L'objectif de ce travail de recherche est d'étudier numériquement le transport et le dépôt de particules dans des milieux poreux à l'échelle des pores.Premièrement, un couplage entre la méthode de Boltzmann sur réseau (LBM) et la méthode des éléments discrets (DEM) est réalisé et utilisé pour simuler l'écoulement d'un fluide chargé en particules. La LBM est utilisée pour décrire l'écoulement du fluide autour des fibres tandis que la DEM est utilisée pour traiter la dynamique des particules. Ce couplage est bidirectionnel dans le sens où le mouvement des particules affecte le flux de fluide et réciproquement. Ce modèle nous a permis de prédire l'efficacité de capture et la chute de pression à l'étape initiale du processus de filtration. Le facteur de qualité est également calculé pour déterminer la qualité de filtration.Ensuite, on se focalise sur l'étude de l'efficacité de la capture de fibres de formes de section transversale différentes (circulaire, losange et carrée). Les résultats issus de nos simulations du processus de filtration de la fibre circulaire concordent bien avec les corrélations empiriques. L'impaction des particules sur la face avant de la fibre de forme carrée est plus importante que dans les cas de fibre de formes circulaire et losange. Cependant, en raison d'une chute de pression plus faible, la fibre de section losange présente une meilleure qualité de filtration. Ensuite, les variations du facteur de qualité dues à l'angle d'orientation et au rapport d'aspect des fibres ont été étudiées numériquement pour la forme rectangulaire. Pour chaque cas, on a déterminé la valeur optimale de la zone au vent pour laquelle le facteur de qualité est maximal. La comparaison des valeurs du facteur de qualité obtenues pour les différentes formes de fibre monte une meilleure performance pour la fibre de section carrée orientée avec un angle de π/4.Enfin, l'influence de l'arrangement des fibres sur la qualité de la filtration est analysée en considérant la configuration en quinconce pour les différentes formes. Les simulations conduites pour différentes tailles de particules et différentes valeurs de la densité (particule/air) montent que la fibre de section losange est plus performante en termes de facteur de qualité pour les particules de grande taille et pour les valeurs de densité élevée. La présente étude fournit des pistes pour optimiser le processus de filtration et prédire la qualité de filtration. / The objective of the present research was to numerically investigate the transport and deposition of particles in porous media at the pore scale. Firstly, a developed coupled lattice Boltzmann method (LBM) and discrete element method (DEM) is used to simulate the fluid-particle flow. LBM is employed to describe the fluid flow around fibers whereas DEM is used to deal with the particle dynamics. The corresponding method is two-way coupling in the sense that particle motion affects the fluid flow and reciprocally. It allowed us to predict the capture efficiency and pressure drop at the initial stage of filtration process. The quality factor is also calculated for determining the filtration performance. Secondly, we focus on the study the capture efficiency of single fiber with circular, diamond and square cross-section, respectively. The results of LBM-DEM for filtration process of single circular fiber agree well with the empirical correlation. The impaction of particles on the front side of square-shaped fiber is more favorable than those on circular and diamond cases. However, diamond fiber exhibits a good filtration performance. Then the variations of quality factor due to the different orientation angle and aspect ratio of rectangular fiber were studied using LBM-DEM. For each case, we have found the optimal value of the windward area to which corresponds a maximum value of the quality factor. The comparison of the performance of the different forms of fibers shows that the largest quality factor is obtained for square fiber oriented with angle π/4.Finally, the influence of the arrangement of fiber on filtration performance is analyzed by considering the staggered configuration. Simulations conducted for several particle size and density show that the diamond with staggered array performs better for large particles and high particle-to-fluid density ratio in terms of quality factor. The present study provide an insight to optimize the filtration process and predict filtration performance.

Metal-organic frameworks are a new class of porous materials that have potential applications in gas storage, separations, catalysis, sensors, non-linear optics, displays and electroluminescent devices. They are synthesized in a "building-block" approach by self-assembly of metal or metal-oxide vertices interconnected by rigid linker molecules. The highly ordered nature of MOF materials and the ability to tailor the framework's chemical functionality by modifying the organic ligands give the materials great potential for high efficiency adsorbents. In particular, MOFs that selectively adsorb CO₂ over N₂, and CH₄ are very important because they have the potential to reduce carbon emissions from coal-fired power plants and substantially diminish the cost of natural gas production. Despite their importance, MOFs that show high selective gas adsorption behavior are not so common. Development of MOFs for gas adsorption applications has been hindered by the lack of fundamental understanding of the interactions between the host-guest systems. Knowledge of how adsorbates bind to the material, and if so where and through which interaction, as well as how different species in adsorbed mixture compete and interact with the adsorption sites is a prerequisite for considering MOFs for adsorptive gas separation applications. In this work, we seek to understand the role of structural features (such as pore sizes, open metal site, functionalized ligands, pore volume, electrostatics) on the adsorptive separation of CO₂, CO and N₂ in prototype MOFs with the help of molecular modeling studies (GCMC simulations). Our simulation results suggest that the suitable MOFs for CO₂ adsorption and separation should have small size, open metal site, or large pore volume with functionalized groups. Some of the experimental challenges in the MOF based adsorbents for CO₂ capture include designing MOFs with smaller pores with/without open metal sites. Constructing such type of porous MOFs can lead to greater CO₂ capacities and adsorption selectivities over mixtures of CH₄ or N₂. Therefore, in the second project, we focused on design and development of small pore MOFs with/without open metal sites for adsorptive separation of carbon dioxide from binary mixtures of methane and nitrogen. We have synthesized and characterized several new MOFs (single ligand and mixed ligand MOFs) using different characterization techniques like single-crystal X-ray diffraction, powder X-ray diffraction, TGA, BET, gravimetric adsorption and examined their applicability in CO₂/N₂ and CO₂/CH₄ mixture separations. Our findings from this study suggest that further, rational development of new MOF compounds for CO₂ capture applications should focus on enriching open metal sites, increasing the pore volume, and minimizing the size of large pores. Flue gas streams and natural gas streams containing CO₂ are often saturated by water and its presence greatly reduces the CO₂ adsorption capacities and selectivities. So, in the third project, we investigated the structural stability of the developed MOFs by measuring water vapor adsorption isotherms on them at different humid conditions to understand which type of coordination environment in MOFs can resist humid environments. The results of this study suggest that MOFs connected through nitrogen-bearing ligands show greater water stability than materials constructed solely through carboxylic acid groups.

Buildings are the primary user of energy in the USA. Within homes, the heating, ventilation, and air condition (HVAC) system is the largest energy consumer. This study: (i) developed a new methodology for simulating filter loading in-situ; (ii) observed the impact of filter loading on AC performance in-situ; and (iii) provided a greater understanding of when a filter is “dirty” and should be replaced. Six central AC systems in the Atlanta metro-region were evaluated. Filter loading was simulated by installing the TrueFlow® airflow metering device and partially taping off the face at 3 different increments. This resulted in measurements at 5 discrete static pressures (no filter, TrueFlow, TrueFlow Taped one, TrueFlow Taped two, and TrueFlow Taped three). The pilot study found that as filter pressure drop increased, airflow rates generally decreased, resulting in higher differences in temperature across the evaporator coil (∆T). There was no observed correlation between absolute humidity across the evaporator coil and either filter pressure drop or system airflow. Overall, as airflow decreased so did sensible, latent, and total capacity. This research can inform decisions about filter replacement and be used to evaluate computer simulation models of HVAC performance.

Mémoire (M.Eng.)--Université du Québec à Chicoutimi, 1997. / Document électronique également accessible en format PDF. CaQCU

Mémoire(M.Eng.)-- Université du Québec à Chicoutimi, 2002. / Document électronique également accessible en format PDF. CaQCU

Orientador: Carlos Alberto Canesin / Banca: Guilherme de Azevedo e Melo / Banca: Marco Antônio Dalla Costa / Resumo: Nesta pesquisa foi desenvolvida uma metodologia para o dimensionamento de reatores eletrônicos para o acionamento de lâmpadas fluorescentes especiais, emissoras de UV (irradiação ultravioleta), aplicadas na purificação de água. A principal contribuição desta dissertação está relacionada ao desenvolvimento de uma metodologia de projeto para adequação do parâmetro conhecido como Dose UV. Esse parâmetro define a quantidade de energia em forma de irradiação ultravioleta à qual devem ser expostos os microrganismos patogênicos presentes na água, para inibir suas funções metabólicas e de reprodução. Neste contexto, foi projetada e implementada uma estrutura purificadora de água potável, aplicando o método TURF (Three-step UV fluence Rate and Fluid dynamics), o qual propõe realizar cálculos em separado do tempo de permanência da partícula exposta à irradiação UV e a quantidade de irradiação UV que a lâmpada usada pode produzir, para em seguida se determinar a Dose UV, teoricamente. Neste trabalho, esse tempo foi determinado com o estudo hidráulico da estrutura utilizando-se o software SolidWorks, e, por outro lado, aplicou-se o modelo matemático MSSS Multiple Segment Source Summation para a obtenção da irradiação ultravioleta fornecida pelo purificador. Devido ao fato das lâmpadas geradoras de irradiação ultravioleta, empregadas neste trabalho, apresentarem um comportamento análogo às lâmpadas fluorescentes convencionais, foram modeladas através de um modelo de Quarto Grau. Desta forma, foi desenvolvido um reator eletrônico capaz de garantir pré-aquecimento controlado dos filamentos das lâmpadas antes de sua ignição, assim como, ajuste adequado para operarem no ponto de potência nominal para a etapa de regime permanente. Além disso, o reator incorpora como estágio de potência na entrada um conversor Flyback com correção ativa do fator de potência ... / Abstract: In this research it was developed a methodology for the design of special fluorescent lamps electronic ballasts applied to water purifiers, through the use of UV radiation. The main contribution of this work it is related to the development of a design methodology to fit the parameter known as UV dose. This parameter defines the amount of energy as UV light to which the pathogenic microorganisms present in water must be exposed to inhibit their metabolic and reproductive functions. In this context, a purifying drinking water structure was designed and implemented, applying the TURF method. This method proposes to calculate separately, the particle exposition time and the amount of UV radiation produced by the lamp, and in a third step, calculate theoretically the UV dose. Thus, the related time was determined with the hydraulic structure model using the software SolidWorks, and through the use of MSSS mathematical model to obtain the UV radiation provided by the purifier. Whereas the behavior of the used UV lamps is similar to conventional fluorescent lamps, they are modeled applying a Fourth Degree model. Hence, an electronic ballast that guaranties a controlled preheating process of the lamp electrodes before the ignition and sets the nominal power point on the steady state, was developed. In addition, the ballast incorporates an input rectifier stage using a Flyback converter with active power factor correction (PFC), in discontinuous conduction mode, with universal input voltage range (90V RMS - 240 V RMS ), attending the limits imposed by IEC 61000-3-2 standard, for class C devices. Finally, it is highlighted that, with the proposed methodology for adjusting the UV dose, could ensure the development of a design that allows full compliance with NSF/ANSI Standard 55: Classes A and B, for the proposed drinking water purifier / Mestre

Made available in DSpace on 2015-05-14T16:52:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-28Bitstream added on 2015-05-14T16:59:44Z : No. of bitstreams: 1 000823144.pdf: 2321402 bytes, checksum: eae662cf5229f77a1f4290d094d1dcfe (MD5) / Nesta pesquisa foi desenvolvida uma metodologia para o dimensionamento de reatores eletrônicos para o acionamento de lâmpadas fluorescentes especiais, emissoras de UV (irradiação ultravioleta), aplicadas na purificação de água. A principal contribuição desta dissertação está relacionada ao desenvolvimento de uma metodologia de projeto para adequação do parâmetro conhecido como Dose UV. Esse parâmetro define a quantidade de energia em forma de irradiação ultravioleta à qual devem ser expostos os microrganismos patogênicos presentes na água, para inibir suas funções metabólicas e de reprodução. Neste contexto, foi projetada e implementada uma estrutura purificadora de água potável, aplicando o método TURF (Three-step UV fluence Rate and Fluid dynamics), o qual propõe realizar cálculos em separado do tempo de permanência da partícula exposta à irradiação UV e a quantidade de irradiação UV que a lâmpada usada pode produzir, para em seguida se determinar a Dose UV, teoricamente. Neste trabalho, esse tempo foi determinado com o estudo hidráulico da estrutura utilizando-se o software SolidWorks, e, por outro lado, aplicou-se o modelo matemático MSSS Multiple Segment Source Summation para a obtenção da irradiação ultravioleta fornecida pelo purificador. Devido ao fato das lâmpadas geradoras de irradiação ultravioleta, empregadas neste trabalho, apresentarem um comportamento análogo às lâmpadas fluorescentes convencionais, foram modeladas através de um modelo de Quarto Grau. Desta forma, foi desenvolvido um reator eletrônico capaz de garantir pré-aquecimento controlado dos filamentos das lâmpadas antes de sua ignição, assim como, ajuste adequado para operarem no ponto de potência nominal para a etapa de regime permanente. Além disso, o reator incorpora como estágio de potência na entrada um conversor Flyback com correção ativa do fator de potência ... / In this research it was developed a methodology for the design of special fluorescent lamps electronic ballasts applied to water purifiers, through the use of UV radiation. The main contribution of this work it is related to the development of a design methodology to fit the parameter known as UV dose. This parameter defines the amount of energy as UV light to which the pathogenic microorganisms present in water must be exposed to inhibit their metabolic and reproductive functions. In this context, a purifying drinking water structure was designed and implemented, applying the TURF method. This method proposes to calculate separately, the particle exposition time and the amount of UV radiation produced by the lamp, and in a third step, calculate theoretically the UV dose. Thus, the related time was determined with the hydraulic structure model using the software SolidWorks, and through the use of MSSS mathematical model to obtain the UV radiation provided by the purifier. Whereas the behavior of the used UV lamps is similar to conventional fluorescent lamps, they are modeled applying a Fourth Degree model. Hence, an electronic ballast that guaranties a controlled preheating process of the lamp electrodes before the ignition and sets the nominal power point on the steady state, was developed. In addition, the ballast incorporates an input rectifier stage using a Flyback converter with active power factor correction (PFC), in discontinuous conduction mode, with universal input voltage range (90V RMS - 240 V RMS ), attending the limits imposed by IEC 61000-3-2 standard, for class C devices. Finally, it is highlighted that, with the proposed methodology for adjusting the UV dose, could ensure the development of a design that allows full compliance with NSF/ANSI Standard 55: Classes A and B, for the proposed drinking water purifier

CAPES / Arranjos tecnológicos que integram sistemas de zona de raízes apresentam-se como uma opção plausível para adequação de efluentes, devido principalmente a sua simplicidade construtiva, baixo custo de implantação/operação e eficiência na remoção de poluentes. Estes sistemas atuam como filtros biológicos cultivados com macrófitas aquáticas, aplicados ao tratamento de esgotos domésticos e industriais. O presente estudo teve por objetivo a construção e o monitoramento de dois sistemas pilotos de tratamento de esgotos por zonas de raízes de fluxo hidráulico vertical livre e afogado, montados em recipientes plásticos com volume total de 220L cada. Neles foi cultivada a espécie vegetal Canna x generalis L.H Bailey (cana- indica), planta heliófita rizomatosa, com folhagens ornamentais e de inflorescências coloridas, cultivada sobre meio suporte com camadas de brita e areia. Os sistemas foram alimentados com substrato sintético tendo glicose como fonte de carbono, sob taxa hidráulica de aplicação de 125,8 L.m-2.dia-1 e matéria orgânica em termos de DQO de 300,93± mg.L-1. O sistema de fluxo afogado apresentou eficiências na remoção de Nitrogênio Total Kjeldahl, DQO e PO 4 de, 55±17%, 95±6% e 46±11% respectivamente. No sistema de fluxo livre as eficiências para remoção de Nitrogênio Total Kjeldahl, DQO e PO4 foram de 57±11%, 96±6% e 41±11%, demonstrando elevada remoção de matéria orgânica e nutrientes para os dois modelos estudados. / Technological arrangements that integrate systems root zone are presented as plausible option for effluents treatment, mainly because of their simplicity in construction, low cost of implementation/operation and efficiency in removing pollutants. These systems act as biological filters planted with macrophytes, applied to the treatment of domestic and industrial sewage. The present study aimed at the construction and monitoring of two pilot systems for sewage treatment of the roots zones of free vertical hydraulic flow and drowned, mounted in plastic containers with a total volume of 220L each. They were cultivated plant species Canna x generalis LH Bailey (cana indica), heliophytic rhizomatous plant with ornamental foliage and colorful flowers, grown on the support medium with layers of gravel and sand. The systems were fed synthetic substrate with glucose as carbon source, under hydraulic application rate of 125,8 L.m-2.day-1 an organic material and in terms of COD of 300,93± mg.L-1. The drowned system flow had removal efficiencies of Total Kjeldahl Nitrogen, COD and PO4 de, 55±17%, 95±6% e 46±11%respectively. In the system of free flow efficiencies for Total Kjeldahl Nitrogen removal, COD and PO4 were 57 ± 11%, 96 ± 6% and 41 ± 11%, showing high removal of organic matter and nutrients for the two models studied.

Submitted in fulfilment of the requirements for the Degree of Master of Engineering, Durban University of Technology, 2017. / In this research, the woven fibre microfiltration (WFMF) fabric which is produced locally in South Africa is used as a membrane material. It is cheaper in price in comparison with the current commercial membrane materials that are in use. The WFMF is also more robust when compared with the commercial membrane materials thus is able to withstand harsh working conditions. From previous studies on the WFMF, it has been shown that it can be used as a membrane material without any compromise to permeate quality. This research seeks to optimize the working conditions of this membrane material (WFMF) with an aim of achieving lower running costs and better anti fouling strategies in comparison to the commercial MBRs. The objectives and aims of this research was to come up with a MBR system whose running cost is lower than that for the commercial systems, which can be adapted for use in any environment, especially in the hardship regions where its robustness would be an added advantage. The performance of the WFMF submerged MBR was also optimised including antifouling operating regimes. This study was done in a pilot plant that was set up at Veolia wastewater treatment plant, Durban Metro Southern Works. The feed water for the pilot plant was pumped from the return activated sludge mixing chamber by means of a submersible pump. The MLSS concentration of the feed water was about 12 g/l. The various investigations that were conducted in the course of this research included the effect of spacing between membrane modules, relaxation steps and frequencies, evaluation of aeration rates and evaluation of coarse vs. fine bubbles which were all aimed at optimizing the performance of the immersed WFMF MBR. The permeate was checked for turbidity and COD levels to ensure that they were within the accepted water standards. From the experiments it is shown that the critical flux increased with an increase in aeration rate which is in concurrence with the literature and a starting flux of 30 LMH was chosen for the running of the pilot plant for the various experimental runs to be carried out. For the pipe diffuser height effect experimental run, the best results were achieved at a height of 5 cm below the membrane modules and the use of a pipe diffuser gave better results than the use of a disc diffuser. For the membrane module spacing effect the best results were obtained at the smallest possible width i.e. 3.5 mm. The best relaxation step sequence was found to be 9 mins on and 1 min off. COD, turbidity and DO was continuously determined during the course of the experimentation. Further studies should be done on use of the disc diffuser with increased surface area of aeration holes and also hole sizes of smaller diameters to check on its effectiveness as a means of reducing fouling on the membrane surface. / M

High-Gradient Magnetic Separation (HGMS) is a powerful separation process that has great potential for industrial wastewater treatment, particularly for the removal and recovery of paramagnetic colloidal particles. The chief advantages of HGMS are that the separation is reversible and potentially selective. However, these advantages are compromised if non-magnetic filtration mechanisms influence significantly the capture of particles. The objective of this study was to identify the chief mechanisms responsible for the removal of ferric oxide (Fe2O3) from water by an HGMS process. This objective was achieved by measuring the effects of applied magnetic induction, collector radius, and fluid velocity on the removal efficiency (RE) of a stainless-steel filter column. These factors were tested on the removal of bare Fe2O3 particles and particles treated with a surfactant (sodium dodecyl sulfate, SDS). The results were compared to the predictions of a trajectory model which simulates particle capture by a magnetic force. The experimental results show that non-magnetic force mechanisms are primarily responsible for the removal of bare Fe2O3 particles for the experimental conditions used in this work. For these particles, the three factors tested had no significant effect on the RE, and 90.1% of the particles were removed without a magnetic force. These results differed sharply from modeling predictions. However, the magnetic force mechanism is primarily responsible for the removal of surfactant-treated Fe2O3 particles. The three factors investigated had a marked effect on the RE, and only 10.8% of the particles were removed without a magnetic force. An increase in magnetic induction from 0.2 to 0.5 T increased the RE from 79.9 to 93.4 %; a decrease in wire radius from 49 to 15 Ym increased the RE from 60.2 to 93.4%, and a decrease in fluid velocity from 0.5 to 0.1 cm/s increased the RE from 69.5 to 95.3%. These results agreed closely with the model predictions.This study demonstrates that by reducing the effect of attractive non-magnetic forces on filtration, surfactant treatment of colloidal particles can potentially preserve and enhance these two key advantages, i.e., regeneration and selectivity of HGMS processes.