KEYNOTE: Modeling and Harnessing Mesoscale Structures in Fluidization and Multiphase Reactors

Mesoscale phenomena are ubiquitous in multiphase reaction systems where the material, reactor and system levels all feature the mesoscale structures, such as molecular assemblies, particle (bubble/droplet) clusters, or reactor networks, respectively. Mesoscale problems are essential to a more fundamental understanding of momentum, mass and heat transfer in the classical study of transport phenomena, and to the mixing, residence time distribution and rate-limiting analysis in the chemical reaction engineering, yet they are beyond the scope of those classical textbooks of chemical engineering. In this presentation, I will highlight a heuristic mesoscale modeling approach for multiphase reactor systems, starting from a conceptual Energy-Minimization Multiscale (EMMS) model and ending at the stability-constrained multifluid CFD model. While the stability condition determines the direction of system evolution, the stability-constrained CFD further describes the dynamics of structure evolution. Then this theory is applied to the simulation of gas-solid fluidization and gas-liquid bubble column reactors, with further extension to gas-liquid-solid three phase flow and stirred tanks. Several industrial applications on meso-scale modeling in liquid-solid polyethylene reactors and liquid-liquid emulsification systems will also be highlighted.