Comparison of Natural Upward and Downward Smoldering Using the Volume Reaction Method
Comparison of Natural Upward and Downward Smoldering Using the Volume Reaction Method
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DOI：
10.1021/ef900646p
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发表时间：
2009-10
期刊：
影响因子：
5.3
通讯作者：
Fang He;F. Behrendt
中科院分区：
文献类型：
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作者：
Fang He;F. Behrendt
采用体积反应法对自然正向阴燃（通常发生在固体燃料的热化学转化过程中）和自然反向阴燃（通常发生在堆料自燃火灾中）进行了理论比较。采用一维垂直传播的堆积木炭粉阴燃模型，其中向上阴燃为反向阴燃，向下阴燃为正向阴燃。计算表明，自然向上阴燃和向下阴燃存在显着差异。以下情况适用于我们的模拟案例：（1）向上阴燃由炭氧化动力学主导，而向下阴燃则由氧气传输控制。(2)向上阴燃的传播速度比向下阴燃快10倍以上，但向上阴燃的碳转化程度远小于向下阴燃。（3）向上阴燃（<630 K）燃料内部温度明显低于向下阴燃（600- 900 K）。（4）在向上阴燃和向下阴燃中，炭化都发生在氧含量很低（<5%）的情况下。通过理论分析预测的这些特性与文献中的实验观察定性一致。
Natural forward smoldering (which normally occurs in thermochemical conversion of solid fuel) and natural reverse smoldering (which normally occurs in self-ignition fire in piled materials) have been compared theoretically using the volume reaction method. One-dimensional vertical propagation of piled charpowdersmolderingwasusedasthemodelcase,inwhichupwardsmolderingisreversesmolderingwhile downward smoldering is forward smoldering. Calculation has revealed that there is significant difference between natural upward and downward smoldering. The following applies in our simulation case: (1) Upward smoldering is dominated by kinetics of char oxidation while downward smoldering is oxygen transport controlled. (2) The propagation velocity of upward smoldering is more than ten times faster than thatofdownwardsmoldering.However,thedegreeofcarbonconversionofupwardsmolderingismuchless thanthatofdownwardsmoldering.(3)Thetemperatureinsidethefuelbedofupwardsmoldering(<630K) issignificantlylowerthanthatofdownwardsmoldering(600-900K).(4)Charoxidationoccursatverylow oxygen fractions (<5%) in either upward or downward smoldering. These characteristics predicted via theoretical analysis are in qualitative agreement with experimental observations in the literature.