Low temperature oscillations of DME combustion in a jet-stirred reactor

The low temperature oxidation behavior of DME in a jet-stirred reactor is investigated. There have been numerous investigations on the low temperature reaction kinetics of DME. In this work, the focus is set on the instabilities that arise at very low temperatures (in the order of 580 K) in a jet-stirred reactor and a numerical analysis of the source of these oscillations is performed. A stability diagram was created where the parameters at which the oscillations were observed are displayed. The temperature oscillations at higher temperatures (around 1000 K) have been shown to be caused by ignition-extinction phenomena, whereas the oscillations observed at low temperatures are believed to be of thermokinetical origin, with the build-up of a semi-stable species (hydroperoxide-methylformate HPMF), its dissociation at increasing temperatures with the subsequent formation of large quantities of formaldehyde that increase the temperature giving rise to the first-stage ignition observed and at the same time act as inhibitor to the reaction. The continuous flow through the reactor brings the system back to its original state, and the process begins anew. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.