Experimental study of 2,5-dimethylfuran and 2-methylfuran in a rapid compression machine: Comparison of the ignition delay times and reactivity at low to intermediate temperature

In this work, low to intermediate temperature autoignition behaviors of DMF (2,5-dimethylfuran) were investigated at pressures of 16 and 30 bar, temperatures from 737 to 1143 K, and equivalence ratios of 0.5, 0.75, 1.0, and 2.0 for different fuel concentrations using a rapid compression machine. Ignition delay times of 1% MF (2-methylfuran) stoichiometric mixture was measured at 16 and 30 bar in order to compare its combustion chemistry with DMF. Two mechanisms were employed to predict experimental ignition data. The mechanism of Somers et al. (2013, 2014) shows reasonable agreement with experimental results when some modifications are incorporated. Both experiments and numerical simulations show that the reactivity of DMF and MF is similar in the low to intermediate temperature range. However, the ignition delay time of MF is slightly more sensitive to temperature, compared to DMF, and a crossover temperature T_c2 was observed, below which DMF preserves a slightly higher reactivity. Kinetic analysis by examining the reaction flux and the sensitivity coefficients at temperatures close to T_c2 were conducted to interpret the dominant reaction kinetics of the ignition delay times of DMF and MF. Finally, comparisons between the ignition delay times of DMF and PRF (primary reference fuel) components (iso-octane, toluene, and n-heptane) was also conducted due to the interests of its practical applications, based on PRF ignition data in literature.