Combustion Enhancement of Bergamot Peel Oil–Diesel Blends Using 2-Ethylhexyl Nitrate as a Cetane Improver in a CRDI Diesel Engine

The continued dependence on petroleum-derived diesel in compression ignition (CI) engines presents a persistent challenge for energy security and environmental sustainability. Diesel engines remain the backbone of heavy transport and many industrial applications due to their high thermal efficiency and durability, yet the need to meet stringent emission standards (e.g., BS-VI/Euro-VI) and reduce greenhouse-gas and particulate emissions has intensified the search for renewable fuel alternatives (Kaur et al., 2026). Plant- and fruit-derived oils recovered from waste streams have attracted attention as partial diesel substitutes because their intrinsic oxygenation, volatility, and biodegradability can improve combustion quality and reduce soot and unburned hydrocarbon emissions (Han et al., 2025). Studies across different low-viscosity bio-oils reveal consistent trends: improved atomization and reductions in smoke, CO and HC are often achievable at moderate blend ratios, albeit with trade-offs in ignition quality that must be addressed for safe, wide-scale adoption (Ashok et al., 2018).