Migration Velocity and Electric Wind

To estimate the particle migration velocity, it is assumed that (1) particles are spherical and have the same size (2) all particles are charged to the same extent (3) the particle motion is governed by the Coulomb force and the Stokes drag only and (4) the direction of the applied electric field is perpendicular to the direction of the suspension flow. 

The equation for the particle motion in the direction of the electric field is given by dC/D 

Define the migration velocity Um as the terminal velocity of particles in the electric field. From Eq. (7.34), we have qE 

It can be shown that for fine particles (dp 10 (tm) in an electrostatic precipitator the migration velocity of the particle is usually much higher than the corresponding particle terminal velocity in the gravitational field. For this reason, fine particles are commonly separated by electrostatic precipitation. 

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