Numerical Comparison of Prediction Models for Aerosol Filtration Efficiency Applied on a Hollow-Fiber Membrane Pore Structure

Abstract

Hollow-fiber membranes (HFMs) have been widely applied to many liquid treatment applications such as wastewater treatment, membrane contactors/bioreactors and membrane distillation. Despite the fact that HFMs are widely used for gas separation from gas mixtures, their use for mechanical filtration of aerosols is very scarce. In this work, we compared mathematical models developed for the prediction of air filtration efficiency by applying them on the structural parameters of polypropylene HFMs. These membranes are characteristic of pore diameters of about 90 nm and have high solidity, thus providing high potential for nanoparticle removal from air. A single fiber/collector and capillary pore approach was chosen to compare between models developed for fibrous filters and capillary-pore membranes (Nuclepore filters) based on three main mechanisms occurring in aerosol filtration (inertial impaction, interception and diffusion). The collection efficiency due to individual mechanisms differs significantly. The differences are caused by the parameters for which the individual models were developed, i.e., given values of governing dimensionless numbers (Reynolds, Stokes and Peclet number) and also given values of filter porosity and filter fiber diameter. Some models can be used to predict the efficiency of HFMs based on assumptions depending on the conditions and exact membrane parameters.

Airborne nanoparticle collection efficiency of a TEM grid-equipped sampling system

“…Particles were collected onto the filter surface or deposited on the wall of filter pores. Distinct capture mechanisms were found: a) capture of small particles by Brownian diffusion to the pore wall of filter, and b) by Brownian diffusion on the surface of filter, c) capture of large particles by impaction, and d) interception (Bulejko 2018;Rubow 1981;Spurny et al 1969). Gravity sedimentation can be neglected for particle size smaller than 500 nm (Zhu et al 2017).…”

Uncertainty assessment for the airborne nanoparticle collection efficiency of a TEM grid-equipped sampling system by Monte-Carlo calculation

“…Particles are collected onto the filter surface, or depositing on the wall of the filter pores. Distinct capture mechanisms were found: a) filter pore wall capture by Brownian diffusion, and b) interception; filter surface capture by c) Brownian diffusion, and d) impaction [39][40][41].…”

Fully Polymeric Distillation Unit Based on Polypropylene Hollow Fibers

“…The possibility of using renewable energy sources, such as waste heat, solar energy, or geothermal energy, may allow the integration of membrane distillation with other processes, making it more favorable energy-wise and therefore promising on an industrial scale [ 4 , 5 ]. Another possible use of the polymeric hollow fiber membrane is for aerosol or gas filtration [ 6 , 7 , 8 , 9 ].…”