Experimental investigation on the smoldering limit of scraps of paper initiated by a cylindrical rod heater
Experimental investigation on the smoldering limit of scraps of paper initiated by a cylindrical rod heater
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DOI：
10.1016/j.proci.2018.07.049
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发表时间：
2019
影响因子：
3.4
通讯作者：
Hui Yan;O. Fujita
中科院分区：
文献类型：
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作者：
Hui Yan;O. Fujita
实验测定了几种堆积密度的纸屑在不同外部空气流量下的阴燃着火温度。将压缩的纸屑床装入垂直燃烧室中以获得不同的体积密度，并将电设定的棒式加热器的温度加热到350至450 °C之间的温度。一旦棒加热器达到设定温度，则关闭电流供应，并将加热器嵌入填充有纸屑填充床的垂直燃烧室的中间。通过记录燃烧室内不同位置的温度变化，得到了不同体积密度的纸屑在不同外部空气流量下的着火极限。结果表明，在无外部空气流动时，着火温度随堆密度的增加先降低，在达到临界值后，堆密度的增加导致着火温度升高。此外，我们发现，即使在静止的情况下（没有外部空气流动），对于发生点火的情况下，阴燃前锋首先到达燃烧室的底部侧，然后传播到上部侧。在有外部气流的情况下，阴燃锋在着火时也向燃烧室底部传播，外部气流对低容重、中容重和高容重纸屑床的着火极限分别起着不同的作用。
The ignition temperature for smoldering in scraps of paper has been determined experimentally for several bulk densities under different external air flows. Beds of compressed scraps of paper were packed into a vertical combustion chamber to achieve different bulk densities and the temperature of an electrically set rod-heater was heated to temperatures between 350 and 450 °C. Once the rod-heater had reached the set temperature, the electric current supply was then turned off and the heater was embedded into the middle of the vertical combustion chamber filled with a packed bed of paper scraps. We obtained the ignition limit of the scraps of paper for different bulk densities under different external air flows by recording the temperature evolution at different positions in the combustion chamber. Results show that without external air flow, the ignition temperature first decreased with an increase in bulk density, then after a critical value, an increase in bulk density led to an increase in the ignition temperature. Furthermore, we found that even under a quiescent case (without external air flow), for the cases where ignition occurred, the smoldering front first reached the bottom side of the combustion chamber, then propagated to the upper side. As for cases with external air flows, again the propagations of the smoldering front towards the bottom side of the combustion chamber were observed in the cases where ignition happened, and external air flows played different roles in ignition limit of paper scraps bed with low bulk density, medium bulk density and high bulk density regime, respectively.