Development of Ammonia Reaction Kinetic Mechanism under Engine-Relevant Conditions

Reliable reaction kinetic mechanisms are crucial for numerical simulations of engine working processes. This study aimed at the lack of a high-pressure ammonia reaction kinetic mechanism suitable for engine-relevant conditions currently and evaluated the existing ammonia reaction kinetic mechanisms from multiple dimensions. An ammonia reaction kinetic mechanism, consisting of 34 species and 286 reactions, was constructed and subsequently optimized using a genetic algorithm and Powell algorithm to refine the reaction kinetic parameters. The optimized ammonia reaction kinetic mechanism was verified through fundamental combustion characteristic experiments and internal combustion engine tests. The results demonstrated that the optimized mechanism accurately predicted fundamental combustion characteristics, including the ignition delay time, laminar flame speed, and species concentrations. Additionally, the mechanism successfully simulated the compression and power strokes of spark ignition engines. This work provides an accurate reaction mechanism for numerical simulations of ammonia internal combustion engines.