Effect on Radiant Heat Transfer at the Surface of a Pool Fire Interacting With a Water Mist

It is well established that the use of water mist can be an attractive alternative to gaseous suppression agents to extinguish fires for specific scenarios. Among the main mechanisms, which act together to extinguish fires when using a water mist: heat extraction, oxygen displacement, and radiant heat attenuation, the last one has received the less attention, especially regarding the energy balance at the fuel surface and, therefore, the rate of generation of flammable vapors. The objective of this work is to analyze, on the one hand, the perturbing influence of a mist addition as an opposed flow to a small-scale liquid (heptane) pool fire structure, especially at its base, the more interesting zone regarding the mechanisms of flame stabilization and extinction and, on the other hand, the effect on the surface radiant heat feedback. Experiments conducted give an order of magnitude estimate in essential agreement with a radiation computation, based on the mappings, previously obtained, of the two major parameters: temperature and extinction coefficient, that determine the thermal radiation of the flame. The important information is the confirmation that radiation attenuation cannot be identified as a predominant mechanism of extinguishment.