Supan Wang , Kaifeng Wang , Chunyin Zhang , Xinyan Huang
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引用次数: 0
摘要
点火涉及燃料层和热颗粒之间的动态相互作用,但对快速移动的热颗粒点火的科学理解仍然有限。在这里,我们用不同水平速度、温度和尺寸的热钢粒子来点燃垂直取向的低密度可发性聚苯乙烯泡沫。高速粒子可直接嵌入泡沫中,达到闪点、着火点或不着火的效果,而低速粒子则会从泡沫中弹出,不会着火。结果表明,对于温度为 1150 °C 的粒子,其嵌入的最小速度为 12.00 m/s。随着粒子温度的升高,热粒子嵌入或点燃的临界速度略有降低。这些高速粒子的最低点火温度比接近静态或低自由落体速度的粒子高 200 °C,这是因为粒子的停留时间较短,不足以产生可燃混合物。此外,当颗粒速度太慢无法弹开也太快无法嵌入时,它将部分嵌入样品表面烧毁燃料,构成最大的火灾隐患。这加深了我们对热运动粒子与保温泡沫之间复杂相互作用的认识,从而降低了建筑外墙的点火风险。
Spotting ignition of plastic foam by a fast-moving hot metal particle
Spotting ignition involves dynamic interaction between fuel bed and hot particles, but the scientific understanding of the ignition by a fast-moving hot particle is still limited. Herein, a hot steel particle with various horizontal velocities, temperatures, and sizes is shot to ignite vertically oriented low-density expandable polystyrene foam. A high-speed particle can directly get embedded into the foam to achieve flash-point, fire-point, or no ignition, while a low-speed particle bounces away from the foam without ignition. Results show that for a particle of 1150 °C, its minimum velocity for embedding is 12.00 m/s. Such a critical velocity for hot-particle embedded or ignition slightly decreases as particle temperature increases. Minimum ignition temperature of these high-speed particles is 200 °C higher than that of near-static or with a low free-fall velocity, due to the shorter residence time and insufficient to produce a flammable mixture. Moreover, when the particle is neither too slow to bounce away nor too fast to get embedded, it will be partially embedded on the sample surface to burnout the fuel, posing the biggest fire hazard. It deepens our knowledge of the complex interaction between hot moving particles and insulation foam to reduce spotting fire risk for building façade.
期刊介绍:
Fire Safety Journal is the leading publication dealing with all aspects of fire safety engineering. Its scope is purposefully wide, as it is deemed important to encourage papers from all sources within this multidisciplinary subject, thus providing a forum for its further development as a distinct engineering discipline. This is an essential step towards gaining a status equal to that enjoyed by the other engineering disciplines.