The impact of Miller cycle in combination to exhaust gas recirculation and post-injection on controlling diesel engine NO x

To meet the requirements of increasing stringent emission regulations, innovative solutions are adopted to reduce NOx emissions from diesel engines. In this study, the GT-Power software was utilized to investigate NOx control possibility of Miller cycle in combination with exhaust gas recirculation (EGR) and post-injection in a diesel engine. The results indicate early intake valve closing reduced compression work, resulting in a power increase of 0.3 kW. Furthermore, the cooling effect of Miller cycle lowered maximum temperature by 24.5 K and NOx emissions by 17.4%. Miller cycle and EGR combination was able to lower NOx emissions by 83.7%, although it resulted in higher Soot emissions. Adding post-injection help to mitigate this issue, lowering NOx emissions by over 20% and Soot emissions by 5.8%. Finally, the combination of MD75 + 12% EGR +2.5 mg post-injection mass at 34°CA ATDC achieved a 76.1% reduction in NOx emissions with only a 2.6% impact on brake power using modeFRONTIER for multi-objective optimization.