Characterization of the Temperature Profile near Contact Lines of an Evaporating Sessile Drop

Xiaodong Zhang, Yugang Zhao () and Dongmin Wang
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Xiaodong Zhang: Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Yugang Zhao: Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Dongmin Wang: Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China

Energies, 2023, vol. 16, issue 6, 1-12

Abstract: Evaporation of a sessile drop is ubiquitous in nature and has many industrial applications. Despite extensive studies over recent decades, a critical issue, i.e., how temperature varies near contact lines, remains elusive. In this work, we report to date the first direct experimental measurement showing the microscopic temperature distribution near contact lines of an evaporating pinned sessile drop. Using a fluorescence-based thermometry, we find that the temperature at the free interface near contact lines varies drastically along the radial direction, engendering a concentric fringe pattern that evolves over the evaporation lifespan. The formation of such fringe patterns is attributed to a combined mechanism of locally enhanced evaporative cooling at the drop edge and the development of interfacial convective vortices due to Bénard-Marangoni instability. We also study the evaporation dynamics at different initial contact angles and find that the characteristics of this fringe pattern vary as the initial contact angle decreases. Our experimental investigation and theoretical analysis in this work reveal insights to the understanding of droplet evaporation dynamics in various heat transfer systems.

Keywords: drop evaporation; Bénard-Marangoni instability; temperature measurement; microscopic fluorescence-based thermometry (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
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