Synthesis and characterization of carbon nanotubes from engine soot and its application as an additive in Schizochytrium biodiesel fuelled DICI engine

The present work investigated the synthesis of carbon nanotubes from engine soot particles by laser ablation vaporization method. The synthesized carbon nanotubes were characterized structurally by X-ray Diffraction, Scanning Electron Microscopy, Raman Spectroscopy and Thermogravimetry Analysis. Further, the effects of adding carbon nanotubes in to Schizochytrium methyl ester-diesel blended fuel (20% by volume Schizochytrium methyl ester + 80% diesel and 40% by volume Schizochytrium methyl ester + 60% diesel; symbolized by SCME 20 and SCME 40 respectively) were investigated on the performance, combustion and emission characteristics of direct injection diesel engine. The carbon nanotubes were mixed ultrasonically at two concentrations of 25 and 50 ppm in SCME 20 and SCME 40 individually. All blends were investigated under different engine loading conditions and their results reported that by adding carbon nanotubes at 25–50 ppm of SCME 20 increased the brake thermal efficiency by 2.5% and decreased the brake specific fuel consumption by 3.2% when compared to the neat SCME 20 blend. The maximum heat release rate and peak in-cylinder pressure were found increased by 5% and 4%, respectively. More specifically, the engine exhaust emissions such as UHC, CO, NOxand smoke found reduced by 14.28%, 23.07%, 5% and 21.52% respectively, at a concentrations of 50 ppm in SCME20 blends. The result showed that the concentrations of 50 ppm in SCME20 possess the optimum enhancement in the performance and emissions of the DICI engine.