Effects of Oxygen-Enriched Air on Diesel Engine Exhaust Emissions and Engine Performance

Current results indicate that oxygen-enrichment of engine intake air will reduce most diesel emissions and help meet stricter emission standards. However, there are both advantages and disadvantages with this method of emission control. To overcome the disadvantage of increasing NOx emissions with increasing oxygen, low levels of enrichment (21.5 and 22.5% 02) were used, as well as retardation of injection timing. By using these optimized conditions, NOx levels were kept at the same value as the unenriched-air, while particulates and smoke emissions were reduced by 15 to 30%.