Combustion and Exhaust Emission Characteristics of DME in a Common-rail Diesel Engine

Abstract : An experiment was conducted with a common-rail direct injection diesel engine operated with neat dimethyl ether (DME). In order to investigate the effect of combustion characteristics and emission reduction of DME fuel, the experiment was performed at various injection pressure from 35 MPa to 50MPa. Also, the exhaust emissions from the engine were compared with that of diesel fuel. In this work, Cooled EGR was implemented to reduce NO x exhaust emissions. The results showed that DME has shorter ignition delay than that of diesel fuel. Despite of the increased NO x emissions with DME at an equal engine power compared to the case of fueling diesel, the engine emitted zero soot emissions all over the operating conditions in this work. NO x emission can be decreased greatly by adopting 45% of EGR while maintaining zero soot emission. Judging from the result of engine test, DME is a suitable fuel for common-rail diesel engine due to it's clean emission characteristics. Key words