Comparing TiO <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e219" altimg="si1.svg"> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> and CuO nanoparticles as additives to impro

This study evaluates the effects of TiO 2 and CuO nanoparticles as additives to a 15% n-butanol-diesel blend (BuD) on the performance and emissions of a four-stroke diesel engine. Tests at varying torque loads revealed that while n-butanol blending alone increased fuel consumption and energy use compared to pure diesel, the addition of 50 ppm TiO 2 or CuO nanoparticles significantly mitigated these drawbacks, enhancing fuel efficiency and ignition quality. Key emission pollutants—CO, HC, and particulate matter—were notably reduced with nanoparticles, attributed to their catalytic and oxygen-supplying roles promoting more complete combustion. However, NOx emissions increased with n-butanol and nanoparticle use, highlighting a trade-off that needs further mitigation strategies. This work uniquely compares TiO 2 and CuO nanoparticles under identical conditions, providing new insights into their differential catalytic effects on butanol-diesel combustion and emissions. The findings support TiO 2 and CuO as cost-effective additives to optimize biofuel blends for cleaner and more efficient engine operation. • TiO 2 & CuO NPs improve n-butanol-diesel blend (BuD) engine efficiency. • NPs reduce BSFC increase from butanol, enhancing fuel consumption. • At 2 N.m, BuDTi & BuDCu reduce BSFC by 17% and 13% vs BuD. • Metal oxides’ high surface area boosts BuD fuel’s calorific value. • Study shows NPs optimize BuD for performance and lower emissions.