ENHANCED POWER-LAW AGGLOMERATE GROWTH IN THE FREE-MOLECULE REGIME

Aerosols generated at high temperatures tend to form agglomerates whic h can be characterized by a power law exponent, similar to a fractal d imension. The coagulation dynamics of these particles can be described by a modified collision kernel for the free molecule regime. The coll ision kernel for power law (fractal-like) particles is a homogeneous f unction, and the equation is solved using self-preserving size distrib ution theory for fractal dimensions between 2 and 3. The effects of fr actal dimension and primary particle size on agglomerate growth and th e size distribution are very strong. Agglomerate growth is rapid at lo w fractal dimension and fine primary particle size, because the collis ion cross-section is much larger for the same agglomerate mass. The ef fect of primary particle size on the rate of particle growth becomes m ore significant with decreasing fractal dimension, and the particle si ze distribution becomes much broader at low fractal dimensions.