Wall chemical effect on DME/air weak flames (U_in = 1.5 cm/s, ϕ = 0.85) was investigated using a micro flow reactor with a streamwise temperature gradient experimentally. The quartz channel used in this study has a rectangular cross-section of 1.5 × 5 mm, which offers a good optical access for the planar laser-induced fluorescence (PLIF) measurement. The walls can be replaced for examining wall chemical effects of different wall materials. Wall surface materials, quartz, SiC, type 321 stainless steel (SUS321), iron, nickel and chromium, were employed. For SiC, SUS321 and metals, a 150-nm-thick film is deposited on the inner surface of the quartz channel to achieve different wall chemical boundary with identical thermal boundary condition. Streamwise distributions of DME, CO and CO₂ in the weak flame were measured with the gas chromatography (GC), and HCHO and OH distributions were measured through PLIF. It is found that species distributions in both the low- and high-temperature oxidation zones of the weak flame are significantly altered for different wall surface materials. Comparing with that in the quartz and SiC-coated channel, DME in the SUS321-coated channel has a much higher concentration in the negative temperature coefficient (NTC) region, while CO and HCHO have lower concentrations. The peak of OH is shifted downstream, and so as the rising of CO₂. According to the results of the pure metal-coated channels, iron and nickel in the SUS321 should be responsible for the changes. These results suggest that the wall chemical effect of metal may exert strong influence on the low-temperature oxidation, which changes the species pool in the cool flame and leads to a modification of the hot flame region downstream.

 使用具有流向温度梯度的微流反应器，研究了壁化学对DME /空气弱火焰（U _in  = 1.5 cm / s，ϕ = 0.85）的影响。本研究中使用的石英通道的横截面为1.5×5 mm，为平面激光诱导荧光（PLIF）测量提供了良好的光学通道。可以更换墙壁以检查不同墙壁材料的墙壁化学作用。墙面材料，石英，SiC，321型不锈钢（SUS321），铁，镍和铬，被雇用。对于SiC，SUS321和金属，在石英通道的内表面上沉积150 nm厚的膜，以在相同的热边界条件下获得不同的壁化学边界。用气相色谱仪（GC）测量弱火焰中DME，CO和CO _2的流向分布，并通过PLIF测量HCHO和OH的分布。发现对于不同的壁表面材料，弱火焰的低温和高温氧化区中的物质分布都发生了显着变化。与石英和SiC涂层通道中的DME相比，SUS321涂层通道中的DME在负离子中的浓度更高温度系数（NTC）区域，而CO和HCHO的浓度较低。OH的峰向下游移动，因此CO ₂上升。根据纯金属通道的结果，SUS321中的铁和镍应负责变化。这些结果表明，金属的壁化学作用可能会对低温氧化产生强烈影响，从而改变冷火焰中的物质库并导致下游热火焰区域的改变。