Mechanism Study On The Pool Fire Suppression With Water Mist

In recent years, with the environmental issues become more prominently, there is growing emphasis on environmental protection. In the field of fire suppression, the old extinguishing agent is gradually quit the stage and at the some time a new generation of fire extinguishing agent is on the rise. Water mist as a new direction in the field of fire suppression caused the world’s attention in recent years.In this paper, the fire enhancement phenomenon and the mechanism on fire extinguishing have been studied with numerical simulation and experiment. The result shows, in the early time, when the mist is applied, the phenomenon of flame strengthen is very common. The main reason of the flame enhancement will be divided into three factors, The first is the disturbance of water mist, which can introduce oxidant from surroundings; The second is the interaction between water mists and flame, which may cause the water-gas reaction and produce more combustible gas. The third is the physical effection between water mist and pool fires, when the droplets get to the fuel surface, it splashes a lot of oil droplets, making the evaporation speed more quickly, thereby strengthening the burning. It shows that the first and the third elements are the main factors when the fuel is petrol, diesel or kerosene. the second element may be exist, but not the main factor about the flame enhancement. For alcohol, the flame strengthen only because the third factor.In numerical simulation,parameters are as possible as consistent with the experimental parameters. Use alcohol as the fuel, the oil pan simplified as a jet flame with low speed, which speed is calculated by the evaporation rate of alcohol.Through the analysis of temperature and reaction diagram, the main factor of fire suppression is the evaporation of water mists in flue gas and take quantity of heat; at the same time it also can diluted fuel, when the fuel concentration reach to a certain extent, the flame goes out. From the fire suppression time, we can see large-scale fire use shorter time compared with small-scale in suppression process, which is consistent with the actually fire suppression process. This shows that using Fluent simulation has some significance for practical application.