Autoignition Chemistry of Gasoline Surrogates Relevant to HCCI Operating Conditions

在过去的几年中，均质充量压缩点火（HCCI）燃烧作为提高汽油发动机燃料经济性的成本有效的手段受到了广泛关注。HCCI发动机提供了10至15%的燃油经济性的改善和显着减少氮氧化物的排放量相比，今天的传统SI发动机的潜力。虽然HCCI燃烧的潜在好处很大，但这种燃烧模式在实施之前必须解决几个实际开发问题。该项目的目标之一是开发由少量（少于10种）纯烃组分制成的替代燃料，其在代表HCCI燃烧的条件下密切模仿汽油的全局点火特性。替代燃料的使用是一种可行的方法，使发展的化学动力学机制的实际燃料易于处理。本研究旨在对与HCCI工况相关的替代燃料进行动力学研究，并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。本研究计划为期三年，其主要重点是使用独特设计的快速压缩机，通过实验确定汽油替代燃料的纯组分和混合组分的点火特性。实验条件将包括10-50巴的压缩压力和650-1100 K的充气温度。基于所测量的压力轨迹，可以获得关于第一和第二阶段点火的延迟时间、与第一阶段点火相关联的热释放以及燃料燃烧速率的信息。感兴趣的纯燃料组分包括正庚烷、异辛烷、甲苯、1-戊烯和甲基环己烷，同时还将使用研究级汽油进行实验。实验工作将首先集中在这五个组成部分的调查，在一系列的压力，温度，空气燃料比，和稀释水平的净形式。随后，这些纯碳氢化合物将被混合到测试燃料中，包括二元、三元和更高阶的混合物，这些混合物将被评估以确定其点火特性是否与完全混合汽油的点火特性相匹配。随着基准实验数据在定义明确的配置中的可用性，可以系统地研究燃料动力学，这代表了朝着开发用于汽油替代燃料的稳健的详细的和简化的化学机理的重要一步。对于综合动力学建模，文献实验数据从激波管，流动反应器，火焰也将包括和考虑。人们认识到，这些纯燃料的动力学是相当复杂的，尚未得到正确的理解。这项研究计划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。这些结果对于成功开发HCCI发动机至关重要。通过这项研究，提高对汽油替代燃料的认识，将有助于克服研发障碍，通过数值模拟进行可靠的预测和探索，HCCI发动机的发展。估计表明，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可能会大幅节省。此外，进行的研究将直接有助于改善本科生和研究生的学习经验。通过积极参与前沿燃烧研究，可以吸引有才华的学生留在科学/工程领域，并为迎接清洁和高效能源利用领域的挑战做好充分准备。

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.