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Ferramenta computacional para geraÃÃo distribuÃda a partir de sistemas hÃbridos renovÃveis / Computational tool to distributed generation of hybrid systems for renewable energyRebeca Catunda Pereira Machado 29 April 2013 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A presente dissertaÃÃo apresenta o desenvolvimento de uma ferramenta computacional de auxÃlio ao planejamento energÃtico chamada de GDHER (GeraÃÃo DistribuÃda de Sistemas HÃbridos de Energias RenovÃveis) A ferramenta pode ser utilizada sem custo uma vez que foi desenvolvido atravÃs do Calc um programa de planilha eletrÃnica semelhante ao Excel que faz parte de um pacote de vÃrios aplicativos livres da Broffice ApÃs identificar algumas limitaÃÃes dos principais softwares disponÃveis no mercado foi desenvolvida uma nova ferramenta adaptada à realidade brasileira principalmente voltada Ãs Ãreas rurais e isoladas que utiliza o portuguÃs como idioma e possui uma interface bastante amigÃvel facilitando sua compreensÃo e operaÃÃo pelo usuÃrio A ferramenta permite o usuÃrio fazer dimensionamento de algumas modalidades de geraÃÃo de energia elÃtrica a partir de tecnologias limpas como a solar fotovoltaica aerogeradores e biodigestores e atravÃs de uma anÃlise financeira esses sistemas sÃo comparados com a extensÃo da rede de energia elÃtrica permitindo que o usuÃrio obtenha um prognÃstico de viabilidade A ferramenta tambÃm permite fazer o dimensionamento e a anÃlise financeira de configuraÃÃes de sistemas hÃbridos como fotovoltaico-eÃlico fotovoltaico-biodigestor e biodigestor-eÃlico a fim de encontrar a configuraÃÃo Ãtima para o projeto Para validaÃÃo da ferramenta foi feito um estudo de caso e a partir da anÃlise financeira e anÃlise de sensibilidade a modalidade de fornecimento de energia elÃtrica mais viÃvel para os sistemas individualizados sÃo os biodigestores em seguida sÃo os mÃdulos fotovoltaicos e a rede elÃtrica e por Ãltimo sÃo os aerogeradores De acordo com a anÃlise financeira dos sistemas hÃbridos a configuraÃÃo mais lucrativo à 75% da demanda sendo atendida por biodigestores e 25% por mÃdulos fotovoltaicos Os resultados sÃo apresentados atravÃs de tabelas e grÃficos para melhor compreensÃo do usuÃrio Com todas essas caracterÃsticas a ferramenta proposta permite dimensionar sistemas com mÃxima eficiÃncia e menor custo obtendo assim sistemas mais adequados e confiÃveis tanto do ponto de vista tÃcnico como financeiro / This work presents the development of a computational tool to aid in energy planning called GDHER (Distributed Generation of Hybrid Systems for Renewable Energy) The program can be used without cost since it was developed through the Calc a program of electronic spreadsheet similar to Excel which is part of a package of several free applications of Broffice After identifying some limitations of the main software available on the market we obtained a new tool adapted to the Brazilian reality especially to rural and isolated areas which uses the portuguese as language and has an interface very user friendly facilitating the understanding and operation of the program by the user The program allows the user to do the scaling of some methods of electricity generation from clean technologies such as solar photovoltaics wind turbines and biodigesters and through a financial analysis these systems are compared with the extension of the network of electric energy allowing the user get a prognosis of viability The tool also allows the user to do the scaling and the financial analysis of some configurations of hybrid systems like photovoltaic-wind photovoltaic-digester and wind-digester in order to find the optimal configuration for the project For validation of the program it was done a case study and from the financial analysis and sensitivity analysis the modality of electric energy supply more viable for individualized systems are the digesters then are the photovoltaic modules and the electrical network and finally are the wind turbines According to the financial analysis of hybrid systems the configuration more profitable is 75% of demand being served by biodigesters and 25% by photovoltaic modules The results are presented using tables and graphs for better understanding of the user With all these features the tool allows to scale systems with maximum efficiency and lower costs thereby obtaining more appropriate and reliable systems both from the technical point of view as financial
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Caractérisation et modélisation du comportement des alliages TiFe dédiés au stockage solide d'hydrogène. : Application à l'amélioration des performances d'un réservoir à hydrures métalliques / Characterization and modeling of the behavior of TiFe alloys dedicated to hydrogen solid storage : Application to improving the performance of a metal hydride tankZeaiter, Ali 27 March 2017 (has links)
Les problèmes environnementaux et économiques, engendrés par l’usage des produits pétroliers, et la pénurie de ces énergies fossiles ont conduit à rechercher d’autres sources d’énergies, renouvelables et respectueuses de l’environnement. Nombre de ces sources sont intermittentes et nécessitent de prévoir des solutions de stockage. Le gaz de dihydrogène apparait comme un bon candidat pour remplir cette fonction. L’élément hydrogène, abondant dans la nature, présente sous sa forme gazeuse un pouvoir calorifique de 140 MJ/kg, soit 2,5 fois celui de l’essence. La filière ’hydrogène’ s’appuie sur 3 piliers : la production, le stockage-la distribution et l’utilisation. Le stockage d’hydrogène est traditionnellement réalisé par compression, sous des pressions allant de quelques bars à plusieurs centaines, et par liquéfaction à 20 K. La faible densité volumique de ces deux types de stockage (42 et 70 kgH2/m3) associée à de sérieux problèmes de sécurité et de conception mécanique, rend le stockage solide dans les alliages métalliques particulièrement pertinent pour certaines applications. Cette solution favorise le développement de réservoirs de conception sûre, compacts et ayant une grande densité volumique de 120 kgH2/m3 pour les alliages TiFe par exemple. Ce type d’hydrure a été retenu dans le cadre de ce travail parce qu’il présente des températures et pressions d’utilisation relativement proches des conditions ambiantes, mais aussi parce qu’il ne contient pas de terre rare d’utilisation relativement proches des conditions ambiantes, mais aussi parce qu’il ne contient pas de terre rare. La présente étude vise à caractériser et modéliser le comportement d’hydruration/déshydruration de l’alliage TiFe0.9Mn0.1, en vue d’améliorer ses performances lorsqu’il est intégré à un système de stockage. Dans un premier temps, nous nous sommes attachés à caractériser expérimentalement l’alliage TiFe0.9Mn0.1 sous forme de poudre en le décrivant sur les plans morphologique, chimique et thermodynamique. Ensuite, deux stratégies d’amélioration ont été testées, la première repose sur un traitement mécanique par broyage planétaire à billes, la deuxième considère un traitement thermochimique à température et durée de maintien données. Ces deux stratégies ont permis d’accélérer le processus d’activation de la poudre, mais le broyage planétaire à billes a détérioré de façon notable la cinétique apparente de désorption. Le traitement thermochimique n’a quant à lui pas dégradé les domaines d’équilibre et n’a donc pas eu d’effet néfaste sur les cinétiques de réaction. Les deux paramètres les plus importants de ce traitement, température et temps de maintien, ont été optimisés. D’autres paramètres restent à affiner.[...]La conception d’un système de stockage solide d’hydrogène exige la bonne compréhension des aspects macroscopiques, mais aussi microscopiques, de la réaction d’hydruration, et requiert donc des recherches complémentaires pour trouver de nouveaux axes d’amélioration de ses performances. / He environmental and economic problems caused by the use of petroleum products and the scarcity of these fossil fuels have led to the search for alternative sources of energy, which are renewable and respectful of the environment. Many of these sources are intermittent and require storage solutions. Hydrogen gas appears as a good candidate for this function. The hydrogen element, abundant in nature, has in its gaseous form a calorific value of 140 MJ / kg, i.e. 2.5 times that of gasoline. The 'hydrogen' sector is based on 3 pillars: production, storage, distribution and use. The storage of hydrogen is traditionally carried out by compression, under pressures ranging from a few bars to several hundreds, and by liquefaction at 20 K. The low density of these two types of storage (42 and 70 kgH2 / m3) associated with serious problems of safety and mechanical design, make solid storage in metal alloys particularly relevant for some applications. This solution favors the development of safe, compact design tanks with a high density of 120 kgH2/m3for TiFe alloys, for example. This type of hydride has been retained in this work because it has operating conditions of temperatures and pressures that are relatively close to ambient conditions, and also because it does not contain rare earth elements. The aim of this study is to characterize and model the hydriding/dehydriding behavior of the TiFe0.9Mn0.1 alloy, in order to improve its performance when it is integrated into a storage system. We first tried to characterize the alloy TiFe0.9Mn0.1 in powder form by describing it morphologically, chemically and thermodynamically. Then, two strategies of improvement were tested, the first one based on a mechanical treatment by planetary ball milling, the second considers a thermochemical treatment at given temperature and duration. Both strategies accelerated the process of powder activation, but the planetary ball milling significantly impaired the apparent desorption kinetics. The thermo-chemical treatment did not degrade the equilibrium domains and thus did not have an adverse effect on the reaction kinetics. The two most important parameters of this treatment, temperature and holding time, have been optimized. Other parameters remain to be refined.In addition to this experimental characterization, we have undertaken to describe the hydriding / dehydriding reaction macroscopically. The model allows to account for the thermodynamic response of the hydride within a reservoir. This work presents the results obtained on a tank containing 4 kg of TiFe0.9Mn0.1 powder when different hydrogen loading / unloading scenarios are considered: (i) loading / unloading under constant pressure, (ii) loading / unloading under an initial dose ( Method of Sievert), iii) loading / unloading under inlet or outlet flux of hydrogen. For each scenario, the effect of the coupling with a heat exchange system on the filling / emptying times is analyzed and optimal operating conditions are proposed. Finally, a sensitivity study using the Morris method is presented, and the most influential parameters of the model on the reaction rates are identified. The design of a solid hydrogen storage system requires a good understanding of the macroscopic as well as the microscopic aspects of the hydriding reaction and therefore requires further research to find new directions for improving its performance.
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