Evaporation of sessile ethanol-water droplets on a critically inclined heated surface

Katre, Pallavi and Gurrala, Pradeep and Balusamy, Saravanan and Banerjee, Sayak and Sahu, Kirti Chandra (2020) Evaporation of sessile ethanol-water droplets on a critically inclined heated surface. International Journal of Multiphase Flow, 131. p. 103368. ISSN 03019322

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The evaporation of a binary sessile ethanol-water droplet on an inclined substrate is studied experimentally just below the critical sliding angles for different substrate temperatures. A customized goniometer equipped with a CMOS camera and an infrared (IR) camera is used. The droplet is observed to remain pinned in the advancing side during the evaporation process, while the receding side contracts. The asymmetry in the advancing and receding contact angles of the droplet on inclined substrate results in complex thermo-solutal Marangoni convection that is captured through IR images. The droplet exhibits two distinct oscillatory water-rich cold regions around the advancing contact line during the early stage of evaporation, while the more volatile and lighter ethanol creates a hotter and rapidly evaporating cell near the receding side. As ethanol evaporates away, the ethanol rich cells collapse producing thermal pulsations along the incline. Subsequently, the thermal patterns become similar to that of the pure-water droplet. It is also observed that the thermo-solutal driven oscillatory convection increases with increasing substrate temperature. Despite the complexity in convection dynamics, the evaporation rate exhibits a universal behavior in the normalized time at different substrate temperatures which can be represented by piecewise linear fits at the early and late stages of evaporation.

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IITH Creators:
IITH CreatorsORCiD
Gurrala, PradeepUNSPECIFIED
Balusamy, SaravananUNSPECIFIED
Banerjee, SayakUNSPECIFIED
Sahu, Kirti ChandraUNSPECIFIED
Item Type: Article
Uncontrolled Keywords: Advancing and receding contact angles; Different substrates; Evaporation process; Oscillatory convection; Solutal Marangoni convections; Substrate temperature; Thermal pulsation; Universal behaviors;Cameras; Drops; Ethanol; Evaporation; Infrared imaging; Piecewise linear techniques
Subjects: Physics > Mechanical and aerospace
Divisions: Department of Mechanical & Aerospace Engineering
Depositing User: . LibTrainee 2021
Date Deposited: 09 Aug 2021 04:22
Last Modified: 09 Aug 2021 04:22
URI: http://raiith.iith.ac.in/id/eprint/8731
Publisher URL: http://doi.org/10.1016/j.ijmultiphaseflow.2020.103...
OA policy: https://v2.sherpa.ac.uk/id/publication/12596
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