Numerical investigation of the coalescence behavior of carbon nanoparticle based on the cluster-cluster aggregation model considering the experimental coalescence characteristic time

The coalescence behavior of carbon nanoparticle, such as soot and carbon black, has not been so much discussed. This study delves into the intricate behavior of nanoparticle aggregates, with a keen emphasis on the variations in their shape and size based on coalescence dynamics. The coalescence rate obtained from previous experimental results was implemented in an aggregate mean free path cluster-cluster aggregation model. The effect of coalescence on morphology was examined by classifying the aggregates obtained using the cluster-cluster aggregation model in terms of their complexity. We contrasted the results of cluster-cluster aggregation simulation with experimental aggregate shape analyzing electron microscopy images and experimental primary particle size distribution. When neglecting coalescence, proportion of branched-shape aggregates was higher, whereas accounting for coalescence resulted in predominantly ellipsoidal or spherical particles. Contrasting simulations with experimental data reveals that filter-sampling methods may overemphasize aggregate complexity. Contrarily, thermophoretic sampling provided a closer match to simulation predictions. A pivotal finding was that the coalescence model, when coupled with accurate experimental sampling techniques, aligns closely with the experimental observations.