State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, PR China.
J Hazard Mater. 2011 May 15;189(1-2):34-9. doi: 10.1016/j.jhazmat.2011.01.101. Epub 2011 Feb 1.
A series of comparative laboratory-scale experiments were carried out in the Lhasa plateau and the Hefei plain respectively to investigate the characteristics of flame spread over the extruded polystyrene (XPS) foam, a typical thermal insulation material. Flame shape and the temperature profile in solid phase were monitored, and the effects of altitude on the heat transfer process were analyzed. The results show that the temperature rise with time undergoes three stages: the preheating stage, the melting stage and the pyrolysis stage. The durations of the melting and pyrolysis stages on plateau are longer than that in plain, which sequentially results in a lower flame spread rate on plateau. Comparing of the temperature change rate curve on plateau with that in plain, it is found that the peak characteristics of the curves in the pyrolysis stage changed from single peak to multi-peaks, which suggests that the altitude difference might change the pyrolysis mechanisms of XPS material. Moreover, the sample scale effects on flame spread are also explored. Two different regimes are found in flame spread behavior with sample scale at the both altitudes. The spread rate drops with sample scale in convection regime and rises in radiation regime.
分别在拉萨高原和平顶山地区进行了一系列实验室规模的对比实验，以研究挤出聚苯乙烯（XPS）泡沫这种典型隔热材料表面火焰传播的特性。监测了火焰形状和固相温度分布，并分析了海拔高度对传热过程的影响。结果表明，升温过程随时间经历三个阶段：预热阶段、熔融阶段和热解阶段。高原地区的熔融和热解阶段持续时间比平原地区长，导致高原地区的火焰传播速度较低。对比高原和平原地区的温度变化率曲线发现，热解阶段曲线的峰值特征从单峰变为多峰，这表明海拔差异可能改变了 XPS 材料的热解机制。此外，还探讨了样品规模对火焰传播的影响。在两个海拔高度下，火焰传播行为的样品规模存在两种不同的模式。在对流区，随着样品规模的增加，传播速度下降；在辐射区，传播速度随样品规模的增加而上升。
