Skin Effect in Nanofiber Filtration of Submicron Aerosols

Abstract Nanofiber filter, with fibers 0.1-0.3 micron diameter, has been used to effectively remove submicron aerosols. Despite the effectiveness of capture, the pressure drop of the filter is high and increases with solids loading. In this study, the pressure drop and capture efficiency of nanofiber filter were investigated experimentally. In particular, the empirical model of Brown was used to determine the solids distribution across the filter thickness using the experimental parameters. It was found that there is a large pressure gradient across the thin nanofiber layer, and likewise deposited solids distributed largely non-uniformly across the filter thickness, with more solids deposited near the pressure face compared to the downstream face. This is almost equivalent to a "skin layer" as typically found with liquid filters. This skin layer effect for the air filtration using nanofiber filter can be mitigated by installing a microfiber filter upstream of the nanofiber filter. The skin layer of the nanofiber air filter can be relieved with this configuration. This is confirmed by a lower measured pressure drop