Simulations of Dissolution of Structured Particles

This thesis presents a new modelling framework for the simulation of detergent powder dissolution. Focusing on population of particles containing multi ingredients with porous structure, the general model framework links mixing system power and particle dissolution behaviour by combining convective dissolution equations and
computational fluid dynamics simulation.
Particle dissolves in a variety way due to many factors for example particle shape and size, pore structure, agitation speed, solvent material and temperature. It is difficult to quantitatively conclude these factors on dissolution. As a result, detailed simulations based on Lattice-Boltzmann method are carried out to investigate factors for instance particle shape, surface area to volume ratio and pore structure separately. Later on, both experiment and simulation methods have been studied to explore the effects of agitation and particle wetting process. Results show that surface area to volume ratio plays a more important role in terms of particle related properties. Results also indicate that agitation affects dissolution significantly comparing to the other studied factors.
The new dissolution model, expressed as a coupled system of numerical and computational issues, is used to predict particle dissolution behaviour in a well mixed system. Simple case study of single ingredient non porous particle sodium carbonate (provided by Proctor and Gamble) successfully shows the capability of the model by validating modelling results with experimental results. Later on, more complicated case study of multi ingredients porous detergent powder (PANDORA, one of the semi product in Proctor and Gamble) suggests that this model can predict
porous particle dissolution while the particles are treated as spheres with envelope density.
Based on the good agreements between modelling and experiment data, this model can be applied for predicting bulk particle dissolution behaviour in different mixing
systems, or the same mixing system but different bulk particle.