Efficiency of energy release by burning of layered leaf fuels under external radiant heat flux was studied using a cone calorimeter. By performing the ignition and sustained burning measurements with coniferous and broadleaf plants, a method was developed to determine the combustion efficiency during sustained burning χ_c. Experimental results showed that at the same radiant heat flux, an increase in the sample mass (density) leads to substantial decrease in χ_c followed by a level‐off, and the increase in leaf moisture content results in significant reduction of χ_c. Analysis indicated that χ_c is essentially independent to the sample mass when a sample is constituted by three layers. By defining a ratio of the amount of CO produced to that of O₂ consumed during measurement ϕ_CO/O2, χ_c was found to be well correlated by ϕ_CO/O2 with the form χ_c = 0.2166ln[0.4655/(ϕ_CO/O2 − 0.03177)], thereby highlighting that energy release efficiency of a sample mainly relies on the extent of O₂ consumed to convert into CO. The parameter χ_c acts as an indicator to reveal the combustion states of a fuel during testing, and the parameter ϕ_CO/O2 can be used as an index to evaluate the capacity of leaf fuels to emit toxic gases in specific fire scenarios.

中文翻译：

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外部辐射热通量下分层叶片燃料持续燃烧的效率

使用锥形量热仪研究了在外部辐射热通量下燃烧层状燃料产生的能量释放效率。通过执行点火和持续燃烧与针叶林和阔叶植物测量，方法开发期间持续燃烧确定燃烧效率χ _Ç。实验结果表明，在相同的辐射热通量，增加样品质量（密度），因而在显着降低χ _Ç随后是水平截止，并在显著减少的增加叶的水分含量的结果χ _Ç。分析表明，χ _Ç当样品由三层组成时，它基本上独立于样品质量。通过定义的CO的量的比率产生到的O- ₂测量期间消耗φ _{CO / Ò 2}，χ _Ç被发现很好地相关φ _{CO / ö 2}与表单χ _Ç = 0.2166ln [0.4655 / （φ _{CO / ö 2}  - 0.03177） ]，从而突出的样品的能量释放效率主要依赖的O-程度₂消耗转换成CO参数。χ_c用作显示燃料在测试过程中燃烧状态的指标，参数ϕ _{CO / O 2}可以用作评估叶片燃料在特定火灾情况下释放有毒气体的能力的指标。