Time History of Hydrocarbon Fuels and Aromatics in Diesel Combustion

Abstract

Chemical behaviors of diesel fuel and the effects of aromatic on diesel combustion were experimentally investigated using a rapid compression machine and a total gas-sampling device. Aromatic component was varied independently as fuel property while keeping the cetane number and sulfur content. The authors analyzed the composition of the individual hydrocarbons (C_1 to C_<20>), NO_x and inorganic gases. The results show that the concentration of heavy hydrocarbons rapidly decreases during ignition delay period due to thermal cracking into middle and low boiling-point hydrocarbons. However, the fuel including aromatic is decomposed with difficulty because of the lower decomposition rate of not only aromatic component but also other heavy saturate hydrocarbons, which causes the high concentration of middle boiling-point hydrocarbons at diffusion combustion period and late oxidation. NO_x concentration also proceeds later at the end of combustion and reaches higher level than in aliphatic hydrocarbon fuel.