(420g) Spray Drying for Uniform Sized Particle Formation: A Multiscale Modeling and Simulation Approach

In this talk, we will share with the audience our past and on-going efforts on developing multiscale models for MDSD to realize virtual manufacturing of functional powder products. We have been pursuing multiscale models for the integrated system of the spray drying process and the particle product. At the dryer scale (macro), a comprehensive CFD model has been developed to take care of the multi-stage drying process. Coupling the level set model with a solid mechanics model of a piezo-ceramic nozzle allowed us to computationally explore mono-disperse droplet formation through atomization. A unique discrete phase model (DPM) was developed to track evaporating droplets flying through chambers with distinctively different sizes, i.e., the small dispersion chamber followed by the big drying chamber. For the first time, droplets in MDSD can be tracked from generation to the end of the drying stage. At the single droplet scale (meso), a liquid-gas two phase flow model coupled with the moving mesh ALE method was developed to simulate the droplet drying process. The ability of quantifying the local evaporation rate and characterizing crust formation enabled us to track the shape evolution of a shrinkage droplet. At the droplets’ surface layer scale (micro), a coarse-grained lattice Monte Carlo (LMC) approach is being developed to simulate evaporation induced self-assembly of solute molecules. Evolution of the nanoscale surface morphology and composition under different drying conditions could then be systematically investigated. By resorting to this multiscale simulation platform, a number of new designs and optimized operations have been successfully identified, which can lead to improved production rate and reduced cost without sacrificing powder quality. In addition to the above listed advances, we would also like to discuss with experts in the audience the key challenges faced by us when developing individual-scaled models with a hope to seek collaborations.