama de escassez de combustível convencional fóssil e disponibilidade hidráulica para a produção de energia elétrica, fontes alternativas de energia renovável se tornam cada vez mais urgentes e necessárias. O hidrogênio é o elemento químico mais abundante disponível no planeta, tornando-se um potente candidato para suprir essa escassez de energia, pois, é capaz de conter um grande potencial energético comparável aos combustíveis fósseis, como a gasolina ou carvão. Sendo ele um vetor energético, não se tem a possibilidade de sua \"extração\" direta, porém, técnicas de obtenção do hidrogênio são bastante flexíveis, conhecidas e utilizadas comercialmente. Este trabalho teve como objetivo o estudo e construção de um sistema para produção de energia limpa a partir da produção de hidrogênio gasoso por eletrólise da água em meio alcalino, fazendo uso de um painel fotovoltaico como fonte alternativa de energia elétrica, bem como, a análise da eficiência energética desta produção. Para garantir a obtenção dos gases hidrogênio e oxigênio separadamente foi utilizada uma membrana separadora de gases, o Zirfon&reg; Perl, permitindo a eletrólise pelo eletrolisador projetado e construído especificamente para este estudo, sem a necessidade de um sistema de circulação do eletrólito. Para uma análise comparativa das eficiências, produziu-se hidrogênio por eletrólise alcalina de uma solução aquosa de KOH (1M) com energia fornecida por uma fonte externa DC e por um painel solar ligado diretamente ao eletrolisador. O cálculo dessa eficiência foi feito pela relação entre a energia fornecida à eletrólise pelas fontes (solar e externa) e a energia do hidrogênio produzido com base no seu poder calorífico inferior (LHV). Além disso, curvas de carga de tensão e corrente do painel solar foram levantadas e estudadas para garantir a efetividade da ligação direta com o eletrolisador, bem como ensaios de EIE (Espectroscopia de Impedância Eletroquímica) foram realizados para análise da corrosão do eletrodo anódico e determinação da resistência ôhmica do sistema eletrolisador. Foram realizadas medidas e obtidas a eficiência energética com quatro montagens de sistemas eletrolisadores: 4 células com suprimento de energia por uma fonte externa DC, resultando em uma eficiência de 48,21%; 4 células e painel solar, 44,85%; 1 célula e fonte externa, 23,52 %; 1 célula e painel solar, 23,10%. Também foram calculadas eficiências energéticas da produção do hidrogênio em função do aumento de energia fornecida à eletrólise. Todas as aquisições dos parâmetros da eletrólise foram realizadas com um sistema automático projetado e construído especificamente para este trabalho, de forma que os dados foram obtidos a cada segundo, fornecendo valores em tempo real. Os resultados obtidos, tanto sobre os parâmetros importantes para que uma eletrólise para produção de hidrogênio possa se tornar eficiente energeticamente, como sobre as soluções para o desenvolvimento de um sistema com painel fotovoltaico que alimente diretamente o eletrolisador, serão de vital importância para continuação da pesquisa que envolva a utilização otimizada do hidrogênio em locais onde a energia elétrica proveniente de concessionárias seja escassa ou até mesmo inexistente. / The scenario of conventional fuel shortages (fossil and hydraulic availability for the production of electricity) shows us that alternative sources of renewable energy become more urgent and necessary. Hydrogen is the most abundant chemical element available on the planet, making it a potent candidate to address this energy shortage, since it is able to contain a large energy potential comparable to fossil fuels such as gasoline or coal. Being an energetic vector, one does not have the possibility of its direct \"extraction\", but techniques of obtaining hydrogen are quite flexible, known and used commercially. The objective of this work was the study and construction of a system for the production of clean energy from the production of gaseous hydrogen by electrolysis of water in alkaline medium, making use of a photovoltaic panel and an external source of electric energy, as well as the analysis the energy efficiency of this production. In order to guarantee the hydrogen and oxygen gases separately, a gas separation membrane, Zirfon&reg; Perl, was used allowing electrolysis by the electrolyzer, designed and built specifically for this study, without the need for an electrolyte circulation system. For a comparative analysis of efficiencies, hydrogen was produced by alkaline electrolysis of an aqueous solution of KOH (1M) with energy supplied by an external DC source and by a solar panel connected directly to the electrolyser. The calculation of this efficiency was made by the relation between the energy supplied to the electrolysis by the sources (solar and external) and the energy of the hydrogen produced based on its Lower Heat Value (LHV). In addition, voltage and current load curves of the solar panel were collected and studied to ensure the effectiveness of the direct connection with the electrolyser, as well as IEE (Electrochemical Impedance Spectroscopy) tests were carried out to analyze the corrosion of the anodic electrode and determination of the ohmic resistance of the electrolyser system. Measurements and energy efficiency were obtained with four electrolyser systems assemblies: 4 cells with energy supply by an external DC source, resulting in an efficiency of 48.21%; 4 cells and solar panel, 44.85%; 1 cell and external source, 23,52%; 1 cell and solar panel, 23.10%. Energy efficiencies of hydrogen production were also calculated as a function of the increase in energy supplied to the electrolysis. All the electrolysis parameters were acquired with an automated system designed and built specifically for this work, so that the data were obtained every second, providing real-time values. The results obtained in this work, both on the important parameters so that an electrolysis for hydrogen production can become energy efficient, and on the solutions for the development of a system with photovoltaic panel that directly feed the electrolyser, will be of vital importance for continuation of the research that involves the optimized use of hydrogen in places where the electric energy coming from concessionaires is scarce or even non-existent.
50

Wind –induced Pressure Quantification on Gable Roof Flush-Mounted Solar Panels Systems

Yakoub, Haisam 15 March 2019 (has links)
Abstract Photovoltaic (PV) solar panels are solar energy collection systems with increasing terrestrial and roof applications reported worldwide. If the terrestrial mounting does not require specific wind resistance verifications, installing them on top of flat and gable roofs implies a drastic change of the roofing systems geometry, thus a re-evaluation of the wind-induced pressure is necessary. Among the roof top applications, provisions exist for the flat roofs mounted solar panels, however, design recommendations for wind-induced loadings on PV solar panels arrays flush-mounted on gable roofs are not fully developed in current wind loading standards (SEAOC PV2-2012) and building codes (ASCE 07, NBCC 2015), in spite of the numerous applications on residential and agricultural buildings, primarily due to the limited research investigating this topic. The current dissertation employs CFD k-ɛ and LE (Large Eddy) simulations for analyzing the effects of wind acting on solar panels flush-mounted on gable roofs, considering the influence of several parameters such as: the slope of the gable roof, the wind directions, the spaces between the adjacent solar panel arrays and the clearance between the roof surface and the solar panels. A comprehensive database of solar panels with different installation parameters subjected to wind speeds were developed under the current research project. The database includes detailed distribution of wind-induced pressure coefficients for the three parallel surfaces constituting the roof-solar panels systems: the top and bottom surfaces of the panels, and the roof surface under the panels, which represents a novel approach in investigating and clarifying the wind effects on solar panels. This approach also provides in detail the variation of the pressure coefficients on the three surfaces, due to the change of installation conditions (roof slope, arrays spacing, roof clearance) and wind parameters (wind speed and wind direction). As an original contribution to the existing knowledge, this thesis found that the installation of solar arrays on gable roofs, redistributes the wind-induced pressure on both sides of the roof windward and leeward, resulting in total horizontal wind-induced pressures on the entire roof lower than that registered on the corresponding roof without solar panels. In addition, dominant resultant pressure coefficients on solar panels concluded to be lower than for the roof without panels. When the roof clearance increases, total average pressure coefficients on the roof supporting the panels decreases on both, windward and leeward sides of the roof. Moreover, when the roof clearance increases, the pressures in the cavity decrease significantly on both windward and leeward sides of the roof, which could impact the requirements for installing and fixing such panels on gable roofs. For example, for 10” clearance the flush-mounted solar panels were subject to pressure instead of suction. Similarly, when panel array spacing increases, the magnitude of the net mean pressure coefficients on the roof surface under the solar panels further decreases for all wind directions investigated.

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