Effect of electrode shape in dielectric barrier discharge plasma reactor for NOx removal

An experimental study on nitrogen oxides (NOx) removal from a simulated diesel engine exhaust gas was carried out in geometry of various electrodes for dielectric barrier discharge reactor to improve the removal efficiency. The electrodes employed in the experiment were a plane, a trench, and a multipoint geometry. The right-pyramids, which were used as multipoint, had 45° tip angle and a height of 1-5 mm. The multipoint electrodes have 528-5000 pyramids in an area of 132 cm² (22 × 6 cm). The trench electrode has knife-edge rails with 5-mm height and 45° tip angle. The alumina dielectric barrier coated plane electrode was used as a high-voltage electrode, to which a sinusoidal high voltage was applied with frequency of several tens kilohertz. The N₂:O₂=9:1 mixed gas containing 200-ppm NO was used as simulated gas with gas flow rate of 5 L/min. NO removals in case of the plane and the trench electrodes were lower than that in case of multipoint one. NO removal yield drastically decreases with increasing the number of pyramids on the electrode. NO removal efficiency was almost independent of the pyramid projection height under our experimental condition.