Stratified injection strategies: Deciphering the emission and combustion synergies of n-butanol/diesel blends in single cylinder engines

• Effect of injection timing and pilot fuel quantity sweep (25 %–75 %) • Advanced combustion phasing with early I.T. and higher PIFP. • Retarded I.T. lowered NO X footprint. • Reduced soot-HC-CO-CO 2 with higher n-butanol, early I.T. and higher PIFP. • Exergy efficiency and BSEC rose with higher PIFP. This study investigates the feasibility of mixed-fuel combustion in a conventional single-cylinder engine utilizing diesel and n-butanol. The primary objective is to identify optimal operational parameters without modifying the engine’s inherent specifications. To achieve this, three distinct fuel injection strategies were evaluated based on the engine’s default diesel calibration under full load, incorporating both single and split injection techniques. The study indicated that the synergistic use of diesel and n-butanol, combined with advanced injection timings and an increased proportion of pilot fuel, enhances both peak pressure and the peak rate of heat release. Split injection techniques notably shortened the ignition delay, culminating in a significant decrement in the oxides of nitrogen emissions — a reduction of 91 % relative to pure diesel combustion and 54 % compared to corresponding single injection event (M23). Fuel strategy of 25 % butanol energy with 75 % pilot mass share exhibited the lowest measure in soot, hydrocarbon, carbon monoxide and carbon dioxide footprint. These emissions observed 52 %, 29 %, 58 % and 34 % respectively reduction with respect to corresponding M23 operation. The lowest measure of brake-specific energy consumption enhanced by 12 %, while the highest measure in exergy efficiency rose marginally by 5 % compared to corresponding M23 strategies. This research underscores the potential of n-butanol as partial diesel substitute and accentuates the merits of split injection for superior combustion control. Given these promising outcomes, we advocate for a more comprehensive study, employing multi-objective optimization techniques, to further explore emission and performance characteristics in gen-set diesel engines.