PREDICTION AND CORRELATION OF ACCESSIBLE AREA OF LARGE MULTIPARTICLE AGGREGATES

Aggregates (composed of large numbers of primary particles) are produc ed in many engineering environments. One convenient characterization i s the fractal dimension, the exponent describing how the number of pri mary particles in each aggregate scales with radial distance from its center of mass. We describe a finite-analytic pseudo-continuum predict ion of the normalized accessible surface area of an isothermal quasi-s pherical fractal aggregate containing N (>> 1) primary particles, on t he surfaces of which a first-order chemical process occurs. Results ar e displayed for specific fractal dimensions (2.5, 2.18, and 1 8) frequ ently observed in aggregating systems. An effective Thiele modulus is used to develop an efficient and accurate scheme for predicting/correl ating the effectiveness factor for an aggregate containing N primary p articles in terms of aggregate fractal dimension, reaction probability , and Knudsen number. Our methods now allow calculations of the access ible surface area of populations of aggregates, provided pdf-(N, D(f), ...)- is known for the populations of interest.