Effect of secondary flows and turbulence on electrostatic precipitator efficiency

Experiments on a negative corona wire-plate precipitator have shown that there exist axial rolls of secondary flow superposed an essentially uniform bulk flow. The effect of such rolls on efficiency is studied by an idealized model of a duct precipitator. The model employs approximate velocity distributions of rolls, a constant turbulent diffusivity of particles, and a uniform particle drift velocity due to the electrical field. Results show that increasing roll strength decreases the efficiency, which can take values less than the Deutsch limit for weak diffusion. For zero diffusion, rolls above a certain strength limit the maximum efficiency to values less than unity, hence lead to net leakage for any precipitator length.