A New Collision Kernel And Its Application Of The Coagulation Induced By Brownian Motion And Simultaneously Fluid Shear

The characterization of fine particles is an area of immense significance to many industrial endeavors. According to the survey,70%of all industrial processes deal with fine particles at some point. Aggregation is a natural phenomenon during these processes. How to predict the evolution of particle size distribution in the coagulation process has been an issue concerned by the scientific community.Usually, there are three mechanisms that control the process of particle collision, which are:Brownian movement, fluid shear and the differential sedimentation. It is usually assumed that these mechanisms of particle collisions are independent and when they operate simultaneously the aggregation rates are additive directly, but the rationality of this assumptions has not been validated theoretically or experimentally.In this work, based on the convective diffusion equation, we derived a new collision frequency function using an approximation scheme, which integrates Smoluchowski’s kinetics, interaction energy between collision particles, and the comprehensive influence of Brownian and shear collision mechanisms. In this process, we derive and fitting for the approximate analytic formula of the hydrodynamic function, when the particle size is unequal. We also try to get the simplified formula of the collision efficiency.In order to verify the rationality of the additivity assumption, we solved and compared our comprehensive collision frequency and the additivity assumption frequency. The results show that, the fitting of two collision frequency curves is very good. This proved that, the additivity assumption is reasonable. Using these two collision frequency, we solved the discrete coagulation kinetics model. The simulation results are in good agreement with the experiment results in literature.