A comprehensive parametric, energy and exergy analysis for oxygenated biofuels based dual-fuel combustion in an automotive light duty diesel engine

Presently methanol based dual fuel reactivity controlled compression ignition (DFRCCI) has more and more attention in fuel and engine research field because of its potential in reducing the engine-out harmful emissions and evading the dependency on fossil fuel resources. However, while using methanol along with diesel in DFRCCI combustion, a substantial increase in incomplete combustion loss was observed at lower loads due to lower fuel stratification, global reactivity and in-cylinder temperature. Hence, to address this limitation, diesel fuel was replaced by a biodiesel, and a detailed experimental study was performed with energy and exergy analysis to show the potential of biodiesel over diesel. In this study, a modified automotive diesel engine was tested under CDC and DFRCCI combustion strategy using Methanol/ Diesel (M/D) and Methanol/Biodiesel (M/BD) fuel combinations at 2100 rpm, 3.4 bar BMEP load condition. The experimental parametric study shows that 60% of methanol energy can be effectively utilised with an advanced direct injection and a moderate level of exhaust gas recirculation. Energy analysis clearly indicated the reason for the improvement in brake thermal efficiency in DFRCCI combustion. Reduced energy loss in the exhaust and coolant, increased brake thermal efficiency was observed in DFRCCI compared to CDC. However, increased incomplete combustion loss was observed in M/D DFRCCI combustion compared to CDC. Whereas, reduced incomplete combustion loss was observed while using biodiesel instead of diesel due to increased fuel stratification caused by the physical properties of biodiesel and in-cylinder temperature. Further, lower exergy destruction was observed in M/BD DFRCCI compared to M/D DFRCCI combustion.