Inverse-thermocapillary evaporation in a thin liquid film of self-rewetting fluid

Citation

Lim, Elaine and Kueh, Tze Cheng and Hung, Yew Mun (2020) Inverse-thermocapillary evaporation in a thin liquid film of self-rewetting fluid. International Journal of Numerical Methods for Heat & Fluid Flow. pp. 1-20. ISSN 0961-5539

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Abstract

Purpose–The present study aims to investigate the inverse-thermocapillary effect in an evaporating thinliquidfilm of self-rewettingfluid, which is a dilute aqueous solution (DAS) of long-chain alcohol.Design/methodology/approach–A long-wave evolution model modified for self-rewettingfluids isused to study the inverse thermocapillary characteristics of an evaporating thin liquidfilm. Theflowattributed to the inverse thermocapillary action is manifested through the streamline plots and theevaporative heat transfer characteristics are quantified and analyzed.Findings–The thermocapillaryflow induced by the negative surface tension gradient drives the liquidfrom a low-surface-tension (high temperature) region to a high-surface-tension (low temperature) region,retarding the liquid circulation and the evaporation strength. The positive surface tension gradients of self-rewettingfluids induce inverse-thermocapillaryflow. The results of different workingfluids, namely, water,heptanol and DAS of heptanol, are examined and compared. The thermocapillary characteristic of a workingfluid is significantly affected by the sign of the surface tension gradient and the inverse effect is profound at ahigh excess temperature. The inverse thermocapillary effect significantly enhances evaporation rates.Originality/value–The current investigation on the inverse thermocapillary effect in a self-rewettingevaporating thinfilm liquid has not been attempted previously. This study provides insights on thehydrodynamic and thermal characteristics of thermocapillary evaporation of self-rewetting liquid, which giverise to significant thermal enhancement of the microscale phase-change heat transfer devices.

Item Type: Article
Uncontrolled Keywords: Liquid films, Long-wave evolution model, Self-rewetting fluid, Surface tension gradient, Thermocapillary evaporation
Subjects: Q Science > QC Physics > QC170-197 Atomic physics. Constitution and properties of matter Including molecular physics, relativity, quantum theory, and solid state physics
Divisions: Faculty of Engineering and Technology (FET)
Depositing User: Ms Rosnani Abd Wahab
Date Deposited: 28 Dec 2020 09:19
Last Modified: 28 Dec 2020 09:19
URII: http://shdl.mmu.edu.my/id/eprint/7911

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