- Author
- Chandra, S. | diMarzo, M. | Qiao, Y. M. | Tartarini, P.
- Title
- Effect of Liquid-Solid Contact Angle on Droplet Evaporation.
- Coporate
- University of Toronto, Ontario, Canada Maryland Univ., College Park Universita di Bologna, Italy
- Sponsor
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
- NIST GCR 96-687; Paper 15, June 1996,
- Distribution
- Available from National Technical Information Service
- Keywords
- water sprays | droplets | evaporation | stainless steels | experiments | computer models | water | hot surfaces | heat transfer | solid surfaces
- Identifiers
- investigate experimentally the effect of varying contact angle on the evaporation rate of water droplets; measure the evolution of contact angle, contact diameter, and droplet volume during evaporation; verify that the numerical model of droplet evaporation accurately predicts the effect of contact angle variation; study, using the model, how heat transfer from the solid surface changes with contact angle; examine the possibility of improving spray cooling efficiencies by enhancing surface wetting by droplets
- 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 90º to 20º 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.