Abstract Several different ether components have been proposed as renewable replacements for diesel fuel in compression ignition engines. From a fundamental point of view, blends of n-heptane and dimethyl ether (DME) have been considered in this study, where n-heptane is a single-component diesel surrogate and DME acts as a representative for oxymethylene ethers. n-Heptane and n-heptane / DME blends have been investigated experimentally under laminar premixed low-pressure and non-premixed atmospheric-pressure counterflow flame conditions. For the premixed case, a series of three fuel-rich flames was studied with oxygen as the oxidizer, at a constant C/O ratio of 0.47, pressure of 4 kPa, with 50% argon dilution, and an equivalence ratio ϕ near 1.5, burning pure n-heptane and mixtures of n-heptane with DME in the ratios 1:1 and 1:4. In the non-premixed counterflow configuration, two fuel/oxygen/argon flames were studied with pure n-heptane and a 1:1 DME–n-heptane mixture as the fuel. Electron ionization molecular-beam mass spectrometry was used for both flame configurations to investigate the flame structure and determine quantitative mole fraction profiles of stable and reactive species formed in the combustion process. Particular attention was given to the changes caused by partial replacement of n-heptane by DME. Notwithstanding the experimental focus of this work, the experimental results were compared with predictions from a model suitable for both n-heptane and DME that was combined for this case from recent mechanisms available in the literature for these fuels. While the overall flame structure was not significantly altered upon DME addition, with some smaller differences mainly due to temperature effects, more prominent changes and interactive effects were found for a number of primary decomposition products, oxygenated species, and higher-molecular hydrocarbon compounds. In most cases, experimentally observed trends, but not always quantitative changes, could be satisfactorily reproduced and explained by the model.

中文翻译：

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添加二甲醚对正庚烷燃烧影响的层流预混和非预混火焰研究

摘要 几种不同的醚组分已被提议作为压燃式发动机中柴油燃料的可再生替代品。从基本的角度来看，本研究中考虑了正庚烷和二甲醚 (DME) 的混合物，其中正庚烷是单组分柴油替代品，而 DME 作为甲醛醚的代表。正庚烷和正庚烷/二甲醚混合物在层流预混低压和非预混常压逆流火焰条件下进行了实验研究。对于预混情况，以氧气为氧化剂，在恒定的 C/O 比为 0.47、压力为 4 kPa、氩气稀释度为 50% 和当量比 φ 接近 1.5 的情况下，研究了一系列三种富含燃料的火焰，燃烧纯正庚烷和正庚烷与 DME 的比例为 1:1 和 1:4 的混合物。在非预混逆流配置中，使用纯正庚烷和 1:1 DME-正庚烷混合物作为燃料研究了两种燃料/氧气/氩火焰。电子电离分子束质谱法用于两种火焰配置，以研究火焰结构并确定燃烧过程中形成的稳定和反应性物种的定量摩尔分数分布。特别注意了由 DME 部分替代正庚烷引起的变化。尽管这项工作的实验重点是，将实验结果与适用于正庚烷和二甲醚的模型的预测进行了比较，该模型在这种情况下结合了这些燃料文献中可用的最新机制。虽然加入 DME 后整体火焰结构没有显着改变，除了一些主要受温度影响的较小差异外，一些初级分解产物、含氧物质和高分子烃化合物的变化和交互作用更为显着。在大多数情况下，模型可以令人满意地再现和解释实验观察到的趋势，但并不总是定量变化。