Effect of heat flux on combustion of different wood species

The fire safety of wood is the most important concern in its structural and architectural applications. In this work, the combustion of three typical wood species, namely, oak, larch and red cedar exposed to various heat fluxes was studied using the cone calorimeter. The fire performance including heat release rate, charring rate, production of toxic carbon monoxide and release of carbon dioxide was quantified. It is found that the fire performance of the wood species exposed to a low heat flux of 20 kW/m² differs completely from that exposed to a heat flux higher than 35 kW/m². The effect of temperature on wood pyrolysis is attenuated with the increment of temperature. Compared with oak and larch, the fire performance of red cedar is more dependent on heat flux. Although red cedar requires less time to be ignited, it has the lowest heat release rate and the smallest amount of heat release, and exhibits a slower flame spread speed and the fastest charring rate with a high fire resistance rating. The satisfactory fire resistance of red cedar with a minimal heat flux effect on pyrolysis is correlated to the relatively high lignin content. Our findings provide guidance for woody structural design with a reduction in the emissions of harmful compounds.