Synthesis of graphene oxide nanoparticles and the influences of their usage as fuel additives on CI engine behaviors

Highlights: • Synthesis of graphene oxide nanoparticles and examination by SEM, FTIR, TGA, and XRD. • Improvement of poor properties of waste cooking oil-diesel fuel with GO nanoparticles. • Simultaneous reduction in HC, CO and NOx with the doping of GO nanoparticles into fuel types. • Improved the worsened engine performance outputs arising from waste cooking oil biodiesel. • Shorter ignition delay due to the improved cetane number and accelerating chemical reactions with GO nanoparticles. The present paper aims to investigate the synthesis of graphene oxide (GO) nanoparticles, and the comprehensive investigation of their use along with the waste cooking oil methyl ester (WCO) and diesel fuel blend on combustion, injection, performance, and emission characteristics of a diesel engine under varying engine loads from 3 to 12 Nm with the gaps of 3 Nm at a fixed speed of 2400 rpm. The test fuels named B0 (completely neat diesel fuel), B15 (85% diesel and 15% WCO), B15 + 100 ppm GO (B15 and 100 ppm GO), B15 + 500 ppm GO (B15 and 500 ppm GO), B15 + 1000 ppm GO (B15 and 1000 ppm GO). In the results, it is noticed that blending of biodiesel into conventional diesel fuel drops the brake thermal efficiency (BTE) by 2.67%, CO by 7.5%, HC emissions by 8.53%, and increases the brake specific fuel consumption (BSFC) by 5.54%, and NOx emissions by 3.37% compared to those of reference-fuel B0. However, nanoparticle-added test fuels exhibit a respectable enhancement in all performance and emission characteristics. With the addition of GO nanoparticles, BTE increases by 7.90%, and BSFC drops by 9.72% due to the improved energy content of test fuels. On the other hand, NOx is pulled back by 15.17% due to both superior surface to volume area ratio and thermal properties of GO nanoparticles. Moreover, GO nanoparticles act as the oxygen buffer, and catalyst the chemical reactions until the combustion process. Accordingly, GO ensures more complete combustion, and therefore reduces CO emission by 22.5% and HC emission by 30.23%. In the conclusion, the present paper declares that GO nanoparticles can give a satisfying solution to improve the worsened characteristics arising from biodiesel and diesel binary blends in CI engines.