Kinetic study on the effect of DME addition on ignition delay time of n-butane

Ignition delay times of dimethyl ether (DME) and n-butane blends were measured by using shock tube at different dimethyl ether blending ratios, temperatures and pressures. Mechanism validations were made using different chemical kinetic models. A new C5 chemical kinetic model with DME submodel was proposed and it can well predict the experimental ignition delay times of pure n-butane, DME and their blends. Results show that increasing pressure can promote the ignition delay time. Ignition delay time decreases with increasing dimethyl ether blending ratio, and this was interpreted by the analysis of H and OH radical behaviors. Sensitivity analysis and reaction pathway show that, at high temperature, the H-abstraction reactions play a dominant role in the consumption of fuel compared to the unimolecular decomposition reactions. At high temperature, with the increase of DME blending ratio, the branching ratios of H-abstraction on fuel (DME and n-butane) consumption are decreased and those of unimolecular decomposition are increased.