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Effect of Liquid-Solid Contact Angle on Droplet Evaporation.


pdf icon Effect of Liquid-Solid Contact Angle on Droplet Evaporation. (909 K)
Chandra, S.; diMarzo, M.; Qiao, Y. M.; Tartarini, P.

NIST GCR 96-687; Paper 15; June 1996.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Available from:

National Technical Information Service
Order number: PB96-202304

Keywords:

water sprays; droplets; evaporation; stainless steels; experiments; computer models; water; hot surfaces; heat transfer; solid surfaces

Abstract:

The effect of varying initial liquid-solid contact angle on the evaporation of single droplets of water deposited on a stainless steel surface is studied using both experiments and numerical modeling. Contact angle is controlled in experiments by adding varying amounts of a surfactant to water. The evolution of contact angle and liquid-solid contact diameter is measured from a video record of droplet evaporation. The computer model is validated by comparison with experimental results. Reducing contact angle increases contact area between the droplet and solid surface, and also reduces droplet thickness, enhancing heat conduction through the droplet. Both effects increase droplet evaporation rate. Decreasing the initial contact angle from 90DG to 20DG reduces droplet evaporation time by approximately 50%. The computer model is used to calculate surface temperature and heat flux variation during droplet evaporation: reducing contact angle is shown to enhance surface cooling.