Autoignition Delay Time Measurements for Mixing Controlled Compression Ignition Conditions of Dimethyl Ether and Propane Lean Mixtures

Fuel blends of dimethyl ether (DME, CH3OCH3) and propane (C3H8) have the potential to substitute for diesel fuel in compression-ignition engines. There is a large incentive to phase out the use of diesel fuel because of its harmful combustion byproducts, including CO2, NOx, SOx, and particulate matter. Propane and DME blends have been proposed as cleaner burning fuels and produce significantly less CO2 than diesel, but these fuel blends need to be characterized at engine-relevant conditions before they can be implemented. To develop accurate chemical kinetic models, the combustion of propane and DME blends needs to be studied at a wide range of pressures, temperatures, and lean-to-rich equivalence ratios. In this work, IDT measurements of DME/ Propane blends were measured using a shock tube at 60-80 bar and 700-1100 K at an equivalence ratio of Phi = 0.5. IDTs under these conditions are not yet available in the literature. Experimental IDTs were compared with simulated values using state-of-the-art chemical kinetic mechanisms. The simulations overpredicted the IDTs at all conditions, with the most significant deviations in the negative temperature coefficient region. A sensitivity analysis was conducted to identify reactions contributing to this discrepancy, and reactions were updated to better predict this behavior.