Experimental Study Of Water Mist Fire Extinguishing To The Building Fire On Heat Release Rate

In recent years,the number of high-rise buildings in China has continuously increased,and major accidents such as building fires often occur in and around cities.Therefore,it is particularly important to study how to effectively extinguish fires.The water mist fire extinguishing technology has the characteristics of less water consumption,small impact on the object to be protected,no damage to the environment,and no pollution,and thus plays a significant role in extinguishing the fire.The water mist fire extinguishing effect is affected by various factors.During the actual use,the fire extinguishing test should be carried out according to the selected fine water mist nozzle and the actual fire extinguishing scene,so as to optimize the nozzle arrangement of the fine water mist fire extinguishing system and obtain the best fire extinguishing effect.Therefore,it is necessary to find out in the field of building fires,how much influence does the fine water mist have on the fire intensity(heat release rate)? Based on the above understanding,in this paper,a small-flow nozzle is selected to perform the experiment of water mist eliminating the oil fire in the building space.and the influence of water mist fire extinguishing factors on the heat release rate is studied and analyzed.First of all,for the experimental test of the heat release rate(from 0 to 20 KW)under the conditions of water mist,the horizontal offset distance of the oil pan from the sprinkler in the building space,the vertical distance between the oil pan and the sprinkler,the area of the oil pan,the pre-burning time and the nozzle pressure were studied.Secondly,the influence of the peak heat release rate of ethanol and the peak arrival time of heat release rate under the condition of water mist were discussed.Theresults show that there is an optimal fire extinguishing position for each offset distance.Under this position,the fine water mist has the best suppression effect on the heat release rate,and the change of the distance size has a linear relationship with the peak value of the ethanol heat release rate and the peak arrival time of the heat release rate,the peak value of ethanol heat release rate increases with the increase of oil pan area,and the time for ethanol combustion gradually decreases with the increase of area;the longer the pre-burning time,the higher the peak heat release rate of ethanol,and the peak heat release rate of the arrival time is gradually reduced,under certain conditions of fog flux,the earlier the application of a fine mist before the stable combustion of ethanol,the better the fire extinguishing effect;with the increase of the pressure of the fine mist nozzle,the fog flux and the fog momentum of the fine water mist increase,and the effect of the fine water mist on the ethanol release rate is better.Finally,the effect of water mist on the heat release rate of ethanol under different water-blown conditions and different ventilation start-up times was studied.Under different ventilation wind speed conditions,the peak heat release rate is exponentially related to wind speed,and the peak heat release rate arrival time is exponentially related to wind speed;under different ventilation start-up time,the earlier the ventilation start-up time is,the greater the peak value of ethanol reaches.The time required to reach the peak of the heat release rate gradually decreases.