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 press ure across beds of silica aerogel microspheres as a function of flowrate. T hese measurements showed a permeability of 2.2 x 10(-7) cm(2) for the bed o f aerogel microspheres. The beds were then used to capture airborne particl es in the 20-2000 nm size range. The aerosol collection performance for the test beds was investigated at three flowrates corresponding to face veloci ties 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 col lection efficiency went from 93% to 76% to 64%. It was also determined that the aerosol particle size resulting in minimum collection efficiency shift ed from 570 to 315 to 300 nm with increasing face velocity. The flow regime determined from the first experiment was used to explain aerosol depositio n in the test beds of silica aerogel microspheres. (C) 2001 Elsevier Scienc e B.V. All rights reserved.