Study on Fire Suppression System of Water Mist and Spray Nozzle
|School||Hebei University of Technology|
|Course||Thermal Power Engineering|
|Keywords||halon water mist atomization effervescent atomization flow characteristics atomization performances extinguishing effectiveness|
With the gradually limited and falling into disused of halons, water mist fire suppression system has been one of the important study items on fire technique because its characteristics on without pollution, quickly fire suppression, using little water and few damage on object protected. Effervescent atomization technique is a method of producing water mist through twin flow, which has many advantages in terms of smaller drop size and lower injection pressures. Furthermore, the amount of atomizing gas required is considerably less than what is employed in all other twin-fluid atomization techniques. Based on the mechanism of effervescent atomization, a new effervescent atomization system of water mist was designed. These developed a new technique for new method of producing water mist.An effervescent atomizer for producing water mist designed first in this work, and an experimental platform constructed for measurement. Dual PDA. turbo flow meter and digital camera were used to measure and record characteristics of flux, particles distributing, and water mist field macro-characteristics. At the same time, the regularity of carbon dioxide solubility was measured and analyses.From the experiment we found that the main factor, which has significant influences on flux characteristics, is the diameter size of throttle orifice. The water mist field macro-characteristics represent the dimension of throttle orifice evidently influence the type of the twin-fluid in the mixing-chamber. The stability of spray was evidently improved by fitting a spoiler after the throttle orifice, and compared with mist of atomizer without swirl the cone angle was increased. The drop velocity profiles illustrate that: the mean velocity is highest on the center axis; the change is very distinct in the range of 0-20mm; on the radical the mean velocity declines firstly and then decreases, finally trends to flat; the speed of drop is closely related to quantity dissolved of the carbon dioxide. From the drop size profiles we can see that the particle diameter distributing of water mist show axis symmetry, simulated to distributing of particle velocity. The mean particle diameter was larger at radial plane far from discharge orifice than at little distance from discharge orifice, and the particle was equality. The two liquid fires were extinguished quickly by water mist, and there was a interior burning phenomenon when the wood flame extinguished quickly.The research result shows that bubbling effervescent atomization system was feasible used in water mist. This system can economize mass material and superiority in economy performance. We hope the new system will be used in fire suppression in the future.