Influence of adding multiwalled carbon nanotubes to waste cooking oil biodiesel on the performance and emission characteristics of a diesel engine: an experimental investigation

The current experimental work focuses on the influence of adding multiwalled carbon nanotube (MWCNT) with waste cooking oil methyl ester (WCME) on the performance, emission and combustion parameters of compression ignition engine. The MWCNT was scrutinized using TEM and XRD analysis, and then it was blended with waste cooking oil biodiesel fuel at a fraction of 25, 50, and 75 mg/L using ultrasonicator. These blends were tested under different engine loads and a constant speed of 2000 rpm. The experimental outcomes demonstrated that by adding MWCNTs to WCME fuel, the cylinder peak pressure, peak pressure rise rate, and heat release rate were slightly reduced in comparison with pure WCME fuel. The innovated fuel blend significantly decreased NOx, CO, and UHC. Additionally, the brake thermal efficiency was amended remarkably, and the specific fuel consumption was reduced compared with pure WCME fuel. According to the comparisons of engine performance and emissions, the recommended dose level of MWCNTs with WCME fuel was concluded to be 50 mg/l, which gave a substantial improvement in all engine performance characteristics (where NOx was reduced by 40%, CO by 40%, UHC by 50% and bsfc by 18%).