In order to improve urban air quality and to meet legislation requirements, vehicular technology is constantly advancing. It focus on techniques that reduce both fuel consumption and emissions of greenhouse gases as well as harmful pollutant emissions. The technologies, however, have different impacts depending on the city, its traffic conditions and urban planning as well as other socio-economic and cultural factors that affect the driving stile. Thus, standard drive cycles such as NEDC, FTP75 or others may not represent properly the actual condition and are being progressively replaced by real-world driving cycles. This paper aims to analyze the impact of real driving conditions in the city of Santa Maria, in southern Brazil, in respect to emissions and fuel consumption. Data of real world driving cycles were collected for motorized transport and introduced into computational models to simulate vehicles traveling in predetermined route. Urban buses and passenger cars were evaluated in different traffic conditions. Underestimation of more than 50% in emissions were observed in heavy traffic conditions across the indicated in standard cycles. Simulation of techniques to reduce pollutant emissions in Diesel engines has confirmed more than 90% reductions in emissions of PM, CO, HC, and 40% of NOx, operating under real conditions. / Objetivando a melhoria na qualidade do ar urbano e o atendimento à legislação, a tecnologia veicular está em constante desenvolvimento. O foco está em técnicas para redução, tanto do consumo de combustível quanto de emissões de gases do efeito estufa. As tecnologias, entretanto, possuem diferentes impactos dependendo da cidade, das condições de tráfego e do planejamento, assim como demais fatores socioeconômicos e culturais que interfiram no modo de condução. Com isso, ciclos padrões de condução, como NEDC e FTP75, por exemplo, não representam com propriedade a condição atual de tráfego e estão sendo gradativamente substituídos pelos ciclos reais de condução. Esta dissertação objetiva analisar o impacto de ciclos reais no trânsito urbano da cidade de Santa Maria- RS, no âmbito de emissões e consumo de combustível. Dados de ciclos reais de condução foram coletados para meios de transporte motorizados e introduzidos em modelos computacionais, visando simular um veículo percorrendo o trajeto pré-estabelecido. Assim, avaliaram-se carros de passeio e ônibus urbanos em diferentes condições de tráfego. Em posse dos resultados foram realizadas as comparações com ciclos padrão existentes, onde verificaram-se subestimações de mais de 50% nas emissões por ciclos padrão frente à condições reais de tráfego intenso. A simulação de sistemas para a redução nas emissões de poluentes em motores Diesel, operando em condições reais, confirmou reduções de mais de 90% nas emissões de MP, CO e HC e de 40% nas emissões de NOx.

Este trabalho propõe um método com base no planejamento estatístico de testes de confiabilidade para proporcionar um tratamento quantitativo aos dois primeiros níveis da abordagem de padrões baseados em metas (Goal-Based Standards). O uso do método é demonstrado em dois exemplos práticos, através da sua aplicação na meta de confiabilidade dos componentes do sistema de pós-tratamento de gases de exaustão, em motores a diesel de veículos automotivos e marítimos. Os fundamentos do trabalho incluem a teoria do planejamento estatístico de testes de confiabilidade, os princípios do GBS, tipos e características de metas de confiabilidade, a ferramenta de avaliação de segurança formal (FSA), e da análise do modo e efeito da falha (FMEA). A originalidade da contribuição do trabalho está na combinação das técnicas de planejamento de testes de confiabilidade com os princípios do GBS para quantificar o nível de atendimento das metas de confiabilidade. Dessa forma, é possível ajustar o programa de testes na verificação das metas de segurança, aumentando o conhecimento sobre o desempenho do sistema. O método é de simples aplicação permitindo a sua aplicação expedita e integrada aos processos de desenvolvimento de sistemas. / This research proposes a probabilistic method based on reliability test planning in order to provide a quantitative approach to the Tier I and II of the Goal-Based Standards (GBS). The use of the method is exhibited through its application in the reliability goal of the components of the exhaust gases post-treatment system in diesel engines for automotive and marine vehicles. The fundamentals of this work includes the theory of statistical design of reliability tests, the GBS principles, a brief description of the types and characteristics of reliability goals, the tool of Formal Safety Assessment (FSA) recommended for marítima projects, and the risk qualitative methodology based on Failure Mode Effect Analysis (FMEA). This theoretical framework was applied to two practical examples, one in the automotive industry and the other in the shipbuilding sector. The originality of this research lies in the combination of the reliability test planning techniques with the principles of GBS, in order to verify, from the whole project tests planning, the reliability goals of the basic components as a fundamental step in the assessment of system safety. The testing program can be adjusted to focus on verifying the safety goals, so that the level of knowledge about the product performance before it is delivered to the client. This work also offers the benefit of providing an easy method of system safety assessment, which allows a large number of companies to use it and to integrate it into their product development process.

[ES] Para cumplir los límites de emisiones impuestos por los gobiernos y reducir el impacto negativo en el medio ambiente, el uso de sistemas de postratamiento (ATS) se ha convertido en algo esencial para los motores de combustión interna. Los ATS en los trenes motrices están planteados para lograr una alta eficiencia de reducción de contaminantes en las condiciones de funcionamiento diseñadas, para lo cual el sistema de control necesita conocer el nivel de desgaste del catalizador, así como confiar en la información de retroalimentación de los subsistemas de los ATS. Además, es posible aumentar la capacidad de reducción de contaminantes de los catalizadores mediante estrategias de control inteligentes. Ante este escenario, esta tesis pretende aplicar técnicas de monitorización y diagnóstico para garantizar el pleno funcionamiento del ATS, y estrategias de control óptimo para mejorar la reducción de las emisiones de NOx con bajo consumo y deslizamiento de NH3. Para lograr este objetivo, se han planteado dos caminos: ¿ Desarrollo de modelos de alta precisión para la predicción de las emisiones de NOx y NH3 acoplados a un algoritmo de fusión de datos, siendo aplicados para diagnosticar el sistema en dos enfoques específicos: detección del nivel de fallo de inyección de amoníaco en el ATS y estimación del estado de envejecimiento del catalizador del ASC. ¿ Uso de modelos físicos orientados al control para mejorar la estrategia de inyección de amoníaco. Se optimizaron dos escenarios, primero, un enfoque de referencia para la optimización off-line conociendo de antemano el ciclo de conducción, logrando así la máxima capacidad del sistema para reducir los NOx con el mínimo consumo de NH3. En segundo lugar, la optimización on-line mediante la técnica de control predictivo de modelos (MPC) con el objetivo de conseguir la máxima reducción de NOx con un deslizamiento de NH3 aguas abajo del catalizador ASC inferior a un límite preestablecido. Todos los modelos desarrollados y los enfoques propuestos se implementaron en un banco de pruebas totalmente instrumentado y se validaron experimentalmente, alcanzando resultados satisfactorios en ambos enfoques, diagnóstico y control. / [CAT] Per a complir els límits d'emissions imposats pels governs i reduir l'impacte negatiu en el medi ambient, l'ús de sistemes de posttractament (ATS) s'ha convertit en una cosa essencial per als motors de combustió interna. Els ATS als trens motrius estan plantejats per a aconseguir una alta eficiència de reducció de contaminants en les condicions de funcionament dissenyades, per a això el sistema de control necessita conéixer el nivell de desgast del catalitzador, així com confiar en la informació de retroalimentació dels subsistemes dels ATS. A més, és possible augmentar la capacitat de reducció de contaminants dels catalitzadors mitjançant estratègies de control intel·ligents. Davant aquest escenari, aquesta tesi pretén aplicar tècniques de monitoratge i diagnòstic per a garantir el ple funcionament de l'ATS, i estratègies de control òptim per a millorar la reducció de les emissions de NOx amb baix consum i lliscament de NH3. Per a aconseguir aquest objectiu, s'han plantejat dos camins: ¿ Desenvolupament de models d'alta precisió per a la predicció de les emissions de NOx i NH3 acoblats a un algorisme de fusió de dades, sent aplicats per a diagnosticar el sistema en dos enfocaments específics: detecció del nivell de fallada d'injecció d'amoníac en l'ATS i estimació de l'estat d'envelliment del catalitzador del ASC. ¿ Ús de models físics orientats al control per a millorar l'estratègia d'injecció d'amoníac. Es van optimitzar dos escenaris, primer, un enfocament de referència per a l'optimització off-line coneixent per endavant el cicle de conducció, aconseguint així la màxima capacitat del sistema per a reduir els NOx amb el mínim consum de NH3. En segon lloc, l'optimització en línia mitjançant la tècnica de control predictiu de models (MPC) amb l'objectiu d'aconseguir la màxima reducció de NOx amb un lliscament de NH3 aigües avall del catalitzador ASC inferior a un límit preestablit. Tots els models desenvolupats i els enfocaments proposats es van implementar en un banc de proves totalment instrumentat i es van validar experimentalment, aconseguint resultats satisfactoris en tots dos enfocaments, diagnòstic i control. / [EN] To meet the emission limits imposed by governments and reduce the negative outcome on the environment, the use of after-treatment systems (ATS) has become essential for internal combustion engines. The ATS in powertrains are devised to achieve high pollutant abatement efficiency under the design operating conditions, for which the control system needs to know the catalyst wear level as well as to rely on feedback information from the ATS subsystems. Furthermore, it is possible to increase the pollutant reduction capacity of catalysts through intelligent control strategies. Looking at this scenario, this thesis intends to apply techniques of monitoring and diagnosis to guarantee the full operation of the ATS, and optimal control strategies to improve the reduction of NOx emissions with low NH3 consumption and slip. To this aim, two paths were outlined: ¿ Development of high accuracy models for the prediction of NOx and NH3 emissions coupled with a data fusion algorithm, being applied to diagnose the system in two specific approaches: detection of the ammonia injection failure level in the ATS and estimation of the ASC catalyst ageing state. ¿ Use of physical control-oriented models to improve the ammonia injection strategy. Two scenarios were optimized, firstly a benchmark approach for off-line optimization knowing in advance the driving cycle, thus achieving the maximum capacity of the system to reduce NOx with minimum NH3 consumption. Secondly, on-line optimization through the model predictive control (MPC) technique aiming the maximum NOx abatement with NH3 slip downstream the ASC catalyst below a pre-established threshold. All developed models and proposed approaches were implemented in a fully instrumented test bench and experimentally validated, reaching satisfactory results in both approaches, diagnosis and control. / Nakaema Aronis, A. (2023). Control and Diagnosis of a SCR-ASC After-Treatment System for NOx and NH3 Emission Reduction Under Real Driving Conditions and Potential System Failure [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/192476

Deactivation of catalysts were investigated focusing on three industrial processes: 1) Selective Catalytic Reduction (SCR) for abatement of NOx from biomass combustion using V2O5-WO3 /TiO2 catalysts; 2) Catalytic oxidation of volatile organic compounds (VOC) from printing industries using a Pt/γ-Al2O3 catalyst; and 3) Ni and Pt/Rh catalysts used in steam reforming reaction of bio-syngas obtained from biomass gasification. The aim has been to simulate industrial conditions in laboratory experiments in order to comprehend influence of compounds affecting catalysts performance. Typical catalyst lifetimes in industrial processes are several years, which are a challenge when accelerating deactivation in laboratory scale experiments where possible exposure times are few hours or days. Catalysts can be introduced to deactivating compounds through different routes. The first method examined was gaseous exposure, which was applied to deactivate VOC oxidation catalyst through exposure of gaseous hexamethyldisiloxane. The second method involved wet impregnation and was used for impregnation of SCR catalyst with salt solutions. The third method was based on exposure and deposition of size selected particles of deactivating substances on the catalyst. The latter device was developed during this work. It was applied to monolithic SCR catalysts as well as to pellet catalysts intended for steam reforming of biomass gasification syngas. Deactivated SCR catalyst samples by size selected exposure method were verified and compared with SCR catalysts used in a commercial biomass boiler for 6 500 h. Evaluations of fresh and deactivated samples were investigated using BET surface area; chemisorption and temperature programmed desorption (TPD); surface morphology using Scanning Electron Microscopy (SEM) and poison penetration profile through SEM with an Electron Micro Probe Analyser (EMPA) also equipped with a energy dispersive spectrometer (EDS); chemical analysis of accumulation of exposed compounds by Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP-AES); and influence on catalyst performance. The size selected generated particles of deactivating substances were characterized with respect to mean diameter and number size distribution through Scanning Mobility Particle Sizer (SMPS) and mass size distribution applying an Electric Low Pressure Impactor (ELPI). Results from catalyst characterization methods were useful tools in evaluation of catalyst deactivation routes. Understanding deactivation processes and impact on catalyst performance is vital for further optimization of catalysts with respect to performance and lifetime. Further research in this field can provide more resistant catalysts for application in industry leading to higher commercial benefits and further application of environmental catalysts in thermo-chemical conversion of biomass.

No description available.

This thesis describes a new concept, applicable to high-power current-sourced conversion (CSC), where a controllable firing-angle shift is introduced between series and parallel converters to enable independent active and reactive power control. The firing-shift concept solves a difficult problem, by giving thyristor based CSCs the control flexibility of pulse-width modulated (PWM) converters, but without a loss in efficiency or rating. Several configurations are developed, based on the firing-shift concept, and provide flexible, efficient solutions for both very high power HVDC transmission, and very high current industrial processes. HVDC transmission configurations are first developed for 4-quadrant high-pulse operation, based on the series connected multi-level current reinjection (MLCR) topology. Independent reactive power control between two ends of an HVDC link are proven under firing-shift control, with high-pulse operation, and without on-load tap changing (OLTC) transformers. This is followed by application of firing-shift control to a bi-directional back-to-back HVDC link connecting two weak systems to highlight the added dc voltage control flexibility of the concept. The fault recovery capability of an MLCR based ultra-HVDC (UHVDC) long distance transmis-sion scheme is also proven under firing-shift control. The scheme responds favourably to both ac disturbances and hard dc faults, without the risk of commutation failures and instability experienced during fault recovery of line-commutated conversion. The two-quadrant capability of very high current rectification is also proven with configurations based on phase-shifted 12-pulse and MLCR parallel CSCs. The elimination of the electro-mechanical OLTC/satruable reactor voltage control, the high-current CSC’s biggest shortcoming, greatly improves controllability and with firing-shift control, ensures high power-factor for all load conditions. This reduces the reactive power demands on the transmission system, which results in more efficient power delivery

La SCR (Selective Catalytic Reduction) permet de réduire les oxydes d'azote (NOx) à l'intérieur d'une ligne d'échappement d'un véhicule Diesel à l'aide d'une solution réductrice à base d'urée injectée en amont d'un catalyseur. L'urée est convertie en NH3 par pyrolyse et hydrolyse, et NH3 réduit les NOx enN2 sur le catalyseur. Cependant, comme cette technique met en jeu un ensemble de réactions très complexes, beaucoup de réactions parasites peuvent entraîner la formation de produits secondaires contenant de l'azote et perturber le bon déroulement du procédé. Par conséquent, l'élaboration d'une étude sur la mesure de ces produits secondaires et de leurs conditions de formation est donc essentielle pour la bonne calibration de la SCR. Si pour certains composés, les techniques de mesures sont encore à développer, dans tous les cas, on se trouve confronté à des problèmes liés au prélèvement des espèces. L'objectif de la thèse est d'identifier, de comprendre et de quantifier les phénomènes qui entrent en jeu et qui perturbent l'analyse des composés azotés dans la ligne d'échappement et dans la ligne de prélèvement. Le travail a été mené selon différents axes de recherche : la comparaison des méthodes de mesure de composés azotés en situation réelles dans les gaz d'échappement d'un moteur Diesel muni d'un catalyseur SCR, l'étude du prélèvement des composés azotés et notamment NH3 dans une ligne de prélèvement standard et la modélisation des pertes dans une ligne de prélèvement. A la fin de ce travail, nous avons évalué l'impact des conditions de prélèvements : température des gaz, composition et/ou longueur des lignes de prélèvement, sur les résultats de la mesure. Ce travail nous permet d'apporter des suggestions pour améliorer le prélèvement et les mesures des composés azotés présents à l'échappement d'un véhicule Diesel équipé d'une SCR.

Dans le cadre du projet FNRAE COTECH, nos travaux avaient pour objectifs d'améliorer le fonctionnement des structures électroniques à haute température d'une technologie SOI (200°C). La technologie choisie pour ce travail est une technologie de puissance intelligente comprenant une bibliothèque CMOS basse tension (5V), des transistors de puissance LDMOS (25V, 45V et 80V) et des transistors bipolaires NPN et PNP. Afin de caractériser cette technologie en température, dans un premier temps, nous avons conçu un véhicule de test en introduisant certaines règles de dessin bénéfiques pour le comportement en température, à la fois pour les composants basse et haute puissance. Nous avons également étudié une nouvelle architecture de composants combinant au sein d'un même composant un composant MOS et un composant IGBT, dans un objectif d'auto-compensation des effets négatifs de la température. Afin d'optimiser la conception de ces composants mixtes MOS-IGBT, la méthodologie que nous avons adoptée s'est appuyée sur des simulations 2D et 3D sur Sentaurus. Dans le cadre de ce travail, deux véhicules de test ont été réalisés et caractérisés. Ces structures mixtes MOS-IGBT ont été proposées en tant que structures de protection contre les décharges électrostatiques (ESD) pour remplacer une structure de protection de type "power clamp". En s'appuyant sur la simulation 3D, nous avons proposé plusieurs solutions, à la fois topologiques et d'architecture, permettant d'augmenter significativement le niveau de ce courant. Ces diverses solutions ont été validées expérimentalement. Enfin, les bonnes performances de ces structures mixtes ont motivé leur étude en tant que structures de puissance.

Dissertation (Ph.D.)--University of South Florida, 2007. / Includes vita. Includes bibliographical references. Also available online.

The master thesis deals with possibilities of utilization of conventional power plant fly ash after introduction of SNCR (Selective non-catalytic reduction) as a method of flue gas denitrification. Behaviour of fly ash containing products of denitrification, ash with water and stabilizate prepared from contaminated ash was studied. Experiments were focused on the study of various factors affecting the release of ammonia from prepared mixtures. Samples were exposed to the weather conditions to simulate deposition in addition to the laboratory experiment. Influence of the fly ash containing denitrification to mechanical properties and volume stability of pastes and mortars were also studied. The interaction of denitrification products with superplasticizers was studied on pastes. Achieved results were verified on concretes.