Energy consumption has increased drastically during the last century. Currently, the worldwide energy consumption is about 17.4 TW and is predicted to reach 25 TW by 2035. Solar energy has emerged as one of the potential renewable energy sources. Since its first physical recognition in 1887 by Adams and Day till nowadays, research in solar energy is continuously developing. This has lead to many achievements and milestones that introduced it as one of the most reliable and sustainable energy sources. Recently, the International Energy Agency declared that solar energy is predicted to be one of the major electricity production energy sources by 2035. Enhancing the efficiency and lifecycle of photovoltaic (PV) modules leads to significant cost reduction. Reducing the temperature of the PV module improves its efficiency and enhances its lifecycle. To better understand the PV module performance, it is important to study the interaction between the output power and the temperature. A model that is capable of predicting the PV module temperature and its effects on the output power considering the individual contribution of the solar spectrum wavelengths significantly advances the PV module designs toward higher efficiency. In this work, a thermoelectrical model is developed to predict the effects of the solar spectrum wavelengths on the PV module performance. The model is characterized and validated under real meteorological conditions where experimental temperature and output power of the PV module measurements are shown to agree with the predicted results. The model is used to validate the concept of active optical filtering. Since this model is wavelength-based, it is used to design an active optical filter for PV applications. Applying this filter to the PV module is expected to increase the output power of the module by filtering the spectrum wavelengths. The active filter performance is optimized, where different cutoff wavelengths are used to maximize the module output power. It is predicted that if the optimized active optical filter is applied to the PV module, the module efficiency is predicted to increase by about 1%. Different technologies are considered for physical implementation of the active optical filter.

[pt] O Setor de energia elétrica no Brasil vem sofrendo fortes mudanças estruturais, cujo principal objetivo é criar um caráter competitivo para permitir ao setor crescer não mais por investimentos estatais, mas sim pelas mãos do capital privado. Com isso, espera-se que a oferta possa acompanhar a demanda crescente nos últimos anos, devido a falta de investimentos no setor, e fazer com que o risco de déficit de carga no futuro diminua. O Programa Prioritário de Termelétricas, lançado pelo governo federal, vai aumentar a oferta de energia no país com a construção de usinas termelétricas, aproveitando o fato da disponibilidade de gás natural existente, e com isso aumentará a participação de geração térmica na matriz energética brasileira. Essa mudança vai conferir mais confiabilidade ao parque gerador de energia, diminuindo o risco de déficit energético pela redução do nível de água dos reservatórios das usinas hidrelétricas. Além disso, as usinas termelétricas são uma alternativa de curto prazo para o Brasil, pois devido ao reduzido prazo de construção, permitiria o aumento da oferta durante a transição para o mercado competitivo, minimizando com isso os riscos de déficit no futuro. As termelétricas, nessa nova estrutura do setor elétrico brasileiro, podem se declarar flexíveis ou inflexíveis. Uma termelétrica flexível é aquela onde sua energia pode ser comercializada no Mercado Atacadista de Energia (MAE), logo ficando sujeita a volatilidade do mercado spot, mas podendo obter grandes lucros. Uma termelétrica inflexível é aquela onde toda sua energia é comercializada mediante contratos bilaterais, ou seja, a energia gerada não é comercializada no MAE. Isto reduz as incertezas, mas também reduz as oportunidades de grandes lucros. A maior incerteza de um projeto do setor elétrico brasileiro é o preço da energia elétrica que em países onde este setor foi reestruturado, como o Brasil, é determinado através do custo marginal de curto prazo (CMCP), por um modelo de otimização energética não publicado ao mercado. Em vista disso, essa dissertação se propõe a formular um modelo para os preços de energia elétrica no Brasil, avaliar uma planta de geração térmica utilizando a Teoria de Opções Reais aliada a técnica de simulação de Monte Carlo e comparar os resultados com os obtidos por Alessandro de Lima Castro em sua dissertação de Mestrado defendida em abril de 2000 cujo título é Avaliação de Investimento de Capital em Projetos de Geração Termoelétrica no Setor Elétrico Brasileiro Usando Teoria das Opções Reais. / [en] The Brazilian Electricity Sector has experienced strong structural changes, whose main objective is to create a competitiveness character to allow for the sector to grow not more for state investments, but now for the hands of the private capital. So, it is expected that supply can meet the growing demand in the last years, due to the lack of investments in the sector, and consequently reduce the risk of load deficit in the future. The Emergency Program of Thermal Plants, introduced by the federal government, will increase the offer of energy in the country with the construction of thermal plants, taking advantage of the availability of natural gas, and thus, will increase the participation of thermal generation in Brazil. That change will give more reliability to the Brazilian Electric System, reducing the risk of energy deficit due to the reduction of the level of water in the reservoirs of the hydro plants. Besides, thermal plants is a short-term alternative to Brazil, because its construction term is shorter than that of hydro plants, so this will increase the offer of energy during the transition for the competitive market, and so reducing the risk of load deficit in the future. Thermal Plants, in that new structure of the Brazilian Electric Sector, can be declared flexible either or inflexible. A flexible thermal plant is that where its energy can be negotiated in a WholeSale Energy Market, and so being subjects the volatility of the spot market, but it could obtain great profits. An inflexible thermal plant is that where its whole energy is negotiated by through bilateral contracts, that is, the energy generated is not negociated in the WholeSale Energy Market. This reduces uncertainties, but it also reduces the opportunities of great profits. The largest uncertainty of a project of the Brazilian electric sector is the price of electricity, and in countries where this sector was restructured, like in Brazil, it is determined through the short run marginal cost (SRMC), for energetic otimization model not published to the market. Thus, this dissertation intends to formulate a model for the price of electricity in Brazil, to evaluate a thermal plant using Real Options Theory and Monte Carlo simulation, and to compare the results with CASTRO´s dissertation: Evaluation of Capital Investment in Thermoelectric Generation Projects in the Brazilian Electricity Sector Using Real Options Theory. / [es] El Sector de energía eléctrica en Brasil ha sufrido fuertes cambios extructurales, con el objetivo de crear un carácter competitivo que permita el crecimiento de este sector, en manos del capital privado y no más por inversiones estatales. Con esto, se espera que la oferta consiga acompañar la demanda cresciente en los últimos años, debido a la falta de inversiones en el sector, y conseguir que el riesgo de déficit de carga en el futuro disminuya. El Programa Prioritario de Termoeléctricas, lanzado por el gobierno federal, pretende aumentar la oferta de energía en el país con la construcción de centrales termoeléctricas, aprovechando la disponibilidad de gas natural existente. Como consecuencia aumentará la participación de la generación térmica en la matriz energética brasilera. Este cambio dará mayor confiabilidad al parque generador de energía, diminuyendo el riesgo de déficit energético por la reducción del nível de agua de los depósitos de las centrales hidroeléctricas. Además, las centrales termoeléctricas constituyen una alternativa de corto plazo para Brasil que, gracias al reducido plazo de construcción, permitiría el aumento de la oferta durante la transición para el mercado competitivo, minimizando así, los riesgos de déficit en el futuro. Las termoeléctricas, en esta nueva extructura del sector eléctrico brasilero, pueden declararse flexibles o inflexibles. Em una termoeléctrica flexible la energía puede ser comercializada en el Mercado Atacadista de Energía (MAE), sujetándose a la volatilidad del mercado spot, pero pudiendo obtener grandes lucros. Una termoeléctrica inflexível comercializa toda su energía mediante contratos bilaterales, o sea, la energía generada no se comercializa en el MAE. Esto reduce los riesgos, pero también reduce las oportunidades de grandes lucros. El mayor riesgo de un proyecto del sector eléctrico brasilero es el precio de la energía eléctrica que, en países donde este sector fue reextructurado, (como en Brasil) se determina a través del costo marginal de corto plazo (CMCP); a través de un modelo de optimización energética no publicado al mercado. Esta disertación se propone formular un modelo para los precios de energía eléctrica en el Brasil, evaluar una planta de generación térmica utilizando la Teoría de Opciones Reales aliada a la técnica de simulación de Monte Carlo; y comparar nuestros resultados con los obtenidos por Alesandro de Lima Castro en su disertación de Mestrado defendida en abril de 2000 bajo el título Evaluación de Inversión de Capital en Proyectos de Generación Termoeléctrica en el Sector Eléctrico Brasilero Usando Teoría de las Opciones Reales.

Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-17T14:46:07Z No. of bitstreams: 1 ANTÔNIO JOSÉ FERREIRA GADELHA - TESE (PPGEQ) 2016.pdf: 6375453 bytes, checksum: 865ce4649601ce36b03d6876719da6d9 (MD5) / Made available in DSpace on 2018-04-17T14:46:07Z (GMT). No. of bitstreams: 1 ANTÔNIO JOSÉ FERREIRA GADELHA - TESE (PPGEQ) 2016.pdf: 6375453 bytes, checksum: 865ce4649601ce36b03d6876719da6d9 (MD5) Previous issue date: 2016-02 / Capes / A crescente demanda mundial por energia tem levado pesquisadores a buscar o aprimoramento de tecnologias com o objetivo de maximizar a geração de energia nas suas diferentes formas. Entre os diferentes métodos de produção encontra-se a energia produzida através de usinas termelétricas, que corresponde a mais 60% da energia produzida no mundo. Entre os principais problemas causados pela produção de energia em termelétricas está a emissão de poluentes gasosos para a atmosfera. O efluente gasoso emitido através da chaminé de uma termelétrica consiste basicamente de dióxido de carbono (CO2), dióxido de enxofre (SO2), óxidos nitrogenados (NOx), entre outros, que provocam problemas ambientais e de saúde. Neste sentido, o presente trabalho teve como objetivo avaliar a fluidodinâmica da dispersão de poluentes emitidos a partir da chaminé de uma termelétrica através de simulações numéricas utilizando CFD (Ansys CFX 15.0). Como modelo de turbulência utilizou-se o k   padrão. Com base nas simulações do planejamento experimental verificou-se que a variável mais significativa no processo foi a taxa de emissão do poluente seguida pela velocidade do vento. A partir dos resultados obtidos verificou-se que a altura da fonte de emissão apresenta uma influência determinante sobre a dispersão; que a variação lateral da intensidade da velocidade do vento e a variação da frequência com que o vento muda de direção são fatores decisivos na dispersão de espécies gasosas na atmosfera; e que a dispersão ocorre com maior intensidade sob condições atmosféricas instáveis, sob um ângulo de 30° e uma frequência de mudança de direção de 5 minutos. / The growing worldwide demand for energy has led researchers to pursue enhancement technologies in order to maximize the generation of electricity in its different forms. Among the different methods of production is the energy produced by thermal power plants, which accounts for over 60% of the energy produced in the world. It is an energy generated from the combustion of fuels such as coal, diesel oil, natural gas, etc. Among the main problems caused by power generation in thermal power plants is the emission of gaseous pollutants into the air. The off-gas emitted from the flue of a fuel consists mainly of carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), among others, causing environmental and health problems. In this sense, this study aims to evaluate the fluid dispersion of pollutants emitted from the chimney of a thermal power plant through numerical simulations using CFD (ANSYS CFX 15.0). As turbulence model was used k   standard. Based on the experimental design simulations it was found that the most significant variable in the process was the pollutant emission rate followed by wind speed. From the results obtained it was found that the height of the emission source has a decisive influence on the dispersion; that the lateral variation of wind speed intensity and variation of the frequency with which the wind changes direction are decisive factors in the dispersion of gaseous species in the atmosphere; and that dispersion occurs more intensively under instable atmospheric conditions, at an angle of 30 ° and a frequency change of direction of 5 minutes.

Made available in DSpace on 2014-12-17T15:14:34Z (GMT). No. of bitstreams: 1 NeymarPC.pdf: 3020681 bytes, checksum: 48c16b28c034f7abb4c4e6b49c509e50 (MD5) Previous issue date: 2007-09-28 / Water still represents, on its critical properties and phase transitions, a problem of current scientific interest, as a consequence of the countless open questions and of the inadequacy of the existent theoretical models, mainly related to the different solid and liquid phases that this substance possesses. For example, there are 13 known crystalline forms of water, and also amorphous phases. One of them, the amorphous ice of very high density (VHDA), was just recently observed. Other example is the anomalous behavior in the macroscopic density, which presents a maximum at the temperature of 277 K. In order to experimentally investigate the behavior of one of the liquid-solid phase transitions, the anomaly in its density and also the metastability, we used three different cooling techniques and, as comparison systems, we made use of the solvents: acetone and ethyl alcohol. The first studied cooling system employ a Peltier plate, a device recently developed, which makes use of small cubes made up of semiconductors to change heat among two surfaces; the second system is a commercial refrigerator, similar to the residential ones. Finally, the liquid nitrogen technique, which is used to refrigerate the samples in a container, in two ways: a very fast and other one, almost static. In those three systems, three Beckers of aluminum were used (with a volume of 80 ml, each), containing water, alcohol and acetone. They were closed and maintained at atmospheric pressure. Inside of each Becker were installed three thermocouples, disposed along the vertical axis of the Beckers, one close to the inferior surface, other to the medium level and the last one close the superior surface. A system of data acquisition was built via virtual instrumentation using as a central equipment a Data-Acquisition board. The temperature data were collected by the three thermocouples in the three Beckers, simultaneously, in function of freezing time. We will present the behavior of temperature versus freezing time for the three substances. The results show the characterization of the transitions of the liquid / A ?gua ainda representa, em suas propriedades cr?ticas e transi??es de fase,um problema de interesse cient?fico atual, em conseq??ncia das in?meras quest?es em aberto e da insufici?ncia dos modelos te?ricos existentes, principalmente relacionados ?s diferentes fases s?lidas e l?quidas que esta subst?ncia possui. Por exemplo, das 13 formas cristalinas conhecidas, a ?gua exibe diferentes fases amorfas, sendo que uma delas, o gelo amorfo de muito alta densidade (VHDA), foi observada apenas recentemente. Outro exemplo ? o comportamento an?malo na densidade que apresenta um m?ximo a 277K. Para investigar experimentalmente o comportamento de uma das transi??es de fase l?quida s?lida da ?gua, a anomalia na sua densidade e tamb?m a meta estabilidade, usamos tr?s diferentes sistemas de refrigera??o e empregamos como sistemas de compara??o, os solventes: Acetona e ?lcool et?lico. O primeiro sistema de refrigera??o usa uma placa Peltier, um dispositivo relativamente novo, que usa pequenos cubos semicondutores para trocar calor entre duas superf?cies; o segundo foi um refrigerador comum, semelhante aos residenciais, uma geladeira. Finalmente o nitrog?nio l?quido, que ? usado para refrigerar as amostras num container de duas maneiras, uma muito r?pida e outra, quase est?tica. Nesses tr?s sistemas foram utilizados tr?s beckers de alum?nio (com volume de 80ml, cada), contendo ?gua, ?lcool e acetona, fechado se mantidos ? press?o atmosf?rica. Dentro de cada becker foram arranjados tr?s termopares, dispostos ao longo do eixo vertical dos beckers, um pr?ximo a superf?cie inferior, outro ao n?vel m?dio e o ?ltimo pr?ximo a superf?cie superior. Um sistema de aquisi??o de dados foi montado via instrumenta??o virtual usando como equipamento central um Data Acquisitions. Com isso, foram coletados os dados de temperatura pelos tr?s termopares nos tr?s beckers, simultaneamente, em fun??o do tempo de congelamento. Apresentaremos o comportamento de temperatura versus tempo de congelamento para as tr?s subst?ncias. Os resultados mostram a caracteriza??o de transi??es das fases l?quido s?lidas nos tr?s l?quidos, com ocorr?ncia da fase meta est?vel tanto para a ?gua quanto para o ?lcool e acetona, indicando a din?mica da ?gua nos diferentes aparatos de medida

Thermocouples are one of the most commonly used instruments for thermometry at elevated  temperatures. As of today, there are only a few types of thermocouples that are built to withstand a temperature beyond 1600 °C,however they usually have a temperature measurement uncertainty of around 1% at these high temperatures. Beyond the 1600 °C temperature span, most high temperature thermocouples tend to drift in the measurements, causing it to output a faulty and inaccurate read of the actual temperature. This thesis explores the usage of carbon fibers as a material to be used in thermocouples, by the combination of two dissimilar carbon fibers. Polyacrylonitrile (PAN) and rayon based fibers were used up to a temperature of 200 °C, where the output voltage of the thermocouple was logged. The study shows a promising and stable linear output of the electromotive force for this type of thermocouple using commercially available carbon fibers at lower temperatures. A comparison is made between the commonly used thermocouples type K and S, results shows that the carbon thermocouple have around 21% of the thermoelectrical efficiency of that of a type K or S thermocouple at 25 °C. For the case of its functionality at higher temperatures, similar graphite material has been studied through literature and found a potential increase in the thermoelectrical stability at higher temperatures beyond 2000 °C, which show that carbon-based thermocouples are well suited for high temperature measurements. / Termoelement är ett av de mest använda instrumenten för temperaturavläsning vid upphöjda temperaturer. Idag finns det bara några få typer av termoelement som är byggda för temperaturer över 1600 ℃, däremot innehar dom vanligtvis en temperaturmätnings osäkerhet på cirka 1% vid dessa höga temperaturer. Över 1600 ℃ temperaturintervallet har de flesta högtemperatur termoelement en tendens att skifta i mätningarna vilket orsakar en felaktig och inexakt mätning av den faktiska temperaturen. Denna avhandling undersöker användningen av kolfiber som ett material för användning i termoelement, genom kombinationen av två olika grafitfibrer. Polyacrylonitrile- (PAN) och Rayon-baserade fibrer användes i en sammansatt kombination upp till en temperatur av 200 ℃, där spänningen mättes mot temperaturen. Studien visar en lovande och stabil linjär effekt av dess elektromotoriska spänning för denna typ av termoelement med kommersiellt tillgängliga kolfibrer vid lägre temperaturer. En jämförelse görs mellan de vanliga termoelementen av typ K och S vid rumstemperaturer, resultaten visar att grafittermoelementen har cirka 21% av den termoelektriska effektiviteten hos den för en typ K eller S termoelement vid 25 ℃. När det gäller dess funktionalitet vid högre temperaturer har liknande grafitmaterial studerats och funnit en potentiell ökning av den termoelektriska stabiliteten vid högre temperaturer över 2000 ℃, vilket visar att grafitbaserade termoelement gör sig väl lämpade för högtemperaturmätningar.

The determination of the pre-arcing time of a fuse given a specific current is crucial during the selection process if the fuse is to be effective for the given application. Often the data supplied by the manufacturer is enough to determine this time, however this is not always the case. For this purpose a fuse model of a diazed fuse has been developed in order to simulate the pre-arcing times in the range of 2 ms to 2 s. The model is implemented in MATLAB and simulates the pre-arcing time for a given current together with fuse parameters such as the materials and the geometry of the fuse. The model has been tested experimentally by running specific currents designed to represent a wide variety of currents which a fuse might be subjected to. The tests were done on 10A gG fuses for which the current through the fuse was logged and then used as input to the fuse model, the simulated time and the measured time was then compared. The simulated times are in general faster than the measured pre-arcing times, this is mainly due to the rate of change of thermal conductivity of the sand with respect to temperature being approximated in conjunction with thermal radiation not being taken into consideration. More testing needs to be done to validate the model for different current ratings and fuse-element designs. / Att bestämma smälttiden för en säkring som utsätts för en given ström är viktigt för att kunna avgöra om dess prestanda är tillräcklig för en viss applikation. I de flesta fall är det möjligt att använda tillverkarens data tillsammans med vågformen för att bestämma smälttiden, men det kan även inträffa att detta inte är möjligt. För dessa fall har en modell av en diazed säkring utvecklas för att simulera smälttiden inom 2 ms till 2 s. Modellen har implementerats i MATLAB och beräknar smälltiden för en given ström och parametrar för säkringen. Modellen har testats experimentellt genom att säkringar har utsatts för en mängd olika strömmar som representerar de olika strömmar som säkringen kan utsättas för. Testerna gjordes på 10 A gG säkringar där strömmen genom säkringen loggades för att sedan användas som ingångsvärde till modellen, tiderna för den uppmätta smälttiden och den beräknades smälltiden jämfördes sedan. De simulerade smälttiderna är lägre jämfört med de uppmätta, detta beror dels på att förändringen av värmeledningsförmågan med temperaturökning hos sanden är okänd och är uppskattad från referenser och dels på att värmestrålning inte har ingått i modellen. Mer tester behöver utföras för att validera modellen mot fler strömstyrkor och designer. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

[pt] Medidas do desempenho de quatro diferentes motores, todos operando no modo bicombustível Diesel / gás natural, foram realizadas em dinamômetro de bancada. Selecionaram-se os motores a ensaiar por suas características construtivas e operacionais, representativas das distintas aplicações dos motores Diesel (cilindrada, faixa de rotação, uso ou não da turbo- alimentação e arrefecimento do ar de combustão). Variou-se a razão de substituição de Diesel por gás natural de modo a levantar as regiões por onde a operação bicombustível é possível. Embora o foco do trabalho esteja sobre o desempenho também se tomaram dados relativos às emissões (fumaça / opacidade), tanto durante a operação original Diesel, quanto na bicombustível. Foram propostas correlações empíricas para o rendimento térmico indicado, eficiência volumétrica e atrito em motores Diesel. Podem-se usar, na falta de dados experimentais prévios, tais correlações na estimativa do desempenho de motores diferentes dos testados. Os resultados indicam que, por grande parte dos campos de funcionamento, apenas parte do gás natural efetivamente queima. Em motores operando a baixa carga cerca de 20 - 30 % do gás fornecido passa ao coletor de escape sem reagir. Desenvolveu-se um modelo simples para a queima Diesel / gás. Parâmetros empíricos exigidos por tal modelo foram levantados com base dos pontos experimentais obtidos. Sugere-se usar tal modelo na previsão do desempenho Diesel / gás de motores ainda não testados no modo bicombustível. Os resultados sugerem que, em motores operando com razão ar / gás natural superior a, aproximadamente, 30, a queima do gás ocorre apenas no entorno do Diesel. Em misturas de razão ar / gás inferior a 30 a queima em frentes de chama parece ocorrer. Em tais casos fica-se, também, sujeito ao funcionamento com detonação. As correlações empíricas levantadas foram utilizadas na conversão Diesel / gás natural de três diferentes grupos geradores de eletricidade (motores de 212, 535 e 1.570 hp). De forma distinta das medidas tomadas em laboratório as conversões destes geradores foram feitas em campo, sem oportunidade para a medida cuidadosa e metódica de todos os parâmetros de interesse. Os dados verificados nas conversões de tais grupos geradores, quando considerados adequados, foram incorporados ao presente trabalho. / [en] Four Diesel engines, all running on the Diesel / natural gas dual fuel mode, were dynamometer tested. Engines were selected based on their distinct construction, operating parameters and engine field use. The Diesel / natural gas substitution was varied in order to determine the dual fuel operation limits. Measurements related to particulate emissions (smoke and opacity) were also made. Correlations for indicated thermal efficiency, volumetric efficiency and engine friction were proposed. It`s suggested that those can be used on the performance estimate of engines when little or no previous test data is available. The dual fuel test results indicate that, according to engine load, part of the gas does not burn. In engines running on low load as much as 20 - 30 % of the gas supplied simply reaches exhaust manifold unreacted. A simple model for the dual fuel combustion was proposed. An empirical correlation for a combustion parameter, that arouse in the modeling was, base on test results, proposed. It`s suggested that the semi-empirical dual fuel model can be used for the performance estimate of Diesel engines, when burning natural gas, not previously tested on the dual fuel mode. Results indicate that, for engines running on air / gas ratios above 30, combustion appear to remain limited to Diesel droplets neighborhood. For richer mixtures gas combustion appear to occur on flame fronts. Audible knock was noticed on engines running on air / gas ratios below, approximately, 30. The empirical correlations proposed were used for the dual fuel conversion of three different genset engines (212, 535 and 1.570 bhp). Gensets data, when appropriate, is also reported in the present work.

[pt] O trabalho tem como objetivo a conversão de um grupo gerador, originalmente Diesel, para operar no modo Diesel-Gás, onde estes dois combustíveis são administrados simultaneamente no motor. Para tal foi utilizado um grupo gerador de 120KW, com um motor Perkins 1006 TAG (turbo alimentado com intercooler). Medidas experimentais foram realizadas tanto no modo Diesel quanto no bicombustível Diesel-gás. Foram avaliados: desempenho e, principalmente, emissões de poluentes atmosféricos. A redução das emissões foi realizada mediante a restrição parcial do ar de combustão, regulada por uma válvula tipo borboleta, que funciona eletronicamente, posicionada na entrada do coletor de admissão. A relação Diesel-Gás foi também avaliada, onde o segundo combustível era administrado através de um sistema eletrônico de injeção de gás natural. Os resultados indicam que em cargas baixas as reduções de monóxido de carbono e hidrocarbonatos são significativas (50% de redução de HC e 20% de CO) com máximas taxas de substituição. O mesmo se observa em cargas intermediárias. Em cargas médias e baixas observa-se um leve aumento nas emissões de óxido nitroso. Pode-se observar uma melhora no rendimento global do grupo gerador com o aumento da carga e da taxa de substituição. De forma geral, conseguiu-se reduzir os níveis de emissões em altas cargas, principalmente de hidrocarbonetos e monóxido de carbono. / [en] The objective of this study is converting a generator, originally Diesel, to operate in a Diesel-Gas; two fuels are administered simultaneously to the motor. One diesel generator of 120KW model Perkins 1006 TAG (powered with turbo intercooler), running on the Diesel / natural gas dual fuel mode, was tested. Experimental measurements were performed in both the Diesel and dual fuel diesel-gas. Are evaluated performances and; especially air pollutant emissions. The emission reduction was carried out by partial restriction of the combustion air with the help of an electronic throttle valve, positioned before the intake manifold. The ratio Diesel-Gas was evaluated, where the second fuel (natural gas) was administered with one electronic injection of natural gas. The results indicate that at low loads the reductions in carbon monoxide and hydrocarbons are significant (50% reduction in HC and 20% CO) with maximum replacement rates. Something like is observed at intermediate loads. In medium and low loads there is a slight increase in emissions of nitrous oxides. One can observe a slight increase in overall yield of the generator with the increased workload and the replacement rate; in general it was possible to reduce emissions at high loads, especially in hydrocarbons and carbon monoxide.

L’apparition ces dernières années de supraconducteurs réalisés industriellement utilisant des composés à haute température de transition offre la possibilité de nouveaux développements en magnétisme supraconducteur. En effet ils permettent d’augmenter le champ magnétique généré en conservant une cryogénie classique à 4,2K d’une part, et ils ouvrent la voie à des développements d’aimants supraconducteurs fonctionnant entre 10 et 30K d’autre part. Les matériaux supraconducteurs à haute température critique sont alors indispensables pour dépasser les inductions magnétiques de 16 T (cas de l’insert dipolaire HTc pour le Large Hadron Collider du CERN) ou augmenter la densité spécifique d’énergie stockée dans un SMES (Superconducting Magnetic Energy Storage, cas du projet ANR SuperSMES).Les atouts incontestables (température critique, champ magnétique critique, résistance mécanique) apportés par l’utilisation des matériaux supraconducteurs à haute température critique tels que l’YBaCuO dans les aimants supraconducteurs demandent de relever quelques défis. Leur comportement est encore mal compris, surtout lors des transitions résistives. Arriver à protéger ces conducteurs requiert une réflexion nouvelle sur les systèmes de protection destinés à éviter les dégradations thermiques et mécaniques. La réponse à la question « peut-on utiliser ces matériaux de manière pérenne dans les aimants supraconducteurs ? » est incontournable.Des éléments de réponse sont donnés ici. L’utilisation des conducteurs est abordée à travers différentes études expérimentales permettant de mieux connaître le conducteur (caractérisation électrique et modélisation de la surface critique) d’une part et de définir les étapes clés de la fabrication des aimants supraconducteurs à haute température de transition (étude des jonctions entre conducteurs ou entre galettes) d’autre part. Cette étude a abouti à la réalisation de deux prototypes d’aimants ayant permis d’identifier les difficultés liées à l’utilisation des rubans d’YBaCuO. Un modèle thermoélectrique des supraconducteurs à haute température de transition est développé et un code numérique basé sur le logiciel de calcul par Eléments Finis CASTEM permet d’étudier le phénomène de transition résistive, ou quench, dans un conducteur et dans un aimant. Le code a été validé sur des essais réalisés au Laboratoire National des Champs Magnétiques Intenses de Grenoble. Les résultats obtenus ont permis la définition des conducteurs pour les deux projets liés à la thèse et la validation de la protection. / The new industrial superconductors using high critical temperature compounds offer new possibilities for superconducting magnetism. Indeed they allow higher magnetic field with the same classical cryogenics at 4.2 K on one hand, and on the other hand they also pave the way for superconducting magnets working between 10 K and 30 K. The high temperature superconductors are then needed in order to produce magnetic fields higher than 16 T (case of HTS dipole insert for Large Hadron Collider at CERN) or to increase the specific density stored in one SMES (Superconducting Magnetic Energy Storage, in the case of the SuperSMES ANR Project).Nevertheless the indisputable assets (critical temperature, critical magnetic field, mechanical stresses) brought by the use of High critical temperature superconductors like YBCO, used in superconducting magnets, require to solve some challenges. Their behavior is still badly understood, especially during the resistive transitions. To succeed in protecting these conductors we need a new reflection on protection schemes designed to avoid the thermal and mechanical damages. The answer to the question: “Can we use those materials in the long run inside superconducting magnets?” is now inescapable.Some answers are given here. The use of the conductors is approached through various experimental studies to understand the material (electrical characterization and modeling of the critical surface) and to define the key stages of high critical temperature superconducting magnets manufacturing (work on the junctions between conductors and pancakes). This study led to the creation of two coils in order to identify the issues related to the use of YBCO tapes. A numerical thermo-electrical model of the high critical temperature superconductor has been developed and a numerical code based on the CEA software CASTEM (Finish Elements Model) allowed to study the resistive transition (or quench) behavior of those conductor and coil. The code has been confirmed by comparison with some experimental data obtained by the Laboratoire National des Champs Magnétiques Intenses in Grenoble. The results have allowed to define the conductors for the two projects of this thesis and to validate the feasibility of the protection of those conductors.