Particle loss of aerosols with particle diameters between 6 and 2000 nm in stirred tank

Abstract Deposition loss of aerosol particles in a stirred tank has been studied experimentally by observing the time-dependent changes in particle number concentration for various intensities of stirring. The stirred tank used in this study is a standard baffled tank with six-bladed turbine impeller or three-bladed propeller, and the aerosol particles used are monodisperse uncharged NaCl, DEHS (diethylhexyl sebacate), and polystyrene latex particles. The experimental results have shown the clear dependence of the deposition rate on particle size and turbulent intensity of stirring, and also shown that for a given intensity there exists the particle size at which the deposition rate constant becomes minimum. From the comparison of the experimental results with the representative theory of Crump and Seinfeld (J. Aerosol Sci. 12, 405, 1981), it has been found that the experimental deposition rates can be explained well by their theory where the eddy diffusivity near wall is assumed to be proportional to 2.7th power of the distance from the wall. And the equation for predicting the minimum deposition velocity under a given stirring speed has been derived.