An experimental investigation of aerosol collection utilizing packed beds of silica aerogel microspheres

Packed beds of silica aerogel microspheres were used as a collection medium for aerosol particles in the viral and bacterial size range (20–2000 nm). Airflow characteristics were determined by measuring the differential pressure across beds of silica aerogel microspheres as a function of flowrate. These measurements showed a permeability of 2.2×10−7 cm2 for the bed of aerogel microspheres. The beds were then used to capture airborne particles in the 20–2000 nm size range. The aerosol collection performance for the test beds was investigated at three flowrates corresponding to face velocities typically encountered in aerosol filtration work. As face velocity was increased from 3.4 to 20 to 40 cm/s it was determined that the minimum collection efficiency went from 93% to 76% to 64%. It was also determined that the aerosol particle size resulting in minimum collection efficiency shifted from 570 to 315 to 300 nm with increasing face velocity. The flow regime determined from the first experiment was used to explain aerosol deposition in the test beds of silica aerogel microspheres.