Evaporation of squeezed water droplets between two parallel hydrophobic/superhydrophobic surfaces

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:576

Article

He, Xukun¹  Cheng, Jiangtao¹  Collier, C. Patrick²  Srijanto, Bernadeta R.²  Briggs, Dayrl P.² 

[1] Virginia Tech, Dept Mech Engn, Blacksburg, VA 24061 USA

[2] Oak Ridge Natl Lab, Ctr Nanophase Mat Sci, Oak Ridge, TN 37831 USA

关键词: Squeezed droplet evaporation;    Confined space;    Superhydrophobic;    Diffusion-driven model;   

DOI  :  10.1016/j.jcis.2020.05.003

来源: Elsevier

【 摘 要 】

Hypothesis: A liquid droplet is apt to be deformed within a compact space in various applications. The morphological change of a droplet and vapor accumulation in the confined space between two parallel surfaces with different gaps and surface wettability are expected to significantly affect the evaporation dynamics of the squeezed droplet therein. Experiments: Here the evaporation dynamics of a squeezed droplet between two parallel hydrophobic/superhydrophobic surfaces are experimentally explored. By reducing the surface gap from 1000 mu m to 400 mu m, the evolution of contact angle, contact radius and volume of the evaporating droplet are measured. A diffusion-driven model based on a two-parameter ellipsoidal segment geometry is developed to predict the morphology and volume evolution of a squeezed droplet during evaporation. Findings: Evaporation dynamics of a squeezed water droplet via the constant contact radius (CCR) mode, the constant contact angle (CCA) mode, or the mixed mode are experimentally observed. Confirmed by our ellipsoidal segment model, the evaporation of the squeezed droplet is significantly depressed with the decreasing surface gap, which is primarily attributed to vapor enrichment in a more confined geometry. A linear scaling law between droplet volume and evaporation time is unveiled, which is verified by a simplified cylindrical model. (C) 2020 Elsevier Inc. All rights reserved.

【 授权许可】

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