Mestrado em Engenharia Química (IQ)
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Navegando Mestrado em Engenharia Química (IQ) por Por Orientador "Santos, Dyrney Araújo dos"
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Item Proposta de uma nova metodologia para a determinação da transição catarateamento-centrifugação utilizando partículas esféricas e não-esféricas em um tambor rotatório via técnicas de CFD(Universidade Federal de Goiás, 2020-02-18) Benedito, Wanessa Mendonça; Santos, Dyrney Araújo dos; http://lattes.cnpq.br/8987869956010169; Santos, Dyrney Araújo dos; Souza, Thiago Leandro de; Petri Júnior, IrineuRotary drums are widely utilized in several industrial processes, such as drying, mixing, milling, granulation, among others. The widespread frequent use of rotary drums is due to their simple design and their capability to handle materials characterized by broad size distributions with significant differences in their physical properties. The granular flow inside rotary drums can be classified in different forms: sliding, slumping, rolling, cascading, cataracting, and centrifuging regimes. This classification depends on the drum operating conditions and the physical properties of the particulate material envolved in the granular flow. There are have been no reposts in the literature that presents a precise methodology for cataracting-centrifuging transition identification in rotary drums. This identification is carried out exclusively by visual and subjective way. In this context, the present work aims the proposition of a methodology for the cataracting-centrifuging transition identification, for different particle shapes, using the Multiphase Granular Eulerian Model (MGEM), implemented by CFD simulations. When compared to the Lagrangian model (DEM), the mainly difficult associated with Eulerian model is the particle shape representation, since the solid phase is treated as continuous in CFD simulations. The particle shape for non-spherical particles was indirectly represented in the MGEM using the critical solid fraction (αsc), a parameter associated with the Schaeffer’s frictional model. The present work is also dedicated to overcoming this difficulty. The drum length effect on the cataracting-centrifuging transition was also analyzed. Using the methodology herein proposed was verified that the particle shape and the drum length influence the cataracting-centrifuging transition behavior. For nonspherical particles was required lower values of rotation speed to reach the centrifuging regime condition when compared with spherical particles. It was verified that the lower the drum length, the higher the facility associated with the transition for centrifuging regime for both particle shapes.Item Investigação da dinâmica de formação de gotas no interior de microcanais via técnicas de CFD(Universidade Federal de Goiás, 2020-02-18) Chaves, Igor Lima; Santos, Dyrney Araújo dos; http://lattes.cnpq.br/8987869956010169; Santos, Dyrney Araújo dos; Coltro, Wendell Karlos Tomazelli; Souza, Thiago Leandro deMicrofluidics has a recent origin and its development is based on microanalytical methods. Defined as the science and technology that addresses the manipulation of small amounts of fluids flowing into channels of tens to hundreds of micrometers, microfluidics today has a diversity of applications due to their characteristics of control efficiency. In this work, the microfluidics applications are briefly addressed, the physical characteristics phenomena that govern it are elucidated by identifying the general flow characteristics, the relevant phenomena and dimensionless studies of flow in channels on the micro-scale, as well as the interfacial properties, which appear in multiphase systems. The mathematical basis used to study the flow phenomena is still addressed. Computational fluid dynamics (CFD) techniques are used as a methodology for development, to overcome the limits of laboratory experimentation (observed here the numerical control of the value for interfacial properties). For the study of multiphase microfluidic flows, the Multiphase Fluid Volume Model (VOF) is used, which allows the flow to be solved numerically and to observe its behavior through the interfaces between immiscible fluids. Given this, in this work, the VOF model was validated with experimental results, both quantitatively and qualitatively, to predict the entire process of generating drops within microchannels. Additionally, the Adaptive Mesh Refining (AMR) technique was used to better track the interface between the fluid phases. The effects of the microchannel geometry, the physical properties of the fluids and the operating conditions, on the size and rate of droplet generation were evaluated using the multiple regression techniques. A dimensionless correlation was also proposed for the prediction of droplet length in which the relative error was 8.2%.Item Análise da segregação axial e radial em um leito de jorro cônico(Universidade Federal de Goiás, 2020-02-17) Morais, Jéssika Nayara Santos; Santos, Dyrney Araújo dos; http://lattes.cnpq.br/8987869956010169; Duarte, Claudio Roberto; Freitas, Fernanda FerreiraThe particle cyclic and orderly movement inside a spouted bed has as main advantages of this technique, thus enabling an effective particle-particle and fluid-particle contact, which results in high transfer rates of heat, mass and movement. Due to their intrinsic characteristics, spouted beds have been widely used in industrial processes, however, there are some disadvantages operation inherent, the most complex of which are related to the segregation phenomenon, which occurs due to the multicomponent mixtures use in production lines, causing a non-uniform product formation, which compromises the equipment performance. In this way, a better understanding of the segregation phenomenon inside a spouted bed, is of fundamental importance for its design, operation and optimization. In the present work, a non-intrusive methodology using a solidification-slicing approach was used for the investigation of radial and axial segregation behavior in a spouted bed. The effects of diameter, density, and shape of the particles, as well as the initial particle loading, and the inlet air velocity, on segregation were qualitatively and quantitatively assessed. Regarding the results, binary mixtures with aspect, diameter and density ratios, equals a 2.0, 2.0, and 1.9, respectively, show a random mixture condition. Binary mixtures with diameter ratio of 4.5 and density ratio of 5.8, show radial and axial segregation. As regards to radial segregation, the higher or denser particles, tended to form a central core at the spout region, and the smaller or lighter particles, flowed to the annular region near the spouted bed wall. The particle dynamics seemed not to be significantly affected by changing the particle initial loadings in systems with aspect ratio of 2.0 and density ratio of 5.8, however, affected systems with diameter ratio of 4.5. As expected, the increase in diameter and density ratios caused an increase in radial and axial segregation. The segregation phenomenon for binary mixtures with high density ratio, were shown to be dependent of the initial particle loading configuration, but independent of the superficial gas velocity.