Ammonia/hydrogen-fueled combustion represents a very promising solution for the future energy scenario. This study aims to shed light and understand the behavior of ammonia/hydrogen blends under flameless conditions. A first-of-its-kind experimental campaign was conducted to test fuel flexibility for different ammonia/hydrogen blends in a flameless burner, varying the air injector and the equivalence ratio. NO emissions increased drastically after injecting a small amount of NH₃ in pure hydrogen (10% by volume). An optimum trade-off between NOx emission and ammonia slip was found when working sufficiently close to stoichiometric conditions (ϕ = 0.95). In general, a larger air injector (ID25) reduces the emissions, especially at ϕ = 0.8. A well-stirred reactor network with exhaust recirculation was developed exchanging information with computational fluid dynamics (CFD) simulations, to model chemistry in diluted conditions. Such a simplified system was then used in two ways: 1) to explain the experimental trends of NOx emissions varying the ammonia molar fraction within the fuel blend and 2) to perform an uncertainty quantification study. A sensitivity study coupled with latin hypercube sampling (LHS) was used to evaluate the impact of kinetic uncertainties on NOx prediction in a well-stirred reactor network model. The influence of the identified uncertainties was then tested in more complex numerical models, such as Reynolds-averaged Navier–Stokes (RANS) simulations of the furnace. The major over-predictions of existing kinetic scheme was then alleviated significantly, confirming the crucial role of detailed kinetic mechanisms for accurate predictive simulations of NH₃/H₂ mixtures in flameless regime.

氨/氢燃料燃烧是未来能源情景中非常有希望的解决方案。这项研究旨在阐明并了解无焰条件下氨/氢混合物的行为。开展了首例试验活动，以测试无焰燃烧器中不同氨/氢混合物的燃料灵活性，并改变了空气喷射器和当量比。将少量的NH ₃注入纯氢（体积百分比为10％）后，NO排放量急剧增加。当在足够接近化学计量条件的条件下工作时，发现了NOx排放与氨泄漏之间的最佳平衡（ϕ= 0.95）。通常，较大的空气喷射器（ID25）可以减少排放，尤其是在ϕ= 0.8。开发了一个搅拌良好的带有排气再循环的反应器网络，并与计算流体动力学（CFD）模拟交换信息，以模拟稀释条件下的化学反应。然后，以两种方式使用这种简化的系统：1）解释NOx排放的实验趋势，该趋势会改变燃料混合物中的氨摩尔分数； 2）进行不确定性定量研究。在一个搅拌良好的反应堆网络模型中，将敏感性研究与拉丁文超立方采样（LHS）结合使用，以评估动力学不确定性对NOx预测的影响。然后，在更复杂的数值模型中测试已识别不确定性的影响，例如雷诺平均炉膛的Navier-Stokes（RANS）模拟。然后，可以大大缓解现有动力学方案的主要过高预测，₃ / H ₂混合物，无焰状态。