On the effect of the atmosphere on the evaporation of sessile droplets of water

K. Sefiane, S. K. Wilson*, S. David, G. J. Dunn, B. R. Duffy

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

An experimental and theoretical study of the effect of the atmosphere on the evaporation of pinned sessile droplets of water is described. The experimental work investigated the evaporation rates of sessile droplets in atmospheres of three different ambient gases (namely, helium, nitrogen, and carbon dioxide) at reduced pressure (from 40 to 1000 mbars) using four different substrates (namely, aluminum, titanium, Macor, and polytetrafluoroethylene) with a wide range of thermal conductivities. Reducing the atmospheric pressure increases the diffusion coefficient of water vapor in the atmosphere and hence increases the evaporation rate. Changing the ambient gas also alters the diffusion coefficient and hence also affects the evaporation rate. A mathematical model that takes into account the effect of the atmospheric pressure and the nature of the ambient gas on the diffusion of water vapor in the atmosphere and the thermal conductivity of the substrate is developed, and its predictions are found to be in encouraging agreement with the experimental results.

Original languageEnglish
Article number062101
Number of pages9
JournalPhysics of Fluids
Volume21
Issue number6
DOIs
Publication statusPublished - Jun 2009

Keywords

  • drops
  • evaporation
  • thermal conductivity
  • DROPS
  • SUBSTRATE
  • DIFFUSION
  • RATES

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