Enhancing performance, efficiency characteristics, combustion characteristics, and emission control in RCCI engines using wild jujube methyl ester–hexanol–diesel ternary blends: Transitioning toward sustainable cleaner energy
Abstract
This study examines the performance, emission, and combustion characteristics of a reactivity-controlled compression ignition (RCCI) engine fueled by wild jujube methyl ester (WJME) and hexanol–diesel mixtures at hexanol proportions of 0, 25, 50, 75, and 100%, in order to identify the synergistic effects of biodiesel and oxygenated alcohol on engine performance, emission characteristics, and combustion dynamics. The results show that brake thermal efficiency increases with load among all blends, reaching a highest value of 34.1% at full load (WJME10HX20D70), indicating more efficient energy conversion. Likewise, brake-specific fuel consumption decreases with load to a minimum of 0.24 kg/kWh for the same blend, indicating better fuel economy. Exhaust gas temperature rises with load and is also higher for hexanol-enriched blends, indicating more complete combustion. Analysis of emissions reveals that the carbon monoxide (CO), unburnt hydrocarbons (HCs), and smoke opacity were reduced significantly with the addition of WJME and hexanol since the oxygen availability and combustion completeness were improved. The lowest CO (0.18%), HC (27 ppm), and smoke opacity (45%) were achieved with blends which had 20% hexanol. But carbon dioxide emissions and oxides of nitrogen (NOx) emissions were elevated because of improved combustion and increased in-cylinder temperatures, reaching the highest NOx levels of 1120 ppm. Combustion analysis shows an increase in the rate of heat release and in-cylinder pressure peaks with hexanol-blended fuels and lower ignition delay, which confirms the enhanced combustion phasing. All in all, blends of 10–20% WJME with 20% hexanol show best performance and emission properties. The research indicates the prospects of WJME–hexanol–diesel mixtures as environmentally safe fuel substitutes to RCCI engines, and potential expansion of NOx reduction measures.