The Influence of Particle Surface Area-to-Mass Ratio on Flame Residence Time and Mass Loss Rate of Forest Fuel Beds

Combustion duration is a fire behaviour feature relevant for both the effects and management of fire. We burned small-scale laboratory fuel beds (n = 135) of eight fuel types and developed empirical models to describe variation in flame residence and burn-out times, and fuel mass fraction loss rates during flaming and non-flaming combustion; each fuel sample was ignited at once and burned as a pile. Surface area-to-mass ratio of the fuel particles, by itself, allowed accurate prediction of all combustion properties with better performance than surface area-to-volume ratio. Fuel bed structure was also shown to have an influence, fuel load being the variable that further improved all predictions. This work provides evidence that surface area-to-mass ratio is an adequate descriptor of the combustion characteristics of forest fuel beds. Our expectation is that this approach will assist future modelling efforts to obtain simple empirical models to predict the combustion features of free-spreading fires in a wide range of vegetation types.