A more straightforward combustion map for identifying moderate or intense low-oxygen dilution (MILD) combustion regime in a well-stirred reactor (WSR) using initial inlet temperature (T_in) and oxygen mole fraction (X_O2) has been proposed based on previous mathematical criteria provided by Cavaliere and de Joannon ( Prog. Energy Combust. Sci. 2004, 30, 329−366). Furthermore, the detailed evolution of different combustion regimes under the nonadiabatic condition has been comprehensively examined. Results show that there exists a critical X_O2 (X_O2*), below which MILD combustion can be established unconditionally as long as T_in exceeds the self-ignition point (T_si) and beyond which T_in needs to be remarkably promoted to fulfill the mathematical criteria of MILD combustion. Thus, the two regions are termed unconditional MILD combustion (UMC) and conditional MILD combustion (CMC), respectively. For the adiabatic condition, X_O2* is calculated to be 9.7%, indicating that MILD combustion will be more easily achieved with an oxygen-diluted oxidizer than the oxygen-enriched counterpart. Interestingly, X_O2* is found to climb as the heat loss ratio (HLR) increases, suggesting that enhancing the HLR of the WSR would help expand the UMC region, namely, more readily establishing MILD combustion. In addition, high-temperature combustion (HTC) can shift to CMC or even UMC by just enlarging HLR, providing a potential solution to realize MILD combustion in practical applications. However, the combustion regime would further shift to unsteady combustion (USC) or even no reaction (NR) regions once the heat is overextracted. Hence, it would be a challenge for MILD combustion application in intense heat extraction scenarios, such as boilers. Interestingly, higher T_in and lower X_O2 are found able to widen the UMC region under larger HLR conditions. Moreover, CO₂ or H₂O dilution would result in a wider UMC region compared to N₂ dilution, while it is more pronounced for CO₂ due to its highest X_O2*. Besides, the shifting of the combustion regime from HTC to MILD combustion by heat extraction would be more effective with CO₂ dilution than either N₂ or H₂O dilution.

中文翻译：

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在非绝热搅拌器中通过甲烷的T _in和X _O2初始条件重新识别轻度燃烧状态

基于先前的建议，提出了一种更直接的燃烧图，用于使用初始入口温度（T _in）和氧气摩尔分数（X _O2）来确定搅拌良好的反应堆（WSR）中的中等或强烈的低氧稀释（MILD）燃烧方式。通过卡瓦列雷和DE Joannon（提供的数学准则PROG。能源燃烧。科学。 2004，30，329-366）。此外，已经全面检查了非绝热条件下不同燃烧方式的详细演变。结果表明存在一个临界X _O2（X _O2*），如果T _in超过自燃点（T _si），则可以无条件建立MILD燃烧，并且需要显着提高T _in以满足MILD燃烧的数学标准。因此，这两个区域分别称为无条件MILD燃烧（UMC）和有条件MILD燃烧（CMC）。对于绝热条件，X _O2 *计算为9.7％，这表明用氧气稀释的氧化剂比富含氧气的氧化剂更容易实现MILD燃烧。有趣的是，X _O2 *随着热损失率（HLR）的增加，碳纳米管的含量会上升，这表明提高WSR的HLR将有助于扩大UMC区域，即更容易建立MILD燃烧。此外，仅通过增大HLR即可将高温燃烧（HTC）转换为CMC甚至UMC，为在实际应用中实现MILD燃烧提供了潜在的解决方案。但是，一旦热量过度提取，燃烧状态将进一步转变为不稳定燃烧（USC）甚至没有反应（NR）区域。因此，对于MILD燃烧应用在诸如锅炉之类的高热量提取场景中将是一个挑战。有趣的是，发现在较高的HLR条件下，较高的T _in和较低的X _O2能够加宽UMC区域。而且，CO与N ₂稀释相比，₂或H ₂ O稀释将导致更宽的UMC区域，而CO ₂由于其最高的X _O2 *而更显着。此外，通过CO ₂稀释，通过吸热将燃烧方式从HTC燃烧转换为MILD燃烧比使用N ₂或H ₂ O稀释更有效。