Performance, emissions, and tribological assessment of spirulina‐based third‐generation biodiesel doped with metal oxide nanoparticles

Abstract Limited studies have examined the combined effects of various metal‐oxide nanoparticles on engine performance, emissions, and tribological behavior when algae biodiesel is used as a fuel. This study investigates the effects of Al 2 O 3 , CeO 2 , and SiO 2 nanoparticles dispersed in SAME20 (20% Spirulina algae methyl ester and 80% diesel) on diesel engine performance, emission, and tribological behavior. Three distinct nanoparticles at two concentrations (50 and 100 mg/L) were doped into the SAME20 blend, and their combustion, emissions, and wear characteristics were examined. The nanoparticle‐doped fuels were prepared using magnetic stirring followed by ultrasonication to ensure stable dispersion. Experiments were conducted on a single‐cylinder, four‐stroke, water‐cooled diesel engine under varying load conditions, while tribological behavior was assessed using a four‐ball tribometer. Results indicated that nanoparticle addition significantly improved engine performance and reduced emissions compared to SAME20. The SAME20 + 100 mg/L Al 2 O 3 blend achieved the highest BTE of 33.6% and the lowest BSFC of 0.214 kg/kWh at full load. Hydrocarbon, carbon monoxide, and smoke emissions were reduced by 19.49%, 26.47%, and 20.56%, respectively, while nitric oxide emissions increased slightly due to higher in‐cylinder combustion temperatures. Tribological evaluation using a four‐ball tribometer under standardized conditions (40 kg load, 1200 rpm, 75°C, 1 h) revealed substantial improvements, with SAME20 + 100 mg/L Al 2 O 3 reducing the coefficient of friction and wear scar diameter by 36.02% and 35.3%, respectively, compared to SAME20, as confirmed by SEM analysis. Overall, SAME20 + 100 mg/L Al 2 O 3 exhibited superior performance across all evaluated parameters.