Estimation of collection efficiency enhancement factor for an electret fiber with dust load

摘要

In a previous study to investigate how the morphology of particles accumulation on an electret fiber evolves and affects the collection efficiency of the filter at dust-loaded condition,a three-dimensional stochastic model is utilized to simulate the deposition and agglomeration of particles on a cyclindrical electret fiber via two different electrical effects,mamely,induced force (for uncharged particles)and Coulombic force (for charged particles).In the present study,the additional effect of Brownian diffusion is incorporated in the model and the morphology of particle agglomerates obtained in the simulated results is found ot agree well with experimental observations obtained by Hiragi and Kanaoka et al.for boht uncharged and charged particles.In addition,hte ratio of dust-loaded collection efficiency,eta,to the clean-fiber collection effciency,eta_0,can still be approximated as linear function in the casee of weak electrical effects.However,when the electrical parameters are large,the normalized collection efficiencyhas to be represented by two linear relations,i.e.,at low dust load and high dust load.Estimates of hte initial collectin efficiency nad efficiency enhancement factor are given graphically adn tabulated as function of Peclet number,the interception parameter and the two electrical parameters.