Investigation on emission characteristics of a compression ignition enginewith oxygenated fuels and exhaust gas recirculation

Investigations of emission characteristics were carried out on a compressio n ignition, dimethyl ether engine (DME) with exhaust gas recirculation (EGR ) and on a diesel engine with a dimethyl carbonate (DMC) additive. The expe rimental results show that the DME engine with EGR can simultaneously reduc e smoke and NOx emissions. The NOx can be reduced by about 20 per cent for every 10 per cent of EGR introduction, while smoke remains at zero. The die sel equivalent brake specific fuel consumption (b.s.f.c.) shows a slight de crease when DMC is added, while the effective thermal efficiency shows a sl ight improvement. It is found that the smoke reduction rate and smoke show a linear relationship with DMC percentage or oxygen mass percentage in the diesel fuel. For the specific brake mean effective pressure (b.m.e.p.), smo ke will be reduced by 20 per cent for every 10 per cent DMC added and by 40 per cent when the oxygen mass percentage in the fuel reaches 10 per cent. The CO decreases when DMC is added, while NO, shows an increase. This diffe rence is pronounced at a high b.m.e.p. For the specific b.m.e.p., CO and NO , show a linear relationship with DMC mass percentage in the fuel; CO will be reduced by 20 per cent while NO, will be increased by 20 per cent for ev ery 10 per cent DMC added.