Soot particle re-entrainment in a corona discharge reactor

Abstract

Among the various types of diesel after-treatment device, the corona discharge reactor may be considered as a powerful tool for trapping submicron particles. But after precipitation on the electrodes occurs, the re-entrainment of particles is severe and often causes low or negative precipitation efficiency. Experiments were performed to investigate the effect of an applied voltage on the re-entrainment of soot particles from the electrodes. A co-annular laminar diffusion flame burner was used as the soot generator. When a highly negative voltage was applied, exfoliation of the deposited soot particles and an increase in concentration of particles smaller than approximately 150 nm were observed. Turbulence induced from the negative tuft corona and sputtering caused particle re-entrainment from the corona wire and from plates as well. Under soot laden combustion gas, a streamer corona often occurred in the wire-cylinder reactor. Because of its transient nature, streamer corona violently increased the concentration of reentrained particles and CO gas.