Combustion Dynamics of NH₃/H₂ in a Jet-Stirred Reactor

As a highly promising zero-carbon fuel, NH3 has attracted widespread attention. Understanding the chemistry of NH3 combustion is now one of the challenges of combustion dynamics. In this work, experiments investigating NH3/H2 oxidation were conducted in a jet-stirred reactor at atmospheric pressure, covering H2 mole fractions (0–9000 ppm), equivalence ratios (0.6–1.4), and temperatures (800–1300 K). Key products (H2, N2, NO, and N2O) were quantified by gas chromatography. A refined kinetic model for NH3/H2 oxidation was developed by optimizing critical rate constants through the systematic integration of experimental data. The experimental results demonstrate that H2 addition enhances NH3 oxidation, manifesting reduced oxidization temperatures and elevated product mole fractions. Under fuel-lean conditions, NH3 exhibits strong oxidative reactivity, which diminishes with increasing equivalence ratios. At 1100–1300 K under fuel-rich conditions, NH3 pyrolysis becomes significant, marked by rising H2 mole fractions with temperature. Rate of production and sensitivity analyses reveal that the addition of H2 amplifies the H/OH radical pools, accelerating NH3 dehydrogenation. The suppression of HNO, NH, and H2NO intermediate formation under elevated equivalence ratios directly correlates with reduced NO and N2O mole fractions. The model was further validated against literature data for laminar flame speed, ignition delay time, and NH3 pyrolysis. This work establishes fundamental insights into NH3/H2 oxidation dynamics and offers reliable experimental data for modeling.氨（NH₃）作为一种极具前景的零碳燃料，已受到广泛关注。阐明氨的燃烧反应机理，现已成为燃烧动力学领域的核心挑战之一。本研究在常压射流搅拌反应器中开展了氨/氢（H₂）氧化反应的实验研究，实验参数覆盖氢摩尔分数（0~9000 ppm）、当量比（0.6~1.4）以及反应温度（800~1300 K）。主要产物（H₂、N₂、NO及N₂O）通过气相色谱法进行定量分析。本研究通过系统整合实验数据、优化关键速率常数，构建了改进的氨/氢氧化动力学模型。实验结果表明，氢气添加可强化氨的氧化过程，具体表现为氧化温度降低、产物摩尔分数升高。在贫燃工况下，氨展现出较强的氧化反应活性，且该活性随当量比升高而减弱。在富燃工况下的1100~1300 K温度区间内，氨的热解过程变得显著，表现为氢摩尔分数随温度升高而上升。产率及敏感性分析结果显示，氢气添加可扩大H/OH自由基池的规模，从而加速氨的脱氢反应。当量比升高时，HNO、NH及H₂NO等中间产物的生成受到抑制，这与NO和N₂O摩尔分数的降低直接相关。本模型进一步通过文献中的层流火焰速度、点火延迟时间及氨热解实验数据进行了验证。本研究为氨/氢氧化反应动力学提供了基础性认知，同时为相关模型构建提供了可靠的实验数据支撑。