Accurate Determination of Branching Fractions in Ammonia Combustion

氨是一种潜在的碳中性燃烧的过渡燃料。然而，氨的燃烧会产生各种氮氧化物(NOx)，这些氮氧化物是主要污染物，会加剧气候变化。为了减轻NOx对人类健康和环境的影响，政府法规越来越多地要求减少燃烧来源的氮氧化物排放。准确预测NOx生成水平的能力将使工程师和科学家受益，他们需要量化新燃料或新发动机设计对NOx排放的影响。这些氮氧化物次级机制还将使更广泛的大气科学界受益，无论是在地方一级(例如烟雾)还是在全球一级(例如气候变化)。这个项目的目标是测量在氨燃烧动力学中很重要的几个反应的分支分数，特别是那些与各种氮氧化物有关的反应。研究人员假设，通过同时测量两种或两种以上物种的瞬时浓度，分支部分的不确定性可以相对于NOx文献中的当前技术状态而降低。为了验证这一假设，研究人员将使用可调谐半导体激光吸收光谱(TDLAS)来测量激波管中反射激波背后的NO、NO2、N2O、H2O和/或温度的瞬时浓度。这些资料将作为动力学模型的验证目标。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Ammonia is a potential bridge fuel for carbon-neutral combustion. However, the combustion of ammonia can lead to various nitrogen oxides (NOx), which are major pollutants, and which can exacerbate climate change. To mitigate the impact of NOx on human health and the environment, government regulations increasingly require reduced emissions of nitrogen oxides from combustion sources. The ability to make accurate predictions of NOx formation levels will benefit engineers and scientists who need to quantify the impact of a new fuel or a new engine design on NOx emissions. These NOx submechanisms also will benefit the broader atmospheric science community, both at the local level (e.g. smog) and at the global level (e.g. climate change). The goal of this project is to measure the branching fractions for several reactions that are important in the kinetics of ammonia combustion, particularly those related to various nitrogen oxides. The investigators hypothesize that by measuring the transient concentration of two or more species simultaneously, the uncertainty in the branching fractions can be reduced relative to the current state of the art in NOx literature. To test this hypothesis, the investigators will use tunable diode laser absorption spectroscopy (TDLAS) to measure the transient concentration of NO, NO2, N2O, H2O, and/or temperature behind the reflected shock in a shock tube. These profiles will serve as validation targets for a kinetic model.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.