Thesis (M.S.)--Ohio University, Novmeber, 1994. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, June, 1997. / Title from PDF t.p.

Thesis (M.Eng.(Chemical Engineering))--University of Pretoria, 2004. / Title from opening screen (viewed March 18, 2005). Includes summary. Includes bibliographical references.

Thesis (PH.D.)--Michigan State University. Mechanical Engineering, 2008. / Title from PDF t.p. (viewed on Aug. 28, 2009) Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Dr. Spyros Pavlostathis, Committee Member ; Dr. Mustafa M. Aral, Committee Chair ; Dr. Turgay Uzer, Committee Member ; Dr. Ching-Hua Huang, Committee Member ; Dr. Sotira Yiacoumi, Committee Member. Vita. Includes bibliographical references.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 140-150). Also available in electronic version.

The composition of meteorites and the surface of asteroids suggest that planetesimals of the early solar system have undergone partial melting and differentiation. The sepa- ration of the denser metal (Fe-FeS alloy) from the lighter silicate is the most important differentiation process. The melting is mainly induced by the heat produced through the decay of 26Al and 60Fe. The distribution of these heat sources inside the celestial body is not uniform. In fact, 26Al is a lithophile element following the migration of the silicate and 60Fe is a siderophile element following the metal. In modeling the differen- tiation of small bodies it is fundamental to include at least two fluid phases in addition to the solid matrix. This study presents a first time three-phase mixture model for the metal-silicate segregation in a compacting body. The theoretical model is developed fol- lowing the classical averaging approach. The governing equations are then implemented in a numerical model in 1-D spherical geometry. In presence of two fluids, these can exchange their position within the porous matrix even in absence of compaction. They also act a mutual viscous drag force, which results in small fractions of metal to ascend with the lighter silicate, and viceversa. / <p>Validerat; 20151008 (global_studentproject_submitter)</p>

Orientador: Milton Mori / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T21:12:35Z (GMT). No. of bitstreams: 1 SanchezForero_DianaIsabel_M.pdf: 2538568 bytes, checksum: 6a7cfe0d2a9575933ee82525a5cec615 (MD5) Previous issue date: 2012 / Resumo: Colunas de bolhas são dispositivos de contato multifásico para transferência de massa e calor, intensamente utilizados em diferentes áreas industriais. O escoamento e a turbulência destes equipamentos são induzidos pelo movimento ascendente das bolhas. A hidrodinâmica e o comportamento das bolhas em regime homogêneo foram analisados em uma coluna de bolhas retangular em escala de laboratório (50 cm x 20 cm x 220 cm), utilizando as técnicas de velocimetria por imagem de partícula (PIV) e a técnica de sombras Shadow para o estudo das fases contínua e dispersa, respectivamente. O gás foi alimentado através de um distribuidor de 18 furos a várias condições de velocidade superficiais de gás na entrada. As propriedades do escoamento para as duas fases foram determinadas por meio de uma quantidade suficiente de imagens duplas. O campo de velocidade para a fase contínua (líquido) foi obtido por adição de partículas traçadoras fluorescentes. Além disso, a intensidade de turbulência, energia cinética turbulenta e os tensores de Reynolds, foram determinados a partir dos dados obtidos pelas medições experimentais. Os resultados mostram o perfil típico da velocidade axial média do líquido, ascendente na região central e descendente nas proximidades das paredes da coluna. Também, foram encontradas diferenças entre os perfis normal e axial dos tensores, o que sugere que o fenômeno turbulento na coluna de bolhas é produzido pelo caráter anisotrópico desta. Finalmente, o comportamento das bolhas foi analisado determinando a distribuição e o tamanho destas. Verificou-se que o tamanho das bolhas decresce ao longo da coluna devido aos efeitos da deformação e fenômenos de coalescência. Igualmente, encontrou-se o diâmetro médio da bolha na faixa dos 4 milímetros, tamanho típico no regime homogêneo / Abstract: Bubble columns are multiphase contact devices for mass and heat transfer, wich are intensively used in different industrial areas. Flow and turbulence in these equipments are induced by the bubble rise motion. The hydrodynamics and bubble behavior in a homogeneous bubbly flow regime was analyzed in a rectangular laboratory-scale bubble column (50 x 20 x 220 cm) using Particle Image Velocimetry (PIV) and Shadow techniques to study continuous and dispersed phase, respectively. The bubble column was aerated by using 18 holes gas sparger for several superficial gas velocities. The flow properties for both phases were determinate by sufficient number of double images. The velocity field for continuous phase (liquid) was achieved by adding fluorescing tracer particles. In addition, turbulence intensities of the fluid, turbulent kinetic energy and tensors profiles were deduced from experimental measurements. Results show typical axial mean velocity profiles of the liquid, upward flow in the core region and a down-flow near the walls. Also, it was found differences between axial and normal tensors profiles that suggest the turbulent phenomena in the bubble column its produced by the anisotropic behavior. Finally the bubble performance was further analyzed by determining bubble distribution and bubble size. It was found a decreasing bubble size along the bubble column due to the coalescence and deformation effects. Furthermore, is determinate that the bubble diameter is around 4 mm, typical bubble size in a homogeneous bubble flow regime / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química

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