Inhibition mechanism of CHF3 on hydrogen–oxygen combustion: Insights from reactive force field molecular dynamics simulations

Abstract

To mitigate the risks linked to hydrogen and oxygen (H₂–O₂) combustion through CHF₃ additives, Reactive Force Field Molecular Dynamics (ReaxFF MD) simulations are performed in this study. The primary objective is to investigate the inhibition mechanism of CHF₃ on H₂–O₂ combustion from 2000 K to 2800 K. The simulation results demonstrate that the reaction pathways of hydrogen combustion are changed under the extended second explosion limit, and the main radicals involved in elementary reactions transform from H, OH, and O to H, OH, and HO₂. CHF₃ predominantly engages in reactions with H radicals to impede the continuation of chain reactions by forming stable HF molecules. OH radicals react with modest amounts of secondary fluorides such as CHF₂OH, CH₂F, and so on, while HO₂ radicals are combined with even fewer intermediates like CHF₂O and CHFOH to prevent chain propagations. Moreover, comprehensive and novel reaction pathways are proposed for the inhibition of H₂–O₂ combustion by CHF₃. The parameters of the reaction kinetics indicate that the ignition delay is advanced and the activation energy for the combustion process is increased under the influence of CHF₃. This study is expected to provide practical guidance on the inhibition of H₂–O₂ combustion by CHF₃.