Influences of Fiber Geometry on the Performance of Nonwoven Air Filters

Abstract

The effect, of fiber diameter and crimp frequency on the filtration performance of nonwoven fabrics were examined empirically. It was found that if fabric weight and density are kept constant, air permeability varies linearly with fiber diameter. When filtering a very dilute aerosol of submicron particles, the capture efficiency varies linearly with ln d s, where d is the effective particle diameter (taking Brownian motion into account) and s is the interfiber spacing. When a concentrated aerosol is filtered, penetration and specific cake resistance tend to limiting values as the fiber diameter approaches zero. As fiber crimp frequency is varied from zero, Frazier air permeability increases, but capture efficiency and specific cake resistance are affected only by a change from zero to a finite crimp frequency.