Unraveling Soot Inception in Diffusion Flames with State-of-the-Art Sampling, Conditioning and Analysis Techniques

碳质颗粒或烟灰的排放与燃烧装置有关，这些燃烧装置占全球总能源生产的80%以上。释放到大气中的烟尘颗粒对人类健康有害，被认为是气候变化中辐射强迫的第二大贡献者。该项目旨在揭示碳烟开始的机制，即形成最小的碳烟核，随后生长为燃烧装置中总碳烟产生的大部分。虽然燃烧技术的最新改进已经降低了烟尘水平以符合当前的法规，但这种改进导致了更大数量的更小颗粒的释放。因此，烟尘排放的负面影响仍然很大，因为纳米级烟尘颗粒的尺寸小且毒性高。很可能的是，一个基本的了解烟尘开始将不仅有利于目前的减排努力，而且对未来的法规，以限制排放量方面的最小和最有毒的particle.In实际设置，烟尘开始扩散火焰，往往是最常见的配置，其中占上风的烟尘条件。拟议的研究利用专门开发的气溶胶采样，调节和分析技术来测量浓度，尺寸，电荷和火焰产生的碳质材料的组成小于2纳米和3000 Da，无论其物理状态。这些技术将适用于可变的最高温度稳定在一个新的燃烧器配置，允许必要的空间分辨率的扩散火焰的调查。该项目将导致建立一个基础设施，以研究（碳）纳米粒子和分子簇在扩散火焰下定义明确和控制良好的条件。更广泛地说，这一目标的实现将有助于理解气溶胶行为的基本原理，包括纳米颗粒和分子簇的离子碰撞充电。与所提出的方法提供的烟尘核的结构和行为的细节将是有价值的，以提高现有的烟尘models.This奖项的预测能力反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Emissions of carbonaceous particles, or soot, are associated with combustion devices that are responsible for more than 80% of the total energy production worldwide. Soot particles released to the atmosphere are harmful to human health and are considered the second largest contributor to radiative forcing in climate change. This project aims at unraveling the mechanisms of soot inception, that is the formation of the smallest soot nuclei that subsequently grow to be responsible for the bulk of the overall soot production in combustion devices. While recent improvements in combustion technologies have reduced soot levels to match current regulations, such improvements have resulted in the release of a larger number of ever smaller particles. As a result, the negative impact of soot emissions remains substantial because small sizes and high toxicity of nano-sized soot particles. It is likely that a fundamental understanding of soot inception will not only be beneficial for current abatement efforts but also for future regulations to limit emissions in terms of number of the smallest and most toxic particles.In practical settings, soot inception in diffusion flames that tend to be the most common configuration in which sooting conditions prevail. The proposed research takes advantage of purposely developed aerosol sampling, conditioning and analysis techniques to measure concentration, size, charge, and composition of flame generated carbonaceous materials smaller than 2 nm and 3000 Da, regardless of their physical state. The techniques will be adapted to the investigation of diffusion flames of variable maximum temperature stabilized in a novel burner configuration that allows for the necessary spatial resolution. The project will result in the establishment of an infrastructure to study (carbon) nanoparticles and molecular clusters in diffusion flames under well-defined and well-controlled conditions. More broadly, the achievement of this goal will benefit the understanding of the fundamentals of aerosol behavior, including ion collision charging of nanoparticles and molecular clusters. The details about the structure and behavior of soot nuclei provided with the proposed methods will be valuable to improve the predictive capabilities of existing soot models.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.