利用锥形量热仪对人工林杉木、杨木和马尾松的燃烧性进行了研究。木材从受热开始到结束有两个释热峰;木材失重过程与释热过程有着相似的变化曲线,这是失重和释热密切相关的结果;木材开始受热到着火前和炭化过程结束后发烟最大,炭化过程和无焰燃烧阶段发烟最低。对同一树种而言,热源辐射强度、加热面种类和样品厚度对燃烧特性有不同程度影响。热源辐射强度愈强,着火所需时间也越短,木材释热和失重速度越快,烟气浓度和发烟总量增加。加热面为横切面(R×T)的样品着火所需时间比纵切面(L×T或L×R)的长,而且第二释热峰极值增大,平均失重率呈增大趋势。样品厚度对木材引燃时间、燃烧180s的总释热量影响不大,但样品厚度增加使第二释热峰出现延迟且峰值有所下降。当加热面为横切面时,样品厚度增加使平均失重率有下降趋势
Burning behaviour of three wood species (two softwoods and one hardwood) was tested by cone calorimeter in the study. Two kinds of thickness (10 mm and 20 mm) and two types of heated surface [cross section (R×T) and longitudinal section (L×R or L×T)] were chosen, and three levels of irradiance (30kW·m-2 ,40 kW·m-2 and 50 kW·m-2 ) were used. The results showed that there were two heat release rate peaks of the specimens from beginning to end of the irradiation. The mass loss was closely related to the heat release because they indicated the same changing curves. There were two stronger process of smoke, one was before the igniting and another one was after the charring finished. The weakest smoke appears in the charring and flameless combustion stage. Meanwhile, the effects of specimen thickness, heated surface and irradiance level on the ignition time, heat release rate, mass loss rate and extinction coefficient were investigated. The ignition time was decreased and the heat release rates, mass loss rates and extinction coefficient were increased with the increase of the irradiance levels. When the cross section was used as a heated surface, the ignition time was longer and the heat release or mass loss was faster than the longitudinal section. The effect of thickness on the ignition time and the total heat release of 180 s(the period starting at ignition time and ending 180s later) were not significant. With the increase of the thickness, the heat release rate peak at 2nd was delayed and the average mass loss rate was decreased.