煤直接液化航空煤油自着火特性实验及动力学研究

Direct coal liquefaction (DCL) aviation kerosene contains a large amount of cycloalkanes, which is significantly different from traditional aviation kerosene. Studying the ignition characteristics and reaction kinetics of DCL kerosene is of great significance for a deeper understanding of its combustion performance and application. Therefore, in this paper, the ignition delay times of DCL kerosene, RP-3, and their mixture at different equivalence ratios and pressures were measured utilizing a rapid compression machine. The combustion heat release and relative reactivity of DCL and RP-3 kerosene were compared, and the kinetic mechanism of the difference in low-temperature reactivity between two kinds of kerosene was analyzed. The chemical kinetic model of DCL kerosene in the literature was validated using the experimental data, and the prediction performance was significantly improved for the ignition delay times and pyrolysis products by developing the sub mechanism of n-pentylcyclohexane, one major component of the surrogate model. This study shows that DCL kerosene releases more heat after ignition, and its ignition delay time is similar to that of RP-3 at high temperatures (>1 000 K), while slightly higher than that of RP-3 at low temperatures (<750 K). The presence of the large amount of cycloalkanes hinders the low-temperature chain branching reactions, inhibiting the low-temperature activity and reducing the tendency of spontaneous ignition before the fuel enters the main combustion zone.