Impact of graphene oxide nanoparticles on performance, combustion, emissions, and tribological characteristics of...

The growing demand for sustainable energy and stricter emission regulations have accelerated research into renewable biodiesels for compression ignition engines. Algae-derived biodiesel is promising but exhibits lower combustion efficiency and higher emissions compared to diesel. This study investigates the influence of graphene oxide (GO) nanoparticles on the performance, combustion, emission, and tribological characteristics of Spirogyra algae methyl ester (SAME20). GO nanoparticles were characterized using FTIR, XRD, SEM, and EDX analyses. Five fuel blends were prepared and tested in a single-cylinder, four-stroke, direct-injection diesel engine. At full load, SAME20 + 90 ppm GO increased the HRR and peak cylinder pressure by 10.5% and 2.4%, respectively, due to enhanced oxidation and premixed combustion. In terms of engine performance, BTE improved by 8.5%, and BSFC decreased by 7.5%. CO, HC, and smoke emissions decreased by 18.4%, 7.7%, and 10.9%, respectively, while NO_x increased by 5.1% due to higher combustion temperature and oxygen availability. Tribological tests were conducted at 1200 rpm, 75 °C, and 40 kg load for 1 h, showing that SAME20 + 90 ppm GO reduced COF and WSD by 18.6% and 16.2%, respectively, compared to SAME20. SEM images of SAME20 + 90 ppm GO confirm smoother worn surfaces, attributed to the catalytic activity and high surface area of the nanoparticles.