NOTE
A Note on the Growth of Primary Particles in Agglomerate Structures by Coalescence structures form. At higher temperatures further down the jet axis, the primary particles in the agglomerates coalesce (coalescence limited growth), until ambi-Aerosol particles at high concentrations grow by collisions and ent air cooling freezes the primary particle size. In this paper, a model for coalescence. If coalescence is faster, particles remain individual predicting agglomerate and primary particle size is derived, applicable to both and spherical, and primary particle growth is determined by the collision and coalescence limited growth regimes. In a forthcoming paper, this collision rate. When collisions are faster, dendritic agglomerates model will be applied to the free jet system. consisting of a large number of primary particles form. Primary Ulrich and Subramanian (9) described coalescence limited growth of particle growth is then determined by the coalescence rate. In this particles in large agglomerates by defining a coalescence time (by the Note a model is given for predicting primary particle growth based viscous flow mechanism) in which a predefined number of primary particles on the linear decay law for the surface area of a coalescing struc-(chosen to be the average number of neighbors plus one) coalesce com- ture. In the collision-limited primary particle growth regime, the pletely. This model has been applied recently to predict sintering in silver linear decay law is applied to the coalescing pairs of particles. In agglomerates in a heated flow (10).
For a system in which there are both collision and coalescence limited the coalescence-limited regime large agglomerates are present, and growth regions, earlier approaches, which are limited to either regime only, the linear decay law is applied to subregions of the agglomerates.
are not satisfactory. In this paper, we present a model which combines แญง 1996 Academic Press, Inc.
elements of (2), (5), and (9). Agglomerate size is predicted by using the