Numerical Simulation Of Discrete Coagulation And Fragmentation Kinetics Models

Discrete coagulation-fragmentation equation(population balance model) has described the process of particles’motion, collision, flocculation and fragmentation.Mastering the regularity of particle size distribution and the time lag for attainment of steady state, studying the role of fragmentation in coagulation process, and proposing a new idea of spiral flocculation reactor by comparing the speed of the coagulation rates, all of these have great importance on improvement of coagulation efficiency and the control of coagulation process.This article has built the main idea rely on coagulation kinetics foundation and the research of Spicer, using the numerical simulation method based on population balance model and mathematical software Matlab to calculate. In the coagulation processes of the shear force field mechanism, studying the regularity of particles’motion, collision, flocculation and fragmentation under two conditions, one is the values of velocity gradient G are constant, and the other is the values of G are continuous functions, proposing a new coagulation-fragmentation mechanism, makes contribution to the improvement of coagulation efficiency.In the coagulation processes of the shear force field mechanism, the results show that the particle size distribution is self-preserving, that is, after a certain time, the particle size distribution is no longer change and coagulation and fragmentation reach a steady state. In the coagulation process, fragmentation is very important and it can’t be ignored when velocity gradient G are constant, since the neglect of fragmentation is reasonable when velocity gradient G are continuous functions. When the structure of aggregates is fractal, coagulation rate is faster as the decreasing of fractal dimension D.