TitleGranular flow, segregation and agglomeration in bladed mixers
NameRemy, Brenda (author), Glasser, Benjamin J (chair), Pedersen, Henrik (internal member), Shapley, Nina (internal member), Gilchrist, James F (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectChemical and Biochemical Engineering,
DescriptionA large number of industrial processes involve the transport, mixing and storage of particulate systems. While prevalent in industry, particulate processes are commonly plagued by problems due to the complex rheology of these systems. In this work, the behavior of granular materials in a bladed mixer, an industrially relevant geometry, was investigated using computational and experimental techniques. Experimental flows were characterized via Particle Image Velocimetry and image analysis. Discrete element simulations were carried out to examine the effect of a wide range of system parameters. Particulate flows in bladed mixers were found to be periodic with complex flow patterns developing throughout the particle bed. Cohesionless flows were initially studied. For monodisperse flows, two distinct flow regimes were observed: a quasi-static regime where blade speed provides the time scale for momentum transfer and an intermediate regime where stresses scale linearly with blade speed. Particle and wall roughness were found to significantly affect bladed mixer flows. Systems with higher roughness are characterized by enhanced particle motion and mixing. Simple scaling relationships were observed for monodisperse flows in the quasi-static regime. Particle velocities and diffusivities were found to scale linearly with mixer size and blade speed, while stresses scaled linearly with particle bed weight. In polydisperse flows, size segregation was found to occur due to sieving. However, it was found that the extent of segregation can be reduced by introducing intermediate particle sizes in between the smallest and largest particles. Finally, wet particle flows were examined. At low moisture contents, enhanced particle velocities and mixing kinetics were observed in comparison to dry flows. However, at higher moisture contents, particle velocities and mixing rates were observed to decrease. Wet particle flows were characterized by the formation of particle agglomerates. Agglomerate formation led to an increase in particle bed roughness which significantly influenced macroscopic and microscopic flow properties. These findings contribute to the understanding of granular behavior in complex systems. Improved understanding of granular flows will enable the development of first-principles based models which can assist in the design and scale-up of bladed mixer operations and the identification of critical processes parameters.
NoteIncludes bibliographical references
Noteby Brenda Remy
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.