Novel technology for fire suppression using nitrogen-water mist in enclosed spaces

Abstract

Water mists are an effective means of suppressing coal fires in enclosed spaces. In the present work, A new type of nitrogenwater mist atomizer was developed. This atomizing device does not need additional power facilities. Only relying on the interaction between nitrogen generated by nitrogen injection equipment in coal mine and water in underground pipelines, it can produce nitrogen with large flow rate, small droplet size, uniform particle size distribution and sufficient mixing, and water vapor liquid two-phase fluid. The structure and working principle of water atomization device were investigated. Numerical simulations and experimentation using the five-hole probe method were used to assess the velocity distributions generated by the atomization device when employing different starter twist numbers C L , and the optimal number was found. With the increase of C L , the gas rotating jet field in the expansion section tends to be more uniform and stable, and the backflow area of the rotating jet appears earlier. At the same time, the tangential velocity conducive to the liquid atomization process also increases significantly. A fire extinguishing experiment in an enclosed space demonstrated that the water mist produced a significant cooling effect and could reduce the combustion temperature effectively.

Pool fire suppression performance by twin‐fluid water mist under low pressures in an altitude chamber

“…Due to its advantages of cleanness and good fire suppression effectiveness, water mist fire suppression technology has been a subject of many investigations over the last decade 18‐24 . Many achievements have been made in the methods of generating water mist, the measurement of spray characteristics, the fire suppression mechanisms and effectiveness, the influence factors, etc 17,25‐34 . However, the low pressure water mist systems with higher water flow rates, larger droplet sizes, high cost pipe network and nozzle and high requirements for water quality, are barely used in industrial and building fire, hence the applicability of water mist under low pressures has not been given enough research attention.…”