Numerical and experimental investigation of dry particle coating
Department of Mechanical Engineering
Doctor of Philosophy
Dave, Rajesh N.
Fischer, Ian Sanford
Rao, I. Joga
Dry particle coating
Discrete Element Method (DEM)
Computational Fluid Dynamics (CFD)
Dry particle coating is an emerging field in the industries that deal with particulate products and powder processing. Compared to the widely reported experimental studies of the dry particle coating, the theoretical modeling of such processes is found to be less comprehensive. The work presented in this thesis is an attempt to fill this gap.
The first part of the dissertation aims at the numerical investigation
of the hybridization system (Nara Machinery, Tokyo, Japan). The flow
behavior of different materials processed in this device is analyzed
using three-dimensional Discrete Element Method (DEM) as well as the
computational fluid dynamics (CFD) models. The particulate motion is
directly simulated using the D EM c ode, which incorporates the effect
of the fluid drag force, computed through the CFD models. The diagnostic
investigation includes various aspects pertinent to the effectiveness
of the hybridizer system in the coating process. Inter-particle collisions
and particle-wall collisions as well as the normal and tangential forces
between the particles are estimated which play an important role in
the surface modification process of a powder. Experimentally measured
velocities in the mixing chamber are in good agreement with the computed
velocities. CFD results show that the flow field is not significantly
affected as the volume fraction of particles is varied from 3 to 10
percent. Overall, it is found that the combined DEM-CFD model appears
to be an adequate approximation of the behavior of the fluid-particle
system in the hybridizer.
The last part of the dissertation deals with a related, yet different type of numerical study, carried out using the DEM approach, of the granular flows and mixing behavior in the oscillating sectorial containers. Mixing patterns are observed for a wide range of frequencies of oscillation as well as different operating conditions such as the powder loading, the coefficient of friction, and the coefficient of restitution. It is observed that the flow patterns follow a particular trend and there exists a critical frequency at which the mixing rate is very small.
njit-etd2003-026 (201 pages ~ 16,143 KB pdf)
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Created January 8, 2004