UNS: GROWTH KINETICS AND MICROPHYSICAL PROPERTIES OF SOOT SUPERAGGREGATES

1511964（Chakrabarty）最近的研究表明，大规模的明火排放出一种以前未被认识到的烟尘颗粒超聚集体（SA），数量和质量浓度超过70%。这些颗粒可能对人类健康和环境产生了以前无法解释的影响。本研究的目的是产生，在一个可控的方式，模拟那些从大规模的开放式燃烧的烟尘SA，并调查颗粒的形成机制和排放的颗粒特性。本科生和研究生将参与研究工作。 PI还将在夏季为20名学校教师举办教师培训讲习班。传统观点认为，流动性直径（Dm）小于或等于700 nm，空气动力学直径（Da）小于或等于300 nm，分形维数约为1.8是新排放碳烟颗粒的终点形态。初步调查表明，Dm和比表面积的烟尘SA，分别是10倍和3倍，比传统的烟尘颗粒。异常大的Dm值使烟尘SA无法检测使用气溶胶流动性测量仪器。或者，用于估计肺内沉积概率的这些颗粒的Da类似于常规烟灰颗粒的Da。这些自相矛盾的观察烟灰SA属性留下了几个基本的问题没有回答：如何在火焰中的超聚集体生长动力学取决于过程参数，如颗粒体积分数，停留时间，烟灰指数的燃料，燃料/空气流速和温度？ 聚集动力学在正重力（向上上升）火焰系统中有何不同？超集料颗粒的形态和性质对火焰工艺参数的变化有多敏感？该项目旨在回答这些问题，这将带来对煤烟SA的生长动力学及其微物理性质的潜在变革性理解。

1511964(Chakrabarty)Recent studies have shown that large-scale open fires emit a previously unrecognized form of soot particle-superaggregates (SAs), in quantities greater than 70% by number and mass concentration. These particles could have previous unaccounted-for impacts on human health and the environment. The objective of this research is to generate, in a controlled manner, soot SAs that mimic those from large-scale open burns, and investigate the particle formation mechanism and the emitted particle properties. Undergraduate and graduate students will participate in the research effort. The PI will also conduct teachers training workshop for twenty school teachers over the summer.The conventional view holds that mobility diameter (Dm) less than or equal to 700 nm, aerodynamic diameter (Da) less than or equal to 300 nm, and fractal dimension approximately 1.8 is the end-point morphology of freshly-emitted soot particles. Preliminary investigations indicate that Dm and specific surface areas of soot SAs are ten and three times greater, respectively, than those of conventional soot particles. The unusually large Dm values render soot SAs undetectable using aerosol mobility sizing instruments. Alternatively, Da of these particles, which is used for estimating the probability of deposition within lungs, are similar to those of conventional soot particles. These contradicting observations of soot SA properties have left several fundamental questions unanswered: How does the superaggregate growth kinetics in a flame depend on the process parameters such as particle volume fraction, residence time, sooting index of the fuel, fuel/air flow rates, and temperature? How is the aggregation kinetics different in a positive gravity (upward rising) flame system? How sensitive are the superaggregate particle morphologies and properties to changes in the flame process parameters? This project proposes to answer these questions, which will bring about a potentially transformative understanding of soot SA's growth kinetics and their microphysical properties.