Numerical simulation of mixed aerosols deposition behavior on cylindrical cross fibers

Abstract

In the actual dust removal process, aerosol particles with distinct physical properties often coexist. Most studies on fiber filtration focused on the particles of a single species, resulting in a poor understanding of the deposition behavior of mixed aerosols. In this study, the dynamic deposition behavior of mixed aerosol particles containing silica (SiO2) and polystyrene (PS) on cylindrical cross fibers was numerically studied using a lattice Boltzmann model coupled with discrete element method (LB-DEM). The mutual influences between the dynamic particle transport/deposition and the airflow were considered using immersed moving boundary (IMB) scheme. The mixed particles exhibit different deposit morphology and filtration performance from single particulate species mainly in the dendritic filtration stage, where the mixed particles tend to deposit on the lateral sides rather than the front of fibers. The filtration efficiency and pressure drop of mixed aerosols are not a superposition of the individual components. At high particle Stroke number (St), the synergistic deposition of SiO2 particles and PS particles of low elastic modulus occurs, resulting in filtration efficiencies that are approximately-four times greater than any single particulate species. When St is below 1.0, the filtration efficiency is improved with increasing St, which is similar to that of single species. Moreover, at the same flow velocity, the pressure drop rises faster and the flow is easier to be clogged for mixed particle filtration. The pressure drop rising rates of the mixed filtration at a high St range from 0.013 to 0.020, which is more than three times the rates for PS (0.006) and SiO2 (0.003).