Enhancing the Scientific Understanding of Nanoparticle Formation in Flames

燃烧产生的纳米颗粒，如烟灰，已知对人类健康和环境有不利影响。就健康影响而言，煤烟颗粒与心肺疾病以及其他各种健康并发症有关。就环境影响而言，煤烟被认为是仅次于二氧化碳的全球变暖最重要的贡献者之一，因为它具有很强的辐射特性。由于这些原因，现在针对汽车和航空发动机的微粒排放制定了更严格的法规。****为了开发预测模型和更好的燃烧器设计，需要对烟灰形成有一个基本的了解。随着更严格的法规的实施，工业界对精确的预测烟灰模型有强烈的愿望，以帮助设计过程。然而，由于许多煤烟的形成和氧化过程尚不清楚，因此迫切需要对其进行更基本的了解。这些过程包括多环芳烃（PAH）的形成、烟尘的形成、烟尘成核、小烃类的加入导致烟尘生长、以及多环芳烃在表面吸附导致烟尘生长。****我研究的长期愿景是开发一个强大的烟尘形成模型，可以预测火焰中烟尘的质量，大小分布和聚集结构。该模型需要预测当我们改变火焰的温度、压力、燃料结构、混合和停留时间时，烟灰的形成是如何变化的。为了实现这一点，模型需要基于基本过程，并避免拟合参数（就像今天的情况一样）。需要在各种火焰条件下进行详细的实验测量，以研究这些过程并严格验证模型。****短期目标包括(1)解决目前尚未很好理解的每个烟灰形成过程，(2)为相关的一组燃料分子开发一个烟灰形成的综合数据集，(3)开发一个预混停滞火焰的实验装置。因此，将开发一个烟灰形成模型，该模型(1)捕获正在发生的基本物理现象，并减少目前适合实验的调整参数的数量，(2)关注与实际燃料相关的燃料分子，(3)在广泛的非预混和预混火焰实验中得到验证。****烟尘形成的多学科性质使其成为热科学研究领域学生的优秀培训领域。它提供了一个全面的背景，在热科学的理解熏烟火焰需要过程的知识，如流体动力学，质量和传热，热力学，气溶胶动力学，化学反应，相变和辐射传热。这为学生在广泛的热科学领域提供了机会。****

Combustion-derived nanoparticles, such as soot, are known to have adverse effects on human health and the environment. In terms of health effects, soot particles have been linked to heart and lung disease, along with various other health complications. In terms of environmental effects, soot is considered to be one of the most significant contributors to global warming, behind CO2, due to its strong radiative properties. For these reasons, stricter regulations are now targeting particulate emissions in both automotive and aviation engines.****A fundamental understanding of soot formation is needed in order to develop predictive models and better combustor designs. With stricter regulations come into place, industry has a strong desire for accurate predictive soot models to aid the design process. However there is an urgent need for a more fundamental understanding as many soot formation and oxidation processes are poorly understood. These processes include polycyclic aromatic hydrocarbon (PAH) formation, soot inception, soot nucleation, soot growth by the addition of small hydrocarbon species, and soot growth by PAH adsorption on the surface.****The long term vision of my research is to develop a robust model of soot formation that can predict the mass, size distribution and aggregate structure of soot in flames. The model would need to predict how the soot formation changes as we change the flame's temperature, pressure, fuel structure, mixing and residence time. In order to achieve this, the model would need to be based on fundamental processes and avoid fitted parameters (as is the case today). Detailed experimental measurements are needed in a variety of flame conditions to investigate these processes and rigorously validate the model.****Short term objectives include (1) addressing each soot formation process that is currently not well understood, (2) developing a comprehensive dataset of soot formation for a relevant set of fuel molecules and (3) developing an experimental setup for premixed stagnation flames. Thus a model of soot formation will be developed that (1) captures the fundamental physics that is occurring and reduces the number of adjusted parameters that are currently fitted to experiments, (2) focuses on fuel molecules relevant to practical fuels and (3) is validated on a wide range of non-premixed and premixed flame experiments.****The multidisciplinary nature of soot formation makes it an excellent training area for students in the thermo-sciences research area. It provides a comprehensive background in the thermo-sciences as understanding sooting flames requires knowledge of processes such as fluid dynamics, mass and heat transfer, thermodynamics, aerosol dynamics, chemical reactions, phase change and radiation heat transfer. This opens opportunities for students in a wide range of thermo-science fields.****