Extinction limits and flame structures of ETBE, DIPE and TAME non-premixed flames

In this study, extinction limits measurements for Ethyl tert-butyl ether (ETBE), Diisopropyl ether (DIPE) and tert-Amyl methyl ether (TAME) non-premixed flames were carried out by using a counterflow burner. Studies were carried out by supplying a fuel diluted with nitrogen from one duct and an oxidizer stream made up of oxygen and nitrogen from the other duct. Flame structures were also measured. Concentrations of sta-ble species were measured by removing gas samples from the reaction zone by using a quartz microprobe and by analyzing them in a gas chromatograph. Temperature profiles were measured by using a thermocouple. Numerical calculations were performed under the same conditions with experiments to validate chemical kinetics and clarify the peculiarity of ether flames. Experimental results for ETBE, DIPE and TAME flames showed almost the same strain rate at extinction, a 2, E, at same stoichiometric mixture fraction, Z st, and an equilibrium temperature. Comparisons among ether flames having a different carbon number showed that the larger the number of carbon atoms is, the smaller the extinction limit is. a 2, E for ether flames decrease once with an increase of Z st at low Z st conditions. After that, they start to increase. Z st expressing the min-imum value of a 2, E becomes smaller with an increase of carbon atom number. The measured profiles of the temperature and major species showed a similar structure for each fuel. Calculated profiles agreed well with experimental data except for minor species. The reproducibility of chemical kinetic computations and variations in extinction limits with Z st were discussed. (C) 2016 by The Combustion Institute. Published by Elsevier Inc.