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Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 113-125).

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains xiv, 347 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 272-276).

Dissertation (Ph.D.)--University of South Florida, 2005. / Includes vita. Title from PDF of title page. Document formatted into pages; contains 99 pages. Includes bibliographical references.

Ce travail est consacré à l'étude du dépôt des particules de suie transportées par des fumées d'incendie. L'étude de la littérature donne une synthèse des propriétés connues des particules de suie produites par un incendie ainsi qu'une revue de l'état de l'art des outils disponibles pour modéliser leur dépôt. Le code Fire Dynamics Simulator, outil numérique utilisé dans ce travail, permet depuis sa version 6 de simuler le dépôt de suie mais aucune étude expérimentale à échelle réelle ne fournit de données quantitatives de dépôt qui permettraient de valider les performances de l'outil dans ce domaine. Une première campagne expérimentale a donc été réalisée pour pouvoir évaluer FDS et les modèles fournis par la littérature dans le cas du dépôt à échelle réelle de particules de suie produites par la combustion d'heptane. Ces essais ont été suivis d'une seconde campagne expérimentale à échelle réelle avec pour objectif la prise en compte de l'écoulement des fumées le long de la paroi de dépôt et de sa vitesse. Les deux campagnes d'essais à échelle réelle ont enfin été complétées par le montage d'un banc expérimental à petite échelle permettant d'étudier l'influence de la vitesse d'écoulement sur le dépôt de particules produites par un petit foyer, à l'intérieur d'une conduite. / This work is devoted to the study of the deposit of soot particles transported by fire smoke. The literature review provides a summary of the known properties of soot particles produced by fire as well as a review of the state of the art tools to model their deposit. The CFD tool Fire Dynamics Simulator allows since version 6 to predict the deposition of soot. However no full scale experimental study provides quantitative data about thermophoretically driven soot deposition, making validation impossible. A first experimental campaign was conducted to valuate FDS and modelling tools provided by the literature in the case of full-scale deposition of soot particles produced by the combustion of heptane. These tests were followed by a second full-scale experimental campaign with the aim of taking into account the flow of smoke along the wall and its speed. Both full scale campaigns were finally completed by a small-scale experimental bench mounted in order to tudy the influence of the flow rate on particle thermally driven deposition within a duct.

abstract: Black carbon (BC) is the product of incomplete combustion of biomass and fossil fuels. It is found ubiquitously in nature and is relevant to studies in atmospheric science, soil science, oceanography, and anthropology. Black carbon is best described using a combustion continuum that sub-classifies BC into slightly charred biomass, char, charcoal and soot. These sub-classifications range in particle size, formation temperature, and relative reactivity. Interest in BC has increased because of its role in the long-term storage of organic matter and the biogeochemistry of urban areas. The global BC budget is unbalanced. Production of BC greatly outweighs decomposition of BC. This suggests that there are unknown or underestimated BC removal processes, and it is likely that some of these processes are occurring in soils. However, little is known about BC reactivity in soil and especially in desert soil. This work focuses on soot BC, which is formed at higher temperatures and has a lower relative reactivity than other forms of BC. Here, I assess the contribution of soot BC to central AZ soils and use the isotopic composition of soot BC to identify sources of soot BC. Soot BC is a significant (31%) fraction of the soil organic matter in central AZ and this work suggests that desert and urban soils may be a storage reservoir for soot BC. I further identify previously unknown removal processes of soot BC found naturally in soil and demonstrate that soil soot BC undergoes abiotic (photo-oxidation) and biotic reactions. Not only is soot BC degraded by these processes, but its chemical composition is altered, suggesting that soot BC contains some chemical moieties that are more reactive than others. Because soot BC demonstrates both refractory and reactive character, it is likely that the structure of soot BC; therefore, its interactions in the environment are complex and it is not simply a recalcitrant material. / Dissertation/Thesis / Ph.D. Chemistry 2013

Les réglementations européennes étant de plus en plus restrictives en ce qui concerne les émissions de polluants et plus particulièrement les émissions d'oxydes d'azote (NOx) et de suies, l'objectif de ce travail est de fournir des outils de modélisation permettant l'analyse des mécanismes de réduction de ces émissions à la source, c'est-à-dire au niveau de la chambre de combustion. Dans un premier temps, un modèle de tabulation pour la prédiction des oxydes d'azote a été développé. Ce modèle (appelé NORA: NO Relaxation Approach) repose sur une méthode de perturbation d'état d'équilibre et présente l'avantage d'être simple d'utilisation, robuste et totalement indépendant du modèle de combustion turbulente. L'utilisation du modèle NORA permet une amélioration significative des résultats par rapport à une résolution directe du mécanisme de Zel'dovich couplé à une cinétique réduite. Dans un second temps, le travail a porté sur la modélisation des suies avec comme objectif la prédiction des suies en terme de masse et de distribution en taille de particules (PSDF: Particle Size Distribution Function). La méthode sectionnelle a tout d'abord été implémentée dans un solveur de flamme 1-D et validée par rapport à des données expérimentales en flammes laminaires d'éthylène. La question du couplage du modèle de suies avec un modèle de combustion turbulente a ensuite été posée. Ce travail montre que le couplage entre la phase gazeuse et la phase solide n'est pas négligeable. Un premier modèle de combustion mixte (appelé MTKS) utilisant une méthode tabulée et un solveur de chimie détaillé dans les gaz brûlés a été couplé au modèle de suies. L'approche MTKS a été testée dans des réacteurs hétérogènes à volume variable et les résultats sont encourageants. / European rules are more and more restrictive concerning pollutants emissions. This work deals with the modeling of NOx and soot particles. The final aim is to provide modeling tools in order to analyse the mechanismes leading to reduce these emissions in the combustion chamber. First, a tabulated NO prediction model has been developed. This model (called NORA: NO Relaxation Approach) is based on equilibrium state perturbation method. NORA is simple to use, robust and totally independent of the turbulent combustion model. The use of the NORA allows a significative improvement of the results compared to the direct resolution of the Zel'dovich mechanism with a reduce chemistry. In a second part, this work deals with soot predictions with the final aim the prediction of the soot volume fraction and the particle size distribution function (PSDF). The sectional method approach was first implemented in a 1-D flame solver and validated against experimental flames data. The question of the coupling between the soot sectional model and a turbulent combustion model has been addressed. Studies show that the coupling between gaseous and solid phase is non-negligible. A first mixed combustion model (called MTKS) using a tabulated method and a kinetic solver in the burned gases has been coupled to the soot sectional model. The MTKS approach has been tested in heterogeneous variable volume reactors and results are promising.

Les particules de suies issues de moteur Diesel constituent un enjeu de santé publique et sont soumises à des réglementations de plus en plus strictes. Les constructeurs automobiles ont donc besoin de modèles capables de prédire l’évolution en nombre et en taille de ces particules de suies. Dans ce cadre, un modèle de suies basé sur une représentation sectionnelle de la phase solide est proposé dans cette thèse. Le choix de ce type d’approche est d’abord justifié par l’étude de l’état de l’art de la modélisation des suies. Le modèle de suies proposé est ensuite décrit. A chaque instant et en chaque point du maillage, les particules de suies sont réparties en sections selon leur taille et l’évolution de chaque section est gouvernée par : • une équation de transport;• des termes sources modélisant l’interaction avec la phase gazeuse (nucléation, condensation, croissance de surface et oxydation des suies);• des termes sources collisionnels permettant de représenter les interactions entre suies (condensation et coagulation). Ce modèle de suies nécessite donc la connaissance des concentrations locales et instantanées des précurseurs de suies et des espèces consommées par les schémas de réactions de surface des suies. Les schémas fournissant ces informations pour des conditions thermodynamiques rencontrées dans des moteurs Diesel comportant des centaines d’espèces et des milliers de réactions, ils ne peuvent être utilisés directement dans des calculs de CFD. Pour pallier cela, l’approche de tabulation de la chimie VPTHC (Variable Pressure Tabulated Homogeneous Chemistry) a été proposée. Cette approche est basée sur l’approche ADF (Approximated Diffusion Flame) qui a été simplifiée pour permettre son emploi couplé au modèle de suies sectionnel. Dans un premier temps, la capacité du modèle tabulé à reproduire la cinétique chimique a été validée par comparaison des résultats obtenus avec ceux de réacteurs homogènes avec loi de piston équivalents. Finalement, le modèle VPTHC, couplé au modèle de suies sectionnel, a été validé sur une base d’essais moteur dédiée avec des mesures de distribution en taille de suies à l’échappement. Cette base comporte des variations de durée d’injection, de pression d’injection et de taux d’EGR à la fois pour un carburant Diesel commercial et pour le carburant modèle utilisé dans les calculs. Les prédictions des débits horaires de suies et des distributions à l’échappement obtenues sont en bon accord avec les mesures.Ensuite, les résultats du modèle ont été comparés avec les mesures plus académiques et détaillées du Spray A de l’Engine Combustion Network, un spray à haute pression et température. Cette seconde validation expérimentale a permis l’étude du comportement du modèle dans des régimes transitoires. / Soot particles emitted by Diesel engines cause major public health issues. Car manufacturers need models able to predict soot number and size distribution to face the more and more stringent norms.In this context, a soot model based on a sectional description of the solid phase is proposed in this work. First, the type of approach is discussed on the base of state of the art of the current soot models. Then, the proposed model is described. At every location and time-step of the simulation, soot particles are split into sections depending on their size. Each section evolution is governed by: • a transport equation;• source terms representing its interaction with the gaseous phase (particle inception, condensation surface growth and oxidation);• source terms representing its interaction with other sections (condensation and coagulation).This soot model requires the knowledge of local and instantaneous concentrations of minor species involved in soot formation and evolution. The kinetic schemes including these species are composed of hundreds of species and thousands of reactions. It is not possible to use them in 3D-CFD simulations. Therefore, the tabulated approach VPTHC (Variable Pressure Tabulated Homogeneous Chemistry) has been proposed. This approach is based on the ADF approach (Approximated Diffusion Flame) which has been simplified in order to be coupled with the sectional soot model. First, this tabulated combustion model ability to reproduce detailed kinetic scheme prediction has been validated on variable pressure and mixture fraction homogeneous reactors designed for this purpose. Then, the models predictions have been compared to experimental measurement of soot yields and particle size distributions of Diesel engines. The validation database includes variations of injection duration, injection pressure and EGR rate performed with a commercial Diesel fuel as well as the surrogate used in simulations. The model predictions agree with the experiments for most cases. Finally, the model predictions have been compared on a more detailed and academical case with the Engine Combustion Network Spray A, a high pressure Diesel spray. This final experimental validation provides data to evaluate the model predictions in transient conditions.

Orientador: Celso Aparecido Bertran / Tese (doutorado) - Universidade Estadual de Campinas. Instituto de Quimica / Made available in DSpace on 2018-07-27T07:22:09Z (GMT). No. of bitstreams: 1 Marques_CarlaSimoneTafuri_D.pdf: 16927683 bytes, checksum: b7e62e3886759d4afb629fa31db9ec66 (MD5) Previous issue date: 2000 / Resumo: Neste trabalho, realizou-se o estudo da cinética de formação de radicais produzidos no estado eletrônico excitado e o estudo da formação das partículas de fuligem, durante a combustão de misturas de C2H2/O2 e C2H2/O2/Ar produzidas em uma câmara fechada. Na metodologia utilizada, o processo de combustão é turbulento e ocorre na ausência do ar atmosférico. Desta forma, é possível obter uma correlação entre a pressão e composição da mistura que queima, e a formação e reação das espécies presentes na chama. A cinética de formação dos radicais excitados OH*, CHO*, CH* e C2*, principais emissores em chamas de hidrocarbonetos, foi estudada pela determinação de suas intensidades de emissão em função do tempo. A evolução das partículas de fuligem, durante a combustão das misturas ricas em acetileno, foi observada através do espalhamento e absorção da luz de um laser por essas partículas, em função do tempo. Realizou-se também a análise morfológica das partículas formadas por microscopia eletrônica de varredura. As medidas espectroscópicas de emissão dos radicais excitados foram associadas à simulação computacional da cinética de combustão, permitindo se estabelecer um mecanismo reacional para o processo de combustão turbulento da mistura de C2H2/O2 e identificando-se as principais rotas de reação para a formação dos radicais excitados: H + O2 = OH* + O CH + O = CHO* C2H + O2 = CH* + CO2 CH2 + C = C2* + H2 / Abstract: In this work, a kinetic study of radicals in the excited electronic state and a study of soot particles evolution from C2H2/O2 and C2H2/O2/Ar flames in a closed chamber was carry out. In the methodology used the combustion process is turbulent and occurs in the atmospheric air absence. Therefore, we can correlate mixture pressure and composition that burning to species formation and reactions in the flame. The formation kinetic of OH*, CHO*, CH* and C2* excited radicals, which are the main emitters in the hydrocarbon flames was studied by emission intensities as a function of time determination. The soot particle evolution from fuel-rich flames was observed through laser light scattering and absorption. The morphology analysis of these soot particles was executed by scanning electronic microscope. The spectroscopic measurements of emission of excited radicals was associated to computational simulation of combustion kinetics allowing to establish a mechanism of reactions to the turbulent combustion process of C2H2/O2 and to identify the predominant reactions for the formation of excited radicals: H + O2 = OH* + O CH + O = CHO* C2H + O2 = CH* + CO2 CH2 + C = C2* + H2 / Doutorado / Físico-Química / Doutora em Química

Orientador: Leonardo Goldstein Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T09:03:09Z (GMT). No. of bitstreams: 1 Fassani_FabioLuis_D.pdf: 4581004 bytes, checksum: 522f53b51ed91bca9f748a16cea9d03e (MD5) Previous issue date: 2014 / Resumo: A combustão de óleo combustível em equipamentos industriais é um processo que fornece energia para aquecimento, geração de vapor e produção de energia elétrica, entre outros. A fuligem que se forma durante a combustão ocasiona aumento da taxa de transferência de calor por radiação entre os gases produtos da combustão e as superfícies de troca de calor do equipamento de processo, o que ocorre devido à luminosidade da chama. O gás natural tem sido utilizado para substituir o óleo combustível, porém esse gás produz pouca fuligem e pode ocasionar diminuição das trocas térmicas nos equipamentos projetados para óleo combustível. Assim, observa-se que o conhecimento da relação entre a concentração de fuligem na chama e a transferência de calor fornece subsídios para o projeto de caldeiras e fornalhas. O problema abordado nesse trabalho consiste em determinar a relação entre a transferência de calor e a fração volumétrica de fuligem em uma câmara de combustão cilíndrica horizontal, considerando a rotação imposta ao escoamento. O foco principal do trabalho é experimental. Para conduzi-lo, foi projetada e construída uma câmara de combustão dotada de um queimador que induz rotação ao escoamento. A concentração de fuligem foi determinada a partir da variação da intensidade de feixes de luz laser ao passar pela câmara. Complementarmente ao trabalho experimental realizado, para estimar a influência da presença de fuligem, do comprimento da chama e outros parâmetros sobre as trocas térmicas, foi elaborada uma simulação numérica da transferência de calor em uma câmera de combustão cilíndrica, empregando-se o método das zonas. A principal contribuição do trabalho foi indicar que a fração volumétrica de fuligem depende tanto do excesso de ar quanto do número de rotação do escoamento e que para o maior excesso de ar considerado, quanto menor a fração volumétrica de fuligem, menor a taxa de transferência de calor. Os resultados numéricos sugerem que a adoção de um padrão de liberação de energia pela chama foi o fator preponderante para a intensificação das trocas de calor / Abstract: Fuel oil combustion in industrial equipment is a process that provides energy for heating, steam generation and production of electrical energy. Soot produced during combustion causes an increase in the radiation heat transfer rate between the combustion gases and the heat exchange surfaces of the process equipment, due to the flame luminosity. Natural gas has been used as a substitute to fuel oil, but this gas produces little soot and may cause a decrease in the thermal exchanges that take place in equipment originally designed to burn fuel oil. Thus, the knowledge of the relationship between soot concentration in the flame and heat transfer provides subsidies for the design of boilers and furnaces. The issue addressed in this work is to determine the relationship between heat transfer and the soot volume fraction in a horizontal cylindrical combustion chamber, considering the swirling intensity of the flow. The main focus of the work is experimental. To accomplish it, a combustion chamber equipped with a swirl burner to induce rotation to the flow was designed. Soot volume fraction was assessed by means of a laser beam directed towards the chamber. Additionally to the experimental work, a numerical simulation of the heat transfer in a cylindrical combustion chamber was carried out to estimate the influence of soot, flame release pattern and other parameters on the thermal exchanges. The main conclusion of the work was to indicate that the soot volume fraction depends both on the excess air and the swirl number of the flow. In the highest excess air employed, the lower the soot volume fraction, the lower the heat transfer rate. The numerical results suggest that the flame energy release pattern was the most important contributing factor to increase the heat transfer / Doutorado / Termica e Fluidos / Doutor em Engenharia Mecânica