Abstract
Reduction of Nitrogen Oxide (NOx) and soot emissions is extremely important to enable diesel engines to meet future emission norms. Since Low compression ratio (LCR) has the potential for simultaneous reduction of both these emissions, it is important to explore its advantages for Bharat Stage VI emission norms and beyond. Also, intake air boosting in combination with LCR can give extremely encouraging results. This research work aims at investigating the potential of low compression ratio in combination with intake air boosting to get extremely low engine out NOx and soot emissions. For this purpose, a naturally aspirated (NA) common rail direct injected (CRDI) single cylinder diesel engine was converted from its base compression ratio of 18:1 to a lowered compression ratio of 14:1. Further the same engine was equipped with a mechanically driven supercharger for intake air boosting. The experimental investigations have revealed that reduction of compression ratio in combination with intake air boosting have resulted in more than 30% reduction in NOx emissions and 90% reduction in soot emissions with slight penalty in brake specific fuel consumption (BSFC) especially at high speeds. Further, intake air boosting could enable around 15% increase in engine power and torque by increasing fuel injection quantity while retaining the advantages in reduced NOx and soot emissions. Increase of torque and power could also lead to a significant reduction in BSFC in full load operating conditions.