EXPERIMENTAL-STUDY OF AEROSOL FILTRATION IN THE TRANSITION-FLOW REGIME

An experimental study was carried out to investigate the performance of fibrous filters in the transition flow regime, where the fiber radius is of the same order of magnitude as the mean free path of gas molecules. Filter media with the mean fiber diameter of 0.21-0.72-mu-m and the packing density of 0.053-0.08 were used in this study. The transition flow conditions were achieved by reducing the gas pressure in the filter test apparatus. Experiments were performed in the pressure range of 0.1-1.0 atm using monodisperse particles of 0.04-0.45-mu-m diameter range. The particles were generated by the electrostatic classification technique. The particulate penetration through the filter and the Corresponding pressure drop were measured st face velocities ranging from 6 to 19 cm/s. Experimental results showed that the penetration decreased by three to four orders of magnitude as the pressure was reduced from 1.0 to 0.1 atm. It was found that the most Penetrating particle size increased slightly as the gas Pressure was reduced. The pressure drop across the filter was also found to decrease significantly as the pressure was reduced.