自然老化木材燃烧过程热行为特性研究

Analysis on thermal characteristics of naturally aging wood during combustion

为提供古建筑火灾数值模拟及风险评估的基础理论,从自然老化角度入手,选取经过长久自然老化的建筑服役木材作为研究对象,通过扫描电镜(SEM)及热物性试验对比分析自然老化木材与参照木材的外观形态及热传导特征;采用差示扫描量热DSC法,研究自然老化木材在燃烧过程中热释放的阶段特性,分析不同升温速率对老化木材热行为影响特征;基于热流计算并分析老化木材在热反应过程表观活化能分布。结果表明:自然老化木材热扩散能力增强;自然老化作用可降低木材着火及燃烧过程所需能量;其对于木材着火前期能量需求的影响较大,大大降低木材燃烧过程需要的峰值能量壁垒。

In order to provide the basic theory for numerical simulation and risk assessment of historic building fire,with naturally aging wood as research object,their appearance and thermal conduction characteristics and those of reference wood were analyzed by scanning electron microscopy(SEM)and thermal property test from the perspective of natural aging.Then,their thermal release features at different stages during combustion were studied by using differential scanning calorimetry(DSC),and effects of different heating rates on thermal behavior of aging wood were analyzed.Finally,their apparent activation energy distribution during thermal reaction was calculated and analyzed based on heat flow.The results show that the thermal diffusion ability of naturally aging wood is enhanced.Natural aging reduces the energy required in the ignition and combustion process of wood,and has a great influence on energy demand before ignition,thus greatly reducing peak energy barrier needed during ignition.