Attempt and Mechanism of Ultra Low Emission and High Performance Diesel Combustion with Highly Oxygenated Fuel

Significant improvements in exhaust gas emissions and engine performance in an ordinary DI diesel engine were realized with highly oxygenated fuels. The smoke sharply and linearly decreased with increases in oxygen content regardless of the kinds of oxygenates to reach zero at an oxygen content of 38wt-% even at a stoichiometric condition. Diethylene glycol dimethyl ether(DGM) was used as a base oxygenate, and dimethyl carbonate(DMC)or methanol were blended with DGM at a volume ratio of 80:20 for perfectly smoke-free fuels. The NOx, THC, and CO were almost all removed with a three-way catalyst at higher BMEP where the stoichiometric diesel combustion was realized. At lower BMEP with higher excess air the EGR effectively reduced NOx and the three-way catalyst removed almost all THC and CO. The engine output with the highly oxygenated fuels were significantly higher than those of the conventional diesel fuel due to the release from smoke limit.