Abstract:

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 2^nd was delayed and the average mass loss rate was decreased.

Key words: Burning behaviour, Plantation wood, Cone calorimeter