Fire Safety Science Digital Archive

Effects of phase change on the flame spread over the porous solid soaked with a combustible liquid have been analyzed for the case when the main mode of heat transfer is conduction. In the model, the fuel-soaked layer is assumed to be divided into three regions: liquid-solid region; three-phase region; vapor-solid region. It is shown that the flame spread rate increases with the thickness of three-phase region. The thickness of the three-phase region increases with the decrease of the diameter of solid particles because of the capillary effects. These results imply that the flame spread rate decreases with the increase of the diameter of solid particles. Thus, the decreasing tendency of the flame spread rate can be explained. The flame behavior as well as the temperature distributions predicted in the present study fairly well coincides with the experimental results, and the model developed here is shown to be valid.