Investigating the engine performance, emissions and soot characteristics of CI engine fueled with diesel fuel loaded with graphene oxide-titanium dioxide nanocomposites

Despite progress in the use of electric motors for transportation systems, petro-diesel remains the primary fuel for driving heavy machinery across numerous economic sectors. In this study, the performance, combustion and emissions characteristics, and soot morphology of compression ignition (CI) engine running on diesel fuel, with different nanoparticles were investigated. Three different nanoparticles with a concentration of 50 mg/l were considered. These are graphene oxide (GO), titanium oxide (TiO2) and GO doped with TiO2 (GO-TiO2). The experiments were carried out on a single-cylinder, air-cooled, 4-stroke CI engine at a speed of 2000 rpm, and different engine loads. The soot was sampled from the exhaust line on a fiberglass substrate, using a vacuum pump, and its morphology was observed with a high-resolution transmission electron microscope (HR-TEM). The results showed a 12% average reduction in fuel consumption for diesel/TiO2 fuel compared to neat diesel. Furthermore, the in-cylinder pressures for all the fuel blends, especially at peak load, are greater than that of neat diesel fuel. The GO nanoparticles led to comparable levels of NOx emissions to those of neat diesel, while TiO2 and GO-TiO2 enhanced the formation of NOx. CO emissions were found to increase with the addition of considered nanoparticles. The fringe length and tortuosity were shown to increase for D100 + GO-TiO2 compared to diesel fuel by 11% and 7%, respectively. A sparse fringe pattern was also observed for the D100 + GO-TiO2 agglomerate. This indicates a more reactive soot, due to the presence of oxygen atoms supplied by the nanoparticles during combustion.