As an alternative fuel to diesel in compression-ignition (CI) engines, dimethyl ether (DME) has gained interest in combustion research due to its high cetane number for fast ignition and ultra-low emission of particulate matter. In this study, ignition and important intermediate species including formaldehyde (CH₂O) are experimentally investigated in a constant-volume combustion vessel facility that includes a fuel injection system for spray-like behavior of liquid DME. Experiments of different oxygen concentrations simulating various levels of exhaust-gas recirculation (EGR) were performed to study its corresponding effect on the flame structure and emissions from DME combustion. Results from the experiment were then used to validate a 3-D CFD simulation using a detailed chemistry solver. Different stages of ignition characterized by temperature profile, and certain species (e.g., CH₂O for cool flame) after start of injection, are provided to conceptualize the DME combustion process under the effect of low-to-high oxygen ambient gas concentrations. Both simulations and experiments showed that there is a supporting link between CH₂O formation and low-temperature combustion prior to diffusion-controlled flame uniquely for DME. By studying the temperature and equivalence ratio dependence of the reacting spray at different O₂ levels, different stages of ignition along with the formation of CH₂O suggested that the start of the depletion of CH₂O can be used as an ignition indicator.

作为压缩点火（CI）发动机中柴油的替代燃料，二甲醚（DME）由于其十六烷值高，可快速点火且颗粒物质超低排放而引起了燃烧研究的兴趣。在这项研究中，点火和重要的中间物种包括甲醛（CH ₂O）是在恒定体积的燃烧容器中进行实验研究的，该设备包括一个用于液体DME的喷雾状行为的燃料喷射系统。进行了不同氧气浓度的模拟不同排气再循环（EGR）水平的实验，以研究其对火焰结构和DME燃烧排放的相应影响。然后将实验结果用于使用详细的化学求解器验证3-D CFD模拟。不同的着火阶段，其特征在于温度曲线和某些种类（例如，CH ₂在开始喷射后，用O表示冷火焰），以概念化在低至高氧气环境气体浓度的作用下DME燃烧过程。模拟和实验均表明，在DME独特的扩散控制火焰之前，CH ₂ O的形成与低温燃烧之间存在支撑联系。通过研究在不同O ₂水平下反应喷雾的温度和当量比依赖性，在不同的点火阶段以及CH ₂ O的形成表明，CH ₂ O耗尽的开始可以用作点火指示剂。