Deposition and reentrainment of colloidal particles in disordered fibrous filters under chemically and physically unfavorable conditions

초록

This study is to establish computational fluid dynamics (CFD) simulations of disordered fibrous filters under unfavorable conditions to investigate the effects of chemical and physical factors on filtration performance. We employed a discrete phase model (DPM) to track individual particles, and user-defined functions were implemented to consider the particle deposition to the collector surface via interception and interaction energy. During the DPM process, calculations based on interactional and fluid hydrodynamic effects were proceeded for all injected individual colloids. The results of filtration and collision efficiencies of the single collectors obtained by our CFD simulations showed a very good agreement with the existing expressions and data, accurately predicting the trends of particle deposition and reentrainment. After the validation of the developed particle tracking method, the disordered fibrous filters with randomly distributed monodisperse fibers were studied. The results showed that the reentrainment of deposited particles was enhanced with increasing fluid velocity and solid volume fraction and decreasing fiber size due to the hydrodynamic effects. Moreover, the combined effect with ionic strength, Hamaker constant and zeta potential determined particle deposition behavior by altering particle/filter interactions. The developed simulation method for predicting filtration performance does not contain any free parameters or empirical factors.

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