Shock tube and comprehensive kinetic modeling study of ammonia/diethyl ether (DEE) mixtures

Abstract

Ammonia (NH₃) is a promising alternative clean fuel due to its carbon-free and high hydrogen content, along with the well-established infrastructure for storage and distribution. To overcome the issue of the low reactivity of NH₃, a feasible strategy is co-burning ammonia with highly reactive fuels. Diethyl ether (DEE) is considered a promising alternative and biomass-oxygenated clean diesel substitute. Therefore, the NH₃/DEE blend is also a promising carbon neutral alternative fuel. In this work, we measured the ignition delay times (IDTs) of NH₃/DEE mixtures with DEE fractions (X_DEE) of 0.05, 0.10, 0.30, and 1.00 at equivalence ratios of 0.5, 1.0, and 2.0, pressures of 1.75 and 10 bar, and temperature ranges from 1102 K to 1673 K in a shock tube. The DEE-NH₃ model was proposed in this work, which included the DEE sub-model, NH₃ sub-model, and some new cross-reactions between N-containing species and C-containing species. The DEE sub-model from Shrestha et al. (Fuel Communications, 2022) was modified in this work, NH₃ sub-model was from our previous work (Reaction Chemistry & Engineering, 2023). The DEE-NH₃ model was extensively validated by the IDTs, laminar flame speeds (LFSs), and species profiles (SPs) of NH₃/DEE mixtures as well as pure DEE and NH₃. The comparison of the prediction performance between the DEE-NH₃ model and the Shrestha model was conducted for the ignition, flame propagation, and NH₃ consumption. The effects of the cross-reactions on the NH₃/DEE ignition and combustion were studied in detail.