Experimental and numerical low-temperature oxidation study of ethanol and dimethyl ether

Low-temperature combustion (LTC) receives increasing attention because of its potential to reduce NO x and soot emissions. For the application of this strategy in practical systems such as internal combustion engines and gas turbines, the fundamental chemical reactions involved must be understood in detail. To this end, reliable experimental data are needed including quantitative speciation to assist further development of reaction mechanisms and their reduction for practical applications. The present study focuses on the investigation of low-temperature oxidation of ethanol and dimethyl ether (DME) under identical conditions in an atmospheric-pressure laminar flow reactor. The gas composition was analyzed by time-of-flight (TOF) mass spectrometry. This technique allows detection of all species simultaneously within the investigated temperature regime. Three different equivalence ratios of ϕ = 0.8, 1.0, and 1.2 were studied in a wide, highly-resolved temperature range from 400 to 1200 K, and quantitative species mole fraction profiles have been determined. The experiments were accompanied by numerical simulations. Their results clearly show the expected different low-temperature oxidation behavior of both fuels, with a distinct negative temperature coefficient (NTC) region only observable for DME. With detailed species information including intermediates, differences of the kinetics for both fuels are discussed. Small modifications of the mechanisms served to identify sensitivities in the model. The experimental results may assist in the improvement of kinetic schemes and their reduction.