On the Filtration efficiency of Composite Media Composed of Multiple Layers of Electret Media

ABSTRACT The intention of this study is to find out the reasoning for the discrepancy between the measured and calculated filtration efficiencies of composite media composed of multiple layers of base electret media reported in previous studies. Size-fractionated particles in neutral, single-charged, and Boltzmann-stationary-charge-distributed were prepared to measure the filtration efficiency of multi-layered electret media. It was found that the reported discrepancy was attributed to the charge distribution of the test particles. This result further suggests that the charge distribution of the test particles must be taken into consideration for the filtration efficiency prediction of multi-layered electret media.