Wall loss rate of polydispersed aerosols

Wall loss rates of polydispersed aerosols in a stirred vessel were studied theoretically and exp eri mentally. A formula for the polydispersity factor of the wall loss rate was derived using the moment method or log-normal si ze distribution and compared with numerical calculations. The representativ e theory of Crump and Seinfeld (1981) was used as the wall loss rate of mon odispersed aerosols in which the Brownian diffusion, the turbulent eddy dif fusion, and the gravitational settling are included as wall loss mechanisms . The results of the analysis show that the wall loss rate of a polydispers ed aerosol is substantially higher than that based on a monodispersed size distribution model if the particle size distribution can represented reason ably well by a log-normal function. The existing diagram showing the loss r ate as a function only of the particle size was expanded to include the pol ydispersity effects. Experimental measurements of particle wall toss rate w ere performed by observing the time-dependent changes in particle number co ncentration for various stirring intensities in a cylindrical stirred chamb er. It was shown that by correcting for the polydispersity effect, the depe ndence of the wall loss rate on particle size and stirring intensity agreed with the theory of Crump and Seinfeld (1981).