Parametric sensitivity analysis of split injection coupled varying methanol induced reactivity strategies on the exergy efficiency enhancement and emission reductions objectives in a biodiesel fuelled CI engine

Highlights: • Simultaneous reduction in NOx and soot emission was observed in RCCI operation. • The exergy efficiency drastically increases with the induction of methanol. • Fluctuations in the combustion cycles increased at higher methanol participation. • The biodiesel RCCI operation demonstrates significant reductions in soot emissions. • The biodiesel RCCI operation exhibited higher exergy efficiency than diesel. The present study endeavours to exploit the benefits of reactivity controlled operation by leveraging significantly higher methanol participation through a decoupled methanol utilization strategy with Madhuca Longifolia biodiesel and conventional diesel as the pilot fuel under varying split injection profiles. The investigation was carried out at 10%, 25% and 50% pilot mass percentage, while the injection timings of pilot and main injection were varied in between −35 and −55 and −5 to −15 aTDC respectively. The results showed that the higher methanol participations caused longer ignition delays which lead to the shifting of the CA50 rightwards beyond the top dead centre. Reduction in maximum pressure rise rate was also evident in the RCCI regime. Compared to the baseline operation of single injection, the methanol/biodiesel RCCI operation under split injection strategy observed a maximum of 86% enhancement in exergy efficiency along with the maximum reductions in NOx and Soot emissions as 86% and 96% respectively. Furthermore, the analysis of Pareto solutions revealed that the methanol/biodiesel RCCI operation yielded 2.8% higher exergy efficiency along with 94% lower emissions of soot compared to its diesel counterpart, while the methanol/diesel operations exhibited 35% lower NOx emissions compared to the equivalent biodiesel RCCI operation.