Durability impact of graphene-enhanced Honge biodiesel on CI engine components

The present study investigates the durability and performance of a single-cylinder, water-cooled, direct injection CI engine operated for 250 h at full load using a B20 Pongamia biodiesel blend with 40 ppm graphene nanoparticles (BD-G), compared to diesel. Performance analysis showed BD-G achieved 10.8% higher brake thermal efficiency (BTE) than biodiesel and only 0.19% lower than diesel. Brake specific fuel consumption (BSFC) decreased by 25.7% compared to biodiesel and 5% compared to diesel. Emission results indicated that BD-G reduced NOx by 18% relative to biodiesel but remained 6.7% higher than diesel. CO, HC, and smoke opacity were reduced by 21%, 7.1%, and 11.5% compared to biodiesel, while higher CO2 confirmed more complete combustion due to enhanced fuel utilization from graphene nanoparticles. Durability assessment through SEM revealed greater wear in BD-G-fueled engines, with piston rings showing progressive wear from Top 1 to the oil ring and valves exhibiting erosion due to biodiesel’s moisture content. Fuel pipes also suffered increased degradation. Lubricating oil analysis revealed elevated concentrations of Fe (21.8%), Cu (34.4%), and Cr (47.9%) compared to diesel, attributed to biodiesel’s higher viscosity and density, which cause fuel dilution. Overall, BD-G improves efficiency and emissions but poses durability concerns in extended operation.