NO _X abatement from filtered diesel engine exhaust using battery‐powered high‐voltage pulse power supply

Abstract

The dielectric barrier discharge-based non-thermal plasma technique is one of the most prominent techniques which give peerless results in controlling the concentration of NO X. However, when it comes to the automobile diesel engine, availability of high-voltage pulse power supply is the major constraint. In this study, battery-powered high-voltage pulse power supply for NO X treatment has been proposed. Two types of electrodes: rod type and rod with helical spring type are studied for the treatment of exhaust. Cascaded plasma-adsorbent technique has also been used to enhance NO X removal efficiency. Experiments have been conducted with two different gas flow rates, i.e. 4 l and 6 l/min at laboratory level and have got significant results toward removal of NO X. When the exhaust has been treated with plasma alone, the reactor with rod-type electrode has shown 85% NO X removal efficiency at a specific energy (SE) of 283 J/l with a flow rate of 4 l/min. When the plasma reactor is cascaded with the adsorbent reactor, both adsorbents: 13x molecular sieve (MS13x) and activated alumina are able to remove 100% of NO X with the proposed power supply at a lesser SE.

Impact of High-Voltage Discharge After-Treatment Technology on Diesel Engine Particulate Matter Composition and Gaseous Emissions

“…According to the results in Figure 6 at a fixed exhaust gas flow rate, increasing the input power of HVPS and the reactor's effective length demonstrated an overall increase of DeNO, DeNOx, and NO 2 formation as the result of a higher specific energy density (SED) from 200 to 400 J/L, and a substantial increase in the exhaust gas residence time within the reactor. 7,33,37 Overall, the change of input power from 10 to 20 W (or increased SED) demonstrated a more significant effect on NO 2 formation than the change of the reactor's effective length due to the increase of the highvoltage discharge pulse repetition rate (frequency) promoting the collision of the electrons, and therefore produced a greater concentration of O 3. 17 In addition, increasing the reactor's effective length improved O 3 production by enhancing the contact time between the O 2 -rich exhaust gas and corona discharge.…”

“…The proposed mechanisms of soot reduction by O, OH, O 3 , and NO 2 18,20 through R21 to R29 are shown in the Appendix. Recently, direct DBD-NTP research on diesel exhaust gas treatment has gained momentum due mainly to its effectiveness in generating O 3 from O 2 (R1 and R2 in the Appendix) and NO 2 from NO (R11 to R15 in the Appendix) in diesel exhaust gas for DPF regeneration, 23 NOx/PM reduction in the combination of catalysts, 12,14,24 and/or NOx absorbents 3,7,25 at low temperature.…”

“…The preceding works on NOx−HC−PM reduction using NTP mostly investigated using simulated gas, 5,24,34−36 filtered diesel exhaust gas, 4,[7][8][9]37 or diluted diesel exhaust gas. 15,17,26,29 Few studies have investigated the simultaneous effect of HVD on both gaseous and PM emissions from raw diesel exhaust gas that contains PM and water vapor and can affect the formation of free radicals.…”

“…HVD has been investigated and proved to improve diesel exhaust emissions for gaseous (e.g., NOx, − CO, and THCs) and PM emissions. − Fundamentally, HVD operates using a high potential applied to electrodes between which exhaust gas can flow. Exhaust gas molecules are ionized when present near electrodes and release visible light emission, which is referred to as plasma or known as the fourth state of matter .…”

Response surface methodology-based model for prediction of NO and NO2 concentrations in nonthermal plasma-treated diesel exhaust

“…The possible chemical reactions those can take place in the reactor were given in a study by Saavedra et al [24] with their rate constants. Major reaction pathways have been mentioned in a previous study of the authors [25]. The operating parameters have been varied in such a way to cover all the possible combinations with all the considered levels of each parameter, and corresponding (NO + NO 2 ) concentrations are noted down.…”