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Effect of Dissolved Gases on Spray Evaporative Cooling With Water.

pdf icon Effect of Dissolved Gases on Spray Evaporative Cooling With Water. (1027 K)
Milke, J. A.; Tinker, S. C.; diMarzo, M.

Fire Technology, Vol. 33, No. 2, Second Quarter, 99-114, May/June 1997.


National Institute of Standards and Technology, Gaithersburg, MD


water; evaporation cooling; sprays; solid surfaces; drop sizes; size distribution; data processing; data analysis; surface temperature; automatic sprinkler systems


An experimental investigation of the effect of nondegassed water used to cool a solid surface is presented. The solid surface is subjected to thermal radiant input from three panels positioned above it. The water is deposited on the surface in the form of a sparse spray with droplets of about 10 ml. Previous experiments with degassed water are compared to a new set of experiments. In addition, the effect of dissolved gases (air) is quantified in terms of the overall transient thermal behavior of the solid. A lower steady-state average temperature is achieved when gases remain in the water. This result suggests that the configuration of the liquid droplets on the surface and the radiant heat input into the droplet are altered by the gas bubles in the deposited droplet. This information provides insight into fire control mechanisms by automatic sprinkler systems.