Identification and quantitative analysis of smoldering and flaming combustion of radiata pine

Abstract

Smoldering combustion is an important combustion process in wildfires; however, there are fewer experimental studies recorded in the literature in comparison with flaming combustion. An experimental study was conducted to characterize the initiation of smoldering and flaming combustion of biomass using temporal and spatial temperature profiles, mass loss profiles, and gas analyses. The results show that the peak temperature, temperature rise rate, and average mass loss rate of flaming combustion are much higher than those of smoldering combustion. The results on the ratio of CO to CO₂ for flaming and smoldering combustion show good agreement with the data reported in the literature. The results also show that smoldering combustion can be initiated only under a low air flow; for the experimental apparatus used, this corresponded to flow velocity of ≤38.1 mm·s⁻¹. A combustion progress pathway diagram was developed that describes the stages of smoldering and flaming combustion of a single dry biomass particle. An analysis of combustion kinetic parameters (activation energy and pre-exponential factor) and an energy balance analysis were also conducted to understand the differences between smoldering and flaming combustion.