Quantification of HO2 and other products of dimethyl ether oxidation (H2O2, H2O, and CH2O) in a jet-stirred reactor at elevated temperatures by low-pressure sampling and continuous-wave cavity ring-down spectroscopy

Measuring the formation of HO2 and H2O2 from the oxidation of fuels is challenging but extremely important for determining their tendency to follow chain-termination pathways from R + O-2 compared to chain-branching leading to the production of OH radicals. Furthermore, such data are vital for improving existing detailed chemical kinetics models. Dimethyl ether (DME), a clean renewable fuel, is the simplest ether exhibiting cool flame oxidation chemistry, a key-process for auto-ignition in internal combustion engines. Although the oxidation of DME has been studied in the past, little information is available for the production of HO2 and H2O2. The oxidation of dimethyl ether was performed in a jet-stirred reactor at atmospheric pressure, over a range of temperatures (similar to 540-850 K) and equivalence ratios (phi = 0.5-2) and, for the first time, the concentrations of HO2 and H2O2 were measured using a newly developed experimental setup involving low-pressure sampling and near-infrared cw-cavity ring down spectroscopy. Concentrations of H2O and CH2O were also measured. These new experimental results extend the available kinetic database for the oxidation of dimethyl ether which is needed to assess the validity of combustion kinetics models, as shown here. (C) 2015 Elsevier Ltd. All rights reserved.