Degree Type

Dissertation

Date of Award

1998

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

First Advisor

G. M. Colver

Abstract

The objective of this investigation is to numerically predict the effect of an electric field on a two-dimensional gas-solid fluidized bed. The particles in the bed are taken to be of a uniform size and density forming the particulate phase with a gas (air) taken as the continuum phase. A hydrodynamic model of fluidization utilizes the principles of conservation of mass and momentum describing the multiphase flow equations along with the constitutive equations of gas-solid drag and solids stress;A two-dimensional unsteady-state computer code (K-Fix) was used to observe the effect of an electric field on the gas and solid velocities and the void fraction and pressure in the bed. Special case studies included that of a jet, a bubble, and two bubbles, with and without an electric field. The K-Fix code was modified to include an interparticle force component to account for bed stabilization due to the electric field. In the absence of a field, this force component reduced to a conventional solids stress term. The results show that even without electric fields, bed instabilities are observed below minimum bubbling conditions with a shifting in bed stability observed with the application of an electric field;An important aspect of the study is the comparison of bubble formation with the application of an electric field to that predicted by the modified code, thereby validating the proposed mechanism of an interparticle force. Bubble instability is also compared qualitatively with a second perturbation method for bubble formation along with a comparison of experimental results obtained from another study. Bed circulation resulting from a jet in the presence of an electric field was also investigated.

DOI

https://doi.org/10.31274/rtd-180813-4970

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Forhad Md Hossain

Language

en

Proquest ID

AAI9826542

File Format

application/pdf

File Size

143 pages

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