Theoretical study of methods for improving the energy efficiency of NOx removal from diesel exhaust gases by silent discharge

Abstract

AbstractTo improve the NO removal performance in silent discharge process, we investigated the influence of physical parameters such as current density, channel radius, and pulse duration of one micro‐discharge under a constant reduced electric field strength. The influence of micro‐discharge occurrence locations was also discussed. In order to analyze the NO removal process, we assumed that the pulse micro‐discharges occur repeatedly at the same location in static gas and that the chemical reactions induced by micro‐discharge form many radicals, which react with pollutants and by‐products. The conclusions we obtained are that lower current density, smaller discharge radius, and shorter discharge duration improve NO removal efficiency. These results also mean that the lower discharge energy of one micro‐discharge and the larger number of parallel micro‐discharges increase the NO removal performance. Therefore, making the area of one micro‐discharge small is a desirable way to improve the NO removal performance. Thus, we think that the glow‐like discharge might be more effective than the streamer‐like discharge mode. Next, using the two‐dimensional model, which considered the influence of gas flow, we found that the repeated micro‐discharges at different positions are very effective to increase the De‐NOx performance. The reason is that the reaction of NO2+O→NO+O2 and ozone dissociation reactions are suppressed by the movement of the location of micro discharges. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 1–9, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20556