Initial Collection Efficiency of Electret Filter and Its Durability for Solid and Liquid Particles

Abstract

Expressions to describe initial collection efficiencies of an electret filter for both charged and uncharged particles were derived to cover a wide range of Coulombic force and induced force parameters including the interceptional effect. The prediction equations were in good agreement with the experimental data. Further, electret charge stability in humid air and under exposure to liquid and solid particles was studied by measuring the time dependency of particle penetration. It was found that electret charge is quite stable in humid air but that it gradually disappears when exposed to organic droplets because collected organic droplets spread over the fiber and neutralize dipole charge or weaken the electrical field around the fiber. © 1992, The Society of Chemical Engineers, Japan. All rights reserved.