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Mathematical modelling of the drying of sol gel microspheres

Oberman, Glen James (2011) Mathematical modelling of the drying of sol gel microspheres. PhD thesis, Queensland University of Technology.

Abstract

This thesis presents a mathematical model of the evaporation of colloidal sol droplets suspended within an atmosphere consisting of water vapour and air. The main purpose of this work is to investigate the causes of the morphologies arising within the powder collected from a spray dryer into which the precursor sol for Synroc™ is sprayed. The morphology is of significant importance for the application to storage of High Level Liquid Nuclear Waste. We begin by developing a model describing the evaporation of pure liquid droplets in order to establish a framework. This model is developed through the use of continuum mechanics and thermodynamic theory, and we focus on the specific case of pure water droplets. We establish a model considering a pure water vapour atmosphere, and then expand this model to account for the presence of an atmospheric gas such as air. We model colloidal particle-particle interactions and interactions between colloid and electrolyte using DLVO Theory and reaction kinetics, then incorporate these interactions into an expression for net interaction energy of a single particle with all other particles within the droplet. We account for the flow of material due to diffusion, advection, and interaction between species, and expand the pure liquid droplet models to account for the presence of these species. In addition, the process of colloidal agglomeration is modelled. To obtain solutions for our models, we develop a numerical algorithm based on the Control Volume method. To promote numerical stability, we formulate a new method of convergence acceleration. The results of a MATLAB™ code developed from this algorithm are compared with experimental data collected for the purposes of validation, and further analysis is done on the sensitivity of the solution to various controlling parameters.

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ID Code: 49386
Item Type: QUT Thesis (PhD)
Supervisor: Farrell, Troy, Turner, Ian W., & Sizgek, Erden
Keywords: nuclear waste, TZA sol, sol gel, colloid, coagulation, agglomeration, droplet drying, evaporation, clapeyron equation, mathematical modelling, heat flow, mass transfer, DLVO theory, computational model, control volume, convergence acceleration
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Past > Schools > Mathematical Sciences
Institution: Queensland University of Technology
Deposited On: 27 Mar 2012 17:10
Last Modified: 27 Mar 2012 17:10

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