Experimental investigation of the effects of graphene oxide nanoparticle-added diesel fuels on diesel engine performance and emission characteristics

In this study, the effects of graphene nano-additives on combustion, performance, and emission characteristics of a diesel engine were experimentally investigated. Experiments were conducted on a single-cylinder, direct-injection diesel engine using neat diesel fuel and graphene nano-additive blended fuels at different concentrations (25, 50, 75, and 100 ppm). Engine tests were performed under 0.3, 1, 2, and 3 bar brake mean effective pressure (BMEP) conditions. Combustion analysis was carried out by evaluating in-cylinder pressure, net and cumulative heat release rates, and pressure rise rate (dp/dφ). The results indicated that graphene nano-additives improved the combustion process at low and medium additive concentrations. Notably, the 75 ppm graphene addition resulted in significant increases in maximum in-cylinder pressure and heat release characteristics. However, further increases in additive concentration led to diminishing improvements in combustion behavior. Emission analyses included specific fuel consumption, CO, HC, NOx, and smoke opacity measurements. The addition of graphene nano-additives generally reduced specific fuel consumption as well as CO and HC emissions. NOx emissions increase exhibited variations depending on engine load and additive concentration. Smoke opacity results showed a reduction at low and medium load conditions with graphene addition, whereas higher loads and higher additive concentrations caused an increase in smoke formation. Overall, the experimental results demonstrated that a graphene nano-additive concentration of 75 ppm provides the most balanced improvement in combustion performance and emission characteristics of the diesel engine.