Numerical study on combined cyclone-filter aerosol collector performance

A cyclone was modified by inserting a stainless steel filter to enhance efficiency in collecting fine particles. Velocity and pressure distributions in the combined cyclone-filter were computed by computational fluid dynamics to explain experimental results from a previous study. Two different filter quantities (0.94 g and 1.83 g) were used. The pressure drop was reduced because the filter increased the turbulence intensity, thus reducing of tangential velocity. Insertion of the filter into the annular space of the original cyclone radically hindered the development of a swirl flow. Most of the gas flows axially through the filter. Good agreement between simulation and experimental results was found for the 1.83 g filter (maximum deviation of 5.1%), while for the 0.94 g filter, agreement was acceptable with the maximum deviations - 39.6%. Single-fiber collection efficiencies were calculated. Larger particles (1 µm) were mainly collected by inertial impaction with 65-70% efficiency at 13.3 m/s and 75–79% at 19.9 m/s, whereas, smaller particles (0.3 µm) are mainly removed by diffusion with 92–94% efficiency at the lower and 89–91% at the higher velocity. Therefore, the added filter enhances the fine particle collection efficiency by changing the centrifugal force to diffusion and inertial impaction mechanisms.