Shock tube experiments and numerical study on ignition delay times of ammonia/oxymethylene ether-2 (OME2) mixtures

Recently, ammonia (NH3) becomes an attractive alternative fuel to reduce CO2 emissions. The combustion of NH3 mixed with reactive fuels is a feasible solution to the issue of low reactivity. In the present study, the ignition delay times (IDTs) of NH3/OME2 were measured in a shock tube at an equivalence ratio of 0.5, two pressures of 1.75 and 10 bar, and a temperature range of 1245-1797 K with OME2 mole fractions of 0.05, 0.1, and 0.2. The OME2-NH3 model was proposed including the OME2 model updated in this work, the NH3 model optimized in our previous work, and some cross-reactions between nitrogen-containing species and C1-C4 species. The OME2-NH3 model well predicts the IDTs and species profiles of NH3/OME2 and IDTs and laminar flame speeds of NH3/OME1, as well as the IDTs, laminar flame speeds, and species profiles of OME1 and OME2. The crossreactions considered in this work significantly improve the model prediction. The effects of cross-reactions on the high and low-temperature reactivity of NH3/OME2 were analyzed in detail. The comparison between the OME2-NH3 model and the Li-Shrestha model illustrated that the OME2 model updated in this work significantly improves the model prediction. This research provides archival experimental data for the NH3/OME2 ignition and provides insights into the interactions between OME2 and NH3 by the detailed numerical simulations.