Ignition delay times of diethyl ether measured in a high-pressure shock tube and a rapid compression machine

Ignition delay times of diethyl ether (DEE)/air/argon mixtures were studied in a shock tube in the temperature range from 900 to 1300 K at pressures of 10, 20, and 40 bar and in a rapid compression machine (RCM) at various equivalence ratios between 500 and 1060 K at pressures between 2.5 and 13 bar. Between 2.5 and 5.5 bar, the RCM results show that ignition delay times of DEE exhibit a region (between 590 and 800 K) where ignition delay times are weakly temperature dependent only, while above 833 K and below 590 K, the ignition delay times are strongly temperature dependent. Two-stage ignition was observed in the temperature range from 500 to 665 K in the RCM measurements. At the conditions of the shock tube, a strong pressure and temperature dependence of the ignition delay times was observed, but no non-thermal (NTC) behavior was found in the investigated temperature range. Simulations based on detailed chemistry using the mechanism of Yasunaga et al. (2010) [15] indicate that at high pressures ignition delay times show a high sensitivity towards the two H-atom abstraction reactions by HO2 from diethyl ether. By increasing the rate coefficients of these two reactions relative to the original values by a factor of five, the mechanism well describes our measurements and still well reproduces the original data of Yasunaga et al. (2010) [15].