Optimizing the thermophysical properties and combustion performance of biodiesel by graphite and reduced graphene oxide nanoparticle fuel additive

In this study, 50 and 75 ppm reduced graphene oxide and graphite nanoparticle additives were added to cottonseed oil methyl ester which was obtained by the trasterification method. The effects of the related nanoparticle additives on fuel properties such as viscosity, lower heating value, density and cetane num-ber were determined, and their effects on engine performance and exhaust emissions were experimen-tally investigated. The superior properties of reduced graphene oxide such as superior conductivity, high reactivity and large surface area to engine performance and emissions were experimentally investigated and presented the in this paper. The results indicated that, brake thermal efficiency increased in NPs additive added fuels by 6.92 % in CGt-50, 11.89 % in CGt-75, 14.35 % in CGn-50 and 17.97 % in CGn-75 fuels, respectively compared to C0 fuel at full load. Brake specific fuel consumptions decreased by 6.92 %, 11.25 %, 13.36 and 16.28 %, respectively. At 8 Nm load, the cylinder pressures of nanoparticle added fuels increased between 1.91 % and 5.16 % compared to base fuel. It was concluded that the heat release rate increased with the increase of the NPs additive ratio. Between the rate of 2 %-5.09 % reducing were obtained in ID, 0.84 %-5.85 % in CD for CGt-75 and CGn75 fuels according to C0 fuel. Compared to C0 fuel, CO emissions decreased by 9.48 %, 11.85 %, 14.23 % and 14.99 %, consecutively, in CGt-50, CGt-75, CGn-50 and CGn-75 fuels at full load. Thanks to the nanoparticle additive, the thermophysical properties and heat transfer rate of the fuels improved and the fuel mixture was stabilized, leading to an improve-ment of 8.98 %, 11.79 %, 14.04 % and 15.73 % in HC emissions, respectively. The NPs additive increased the cylinder temperature by 10.59 %-17.72 %, which enhanced NOx emissions. It was also observed that smoke emissions were reduced by 8.57 %-18.09 %.(c) 2022 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).