Predicting NOx emissions from ammonia engines – Fuel and thermal effects

作者：Alexis Cova‐Bonillo, Pedro Gabana, Nikhil Dilip Khedkar, George Brinklow, M. Wu, J.M. Herreros, Soheil Zeraati-Rezaei, A. Tsolakis, Ajith Ambalakatte, Alasdair Cairns, Jonathan Hall · 发表于：International Journal of Hydrogen Energy · 年份：2025 · DOI：10.1016/j.ijhydene.2025.150734 · 被引用次数：9 · 研究领域：Advanced Combustion Engine Technologies、Vehicle emissions and performance、Catalytic Processes in Materials Science

Ammonia, a promising zero-carbon fuel, faces engine application challenges from high NOx and ammonia slip. A key knowledge gap remains in predicting NOx and ammonia slip with chemical kinetic mechanisms within complex engine environments, beyond simple metrics. This research evaluates 14 ammonia combustion mechanisms in a spark-ignition (SI) engine model, using a two-zone thermodynamic approach. Experimental data from stoichiometric pure ammonia combustion in a research engine validate NOx predictions. The analysis details NOx formation, NH 3 slip, NO production rates, and differentiates thermal-NOx from fuel-NOx. While most mechanisms predict NOx within 20 % error, those by Otomo, Stagni, and Nakamura show superior accuracy. Furthermore, a significant divergence in N 2 O predictions was found; only the Konnov mechanism yielded plausible concentrations (14–24 ppm), exposing a common limitation in other models. This study identifies thermal-NOx as ∼75 % of total NOx, offering vital insights for targeted emission control and guiding mechanism selection for engine development. • Thermal-NOx constitutes∼75 % of total NOx from NH 3 stoichiometric combustion. • Otomo, Stagni & Nakamura mechanisms show high predictive accuracy for NOx. • Fourteen kinetic mechanisms were validated with SI engine experimental data. • Konnov mechanism predicts plausible N 2 O emissions.