The nonuniform corona discharge in the wire-plate electrostatic precipitator results in a rotational electric body force which is a source of large-scale secondary flows and turbulence within the flow channel. The electrically induced flow causes large increases in diffusivities detrimental to the particle collection process. Since the electrode geometry and the structure of the corona discharge define the magnitude and character of the electric body force, it is theoretically possible to design a discharge electrode which minimizes electrohydrodynamic flow disturbances. As a first step in this direction, a novel planar electrode design in which electrical discharges are configured to reduce the inhomogeneities of the electric body force is experimentally studied in a negative polarity laboratory electrostatic precipitator. Hot-film anemometer measurements of the electrohydrodynamic turbulent velocity field downstream of the plate electrode are compared to those of a conventional wire-plate precipitator. Results confirm that electrode geometry has a significant role in turbulence production. Although there is some evidence that secondary flows are reduced in the planar geometry, spectral analysis of the flow downstream of the electrodes indicate that the barbed plate design increases turbulence intensity as much as 50% without reducing eddy size. Continued experimentation is necessary to fully assess the possible benefits of such a design.
Bibliographical noteFunding Information:
The support of the 3.S. Environmental Protection Agency through Grant No. R-813645-01-0 is gratefully acknowledged.