Experimental investigation of Al₂O₃ and CeO₂ nanoparticle additives in diesel-cottonseed biodiesel (CSOME) blends for performance and emission mitigation in a CI engine

Diesel fuel is widely used, but environmental pollution and the limited availability of petroleum have raised concerns, prompting the search for cleaner alternatives. Biodiesel-diesel blends are considered eco-friendly options, and adding nanoparticles such as aluminum oxide (Al₂O₃) and cerium oxide (CeO₂) can further improve engine performance and reduce emissions. This study tested a single-cylinder, direct-injection diesel engine using pure diesel (B0), a 20% cottonseed biodiesel-diesel blend (B20), and B20 with 50 ppm Al₂O₃, 50 ppm CeO₂, and a combination of both nanoparticles. The biodiesel was prepared via transesterification and fuel properties, including density, viscosity, flash points, and calorific value, were measured. Engine tests showed that the combined Al₂O₃ and CeO₂ blend achieved the highest brake power of 3.56 kW at 3600 rpm and a brake torque of 8.6 N·m at 2400 rpm, while the lowest brake-specific fuel consumption of 0.258 kg/kW·h was recorded for this blend, indicating improved fuel efficiency. Emissions were significantly reduced: CO decreased to 6.7%, 11.2%, 9.7%, and 23.2%; CO₂ to 4.6%, 8.1%, 8.8%, and 14.8%; and hydrocarbon emissions to 5.9%, 10.2%, 8.1%, and 18.5% for B20, B20 + Al₂O₃, B20 + CeO₂, and B20 + Al₂O₃ + CeO₂, respectively. Oxygen concentration in the exhaust reached 17.97%, demonstrating more complete combustion. Overall, the B20 blend containing both Al₂O₃ and CeO₂ nanoparticles provided the best engine performance, fuel efficiency, and emission reduction, confirming its potential as a sustainable alternative to conventional diesel fuel.