MATHEMATICAL MODELING OF THE BEHAVIOR OF DROPLETS OF GEL-FORMING FIRE EXTINGUISHING SYSTEMS IN HIGH-TEMPERATURE AREA

To increase the efficiency of firefighting the extinguishing gel-forming systems were offered. They represent two separately stored and separatly and simultaneosly applied components. The first component is the gel-forming solution. The second is the catalyst solution for gel formation. When sprayed simultaneosly they intermix on burning or protected surfaces. Their interaction leads to stable gel formation. The gel forms non-flowing fire-protective layer that firmly helds on vertical and inclined surfaces. The aim of this work is to determine the minimal initial size of droplets of the components of gel-forming system that will reliably provide gel formation on the surfaces of solid combustible materials. For this purpose the problem of evaporation of droplets of aqueous saline solution in hot gas environment was considered. Creating the model of evaporation of aqueous saline solution, the equation of mass and energy balance were only used. The equations of gas components movement were substituted by isobaric process condition, and the evaporation was considered as a quasiequilibrium process. After making some reasonable assumptions, a system of equations describing the process of evaporation of droplets of components of the gel-forming system was obtained. The developed mathematical model was solved numerically in a wide range of initial parameters. The maximum distance of spraying of solution droplets that ensured reliable gel-formation on protected surfaces depending on initial droplets radius was estimated. The initial droplets size of more than 0.4 mm ensures the efficiency of gel-forming systems at the depth of fire more than 10 m.