Glowing Combustion

Glowing combustion is the phase of combustion when only embers are visible. Glowing combustion refers to the process of surface oxidation of solids occurring in the final stage of the smoldering process (Simmons 1995). The glowing phase of combustion occurs when there is no longer enough energy to create the aerosol smoke characteristic of the smoldering phase, and thus there is no longer a release of tars, volatiles, or liquids from the fuels. Oxygen in the air can now reach the fuel surface and the charcoal begins to burn with a characteristic yellow glow with no visible smoke.

The main products released by fuels in the glowing phase are the invisible gases carbon monoxide (CO) and carbon dioxide (CO₂). Although the temperatures associated with the glowing phase are usually around 600ºC, much lower than the temperatures associated with flaming combustion, the heat remains in a particular location for longer duration thus large amounts of organic decomposition can occur during this phase (Pyne et al. 1996). The glowing phase eventually ends when the temperature of the surrounding char drops to a point where pyrolysis can no longer occur.