Autoignition Chemistry of Gasoline Surrogates Relevant to HCCI Operating Conditions

均质压缩点火（HCCI）燃烧作为提高汽油机燃油经济性的一种经济有效的方法，近年来受到了广泛的关注。与目前的传统SI发动机相比，HCCI发动机可将燃油经济性提高10%至15%，并大幅减少氮氧化物排放。虽然HCCI燃烧的潜在好处是巨大的，但这种燃烧模式在实施之前必须解决几个实际的发展问题。该项目的目标之一是开发由少量（少于10种）纯碳氢化合物成分制成的替代燃料，这些成分在代表HCCI燃烧的条件下非常接近模拟汽油的全局点火特性。使用替代燃料是一种可行的方法，可以使开发实际燃料的化学动力学机制变得容易。本研究旨在开展与HCCI运行工况相关的替代燃料动力学研究，提供高保真度的基准实验数据，用于验证化学动力学模型的预测能力。这个为期三年的项目的主要重点是通过实验确定纯汽油和混合汽油替代燃料成分的点火特性，使用一种独特设计的快速压缩机。实验条件将包括10-50 bar的压缩压力和650-1100 K的充电温度。根据测得的压力轨迹，可以得到第一级和第二级点火的延迟时间、与第一级点火相关的热释放以及燃料燃烧速率等信息。我们感兴趣的纯燃料成分包括正庚烷、异辛烷、甲苯、1-戊烯和甲基环己烷，而实验也将使用研究级汽油进行。实验工作将首先集中于研究这五种成分在压力、温度、空气燃料比和稀释水平范围内的整齐形式。随后，这些纯净的碳氢化合物将被混合成测试燃料，包括二元、三元和高阶混合燃料，这些燃料将被评估以确定其点火特性是否与完全混合的汽油相匹配。有了明确配置的基准实验数据，可以系统地研究燃料动力学，这是向开发汽油替代燃料的强大详细和简化的化学机制迈出的重要一步。对于综合动力学建模，从激波管，流动反应器和火焰的文献实验数据也将包括和考虑。人们认识到，这些纯燃料的动力学相当复杂，尚未得到适当的理解。在关键实验数据和动力学理解的可用性方面的重大进展，预计从这一提议的工作。这一研究项目将为汽油替代燃料提供宝贵的实验数据库和化学动力学模型。这些结果对于HCCI发动机的成功开发至关重要。通过这项研究加深了对汽油替代燃料的了解，通过数值模拟进行可靠的预测和探索，将有助于克服HCCI发动机发展的研发障碍。估计显示，如果HCCI技术能够从2010年开始成功实施，美国运输部门对汽油的需求将有可能大幅减少。此外，所进行的研究将直接有助于改善本科生和研究生的学习体验。通过积极参与尖端燃烧研究，可以吸引有才华的学生留在科学/工程领域，为迎接清洁和高效能源利用领域的挑战做好准备。

0932559SungHomogeneous charge compression ignition (HCCI) combustion has received much attention during the past few years as a cost-effective means of increasing the fuel economy of gasoline engines. HCCI engines offer the potential for 10 to 15% improvement in fuel economy and dramatic reductions in NOx emissions as compared to today's conventional SI engines. While the potential benefits of HCCI combustion are great, this combustion mode has several practical development issues that must be solved before it can be implemented. One of the goals of this project is to develop surrogate fuels made from a small number (less than 10) of pure hydrocarbon components that closely mimics the global ignition characteristics of gasoline at conditions representative of HCCI combustion. The use of surrogate fuels is a viable approach to make the development of chemical kinetic mechanisms for practical fuels tractable. This proposed research aims to conduct kinetic investigation of surrogate fuels relevant to HCCI operating conditions and provide benchmark experimental data of high fidelity that will be used to validate the predictive capability of chemical kinetic models.The main focus of this three-year program will be to experimentally determine the ignition characteristics of neat and blended components for gasoline surrogate fuels using a uniquely designed rapid compression machine. Experimental conditions will cover the compressed pressures of 10-50 bar and charge temperatures of 650-1100 K. Based on the measured pressure traces, information about the delay times of the first and second stage ignition, heat release associated with the first stage ignition, and the fuel burning rate can be obtained. The neat fuel components of interest include n-heptane, iso-octane, toluene, 1-pentene, and methylcyclohexane, while experiments will be also conducted using research-grade gasoline. Experimental efforts will first focus on the investigations of each of these five components in neat form over a range of pressures, temperatures, air-to-fuel ratios, and dilution levels. Subsequently, these neat hydrocarbons will be blended into test fuels, including binary, ternary, and higher-order blends, which will be evaluated to determine if the ignition characteristics match that of a fully blended gasoline.With the availability of benchmark experimental data in a well-defined configuration, the fuel kinetics can be systematically studied, which represents an important step towards the development of robust detailed and reduced chemical mechanisms for gasoline surrogate fuels. For comprehensive kinetic modeling, literature experimental data from shock tubes, flow reactors, and flames will also be included and considered. It is recognized that the kinetics of these neat fuels is rather complex and not yet properly understood. Significant advances in terms of the availability of critical experimental data and kinetic understandings are expected from this proposed work.This research program will provide an invaluable experimental database and chemical kinetic models for gasoline surrogate fuels. These results are critical for the development of successful HCCI engines. Enhanced understanding of gasoline surrogate fuels through this research will help in overcoming R&D barriers to the development of HCCI engines by making reliable predictions and explorations through numerical simulations. Estimates show that if HCCI technology can be successfully implemented starting from year 2010, large savings in the US demand for gasoline in the transportation sector are possible. Furthermore, the research conducted will directly contribute to an improvement in the learning experience of undergraduate and graduate students. With active participation in cutting-edge combustion research, talented students can be attracted to retain in science/engineering areas and be well prepared to meet challenges in the field of clean and efficient energy utilization.