Fundamental flame studies of soot formation and morphology at elevated pressures

为了实现更高的热效率和更小的发动机体积，内燃机被设计成在比大气压高得多的压力下操作。从燃气涡轮机和柴油发动机排放的主要污染物之一是烟灰，也称为颗粒物质或炭黑，其在操作模式为非预混或部分预混时的燃烧过程期间形成，并且其形成速率通过增加燃烧压力而显著增加。烟尘气溶胶通过改变大气的辐射特性，在区域和全球范围内影响地球的温度和气候。对全球变暖的贡献可能是巨大的，也许仅次于二氧化碳。此外，煤烟在冰雪上的沉积降低了表面反射率，从而捕获了辐射;这可能是全球变暖的四分之一。因此，政府间气候变化专门委员会指出，烟尘气溶胶是导致气候变化的正辐射强迫的第三大贡献者。此外，暴露于烟尘气溶胶是每年造成全球数十万人死亡的原因。很大一部分烟尘是由陆地、空中和海上运输中使用的发动机排放的。控制烟尘气溶胶可以迅速产生区域和全球气候效益，并减少对人类健康的不良影响。控制方法之一是防止或减少燃烧中的烟灰产生。对燃烧中碳烟形成过程的基本了解是这种控制方法的一个组成部分。然而，由于碳氢化合物火焰的高度复杂性，燃烧中烟灰形成过程的化学和物理机制的细节仍然不确定，并且只有少数原理主要针对大气条件而牢固建立。尽管用于运输的大多数燃烧装置在非常高的压力下操作，但我们对高压下烟灰形成的理解并不处于理想的水平，并且基本上缺乏实验数据和补充预测模型。液体生物燃料的烟灰特性并不为人所知，特别是在大多数发动机工作的高压下，这种缺乏了解对在燃气轮机和其他陆地运输发动机中采用生物燃料和混合物具有影响。目前的建议旨在解决这些问题，通过促进知识的进步，在烟尘的形成及其特性，在发动机相关的压力和帮助烟尘排放控制的努力。这将通过在多伦多大学航空航天研究所使用独特的高压燃烧设施以及光学和侵入式燃烧诊断进行精心计划的实验来实现。

To achieve higher thermal efficiencies and smaller engine volumes, combustion engines are designed to operate at pressures much higher than the atmospheric. One of the major pollutants emitted from the gas turbines and diesel engines is soot, also known as particulate matter or black carbon, which forms during the combustion process when the mode of operation is non-premixed or partially-premixed, and its formation rate is significantly increased by increasing the combustion pressure. Soot aerosols affect the Earth's temperature and climate, both regionally and globally by altering the radiative properties of the atmosphere. The contribution to global warming may be substantial, perhaps second only to that of CO2. In addition, the deposition of soot on snow and ice reduces the surface reflectivity thus trapping the radiation; this could be responsible for a quarter of the global warming. As a result, the Intergovernmental Panel on Climate Change states that the soot aerosol is the third largest contributor to the positive radiative forcing that causes climate change. Furthermore, exposure to soot aerosol is responsible for hundreds of thousands of global deaths each year. A significant portion of soot is emitted from engines used in land, air and sea transportation. Controls on soot aerosol can produce rapid regional and global climate benefits as well as reductions of ill effects on human health. One of the approaches in control is prevention or reduction of soot generation in combustion. A fundamental understanding of the soot formation processes in combustion is an integral part of this control approach. However, the details of the chemical and physical mechanisms of the soot formation process in combustion remain uncertain due to the highly complex nature of hydrocarbon flames, and only a few principles are firmly established mostly for atmospheric conditions. In spite of the fact that most combustion devices used for transportation operate at very high pressures, our understanding of soot formation at high pressures is not at a desirable level, and there is a fundamental lack of experimental data and complementary predictive models. Sooting characteristics of liquid bio-fuels are not known well, especially at high pressures where most engines operate, and this lack of understanding has implications in adopting bio-fuels and blends in gas turbines and other land transportation engines. The current proposal aims to address these issues by contributing to the advancement of knowledge in soot formation and its characteristics at engine-relevant pressures and helping with the soot emissions control efforts. This will be accomplished by carefully planned experiments using the unique high-pressure combustion facility, and optical and intrusive combustion diagnostics at the University of Toronto Institute for Aerospace Studies.