Study On Interaction Of Water Mist With Fire Smoke

To prevent the ozonosphere from being destroyed by Halon fire extinguishment agents, it has been an urgent task to find out Halon substitutes from signature of Montreal Protocol. Water mist fire suppression technology has been received considerable attentions by international fire science researchers for the following advantages: no pollution to environment, extinguishing fire quickly, less water consuming and little damage to protected objects. Water mist has smoke scrubbing ability which broadens its application fields. Now investigations on interaction of water mist with fire smoke are underway. Interaction of water mist with smoke is systematically studied experimentally and theoretically in this paper.The micrographs of soot particles of diesel oil and rubber were achieved by Transmission Scanning Electron Microscopy with and without water mist applied. By statistical analysis, it was seen that the average diameter of soot particle increased and the surface density of soot particle decreased with water mist applied. The experimental results show that water mist washes out smoke mainly by dynamics effect, cloud physics effect and transportation mechanism of Steffen flow. Water mist with smaller diameter evaporates quickly which accelerates the formation of supersaturation state, and the volume and weight of soot particle increases as a result of absorbing a lot of vapor. Water mist with smaller diameter suspends in the smoke for a long time which ensures sufficient time for water mist to collide and agglomerate with soot particle, water mist with bigger velocity can strike soot particle effectively which strengthens the collision and coagulation between water mist and soot particle, and accelerates the falling velocity of soot particle.The experimental results show that water mist flux and diameter are the primary factors which determine the decreasing speed of smoke temperature. Water mist flux is the firstly factor, the V_Time0。 increases greatly with water mist flux increasing. Water mist diameter is the secondly factor, the V_Time0 increases a little with water mist diameter decreasing. A pitot tube is used to measure the dynamic pressure of smoke,...