Survey of cleaner combustion in compression ignition engine fueled with nanoadditive-laded biodiesel

This review explores the role of nanoadditives in improving the performance of biodiesel used in compression ignition (CI) engines. The central idea is that introducing nanoparticles (NPs) into biodiesel can enhance combustion, engine efficiency, and emission control without requiring significant engine modifications. The study focuses on widely used NPs such as Al₂O₃, TiO₂, CeO₂, Fe₃O₄, carbon nanotubes, and graphene oxide, examining their catalytic, thermal, and stabilization effects. Biodiesel blends are typically prepared from non-edible oils, purified, and infused with NPs through ultrasonication, sometimes with surfactants to maintain dispersion stability. Key fuel properties, including viscosity, density, calorific value, and oxidation stability, are assessed before engine testing. The review highlights how NPs improve fuel atomization, oxidation reactions, and heat transfer, leading to better ignition and more efficient combustion. Results from the literature show that nanoadditives enhance brake thermal efficiency, reduce fuel consumption, and significantly lower emissions of carbon monoxide, UHCs, and particulate matter. Oxygen-donating NPs like CeO₂ and TiO₂ promote complete combustion and soot reduction, while carbon-based NPs strengthen blend stability and atomization quality. The novelty of this review lies in its systematic analysis of the mechanisms, physicochemical improvements, and performance outcomes of nanoadditives in biodiesel. It also identifies key research gaps, including optimal NP dosage, long-term durability, and large-scale engine validation, offering valuable direction for sustainable CI engine development. • Nano-additives like Al₂O₃, CeO₂, TiO₂, and GO significantly boost biodiesel engine performance and reduce harmful emissions. • Hybrid nano-additives such as Fe₂O₃–Al₂O₃, GO–CuO and RGONP show strong synergistic effects, improving combustion and fuel efficiency. • Hybrid nano-additives help overcome common biodiesel drawbacks like higher NOₓ emissions and lower thermal efficiency, making biodiesel more viable for CI engines. • This review emphasizes need for lifecycle, cost and interaction studies to fully harness nano-enhanced biodiesel for cleaner diesel engines.