Performance and emission evaluation of diesel engine fueled with zinc oxide-dispersed used sunflower oil methyl ester

In the present scenario, the fast depletion of fossil fuels and energy crises motivated the researchers towards finding an alternative sources for energy. In this work, the performance, combustion and emission of hydrothermally synthesized (ZnO) nanoparticles-dispersed used sunflower oil methyl ester in a single-cylinder, four-stroke, direct injection diesel engine with eddy current dynamometer was investigated. The synthesized ZnO nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy to find crystallinity, functional groups, surface morphology and elemental composition. Used sunflower oil methyl ester was produced via conventional one-step alkali catalyst trans-esterification process. Test fuels were prepared with the dispersion of ZnO nanoparticles in the concentration of 10 ppm, 20 ppm and 30 ppm with B20 (20% used sunflower oil methyl ester and 80% diesel) with the aid of magnetic stirrer and ultra-sonication. The test results exposed that the addition of ZnO nanoparticles with B20 gave a better performance in terms of brake thermal efficiency and brake specific fuel consumption compared to B20. The addition of ZnO nanoparticles with 30 ppm concentration was identified as better fuel among all tested fuels. The addition of 30 ppm of ZnO nanoparticles with B20 records 1.78% increases in brake thermal efficiency and 10.34% decreases in brake specific fuel consumption. The emission like CO, HC and smoke was 20%, 15.4% and 17.39% lower than diesel. On the other hand, NOx was slightly higher than diesel but lower than B20.