Influence of EGR and oxygen-enriched air on diesel engine NO-Smoke emission and combustion characteristic

► Oxygen-enriched intake air and proper ratio of low-temperature cold EGR were combined to achieve low NO-Smoke emission. ► A combined n-heptane model containing a detailed PAHs mechanism was developed. ► The mechanism explains diameter growth of soot particles effectively suppressed by oxygen-enriched combustion. ► The mechanism coupled with CFD model well predict NO and Smoke emissions.