Mechanism of colletion of aerosols by an array of oppositely charged drops

摘要

The collection mechanism of charged aerosols by a two-dimensional array of oppositely charged drops is considered. Trajectories of aerosols are computed, using a new simulation program, under conditions of gravity sedimentation of the collecting drops and aerosols. Electric forces, given in spherical coordinate system of each drop, are projected on the spherical coordiante system of the central drop. The equation of motion is solved in this central system using creeping flow apprixmation and the sum of all projected electric forces. Analysis of deviations of streamlines, resulting from the flow apprixmations, is provided. It is shown that for drop spacing larger than 10 diameters, a deviation of less than 3 % is expected at the symmetry axis between the drops. The charges of the collecting drops and aerosols were set in the range below the Rayleigh limit and in accordance with constraints impoosed by the charging mechanism. Collection radius, collection zone, and related efficiencies, are defined for the case of a single drop, and array of drops. In the case of an array of drops, these parameters are defined with respect to the number of rows that produce the given level of collection. Small, low inertia aerosols can be characterized by a monotonic relation between the collection radius and the number of rows. Larger and higher inertia aerosols exhibit multiple radii of collectiion for the same number of rows. Radius and efficiencies of collection are computed for different spacings of the collecting drops, and at different operating conditions. In this context computed data, of minimum number of rows that are required for complete collection, is displayed. Plots of the simulation program disclose the intricate mechanism whereby aerosol trajectories are progressively filtered out within the array. The results of this work show that collection of charged aerosols. by an array of oppositely charged drops, under the conditions of gravity sedimentation, can be highly efficient.