Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2019-03-13T13:12:10Z No. of bitstreams: 1 Dionisson de Andrade Michelotto_.pdf: 2807252 bytes, checksum: 019edcb4e2819bea433fa3dde1057c15 (MD5) / Made available in DSpace on 2019-03-13T13:12:10Z (GMT). No. of bitstreams: 1 Dionisson de Andrade Michelotto_.pdf: 2807252 bytes, checksum: 019edcb4e2819bea433fa3dde1057c15 (MD5) Previous issue date: 2018-10-26 / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / O impacto ambiental ocasionado pela combustão do carvão mineral em máquinas térmicas estimula buscas de alternativas sustentáveis. Uma das alternativas pode ser a substituição do carvão pela biomassa em reatores de leito fluidizado. A velocidade mínima de fluidização das partículas é um parâmetro fluidodinâmico que influencia fortemente o comportamento em projetos de reatores de leito fluidizado. A maioria das pesquisas utiliza como um dos principais parâmetros em suas correlações a esfericidade. Outros estudos afirmam que a razão de aspecto influencia bastante a velocidade mínima de fluidização. Utilizando um reator de leito fluidizado com distribuidor de placa perfurada, partículas de bambu cilíndricas com razões de aspecto de 2, 4 e 6, pertencente ao grupo D da classificação Geldart, foram fluidizadas. Nos resultados experimentais foi possível observar que a razão de aspecto influência na velocidade mínima de fluidização, quanto maior a razão de aspecto, maior a velocidade. Os resultados foram comparados com outros autores, onde cinco ficaram suficientemente próximos dentro de uma variação de 20% dos valores obtidos nos experimentos. Como a fluidização se comportava tipo jorro, foi comparado com correlações de jorro, onde uma única correlação ficou com variação em torno de 20% dos valores obtidos nos experimentos, enquanto as outras correlações ficaram com diferenças maiores. Uma nova correlação foi proposta modificando-se a equação de Ergun através da substituição da esfericidade pela razão de aspecto e ajustando seus coeficientes. Nesta nova correlação os valores da velocidade mínima de fluidização calculados ficaram próximos aos resultados experimentais dentro de uma variação de 15%. / The environmental impact caused by the combustion of mineral coal in thermal plants stimulates researches for sustainable alternatives. One of the alternatives may be the replacement of coal by biomass in fluidized bed reactors. The particle minimum fluidization velocity is a fluid dynamics parameter that strongly influences the behavior in fluidized bed reactor designs. Most academic papers use the sphericity as one of the main parameters in their correlations. Other studies state that the aspect ratio greatly influences the minimum fluidization velocity. Using a fluidized bed reactor with perforated plate distributor, cylindrical bamboo particles with aspect ratios of 2, 4 and 6, belonging to group D of the Geldart classification, were fluidized. In the experimental results it was possible to observe that the aspect ratio influences the minimum fluidization velocity. The results were compared with other authors, where five were sufficiently close within a variation of 20% of the values obtained in the experiments. As fluidization behaved like a spout, it was compared with spout correlations, where a single correlation achieved differences below 20% than the values obtained in the experiments, while the other correlations obtained larger differences. A new correlation was proposed based in the Ergun equation replacing sphericity by the aspect ratio and adjusting its coefficients. In this new correlation the calculated minimum fluidization velocity values were close to the experimental results within a range of 15%.

Fluidized bed dryers are used in the pharmaceutical industry for the batch drying of pharmaceutical granulate. Maintaining optimal hydrodynamic conditions throughout the drying process is essential to product quality. Due to the complex interactions inherent in the fluidized bed drying process, mechanistic models capable of identifying these optimal modes of operation are either unavailable or limited in their capabilities. Therefore, empirical models based on experimentally generated data are relied upon to study these systems.<p> Principal Component Analysis (PCA) and Partial Least Squares (PLS) are multivariate statistical techniques that project data onto linear subspaces that are the most descriptive of variance in a dataset. By modeling data in terms of these subspaces, a more parsimonious representation of the system is possible. In this study, PCA and PLS are applied to data collected from a fluidized bed dryer containing pharmaceutical granulate. <p>System hydrodynamics were quantified in the models using high frequency pressure fluctuation measurements. These pressure fluctuations have previously been identified as a characteristic variable of hydrodynamics in fluidized bed systems. As such, contributions from the macroscale, mesoscale, and microscales of motion are encoded into the signals. A multiresolutional decomposition using a discrete wavelet transformation was used to resolve these signals into components more representative of these individual scales before modeling the data. <p>The combination of multiresolutional analysis with PCA and PLS was shown to be an effective approach for modeling the conditions in the fluidized bed dryer. In this study, datasets from both steady state and transient operation of the dryer were analyzed. The steady state dataset contained measurements made on a bed of dry granulate and the transient dataset consisted of measurements taken during the batch drying of granulate from approximately 33 wt.% moisture to 5 wt.%. Correlations involving several scales of motion were identified in both studies.<p> In the steady state study, deterministic behavior related to superficial velocity, pressure sensor position, and granulate particle size distribution was observed in PCA model parameters. It was determined that these properties could be characterized solely with the use of the high frequency pressure fluctuation data. Macroscopic hydrodynamic characteristics such as bubbling frequency and fluidization regime were identified in the low frequency components of the pressure signals and the particle scale interactions of the microscale were shown to be correlated to the highest frequency signal components. PLS models were able to characterize the effects of superficial velocity, pressure sensor position, and granulate particle size distribution in terms of the pressure signal components. Additionally, it was determined that statistical process control charts capable of monitoring the fluid bed hydrodynamics could be constructed using PCA<p>In the transient drying experiments, deterministic behaviors related to inlet air temperature, pressure sensor position, and initial bed mass were observed in PCA and PLS model parameters. The lowest frequency component of the pressure signal was found to be correlated to the overall temperature effects during the drying cycle. As in the steady state study, bubbling behavior was also observed in the low frequency components of the pressure signal. PLS was used to construct an inferential model of granulate moisture content. The model was found to be capable of predicting the moisture throughout the drying cycle. Preliminary statistical process control models were constructed to monitor the fluid bed hydrodynamics throughout the drying process. These models show promise but will require further investigation to better determine sensitivity to process upsets.<p> In addition to PCA and PLS analyses, Multiway Principal Component Analysis (MPCA) was used to model the drying process. Several key states related to the mass transfer of moisture and changes in temperature throughout the drying cycle were identified in the MPCA model parameters. It was determined that the mass transfer of moisture throughout the drying process affects all scales of motion and overshadows other hydrodynamic behaviors found in the pressure signals.

Fluidized bed dryers are used in the pharmaceutical industry for the batch drying of pharmaceutical granulate. Maintaining optimal hydrodynamic conditions throughout the drying process is essential to product quality. Due to the complex interactions inherent in the fluidized bed drying process, mechanistic models capable of identifying these optimal modes of operation are either unavailable or limited in their capabilities. Therefore, empirical models based on experimentally generated data are relied upon to study these systems.<p> Principal Component Analysis (PCA) and Partial Least Squares (PLS) are multivariate statistical techniques that project data onto linear subspaces that are the most descriptive of variance in a dataset. By modeling data in terms of these subspaces, a more parsimonious representation of the system is possible. In this study, PCA and PLS are applied to data collected from a fluidized bed dryer containing pharmaceutical granulate. <p>System hydrodynamics were quantified in the models using high frequency pressure fluctuation measurements. These pressure fluctuations have previously been identified as a characteristic variable of hydrodynamics in fluidized bed systems. As such, contributions from the macroscale, mesoscale, and microscales of motion are encoded into the signals. A multiresolutional decomposition using a discrete wavelet transformation was used to resolve these signals into components more representative of these individual scales before modeling the data. <p>The combination of multiresolutional analysis with PCA and PLS was shown to be an effective approach for modeling the conditions in the fluidized bed dryer. In this study, datasets from both steady state and transient operation of the dryer were analyzed. The steady state dataset contained measurements made on a bed of dry granulate and the transient dataset consisted of measurements taken during the batch drying of granulate from approximately 33 wt.% moisture to 5 wt.%. Correlations involving several scales of motion were identified in both studies.<p> In the steady state study, deterministic behavior related to superficial velocity, pressure sensor position, and granulate particle size distribution was observed in PCA model parameters. It was determined that these properties could be characterized solely with the use of the high frequency pressure fluctuation data. Macroscopic hydrodynamic characteristics such as bubbling frequency and fluidization regime were identified in the low frequency components of the pressure signals and the particle scale interactions of the microscale were shown to be correlated to the highest frequency signal components. PLS models were able to characterize the effects of superficial velocity, pressure sensor position, and granulate particle size distribution in terms of the pressure signal components. Additionally, it was determined that statistical process control charts capable of monitoring the fluid bed hydrodynamics could be constructed using PCA<p>In the transient drying experiments, deterministic behaviors related to inlet air temperature, pressure sensor position, and initial bed mass were observed in PCA and PLS model parameters. The lowest frequency component of the pressure signal was found to be correlated to the overall temperature effects during the drying cycle. As in the steady state study, bubbling behavior was also observed in the low frequency components of the pressure signal. PLS was used to construct an inferential model of granulate moisture content. The model was found to be capable of predicting the moisture throughout the drying cycle. Preliminary statistical process control models were constructed to monitor the fluid bed hydrodynamics throughout the drying process. These models show promise but will require further investigation to better determine sensitivity to process upsets.<p> In addition to PCA and PLS analyses, Multiway Principal Component Analysis (MPCA) was used to model the drying process. Several key states related to the mass transfer of moisture and changes in temperature throughout the drying cycle were identified in the MPCA model parameters. It was determined that the mass transfer of moisture throughout the drying process affects all scales of motion and overshadows other hydrodynamic behaviors found in the pressure signals.

The present work is concerned with the mathematical modelling of a bed of granular material in a gravitational field vertically fluidised by a vibrating surface. The particles are in rapid motion, and lose energy by inelastic collisions. The steady state is maintained by a balance of the rate of dissipation of energy in inelastic particle collisions and the rate of transfer of energy due to particle collisions with the vibrating surface. The limit where the energy dissipation due to inelastic collisions is small compared to the mean kinetic energy of the particles is considered. This non-equilibrium steady state is similar to a dilute gas at equilibrium with a uniform temperature and an exponentially decaying density, obtained from the ideal gas equation of state. From the analysis of this state, four non-dimensional numbers are derived which uniquely specify the state of the system. A perturbative analysis about the uniform temperature state is carried out and analytical solutions to the macroscopic variables of the system are obtained using two types of approximations. The first is a hydrodynamic model using constitutive relations from the general kinetic theory of granular media, and the second is a kinetic theory formulation derived exclusively for the vibro-fluidised bed. The latter permits an anisotropy between the horizontal and vertical directions due to the anisotropic nature of the source of energy at the bottom wall. The kinetic theory is extended to incorporate the corrections due to the high density effects, which is similar to the Enskog correction to dense gases. An event driven (ED), or hard sphere molecular dynamic (MD), simulation of the vibrated bed is carried out. The quantitative predictions of the theories are validated by the simulation. A systematic probing of the parameter space within the ED simulations revealed two new phenomena in a vibro-fluidised bed which are inhomogeneous in the horizontal direction. These are convection rolls similar to the Rayleigh-Benard instability in fluids, and a clustering instability leading to a phase separation. The instabilities are characterised using a phase diagram. The homogeneous states close to these new states are adequately described by the models developed here. An analysis of the stability of this state could have implications in understanding the instabilities in driven granular materials (such as in sheared media and fluidised beds) in general, and pattern formation in vibrated beds in particular.

During development, higher organisms grow from a single fertilized egg cell to the adult animal. The many processes that lead to the eventual shape of the developed organism are subsumed as morphogenesis, which notably involves the growth of tissues by repeated rounds of cell division. Whereas coordinated tissue growth is a prerequisite for animal development, excessive cell division in adult animals is the key ingredient to cancer. In this thesis, we investigate the collective organization of cells by cell division and cell death. The multicellular dynamics of growing tissues is influenced by mechanical conditions and can give rise to cell rearrangements and movements. We develop a continuum description of tissue dynamics, which describes the stress distribution and the cell flow field on large scales. Cell division and apoptosis introduce stress sources that, in general, are anisotropic. By combining cell number balance with dynamic equations for the stress source, we show that the tissue effectively behaves as a viscoelastic fluid with a relaxation time set by the rates of division and apoptosis. If the tissue is confined in a fixed volume, it reaches a homeostatic state in which division and apoptosis balance. In this state, cells undergo a diffusive random motion driven by the stochasticity of division and apoptosis. We calculate the effective diffusion coefficient as a function of the tissue parameters and compare our results concerning both diffusion and viscosity to simulations of multicellular systems. Introducing a second material component that accounts for the extracellular fluid, we show that a finite permeability of the tissue gives rise to additional mechanical effects. In the limit of long times, the mechanical response of the tissue to external perturbations is confined to a region of which the size depends on the ratio of tissue viscosity and cell-fluid friction. The two-component description furthermore allows to clearly distinguish the different contributions to the isotropic part of the mechanical stress, i.e., the fluid pressure and the stress exerted by cells. Last but not least, we study the propagation of an interface between two different cell populations within a tissue driven by differences in the mechanical control of the rates of cell division and apoptosis. Combining simple analytical limits and numerical simulations, we distinguish two different modes of propagation of the more proliferative population: a diffusive regime in which relative fluxes dominate the expansion, and a propulsive regime in which the proliferation gives rise to dominating convective flows. / Die Entwicklung höherer Organismen beginnt mit einer einzelnen befruchteten Eizelle und endet beim erwachsenen Tier. Die vielen Prozesse, die zur endgültigen Form des entwickelten Organismus führen, werden als Morphogenese zusammengefasst; diese umfasst insbesondere das Wachstum von Geweben durch wiederholte Zellteilungszyklen. Während koordiniertes Gewebewachstum eine Voraussetzung normaler Entwicklung ist, führt übermäßige, unkontrollierte Zellteilung letztlich zu Krebs. In dieser Arbeit untersuchen wir den Einfluss von Zellteilung und Zelltod auf die Organisation von Zellen in Geweben. Die Dynamik wachsender Gewebe wird durch mechanische Bedingungen beeinflusst, die u.a.~Anlass zu Zellbewegungen sein können. Wir entwickeln eine Kontinuumsbeschreibung der Gewebedynamik, die die mechanischen Spannungen und das Zellströmungsfeld auf großen Skalen beschreibt. Zellteilung und Apoptose wirken als Spannungsquellen, die in der Regel anisotrop sind. Indem wir die Erhaltungsgleichung für die Zellanzahldichte mit dynamischen Gleichungen für die Spannungsquellen kombinieren, zeigen wir, dass sich das Gewebe effektiv wie eine viskoelastische Flüssigkeit verhält, deren Relaxationszeit von Zellteilungs- und Apoptose-Raten abhängt. Wenn das Gewebe in einem gegebenen Volumen eingeschlossen ist, erreicht es einen homöostatischen Zustand, in dem Zellteilung und der Apoptose im Gleichgewicht sind. In diesem Zustand unterliegen die Zellen einer diffusiven Bewegung aufgrund der Stochastizität von Zellteilung und Apoptose. Wir berechnen den effektiven Diffusionskoeffizienten als Funktion der Gewebeparameter und vergleichen unsere Ergebnisse sowohl hinsichtlich der Diffusion und als auch der Viskosität mit numerischen Simulationen solcher vielzelliger Systeme. Die Berücksichtigung der extrazellulären Flüssigkeit als einer zweiten Materialkomponente erlaubt uns zu zeigen, dass eine endliche Permeabilität des Gewebes zusätzliche mechanische Effekte bedingt. Auf langer Zeitskalen bleibt die mechanische Reaktion des Gewebes auf externe Störungen auf einen Bereich beschränkt, dessen Größe vom Verhältnis der Gewebeviskosität zum Permeabilitätskoeffizienten abhängt. Die Zweikomponenten-Beschreibung erlaubt darüber hinaus eine klare Unterscheidung der verschiedenen Beiträge zum isotropen Teil der mechanischen Spannung, d.h., des hydrodynamischen und des von Zellen ausgeübten Drucks. Zuletzt untersuchen wir die Dynamik einer Grenzfläche zwischen zwei verschiedenen Zellpopulationen innerhalb eines Gewebes, die durch Unterschiede in der mechanischen Kontrolle der effektiven Zellteilungsraten angetrieben wird. Mithilfe der Kombination einfacher analytischer Grenzfälle und numerischer Simulationen zeigen wir, dass zwei unterschiedliche Ausbreitungsmodi unterschieden werden können: ein diffusives Regime, in dem relative Flüsse die Expansion der stärker wachsenden Zellpopulation dominieren, sowie ein Regime, in dem die Grenzfläche durch konvektive Strömungen angetrieben wird. / Les organismes supérieurs se développent à partir d\'une seule cellule fécondée jusqu\'à l\'animal adulte. Les nombreux processus qui conduisent à la forme finale de l\'organisme sont connus sous le nom de morphogenèse, qui comprend notamment la croissance des tissus par des cycles répétés de division cellulaire. Alors que la croissance coordonnée des tissus est une condition nécessaire au développement des animaux, la division cellulaire excessive chez les animaux adultes est l\'ingrédient clé du cancer. Dans cette thèse, nous étudions l\'organisation collective des cellules par division et mort cellulaire. La dynamique multicellulaire des tissus en croissance est influencée par des conditions mécaniques et peut donner lieu à des réarrangements ainsi qu\'à des mouvements cellulaires. Nous élaborons une description continue de la dynamique des tissus qui décrit la distribution des contraintes et le champ d\'écoulement des cellules sur de grandes échelles. La division cellulaire et l\'apoptose introduisent des sources de contraintes qui, en général, sont anisotropes. En combinant l\'équation de conservation du nombre de cellules avec des équations dynamiques des sources de contraintes, nous montrons que le tissu se comporte de manière effective comme un fluide viscoélastique avec un temps de relaxation fixé par les taux de division et d\'apoptose. Si le tissu est confiné dans un volume donné, il atteint un état homéostatique dans lequel division et apoptose s\'équilibrent. Dans cet état, les cellules subissent un mouvement diffusif aléatoire dû à la stochasticité de la division et de l\'apoptose. Nous calculons le coefficient de diffusion effectif en fonction des paramètres du tissu et comparons nos résultats concernant à la fois la diffusion et la viscosité à des simulations numériques de tels systèmes multicellulaires. En introduisant un deuxième composant qui représente le liquide extracellulaire, nous montrons qu\'une perméabilité finie du tissu donne lieu à des effets mécaniques supplémentaires. Dans la limite des temps longs, la réponse mécanique du tissu à des perturbations extérieures est confinée à une région dont la taille dépend du rapport entre la viscosité tissulaire et le coefficient de frottement entre les cellules et le liquide extracellulaire. La description à deux composants permet en outre de distinguer clairement les différentes contributions à la partie isotrope de la contrainte mécanique, c\'est-à-dire la pression du fluide et la contrainte exercée par les cellules. Finalement, nous étudions la propagation d\'une interface entre deux populations de cellules différentes, due à des différences dans le contrôle mécanique des taux de division et de mort cellulaire. En combinant de simples limites analytiques et des simulations numériques, nous distinguons deux modes de propagation différents de la population cellulaire la plus proliférante : un régime diffusif dans lequel les flux relatifs dominent l\'expansion, et un régime de propulsion dans lequel la prolifération domine et entraine des flux convectifs.

abstract: Amine-modified solid sorbents and membrane separation are promising technologies for separation and capture of carbon dioxide (CO2) from combustion flue gas. Amine absorption processes are mature, but still have room for improvement. This work focused on the synthesis of amine-modified aerogels and metal-organic framework-5 (MOF-5) membranes for CO2 separation. A series of solid sorbents were synthesized by functionalizing amines on the surface of silica aerogels. This was done by three coating methods: physical adsorption, magnetically assisted impact coating (MAIC) and atomic layer deposition (ALD). CO2 adsorption capacity of the sorbents was measured at room temperature in a Cahn microbalance. The sorbents synthesized by physical adsorption show the largest CO2 adsorption capacity (1.43-1.63 mmol CO2/g). An additional sorbent synthesized by ALD on hydrophilic aerogels at atmospheric pressures shows an adsorption capacity of 1.23 mmol CO2/g. Studies on one amine-modified sorbent show that the powder is of agglomerate bubbling fluidization (ABF) type. The powder is difficult to fluidize and has limited bed expansion. The ultimate goal is to configure the amine-modified sorbents in a micro-jet assisted gas fluidized bed to conduct adsorption studies. MOF-5 membranes were synthesized on &alpha;-alumina supports by two methods: in situ synthesis and secondary growth synthesis. Characterization by scanning electron microscope (SEM) imaging and X-ray diffraction (XRD) show that the membranes prepared by both methods have a thickness of 14-16 &mu;m, and a MOF-5 crystal size of 15-25 &#956;m with no apparent orientation. Single gas permeation results indicate that the gas transport through both membranes is determined by a combination of Knudsen diffusion and viscous flow. The contribution of viscous flow indicates that the membranes have defects. / Dissertation/Thesis / M.S. Chemical Engineering 2010

Cette thèse s’inscrit dans le cadre du développement de nouveaux matériaux composites multifonctionnels, permettant de remplacer l’aluminium en tant qu’élément constituant le packaging de l’électronique embarquée dans les avions, afin de rendre ces derniers plus légers. L’association d’un polymère mécaniquement résistant avec des nano-charges conductrices est une alternative prometteuse. Cette thèse concerne l’étude du procédé de Dépôt Chimique à partir d’une phase Vapeur (CVD) en lit fluidisé pour déposer des métaux conducteurs, tels que le fer et le cuivre, à la surface de nanotubes de carbone multi-parois (MWCNTs) produits industriellement (Arkema Graphistrength®C100), enchevêtrés en pelotes poreuses de 388 μm de diamètre. Tout d’abord, afin d’augmenter la réactivité de surface des nanotubes, un procédé d’oxydation en lit fluidisé a été étudié à température ambiante, à partir de plusieurs mélanges gazeux à base d’ozone. Les diverses analyses réalisées (MET, spectroscopie IR, XPS,..) montrent que des groupements chimiques de type hydroxyl, acide carboxylique, éther, … sont greffés de façon uniforme sur toute la surface externe des MWCNTs et que leurs parois externes sont aussi gravées de façon modérée et localisée. Au final, il apparait que les défauts créés et les fonctions oxygénées greffées ont permis d’accroitre le nombre de sites de nucléation sur la surface des nanotubes et donc la masse de métal déposé. Le dépôt de fer à partir de ferrocène Fe(C5H5)2 a été étudié à haute température (entre 400 et 650°C), sous différentes ambiances gazeuses (azote, hydrogène, air, vapeur d’eau). Les analyses réalisées (MEB-FEG, DRX, MET, ICP-MS, ...) montrent un dépôt uniforme du bord jusqu’au coeur des pelotes, de nanoparticules à base de carbure de fer Fe3C prisonnières de l’enchevêtrement des nanotubes. La présence d’hydrogène a permis de minimiser la formation parasite de nano-objets (tubes et fibres). Le dépôt de cuivre à partir d’acétylacétonate de cuivre (II) Cu(C5H7O2)2 a été étudié entre 250 et 280°C sous hydrogène. Les caractérisations réalisées indiquent que des nanoparticules de Cu pur ont été déposées sur l’ensemble des parois externes des MWCNTs, du bord au coeur des pelotes. L’ensemble des résultats obtenus démontre que le procédé de CVD en lit fluidisé est capable de déposer de façon uniforme des métaux à la surface de nanotubes de carbone enchevêtrés en pelotes poreuses, pour des conditions opératoires spécifiquement choisies. / This Ph.D project is part of the development of new composite multi-functional materials allowing replacing aluminum in the on-board electronic packaging of airplanes, to make them lighter. The combination of a polymer mechanically resistant with conductive nano-fillers is a promising alternative. The thesis concerns the study of the Fluidized Bed Chemical Vapor Deposition (CVD) process of conductive metals, such as iron and copper, on the surface of industrial multi-walled carbon nanotubes (MWCNTs, Arkema Graphistrength®C100) tangled in porous balls of 388 μm in diameter. First, in order to increase the surface reactivity of nanotubes, an oxidation process in fluidized bed has been studied at room temperature, from several gaseous mixtures containing ozone. The various analyses (TEM, IR spectroscopy, XPS, …) show that hydroxyl, carboxylic acid, ether, … chemical bonds are grafted uniformly on all the outer surface of MWCNTs and that their outer walls are locally and moderately etched. At the end, it appears that the created defects and the oxygen containing bonds have allowed to increase the number of nucleation sites on the nanotubes surface and then the weight of the deposited metal. The iron deposit from ferrocene Fe(C5H5)2 has been studied at high temperature (between 400 and 650°C) under different gaseous atmospheres (nitrogen, hydrogen, air, water vapor). The analyses (FEG SEM, XRD, TEM, ICP-MS, ...) show a uniform deposit from the outer part to the center of the balls, of nanoparticles containing iron carbide Fe3C. The presence of hydrogen has allowed minimizing the parasitic formation of nano-objects (tubes and fibers). The copper deposition from copper (II) acetylacetonate Cu(C5H7O2)2 has been studied at 250-280°C under hydrogen. The characterizations indicate that nanoparticles of pure copper have been deposited on all the MWCNT outer walls, from the outer part to the center of the balls. The whole results obtained prove that the Fluidized Bed CVD process is able to deposit uniformly metals on the outer surface of MWCNTs tangled in porous balls, for specifically chosen operating conditions.

O objetivo desta dissertação consiste em aprofundar o entendimento dos mecanismos que controlam o atrito lateral sob arrancamento de estacas instaladas por fluidização em areia. A técnica de instalação é estudada como uma alternativa para a utilização de estacas torpedo na fixação de plataformas offshore. Trabalhou-se em laboratório com o arrancamento de estacas metálicas circulares em modelo reduzido. Foram utilizados três diâmetros de estacas modelo, simulando três diferentes escalas: 14 mm (1:76), 16,2 mm (1:67) e 21,3 mm (1:50). Foram realizados 8 ensaios de arrancamento (24 horas após a fluidização) em estacas modelo instaladas por fluidização em solo arenoso com densidade relativa de 50% e submetido à sobrecarga de 2,236 kPa. Foram também realizados 17 ensaios de arrancamento em estacas modelo pré-instaladas (sem fluidização) em areia com densidade relativa de 30%, simulando uma instalação sem perturbação do solo, uma vez que esta é a densidade relativa aproximada que a areia atinge após o processo de fluidização. Os resultados foram comparados com pesquisas anteriores de arrancamento de estacas instaladas por fluidização em areia. Para um aumento médio de 2 vezes a tensão vertical efetiva nas estacas modelo instaladas por fluidização com sobrecarga, observa-se um ganho médio de 1,8 na resistência. O coeficiente de empuxo lateral de serviço para estes ensaios não apresentou diferenças significativas em relação ao mesmo tipo de ensaio sem sobrecarga. As estacas instaladas por fluidização com sobrecarga e estacas pré-instaladas (sem perturbação) apresentam valores de constantes e independentes das profundidades instaladas, com respectivas médias de 0,15 e 0,31. O valor de parece aumentar com o tempo para as estacas fluidizadas (efeito setup) devido à reconstituição das tensões radiais. Os valores de estacas cravadas em areia densa diminuem seu valor com o aumento da profundidade instalada (e da tensão efetiva média atuante), por restrição de dilatação, tendendo ao valor de encontrado para ensaios pré-instalados realizados neste trabalho. / The main goal of this study is to deepen the understanding of the shaft friction behavior under tension loads of piles installed by fluidization in Osório sand. The installation technique is studied as an alternative for the use of torpedo piles in offshore platforms anchoring. This work was done in laboratory with metallic circular piles in reduced model. Three diameters of model piles were used, simulating three different scales: 14 mm (1:76), 16,2 mm (1:67) and 21,3 mm (1:50). Eight pullout tests (24 hours after fluidization) were carried out on model piles installed by fluidization in sandy soil with a relative density of 50% and subjected to a surcharge of 2,236 kPa. Eighteen pullout tests were performed on pre-installed (non-fluidized) model piles in sand with a relative density of 30%, simulating an installation without soil disturbance, since this is the approximate relative density reached after the process of fluidization. The results were compared with previous studies of pullout resistance of fluidized piles in sand. For an average increase of 2 times the vertical effective stress in the model piles installed by fluidization with surcharge, an average increase of 1,8 times is observed in the pullout resistance. The lateral earth pressure coefficient on the pile shaft for these tests did not show significant differences in relation to the same type of test without surcharge. For tests installed by fluidization and pre-installed tests (without soil disturbance), remains constant and independent of the installed depths, with respective averages of 0,15 and 0,31. The value seems to increase with time for fluidized tests (setup effect) due to the reconstitution of the radial tensions. The values for pullout tests in driven model piles in dense sand decrease their value with the increase of the installed depth (and the increase of the vertical effective stress), by restriction of the expansive behavior, tending to the value found for pre-installed tests carried out in this work.

Submitted by Nestor Proenza Perez null (nestor@feg.unesp.br) on 2016-07-25T14:02:32Z No. of bitstreams: 1 TESIS VERSÃO FINAL NESTOR PROENZA.pdf: 3806431 bytes, checksum: e67652e66d5b48b5104953feec776a66 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-07-28T12:09:11Z (GMT) No. of bitstreams: 1 perez_np_dr_guara.pdf: 3806431 bytes, checksum: e67652e66d5b48b5104953feec776a66 (MD5) / Made available in DSpace on 2016-07-28T12:09:11Z (GMT). No. of bitstreams: 1 perez_np_dr_guara.pdf: 3806431 bytes, checksum: e67652e66d5b48b5104953feec776a66 (MD5) Previous issue date: 2016-06-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foi realizada a caracterização física, geométrica e fluidodinâmica do bagaço de cana-de-açúcar visando o projeto e dimensionamento de um gaseificador de leito fluidizado borbulhante para pequena e média capacidade térmica (até 25 MW térmicos). As principais propriedades físicas e químicas como massa específica real, aparente e a granel, assim como os teores de umidade, cinzas, material volátil e carbono fixo presentes neste material foram determinadas aplicando normas vigentes para este tipo de resíduo. Também foi realizada uma caracterização geométrica através de técnicas de análise de imagens, determinando-se a esfericidade e razão de aspecto para todas as faixas de diâmetro de partículas estudadas, obtendo-se um valor médio de 0,39 no caso da esfericidade para o bagaço em seu estado natural. Através do estudo fluidodinâmico verificou-se que partículas de bagaço de cana com diâmetros característicos entre 0,59 – 9,5 mm não são fluidizáveis, apresentando uma tendência a coesão e formação de canais preferenciais. Foi constatado que o emprego dos modelos existentes até agora para a previsão da velocidade mínima de fluidização (Vmf), tanto para partículas de bagaço, quanto para misturas delas com material inerte, não preveem de forma adequada este parâmetro. Indicando erros entre 85% e mais de 100% em cada um desses caso, pelo que foram deselvolvidos dois novos modelos específicos para partículas de bagaço de cana e para misturas delas com areia, os quais previram com melhor exatidão os valores da (Vmf), com um erro máximo de 6,3%, para partículas de bagaço, e de até 30% para 88% das 25 condições experimentais testadas no caso de misturas. Conclui-se também que, para garantir uma boa fluidização, a fração em massa máxima de bagaço na mistura deve ser entre 2 - 5%. Uma nova metodologia é proposta baseada nos novos modelos desenvolvidos para a determinação da (Vmf), tornando possível o projeto e dimensionamento de gaseificadores de leito fluidizado borbulhante, sendo determinado que reatores trabalhando com misturas de bagaço e areia são 30% maiores que reatores empregando somente partículas de bagaço de cana-de-açúcar com uma eficiência a frio de 58,5%. / In this work is carried out a physical, geometric and fluid-dynamics characterization of sugarcane bagasse, aiming to design and sizing a bubbling fluidized bed gasifier for small and medium power (up to 25 MW thermal). The main physical and chemical properties as real density, bulk density and apparent density, as well as, the content of moisture, ash, volatile matter and fixed carbon present in the bagasse, were determined by applying the standars norms suitable for this type of residue. It was also made a geometric characterization by image analysis techniques, being determined the sphericity and aspect ratio for all diameter ranger of studied particles, obtaining an average value of 0.39 in the case of sphericity for bagasse in it is natural form. Through the fluid dynamic study it was found that bagasse particles with typical diameters between 0,59 – 9,5 mm are not fluidizable, showing a tendency to cohesion and formation of preferential channels. It has been found that the use of the existing models to date for determination of the minimum fluidization velocity for bagasse particles and for mixtures of them with inert, do not predict the right way this parameter, introduced errors of up to 85% to over 100% in both cases, therefore were developed two new models specifically for sugarcane bagasse particles and mixtures of them with sand, with a maximum error of 6.3% in the first case, and 30% for the 88% of the 25 experimental conditions tested in the case of mixtures. Concluding that to ensure a good fluidization, the maximum mass fraction of bagasse in the mixture should be between 2 - 5%. A new methodology is proposed based on the new models developed, making possible the design and dimensioning of the bubbling fluidized bed gasifier, determining that reactors working with mixtures of sugarcane bagasse and sand are 30% higher than reactors employing solely sugarcane bagasse particles, with a cold gas efficiency of 58.5%.

Orientador: Antonio Carlos Luz Lisboa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T19:43:19Z (GMT). No. of bitstreams: 1 Porto_PauloSergiodaSilva_D.pdf: 16531970 bytes, checksum: 29f4837be6b441e6118e76a89e91a0ab (MD5) Previous issue date: 2005 / Resumo: Xisto pirobetuminoso é uma rocha sedimentar que contém querogênio, um material orgânico que se encontra disseminado em sua estrutura mineral. O querogênio é extraído por aquecimento a altas temperaturas, em reatores conhecidos como retortas, 1iberando óleo e gás. Este óleo quando refinado produz destilados com as mesmas características encontradas nos de petróleo, sendo considerado uma fonte de energia alternativa. A existência de umidade no xisto na entrada do reator gera uma zona de secagem influenciando na redução da temperatura dos gases e diminuição da eficiência da retorta. O objetivo deste trabalho é investigar a perda de umidade durante a secagem de partículas de xisto, visando conhecer os mecanismos envolvidos. Para obter o perfil de umidade ao longo do tempo foram utilizadas partículas classificadas em três diferentes lotes quanto ao diâmetro médio de partícula (dp): partículas individuais do Lote A (dp = 80 mm e dp = 60 mm); partículas do Lote B que subdivide-se em quatro sublotes (~ = 5,3 mm, dp = 3 mm, dp = 1,5 mm e dp = 0,85 mm) e partículas do Lote C (dp < 0,074 mm). Os experimentos de secagem foram realizados em diversos secadores: partículas do Lote A secas em estufa com circulação de ar a 60°C e 90°C; partículas do Lote B secas em bandeja termogravimétrica a 40°C, 60 °c, 80°C e 100°C e em leito de jorro e leito fluidizado a 50°C e 70°C; partículas do Lote C secas em um analisador termogravimétrico, cujas temperaturas iniciais de 20°C variaram ao longo do tempo até atingir valores máximos de 40 °C, 70°C e 100°C. Exceto os experimentos realizados no ana1isador termogravimétrico, em todos os demais a temperatura foi mantida constante. Utilizou-se o modelo matemático de difusão de Fick, considerando geometrias uni e tri-dimensionais. Na solução destes modelos foram desenvolvidos programas em linguagem Fortran para descrever a variação de umidade das partículas de xisto ao longo do tempo e da posição, levando-se em conta a geometria da partícula e a temperatura do ar de secagem (constante ou variável). Os resultados preditos pelos modelos foram comparados com os experimentais apresentando boa concordância. Estes modelos podem contribuir na estimativa de parâmetros desconhecidos do processo. Quanto ao leito em jorro e leito fiuidizado, verificou-se que são técnicas adeqüadas para a secagem de xisto / Abstract: Oil shale is a sedimentary rock which contains kerogen, an organic matter scattered througout a mineral matrix. Kerogen is extracted by pyrolysis at high temperatures in reactors known as retorts producing oil and gas. The oil, when refined, produces distillates with the same characteristics as petroleum. Oil shale is considered an alternative energy source to petroleum. At the top of a moving bed retort oil shale moisture vaporization consumes energy, thereby reducing the retort efficiency. Oil shale drying has been investigated to optimize pyrolysis. The objective of this work was to investigate the moisture loss during oil shale particles drying to know the mechanisms involved. In order to obtain the moisture profile with time particles classified in three different categories / Doutorado / Engenharia de Processos / Doutor em Engenharia Química