Numerical Simulations of Nanoparticle Fluidization under Pulsation Assistance Using PBM with a Mechanistically Grounded Gas Shear Breakage Kernel: Model Validation and Mechanistic Insights

Gas pulsation significantly improves nanoparticle fluidization quality and facilitates industrial scale-up. However, accurate prediction of pulse-assisted fluidization and understanding of how intermittent gas flow regulates agglomerate breakage-agglomeration dynamic equilibrium remain challenging. Here, a gas shear breakage kernel based on an outer-layer stripping mechanism is proposed and incorporated into the population balance model (PBM). To account for agglomerate size evolution in interagglomerate interactions and energy dissipation, agglomerate-phase constitutive equations are modified within the kinetic theory of cohesive particle flow (KTCPF). A CFD-KTCPF-PBM coupling method is then developed to simulate pulse-assisted nanoparticle fluidization. Model validation against experimental data shows markedly improved prediction accuracy, with the mean absolute percentage error and root-mean-square error reduced to 5.00% and 0.16, representing reductions of 17.1-fold and 20.8-fold relative to the conventional method. Simulations reproduce typical behaviors in the agglomerate particulate fluidization regime. The pulsation-induced improvement in fluidization quality can be interpreted as an equivalent effect of increased gas velocity. By inducing periodic global circulation and dispersed local circulations, gas pulsation suppresses bottom accumulation and promotes bed expansion and gas–solid mixing. This regulation essentially reshapes bed dynamics, transitioning the fluidization from low-efficiency, ordered, and stratified to high-efficiency, chaotic, and intensely mixed regimes. This study provides a validated high-accuracy predictive tool and theoretical basis for nanoparticle pulsed fluidization and its industrial scale-up.