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Water Droplet Evaporation from Radiantly Heated Solids. Final Report. September 1992-May 1994.


pdf icon Water Droplet Evaporation from Radiantly Heated Solids. Final Report. September 1992-May 1994. (4345 K)
Tinker, S. C.; diMarzo, M.

NIST GCR 95-665; 158 p. December 1994.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Available from:

National Technical Information Service
Order number: PB95-217147

Keywords:

industrial plants; cooling; drop sizes; droplets; evaporation; fire research; solid surfaces; sprinkler systems; water sprays

Abstract:

[Former title: Fire Protection in Large Industrial Fires] A model describing the configuration of a water droplet evaporating on the surface of a radiantly heated semi-infinite solid is developed. A shape factor and the solid-liquid-vapor contact angle describe the transient droplet shape, though the initial value of the latter parameter is found to have a negligible effect on the droplet's evaporation. The droplet shape model and a modified radiation heat term are incorporated into a previously developed computer model to predict the evaporation of a single droplet on a semi-infinite solid subjected to radiant heat input. The code predicts transient temperature profiles that agree well with experiment. A simplified, closed-form solution for the prediction of surface temperatures in the vicinity of an evaporating droplet is used to fit the data produced by the single droplet model. This closed-form solution facilitates calculations used in a model for the cooling of a surface by the evaporation of a sparse spray of water. The previously collected data base for sparse spray cooling using degassed water is expanded with a new set of experiments using water containing dissolved gases.