An Experimental Investigation of the Ignition and Oxidation of Biodiesel-Relevant Alkyl Esters at Engine Conditions

[32453]本项目将在类似发动机的高压条件下，以空气作为氧化剂，对与生物柴油相关的大范围（C3-C18）烷基酯的点火和氧化动力学进行激波管实验研究。对纯烷基酯、烷基酯共混物、大酯与石油-柴油替代混合物的共混物进行宏观氧化动力学指标、点火延迟时间和一氧化碳时程的激波管测量。这些测量将提供有关不同烷基酯的总体反应性和氧化过程的时间演变的信息，允许开发和评估这些化合物的动力学机制，并测试PI？S的中心假设，这些烷基酯的有机结构将强烈影响反应活性和反应途径。特别是，CO的测量将提供洞察在负温度系数（NTC）制度下的烷基酯的燃烧行为，其中CO在点火之前的生产是预期的。此外，这些测量将提供深入了解生物柴油和化石柴油之间的动力学差异，从而评估向生物柴油过渡对发动机的影响。提议的实验代表了在激波加热气体中碳氢化合物燃料的第一次CO测量，提议的大酯（C11-C18）实验代表了对这种尺寸的酯的第一次激波管测量。生物柴油相关酯类在类似发动机的高压条件下的点火和氧化动力学尚未得到深入研究。随着未来生物柴油燃料可能的大规模商业化，需要描述其氧化的动力学机制来开发和优化以生物柴油为燃料的高效清洁内燃机。宏观动力学指标（点火延迟和CO时程）将有助于酯氧化机制的发展，提供对不同有机酯结构对氧化的影响的基本理解，并提供生物柴油与化石衍生的同类产品的异同之处的理解。更广泛的影响向生物燃料过渡的广泛社会影响可能是巨大的。该研究旨在为目前尚不存在的与生物柴油相关的大烷基酯的点火和氧化动力学提供实验见解，并将对燃烧动力学建模界和发动机界产生广泛影响。燃烧动力学建模界需要这些目标来开发和验证机制，发动机界需要对生物柴油的反应性、生物柴油和化石柴油的差异以及发动机模拟的简化动力学模型有基本的了解。拟议的研究计划与教育和外展活动密切相关。研究生、本科生和高中生将被招募、指导、教育，并提供学习最先进的实验技术和探索现代能源问题的机会。将努力吸引传统上代表性不足的群体的学生。研究课题和成果将整合到本科和研究生课程中。能源报告也将在网上提供。

1032453OehlschlaegerIn this project an experimental shock tube investigation of the ignition and oxidation kinetics of a wide range (C3-C18) of biodiesel-relevant alkyl esters at engine-like conditions, high pressure with air as the oxidizer will be conducted. Shock tube measurements of macroscopic oxidation kinetic targets, ignition delay times and carbon monoxide time-histories, will be made for the neat alkyl esters, alkyl ester blends, and blends of large esters with petroleum-diesel surrogate mixtures. These measurements will provide information about the overall reactivity of the different alkyl esters and the temporal evolution of the oxidation process, allowing development and assessment of kinetic mechanisms for these compounds, and a test of the PI?s central hypothesis that the organic structure of these alkyl esters will strongly influence reactivity and reaction pathways. In particular, the measurement of CO will provide insight into the combustion behavior of alkyl esters in the negative temperature coefficient (NTC) regime, where CO production prior to ignition is expected. Additionally, these measurements will provide insight into the kinetic differences between bio- and fossil-derived diesels, allowing assessment of the impact a transition to biodiesel will have on engines. The proposed experiments represent the first CO measurements for hydrocarbon fuels in shock-heated gases and the proposed experiments for large esters (C11-C18) represent the first shock tube measurements for esters of this size.Intellectual MeritThe ignition and oxidation kinetics of biodiesel-relevant esters at high-pressure engine-like conditions have not been deeply investigated. With the possible future wide scale commercialization of biodiesel fuels, kinetic mechanisms describing their oxidation are needed for the development and optimization of high-efficiency clean combustion engines operating on biodiesel. Macroscopic kinetic targets (ignition delay and CO time-histories) will aid in the development of ester oxidation mechanisms, provide fundamental understanding on the influence of different organic ester structure on oxidation, and provide an understanding of the differences and similarities biodiesels have with their fossil-derived counterparts.Broader ImpactThe broad societal impact of a transition to biofuels could be enormous. The proposed research seeks to provide experimental insight into the ignition and oxidation kinetics of large alkyl esters relevant to biodiesel which currently does not exist and will have broad impact on the combustion kinetic modeling community who need such targets for mechanism development and validation and the engine community who need basic insight into the reactivity of biodiesel, the differences of bio- and fossil-diesel, and reduced kinetic models for engine simulations. The proposed research program is closely coupled to educational and outreach activities. Graduate, undergraduate, and high school students will be recruited, mentored, educated, and provided the opportunity to learn state-of-the-art experimental techniques and explore a modern energy problem. Efforts will be made to attract students from traditionally underrepresented groups. Research topics and results will be integrated into undergraduate and graduate courses. Energy presentations will also be made available online.