Pressure drop and aerosol filtration efficiency of microfibrous entrapped catalyst and sorbent media: Semi-empirical models

Abstract

A three dimensional network of 4–12μm sintered nickel fibers occupying 2.5–40% (vol.) was used to entrap 5–45% (vol.) aluminum oxide particles with diameters between 90–600μm. Pressure drop was measured at face velocities of ⩽100cm/s, and filtration efficiency was measured using polydispersed aerosols of potassium chloride particles from 0.09 to 5μm (dia.). Traditional models for pressure drop and filtration efficiency use mixing rules when combining two components of different diameters. However, these mixing rules gave large errors because of the significant difference between the diameters of the fibers and the entrapped particles. This study describes semi-empirical models for estimating aerosol filtration efficiency and pressure drop, taking into account the heterogeneity created due to wide diameter variations of the components. An empirical factor accounting for the filtration efficiency due to entrapped particles was added to the single fiber efficiency model by Payet et al. (1992) [15]. An empirical correction factor accounting for heterogeneity due to entrapped particles was needed to fit the data to the pressure drop model developed by Harris et al. (2001) [4]. The modeled filtration efficiency agreed with the experimental results with errors less than 8% for structures with fiber loading from 2.5% to 12% (vol.) and particle loading from 5% to 45% (vol.). Pressure drop model agreed with the experimental results with errors less than 10% for structures with fiber loading from 2.5% to 40% (vol.) and particle loading from 5% to 45% (vol.).