OVERVIEW

All the methods presented here apply the same fundamental assumption, that is, ignition occurs when the surface reaches a critical temperature defined as the ignition temperature. In addition, they assume that the material is chemically inert, has constant thermophysical properties, and is opaque. The methods are all derived assuming one-dimensional heat transfer through the solid with radiant heating on the surface. The first method presented is for thin fuels such as fabrics or paper. There have been only a limited number of studies of thin fuels available, and data sources are scarce. In most cases the engineer is interested in thick fuels such as wood siding on a building. Therefore, the more common thick fuels dominate the ignition literature, and there are several methods of varying complexity available. The methods are in general presented from simple to more complex. The exception to this is the classical thermally thick solution that can be found in the heat transfer text16 and has been described in the context of the ignition problem by Mikkola and Wichman.17 The thermally thick solution is presented just after the thermally thin case but before some other simpler techniques because it gives the most fundamental solution for a one-dimensional solid exposed to a radiant heat flux. Discussing this first should aid the reader in the subsequent discussion. Each method is labeled according to the original author so that the reader can easily locate the original source when additional information is desired.

Each method is first described and...