Abstract Flaming ignition properties of dead and live thin wildland porous fuels submitted to different incident heat flux intensities are examined experimentally using a cone calorimeter. Data are compared to analytical and numerical results of a model that uses an energy balance and includes energy and temperature ignition criteria. The model provides the linear trend of ignition time for large heat flux intensities, but fails to reproduce the behavior of data near threshold ignition, because it does not include explicitly volatiles emission at pyrolysis. A new method is proposed for the estimation of the critical heat flux for ignition of porous fuels, based on the ignition time behavior as a power-law that characterizes phase transitions theory. The critical heat flux for ignition thus estimated has been found small compared to literature data. The discrepancy is due to the probabilistic ignition behavior observed in the critical region and ignored by literature that uses deterministic methods for the estimation of the critical heat flux for ignition. The heterogeneities of fuel particles composition and arrangement could be the major causes of such a probabilistic aspect.

中文翻译：

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点火/非点火相变：一种新的临界热通量估算方法

摘要 使用锥形量热计实验研究了在不同入射热通量强度下死的和活的稀薄荒地多孔燃料的燃烧特性。数据与使用能量平衡并包括能量和温度点火标准的模型的分析和数值结果进行比较。该模型提供了大热通量强度下点火时间的线性趋势，但未能重现接近点火阈值的数据行为，因为它没有明确包括热解时的挥发物排放。基于点火时间行为作为表征相变理论的幂律，提出了一种估计多孔燃料点火的临界热通量的新方法。与文献数据相比，由此估计的点火的临界热通量很小。这种差异是由于在临界区域观察到的概率点火行为而被使用确定性方法估计点火的临界热通量的文献忽略了。燃料颗粒组成和排列的异质性可能是这种概率方面的主要原因。