The Influence of Saw Tooth-Shaped Electrode Form on NO_x Treatment by Trenched Type Discharge Reactor

Recently, air pollution has become a serious problem; acid rain, photochemical smog and the ozone hall are typical phenomena. NOx is one of the air pollution substances and toxic gases. Thus, a decrease in the amount of exhausted NOx is desired, since the density of NOx in the atmosphere is remaining at a stable level or even worse. We have been particularly interested in the removal of NOx in exhaust gas from a vehicle diesel engine by a discharge plasma method in which we proposed superimposing discharge methods. In this study, we use trenched type discharge reactor for NOx removal. This reactor has saw tooth-shaped electrode and plate electrode with dielectric barrier. We expect that surface and silent discharges are generated simultaneously in the same space of reactor. The results show the following: (1) NOx removal rate for the saw tooth-shaped electrode is much higher compared with parallel plate electrode at the same residence time and same discharge power. (2) NOx removal rate increases with decreasing gap length between the saw tooth-shaped electrode and the dielectric barrier, in case of non-gap, surface and silent discharges were observed simultaneously in the same space of reactor. (3) NOx removal rate increases with decreasing depth of groove of the saw tooth-shaped electrode.