(70ad) Evolution of Primary Particle Size Distributions during Coagulation

A new sectional population balance model is used to simulate particle growth by coagulation accounting for the polydispersity of agglomerates and primary particles. This model overcomes the limitation of the 1D and 2D sectional population balance where primary particle size distributions within each agglomerate are averaged, leading to an artificial narrowing of the primary particle distribution during agglomeration. A two-dimensional discretization is proposed that represents the agglomerate size distribution and the underlying primary particle size distribution for each agglomerate section. Assuming identical morphology of agglomerates of equal size, the model recombines the primary particle distributions of coagulating agglomerate sections and tracks the evolution of the agglomerate composition. The new model is validated against the one-dimensional sectional model for the case of silica nanoparticle growth in a spray flame under conditions of full coagulation and no coalescence. Results show perfect conservation of the primary particle population and demonstrate the effect of primary particle polydispersity on coagulation.