LOW NOx COMBUSTION OF DME BY EXHAUST GAS RECIRCULATION

This study focuses on the fundamental characteristics of DME combustion aiming at the development of low-NOx combustion technology with exhaust gas recirculation (EGR) under high pressure. DME has high potential of applicability of exhaust gas recirculation even at the high mixing ratio because of its high burning velocity and low ignition temperature. Prior to the high pressure combustion test, the combustion test under an atmospheric pressure was conducted with laboratory-scale 11.6kW combustor, where O-2 concentration and temperature at the combustor inlet was systematically regulated, so that the exhaust-gas recirculation at various mixing ratios was simulated. The maximum EGR ratio is 91% at the initial air ratio lambda=1.5 with preheated diluted air at 700K. The NOx emission reduced to 14ppm, which is about 13% of that at EGR=0%. The stable combustion sustains even at low oxygen concentration by preheating diluted-air. The exhaust gas recirculation is effective means especially for DME in reducing NOx emission drastically.