Ce travail s'inscrit dans un contexte général qui concerne les procédés de Séparation Liquide Solide (SLS) et plus particulièrement: filtration/compression et séchage. L'objectif de ce travail est de modéliser ces deux procédés en tenant compte du comportement mécanique du produit étudié. Dans la première partie du travail, une caractérisation expérimentale des argiles utilisées (kaolin et bentonite), en rapport avec le séchage, est présentée. Dans un deuxième temps, un modèle thermo-hydro-mécanique général est développé. Le modèle est ensuite testé dans deux situations différentes : unidirectionnelle et bidirectionnelle. La deuxième partie de l'étude est consacrée à l'étude et la modélisation des procédés de filtration/compression. Le modèle développé dans ce travail décrit uniquement la phase de compression, et essaie, comme précédemment, de développer un modèle hydromécanique. Des simulations issues de la résolution numérique du modèle, permettent en partie de valider la démarche entreprise.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-11-01T21:51:37Z No. of bitstreams: 1 AlexandreBarbosaBruno_DISSERT.pdf: 10742068 bytes, checksum: 8856afbc18039f28f1ae0f2c51179126 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-11-08T21:56:39Z (GMT) No. of bitstreams: 1 AlexandreBarbosaBruno_DISSERT.pdf: 10742068 bytes, checksum: 8856afbc18039f28f1ae0f2c51179126 (MD5) / Made available in DSpace on 2017-11-08T21:56:39Z (GMT). No. of bitstreams: 1 AlexandreBarbosaBruno_DISSERT.pdf: 10742068 bytes, checksum: 8856afbc18039f28f1ae0f2c51179126 (MD5) Previous issue date: 2017-08-07 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A radia??o t?rmica ? um mecanismo de transfer?ncia de calor muito importante em processos que envolvem gases participantes, como CO2 e H2O, em temperaturas elevadas. Contudo, a solu??o exata linha-por-linha da transfer?ncia de calor por radia??o em gases participantes ? computacionalmente dispendiosa. Uma das formas de abordagem para esse tipo de problema consiste na utiliza??o dos m?todos de distribui??o-k, como o FSK e SLW, os quais s?o exatos quando aplicados a meios uniformes, mas possuem limita??es no tratamento de meios n?o-uniformes. A aplica??o do m?todo FSK a meios n?o-uniformes requer a ado??o da hip?tese de k-correlacionado (resultando no m?todo FSCK, Full spectrum correlated-k). Isso resulta em um erro devido ao fato dos coeficientes de absor??o de meios reais n?o serem verdadeiramente correlacionados. Diante disto, este trabalho prop?e e investiga uma nova abordagem para considerar meios n?o-uniformes utilizando o m?todo FSK e que n?o requer a hip?tese de k-correlacionado. O m?todo FSK aplicado em conjunto com a abordagem proposta foi denominado FSAK, (Full spectrum averagedk). Com o objetivo de demonstrar a aplica??o do novo m?todo e analisa-lo, o mesmo foi utilizado na solu??o de uma s?rie de casos teste envolvendo gases compostos por CO2 e esp?cies n?o participantes. Os resultados obtidos com o m?todo FSAK foram mais precisos na presen?a de gradientes de temperatura e concentra??o das esp?cies qu?micas mais elevados, condi??es em que o FSCK torna-se menos preciso. Tamb?m verificou-se que o uso de diferentes procedimentos para o c?lculo do coeficiente de absor??o do m?todo FSAK resultam em significativas diferen?as entre os resultados, demonstrando que diferentes procedimentos para o c?lculo desses coeficientes podem levar a diferentes n?veis de precis?o, indicando que procedimentos para o c?lculo da m?dia que tornem o m?todo mais preciso poder?o ser encontrados em futuros trabalhos de pesquisa. / Thermal radiation is a very important mechanism of heat trasnfer in processes that contains participating gases, as CO2 and H2O, at high temperature. However, exact lineby- line solution of radiation heat transfer in participating media is highly computer time consuming due to the dependence of the radiative properties with the wavenumber. A manner to approach such a problem is employing k-distribution methods, as FSK and SLW, which are exact when applied to uniform media, but have limitations in the treatment of non-uniform media. The application of the FSK method to non-uniform media requires the k-correlated assumption (resulting in the FSCK method). This leads to error due the fact that the absorption coefficients of real media are not truly correlated. Therefore, this work proposes and investigates a new approach to solve non-uniform media using the FSK method and which does not require the k-correlated assumption. The FSK method applied with this new approach was labeled FSAK (Full spectrum averaged-k distribution). The method was used to solve a series of problems involving gases composed of CO2 and non-participating species. The results obtained with the FSAK method were more accurate when temperature and species mole fraction gradients where high. It has also been verified that different procedures can be used to average the absorption coefficient, and that the procedure highly influences the accuracy of the results, indicating that averaging procedures to increase the method accuracy could be found in further research works.

With the increased interest in applying Power Factor Correction (PFC) to off-line AC-DC converters, the field of integrated, single-stage PFC converter development has attracted wide attention. Considering the tens of millions of low-to-medium power supplies manufactured each year for today's rechargeable equipment, the expected reduction in cost by utilizing advanced technologies is significant. To date, only a few single-stage topologies have made it to the market due to the inherit limitations in this structure. The high voltage and current stresses on the components led to reduced efficiency and an increased failure rate. In addition, the component prices tend to increase with increased electrical and thermal requirements, jeopardizing the overarching goal of price reduction. The absence of dedicated control circuitry for each stage complicates the power balance in these converters, often resulting in an oversized bus capacitance. These factors have impeded widespread acceptance of these new techniques by manufacturers, and as such single stage PFC has remained largely a drawing board concept. This dissertation will present an in-depth study of innovative solutions that address these problems directly, rather than proposing more topologies with the same type of issues. The direct energy transfer concept is analyzed and presented as a promising solution for the majority of the single-stage PFC converter limitations. Three topologies are presented and analyzed based on this innovative structure. To complete the picture, the dynamics of a variety of single-stage converters can be analyzed using a proposed switched transformer model.