Comparative evaluation of graphene oxide and graphene nanoplatelets as fuel additives on the combustion and emission characteristics of a diesel engine fuelled with diesel and biodiesel blend

Graphene is known for its superior physical properties and widespread engineering application. The present work investigates the effect of graphene-based nanoparticles, namely graphene oxide (GO) and graphene nanoplatelets (GNP), as fuel additives on the combustion and emission characteristics of a turbocharged diesel engine. This study utilized fossil diesel, karanja and waste cooking biodiesel. The nano additives were amalgamated with diesel and biodiesel blends (B20) at proportions of 20, 40, and 60 ppm. Thermo-chemical and particle characterization of the nano additives were tested using thermal gravimetric analysis, Fourier-transform infrared spectroscopy and scanning electron microscope, respectively. The filtration and injector wear characteristics of the nano additive fuel blends were evaluated by filter blocking tendency tester and high-frequency reciprocating rig. A maximum smoke reduction of 29.2% is observed with 40 ppm of GO and 60 ppm of GNP has yielded 26.4% reduction in nitric oxide emission. Among the tested additives, GO shown a lower sooting tendency, whereas GNP has exhibited better emission reduction with respect to NO, CO, and HC. It is concluded that both GO and GNP are attractive fuel additives for better emission control without any consequences on the filterability and injector wear.