摘要
氨(NH_(3))作为一种无碳富氢燃料,与高活性燃料氢(H_(2))混合燃烧是降低传统化石燃料消耗、实现低碳排放的有效手段。受限于详细机理在三维流场计算的高计算成本问题,工程应用亟需低物种数、低反应数且具有较高预测精度的燃烧动力学机理。通过反应分子动力学模拟(ReaxFF MD)研究NH_(3)/H_(2)在不同温度、当量比和掺氢比下的燃烧行为,揭示了NH_(3)/H_(2)混燃的微观反应机理。基于ReaxFF模拟轨迹追踪反应路径,确定NH_(3)燃烧过程中的关键物种与基元反应,构建了含21个物种和37步反应的纯NH_(3)及NH_(3)/H_(2)燃烧反应动力学骨架机理,该骨架机理能够在较宽的温度、压力和当量比下精确再现点火延迟时间(IDT)和层流火焰速度(LFS)。研究可为燃烧数值模拟的高效计算提供理论基础。
Driven by the goal of carbon neutrality,ammonia(NH_(3)),as a carbon-free hydrogen-rich fuel,when mixed with the highly reactive fuel H_(2),represents an effective approach to achieve low-carbon emissions and reduce the consumption of traditional fossil fuels.Constrained by the high computational costs of detailed mechanisms in three-dimensional flow field calculations,engineering applications urgently demand reduced kinetic mechanisms with a low number of species,a low number of reactions,and high prediction accuracy.This study employs reactive molecular dynamics simulation(ReaxFF MD)to investigate the combustion behaviors of pure NH_(3)and NH_(3)/H_(2)mixtures under varying temperatures,equivalence ratios,and hydrogen blending ratios,unveiling the microscopic reaction mechanisms of NH_(3)/H_(2)co-combustion.Simulation results demonstrate that increases in temperature,O_(2)content,and H_(2)blending primarily promote NH_(3)combustion by enhancing the concentrations of active radicals(e.g.,OH and H).Additionally,adjusting the hydrogen blending ratio reduces NO concentration,which is crucial for mitigating nitrogen oxide emissions.Based on ReaxFF simulation trajectories,the reaction paths were traced,key species and elementary reactions in the NH_(3)combustion process were identified,and a skeletal kinetic framework for the combustion reactions of pure NH_(3)and NH_(3)/H_(2),consisting of 21 species and 37 reaction steps,was constructed.The prediction performance of this mechanism and eight other mechanism models was evaluated using ignition delay time,laminar flame speed,and jet-stirred reactor concentration for validation.It was found that while being highly reduced,this mechanism still has high prediction accuracy for ignition delay time and laminar flame speed over a wide range of equivalence ratios and pressures.This research provides a theoretical foundation for efficient large-scale combustion numerical simulations.
作者
赵海越
张厚君
年瑶
韩优
ZHAO Haiyue;ZHANG Houjun;NIAN Yao;HAN You(State Key Laboratory of Chemical Engineering and Low-carbon Technology,School of Chemical Engineer and Technology,Tianjin University,Tianjin 300072,China)
出处
《化工学报》
北大核心
2026年第1期248-264,共17页
CIESC Journal
基金
国家自然科学基金专项项目(T2441001)
天津市自然科学基金青年项目(24JCQNJC01140)。
