UNS: GROWTH KINETICS AND MICROPHYSICAL PROPERTIES OF SOOT SUPERAGGREGATES

UNS：烟灰超聚集体的生长动力学和微观物理特性

基本信息

批准号：
1511964
负责人：
Rajan Chakrabarty
金额：
$ 29.91万
依托单位：
Washington University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2015
资助国家：
美国
起止时间：
2015-06-15 至 2018-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1511964&HistoricalAwards=false
关键词：
UNS GROWTH KINETICS MICROPHYSICAL PROPERTIES

项目摘要

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.

1511964（Chakrabarty）最近的研究表明，大规模的开火散发出一种先前未识别的烟灰颗粒 - 异焦聚集物（SAS）的形式，其数量大于70％，按数量和质量浓度大于70％。这些粒子以前可能对人类健康和环境产生不明显的影响。这项研究的目的是以受控的方式生成烟灰sas，以模仿大规模开放式燃烧的烟灰，并研究粒子形成机理和发射的粒子特性。本科生和研究生将参加研究工作。 PI还将在整个夏季为二十名学校老师进行教师培训研讨会。传统观点认为，迁移率直径（DM）小于或等于700 nm，空气动力学直径（DA）小于或等于300 nm，而分形维度约为1.8，是1.8是新鲜的新鲜人的终点形态。初步研究表明，SOOT SAS的DM和特定表面积分别是常规烟灰颗粒的10和三倍。异常大的DM值使使用气溶胶迁移率尺寸仪器使SOOT SAS无法检测到。或者，这些颗粒的DA（用于估计肺部沉积概率）类似于常规烟灰颗粒的DA。这些对烟灰sa性能的观察矛盾的观察结果使几个基本问题尚未解决：超级聚集在火焰中的生长动力学如何取决于过程参数，例如粒子体积分数，停留时间，燃料，燃料/空气流量和温度的烟雾指数，烟雾索引？正聚集动力学在正（向上上升）火焰系统中有何不同？超级聚集的粒子形态和特性对火焰过程参数的变化有多敏感？该项目建议回答这些问题，这将使Soot SA的生长动力学及其微物理特性具有潜在的变革理解。