UNS: High Pressure Ring Contraction of Cyclic Hydrocarbons

1510039(布雷津斯基)这个项目研究了一些基本燃料在高压和高温条件下的行为(发动机和动力飞机燃烧室中的典型情况)，例如燃料分子破碎或收缩的速度/速度。研究结果对这些条件下碳烟颗粒的形成具有一定的指导意义，有助于清洁燃烧技术的发展。来自代表性不足群体的研究生将参与研究活动。该提案的目的是测量中等大小烯基的环化与β断裂分支比例的压力依赖性。利用激波管，PI试图确定压力依赖的单分子衰减曲线的形状和位置，这些曲线延伸到高压，以及经常被忽视的压力对通过活化体积表示的速率常数的影响。这些燃料在高压和高温条件下会经历更多的环收缩(由于分子笼效应)，而不是裂解成更小的分子，导致碳烟和焦炭的形成增加。除了环收缩热解反应外，双分子氧化反应还会有负的活化量，这会导致速率常数随着压力的增加而显著增加，并取决于与周围分子(如燃烧生成的水)的极性相互作用。PI将研究这些通常被忽视的活化体积效应，以及单分子衰减曲线的扩展形状和位置。

1510039 (Brezinsky)This project studies the behavior of some basic fuels under high-pressure and high-temperature conditions (typical in engines and power plane combustors), such as how fast/slow the fuel molecules will be fragmenting or contracting. The results have the relevance on how soot particulates might form under these conditions, and thus help to develop cleaner combustion technology. Graduate students from under-represented groups will be involved in the research activities.The objective of the proposal is to measure the pressure-dependence of cyclization vs. beta scission branching fraction of midsize alkenyl radicals. Using a shock tube, the PI seeks to identify the shape and position of pressure-dependent uni-molecular fall-off curves that extend to the high pressures and also the often overlooked effect of pressure on the rate constant expressed through the activation volume. These fuels undergo increasing amounts of ring contraction (due to molecular caging effects) under the high-pressure and high-temperature conditions instead of fragmentation into smaller molecules, leading to increased soot and coke formation. In addition to ring contraction pyrolysis reactions, bimolecular oxidation reactions will have negative activation volumes which lead to a significant increase in the rate constant with pressure and, depending on polar interactions with surrounding molecules such as combustion generated water. The PI will investigate these mostly overlooked activation volume effects as well as the extended shape and position of the uni-molecular fall-off curves.