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Experimental Study on Spontaneous Ignition of Wood Exposed to Variable Heat Flux

The ignition of combustible materials is an important process in a fire incident. In this work, an experimental study on the ignition process of wood exposed to a variable heat flux has been carried out. Increasing heat flux is adopted and adjusted to simulate a practical fire environment. The time to ignition, temperature distribution, and mass loss are measured for two species of wood. Both, the increasing rate of incident heat flux and the properties of wood, especially density, obviously affect the results. A conduction model is developed to calculate the surface temperature. A compound ignition criterion is brought out for a variable heat flux.