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 OME₂NH₃ 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 C₁C₄ species. The OME₂NH₃ 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 cross-reactions 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 OME₂NH₃ 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.