Thermal behaviour of glowing firebrands: Implications for non-reactive surfaces

Understanding the thermal behaviour of firebrand piles is essential for assessing their energy transfer characteristics and their impact on underlying materials. Due to experimental limitations in capturing spatial thermal distributions within and beneath the pile, as well as the thermal response of individual firebrands within the pile. This study employed a numerical approach to investigate the thermal performance of smouldering firebrand accumulations. The model examined the effects of varying wind speeds (0.9–2.7 m/s) and coverage densities (0.06 and 0.16 g/cm²) on firebrand surface temperature, released heat flux, and heat flux received by the substrate. Model accuracy was verified by comparing its output with the heat release rate per unit area (HRRPUA) derived from an experimental study, ensuring the reliability of the numerical data. Results showed that increased wind speeds and coverage densities significantly increase both average and localized thermal parameters. For smouldering firebrand accumulations, peak average total heat flux to the substrate ranged from 19 to 52 kW/m², while localized regions within the pile reached up to 120 kW/m². These findings demonstrate the importance of spatial thermal analysis in characterizing firebrand pile behaviour.