Collection efficiencies of large water drops collecting aerosol particles of various densities

A laboratory experiment to study the effect of the density of aerosol material on collection efficiency of water drops, is conducted with MgSO4 and MnCl2 particles. When compared with the earlier results for NaCl and other particles, our observations show that the collection efficiency of water drops increases with increase in impaction parameter, irrespective of whether the change in impaction parameter is caused by the change in the density of particles or the size of particles/water drop. Our results are correlated through the aerodynamical diameter parameter and with earlier experimental results of other investigators for particles of different densities. The agreement between our experimental results and the theory of Slinn (1983, Precipitation Scavenging in Atmospheric Sciences and Power Production, Chap. 11. Division of Biomedical Environmental Research, U.S. Department of Energy) increases with the increase in the density or size of the particles. Moreover, our experimental results confirm the prediction of Slinn's theory that inertial impaction mechanism is dominant for smaller particles if their density is higher. (C) 1997 Elsevier Science Ltd.