Micro leitos fluidizados: um estudo experimental e numérico sobre os efeitos da inclinação em leitos bidispersos

Author(s)

Henrique Barbosa de Oliveira

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Mecânica
• Defense date: 2024-08-20

Examining board members

Erick de Moraes Franklin; Cezar Otaviano Ribeiro Negrão; Rodolfo Marcilli Perissinotto

• Advisor: Erick de Moraes Franklin

Abstract

Micro fluidized beds are basically suspensions of solid particles by an upward fluid flow in a millimeter-scale tube, with applications in chemical and pharmaceutical processes involving powders. Although in many applications beds are polydisperse, previous works considered mostly monodisperse beds aligned in the vertical direction. However, introducing an inclination with respect to gravity leads to different bed patterns and mixing levels, which can be beneficial for some applications. In this MSc Thesis, the behavior of micro gas-solid beds using bidisperse mixtures under different inclinations is investigated. In the experiments, mono- and bidisperse beds are filmed with a high-speed camera, and the images are processed to obtain measurements at bed and grain scales. It is seen that the degree of segregation is larger for vertical beds, and also that mixing varies non-monotonically with inclination, with a maximum degree of mixing in angles between 30°-45° with respect to gravity. The mixing layer forms by the competition between kinetic sieving and local circulation promoted by the fluid flow, which is revealed by computing the mean and the fluctuations of the particles' velocities. Worse fluidization is also observed as the angle relative to the vertical increases, accounting then for the non-monotonic behavior. Numerical simulations are developed within the CFD-DEM framework to mimic the experiments, in this way more information about the fluid flow is revealed. These results bring new insights into mixing and segregation in polydisperse beds, which can be explored for processing powders in industry. Part of this MSc Thesis was written based on Oliveira and Franklin (2024) (AU)

• FAPESP's process: 22/08321-0 - Numerical investigation of particle segregation in polydisperse fluidized beds
• Grantee: Henrique Barbosa de Oliveira
• Support Opportunities: Scholarships in Brazil - Master