Experimental Study of Soot Nanoparticle Formation and Oxidation at Elevated Pressures

建议编号：CBET-0651906首席研究员：戈麦斯，亚历山德罗附属机构：耶鲁大学提案标题：加压下碳烟纳米颗粒形成和氧化的实验研究公开摘要这项研究侧重于加压下碳烟纳米颗粒形成的基本原理，这是一个挑战，因为许多实用系统在这种条件下运行，但那里几乎没有基本数据。燃烧系统的烟尘颗粒排放一直是一个长期存在的环境问题，因为颗粒物及其表面吸附的多环芳烃会对健康造成影响。烟尘的形成也是一个与可能随之而来的潜在工程问题相关的技术问题，例如涡轮机叶片的侵蚀。尽管近年来取得了相当大的进展，但对实际系统中烟尘形成的基本理解仍然是一个令人生畏的挑战。本研究考察了在高压(高达40atm)下运行的逆流燃烧器中气体和液体燃料的碳烟形成，这与燃气轮机和发动机等实际应用有关。将要研究的燃料包括乙烯、乙炔、庚烷和甲苯，这是一组气态和液态燃料，它们的烟尘倾向有很大不同。用这些燃料研究烟尘形成的主要困难之一是，它们非常容易产生烟尘，这个问题在高压下会加剧。如果烟尘产生量太大，就会出现一些实验并发症，使基础研究变得困难。逆流扩散火焰被选为研究的最佳环境，因为它对碳烟形成过程提供了无与伦比的控制水平，抑制了通常困扰高压同流火焰的浮力不稳定性，并且有机会在后续研究中将系统建模为一维。火焰作为一个反应器运行，其中的烟尘装载可以？拨？拨？随心所欲地从开始成核阶段到显着的表面生长和氧化。作为一个额外的新奇之处，通过试验高扩散率稀释剂，如氦，可以稳定足够厚的火焰，即使在高压条件下，也能够以足够的分辨率探测火焰结构。特别强调纳米颗粒，即早期成核阶段。化学物种的特征反映了火焰的结构，并参与了生长过程。在这项工作的影响中，这项努力旨在产生一个数据库，用于验证详细的计算模型。数据集将在网上提供，以便研究人员方便地进行后续建模。这项研究还将延伸到教学和外展活动中。高压下的煤烟研究不容易由经验不足的人进行实验。然而，在研究生和PI的指导下，一些简单的项目，如扫描电子显微镜/透射电子显微镜分析和数据处理软件，将由本科生和高中生完成。

Proposal Number: CBET-0651906 Principal Investigator: Gomez, Alessandro Affiliation: Yale UniversityProposal Title: Experimental Study of Soot Nanoparticle Formation and Oxidation at Elevated Pressures PUBLIC ABSTRACTThis research focuses on the fundamentals of soot nanoparticle formation at elevated pressures, a challenge because many practical systems operate at such conditions but few fundamental data are available there. Emission of soot particles from combustion systems has been a long-standing environmental problem because of the health effects associated with particulate matter and the polycyclic aromatic hydrocarbons adsorbed on their surfaces. Soot formation is also an issue of technical relevance for the potential engineering problems that may ensue; e.g., erosion of turbine blades. Despite considerable progress made in recent years, a fundamental understanding of soot formation in practical systems is still a daunting challenge. The present research examines soot formation of gaseous and liquid fuels in a counterflow burner operated at high pressures, up to 40 atm, that are relevant to practical applications such as gas turbines and engines. Fuels to be studied include ethylene, acetylene, heptane and toluene, a set of gaseous and liquid fuels with significantly different sooting propensities. One of the main difficulties of studying soot formation with these fuels is that they are very prone to soot, a problem that is exacerbated at high pressures. If the soot yield is too abundant, a number of experimental complications ensue that make it difficult to perform fundamental studies. A counterflow diffusion flame was selected as an optimal environment for the research because of the unparalleled level of control that it provides on the soot formation process, the suppression of buoyancy instabilities that typically plague co-flow flames at high pressures, and the opportunity of modeling the system in subsequent studies as one-dimensional. The flame is operated as a reactor in which the soot loading can be ?dialed? at will from the onset of the nucleation stage to significant surface growth and oxidation. As an additional novelty, by experimenting with a high diffusivity diluent such as helium, sufficiently thick flames can be stabilized, despite the high-pressure conditions, to enable the probing of the flame structure with adequate resolution. Particular emphasis is placed on the nanoparticle, early-nucleation stage. Chemical species are characterized that reflect the flame structure and participate in the growth process. Among impacts of the work, the effort is intended to yield a database for general use in validation of detailed computational models. Data sets will be made available on the web to allow convenient access to researchers for subsequent modeling. The research will also spill over into teaching and outreach activities. Soot research at high pressure does not lend itself easily to experimentation by inexperienced hands. However, with the supervision of graduate students and the PI, simple projects, such as on SEM/TEM analysis and data reduction software, will be tackled by undergraduate and upper high-school students.