RO2 and QOOH Chemistry in Dimethylether Combustion

二甲醚(DME，CH3OCH3)作为一种替代清洁燃料具有很大的潜力。它的能量密度类似于目前的生物燃料，如乙醇，与现有的发动机技术兼容，燃烧时NOx和煤烟排放较低，可以通过现有的液化石油气网络进行分配。然而，人们对二甲醚的“低温”(500-900K)燃烧知之甚少；在这种温度范围内的燃烧在新的发动机技术中尤其重要，例如均质压燃(HCCI)。这项建议旨在描述二甲醚燃烧的机理，为学术燃烧界和工业合作者提供有用的信息。这一建议与EPSRC在能源研究中的优先事项相匹配。以前已经有一些关于低温二甲醚氧化的研究，但还没有研究能够直接观察到自由基中间体或避免表面反应的潜在并发症。在目前的方案中，我们将使用一种新型的高温(高达900K)、高压(高达5atm)的湍流管，提供一种适合于在长达数百毫秒的时间尺度上研究自由基反应的无壁反应器。流动管将直接连接到用于检测自由基的低压荧光池和飞行时间质谱仪，用于检测来自链传播和链分支反应(例如CO和甲醛)的拟议产物。我们的实验将探索链传播(受控氧化)和链分支(爆炸氧化)之间的竞争随温度和压力的变化。观察自由基和稳定产物，结合使用同位素标记的前体，将使我们能够确定二甲醚氧化的分子机制。实验结果将与利兹大学和阿贡国家实验室(Klippenstein和Harding博士)进行的理论计算相结合，以给出整个机制的全貌，并允许我们将结果外推到更广泛的温度和压力范围。这项工作的影响将与高威大学燃烧化学中心主任Henry Curran博士一起通过更新的二甲醚燃烧动力学模型以及与激波管或发动机模拟的最终产品研究进行比较来评估。这项工作具有明显的实际和商业意义，我们正在与福特和国际二甲醚协会(IDA，一直到IDA到沃尔沃技术公司和劳斯莱斯等组织)合作，以增强EPSRC投资的影响。

Dimethylether (DME, CH3OCH3) has considerable potential as an alternative clean fuel. It has energy densities similar to current biofuels such as ethanol, is compatible with existing engine technologies, burns with low NOx and soot emissions and can be distributed via available LPG networks. However, relatively little is known about the 'low temperature' (500 - 900 K) combustion of DME; combustion in this temperature range is particularly important in newer engine technologies such as HCCI (homogeneously charged compression ignition). This proposal seeks to characterise the mechanisms of DME combustion providing useful information to the academic combustion community and industrial collaborators. The proposal is matched to EPSRC priorities in energy research.There have been a number of previous studies on low temperature DME oxidation, but no previous study has been able to observe radical intermediates directly or to be free from potential complications of reactions on surfaces. In the current proposal we will use a novel high temperature (up to 900 K), high pressure (up to 5 atm) turbulent flow tube providing a wall-less reactor suitable for studying radical reactions on time scales of up to several hundred milliseconds. The flow tube will be directly interfaced to a low pressure fluorescence cell for radical detection and a time-of-flight mass spectrometer for detection of the proposed products from chain propagation and chain branching reactions (e.g. CO and formaldehyde).Our experiments will probe the competition between chain propagation (controlled oxidation) and chain branching (explosive oxidation) as a function of temperature and pressure. Observation of radicals and stable products, in conjunction with the use of isotopically labelled precursors, will allow us to determine the molecular mechanism of DME oxidation. The experimental results will be combined with theoretical calculations carried both at the University of Leeds and Argonne National Laboratory (Drs Klippenstein and Harding) to give a full picture of the mechanism and allow us to extrapolate our results to wider ranges of temperature and pressure. The impact of the work will be assessed in conjunction with Dr Henry Curran (Director, Centre for Combustion Chemistry, University of Galway) via updated kinetic models of DME combustion and comparison with end-product studies from shock tubes or engine simulations.The work has obvious practical and commercial implications and we are working with Ford and the International DME Association (IDA, and through to IDA to organisations such as Volvo Technologies and Rolls Royce) to enhance the impact of EPSRC investment.