Comparisons of the Emissions of Ethanol/Diesel and n-Pentanol/Diesel Fuel Blends: Engine Test and Kinetic Modeling Study

A comparative study of the effects of ethanol/diesel (DE) and n-pentanol/diesel (DP) blends on the engine performance and emission in a direct-injection diesel engine was carried out. The results show that brake specific fuel consumption increases with increasing alcohol fraction for both DE and DP fuel blends. Nevertheless, DE and DP fuel additions show no significant influence on brake thermal efficiency. Besides, ethanol and/or n-pentanol slightly increase the brake specific gaseous pollutant emissions such as the brake specific total unburned hydrocarbon (BSHC), carbon monoxide (BSCO), and nitrogen oxides (BSNOx), while dramatically reduce particulate emissions. The DE and DP blends show approximately the same level of BSCO and BSHC emissions, while DP blends result in slightly higher BSNOx and particulate emissions. A detailed kinetic model was proposed to calculate the soot formation precursors such as benzene and pyrene. The modeling results show that the length of carbon chain has only slight effect on soot reduction under relatively low oxygen mass content, while ethanol/diesel blend exhibits lower soot formation under high oxygen concentration.