Collection of Particulate Matters in Exhaust Gas Using the Attractive Force Induced by Surface Charging

A novel electrostatic precipitator was developed for collecting and decomposing soot in exhaust gas from combustion devices, including diesel engines. In the precipitator, the dielectric surface works as a collection electrode.As one of the key processes in this technique is charging the dielectric surface, the surface potential distributions were first investigated using glass plates as the dielectric surfaces with a positively biased ac voltage applied to discharge electrodes placed on the glass plate. Results showed that positive ions created by the breakdown of air charged the surface, and the associated intermittent voltage was sufficient for building the surface potential. The area of PM adhesion was then investigated experimentally using real exhaust gas and numerically by simulating the trajectories of the charged particles. The results showed that the uneven surface potential was the essential factor involved in the collection of particles and that the unevenness was due to the intermittent voltage applied to the glass surface. Creating and utilizing the potential unevenness along the dielectric surface for particle collection made this system unique among ESPs (electrostatic precipitator) that have been researched.