Miniaturized gas-solid fluidized beds

Autor(es)

Cunez, Fernando D. ; Franklin, Erick M.

• Tipo de documento: Artigo Científico
• Fonte: MECHANICS RESEARCH COMMUNICATIONS; v. 131, p. 7-pg., 2023-06-26.

Resumo

Fluidized beds are suspensions of grains by ascending fluids in tubes, and are commonly used in industry given their high rates of mass and heat transfers between the solids and fluid. Although usually employed in large scales (tube diameter of the order of the meter), fluidized beds have a great potential in much smaller scales (order of the millimeter) for processes involving powder and fluids. Of particular interest is the pharmaceutical industry, which can take advantage of mm-scale fluidized beds for promoting diffusion of species, classifying grains, or peeling individual particles. This paper reports experiments with a mm-scale gas-solid fluidized bed, which consisted of 0.5-mm-diameter glass particles suspended by an air flow in a 3-mm-ID glass tube. We filmed the bed with a high-speed camera and processed the images with a numerical code for tracking both the entire bed and individual particles. We found that instabilities in the form of alternating high-and low-compactness regions (known respectively as plugs and bubbles) appear in the bed, and that the fluctuating energy of particles (known as granular temperature) is relatively low within plugs. Therefore, mm-scale beds have much reduced agitation and transfer rates when compared to their m-scale counterparts. We show also that increasing the flow velocity does not avoid the appearance of plugs, though the granular temperature increases, mitigating the problem. Our results shed light on detailed mechanisms taking place within the miniaturized bed, providing insights for chemical and pharmaceutical processes involving powders. (AU)

• Processo FAPESP: 16/18189-0 - Leito fluidizado em meio líquido em tubos finos: dinâmica e instabilidades
• Beneficiário: Fernando David Cúñez Benalcázar
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 18/23838-3 - Leito móvel e arrastamento do tipo creep de um leito granular bidisperso em um escoamento laminar
• Beneficiário: Fernando David Cúñez Benalcázar
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 18/14981-7 - Modelagem de escoamentos granulares densos: experimentos, simulações numéricas e análises de estabilidade
• Beneficiário: Erick de Moraes Franklin
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores - Fase 2