Influence of Dielectric Barrier Discharge Power on the Removal of CH4 and NO From Exhaust Emissions of LNG Engines

This study aims to explore the use of Dielectric Barrier Discharge (DBD) technology for the joint treatment of methane (CH4) and nitrogen oxide (NO) in the exhaust of Liquid Natural Gas (LNG) engines during cold starts and at mid to low loads when the exhaust temperature is below 500 degrees C. Through experiment and numerical simulation, the effect of discharge power on the removal efficiency of CH4 and NO in the exhaust of LNG engines was investigated under the condition of simulated flue gas temperature at 438 degrees C. A plasma chemical model suitable for analyzing the mixture of N-2/O-2/H2O/CH4/NO in the exhaust gases of LNG engines was constructed and validated. The study found that the conversion efficiency of CH4 and NO exhibits different trends with the increase of discharge power, and CH4 tends to be oxidized to CO under plasma conditions. Key reaction pathways for the DBD treatment of CH4, NO, CO, and NO2 were identified, and an important chemical reaction pathway with the potential for the joint treatment of CH4 and NO was found: CH3O2 + NO -> CH3O + NO2. Additionally, the crucial pathways for the stable conversion of NO to NO2 were identified: O + NO + N-2 -> NO2 + N-2 and NO + O-3 -> NO2 + O-2, providing forward-looking theoretical guidance for subsequent research on plasma-facilitated selective catalytic reduction of NOx by CH4.