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Influence of nanofiber coating thickness and drop volume on spreading, imbibition, and evaporation

Heinz, Michael ; Stephan, Peter ; Gambaryan-Roisman, Tatiana (2021):
Influence of nanofiber coating thickness and drop volume on spreading, imbibition, and evaporation.
In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 631, p. 127450. Elsevier, ISSN 0927-7757, e-ISSN 1873-4359,
DOI: 10.1016/j.colsurfa.2021.127450,
[Article]

Abstract

It is known that heat transfer resulting from the drop impact onto a hot substrate can be enhanced with the use of nanostructured coatings, such as nanofiber mats, on the substrate surface. One heat transfer enhancement mechanism is related to liquid imbibition into the porous structure and subsequent evaporation. The detailed mechanisms of liquid spreading, imbibition into the porous structure, and evaporation are still not understood. In this work, the influence of nanofiber coating thickness and drop volume on the kinetics of ethanol drop spreading, liquid imbibition and evaporation on a substrate without additional heating are studied. The initial phase of drop spreading as well as the overall processes are studied simultaneously which allows a direct comparison of influencing factors on the different wetting stages or subprocesses. Four different mat thicknesses in the range of 4-42 mu m were investigated, and the results for the drop spreading and evaporation were compared with the bare silicon surface. The results show that, for a mat thickness of 14 mu m and higher, the maximal imbibed area as well as the drying time depend only on the drop volume and are nearly independent of mat thickness. However, for the thinnest mat tested, the imbibed area was significantly smaller and the drying time was longer than for thicker coatings.

Item Type: Article
Erschienen: 2021
Creators: Heinz, Michael ; Stephan, Peter ; Gambaryan-Roisman, Tatiana
Title: Influence of nanofiber coating thickness and drop volume on spreading, imbibition, and evaporation
Language: English
Abstract:

It is known that heat transfer resulting from the drop impact onto a hot substrate can be enhanced with the use of nanostructured coatings, such as nanofiber mats, on the substrate surface. One heat transfer enhancement mechanism is related to liquid imbibition into the porous structure and subsequent evaporation. The detailed mechanisms of liquid spreading, imbibition into the porous structure, and evaporation are still not understood. In this work, the influence of nanofiber coating thickness and drop volume on the kinetics of ethanol drop spreading, liquid imbibition and evaporation on a substrate without additional heating are studied. The initial phase of drop spreading as well as the overall processes are studied simultaneously which allows a direct comparison of influencing factors on the different wetting stages or subprocesses. Four different mat thicknesses in the range of 4-42 mu m were investigated, and the results for the drop spreading and evaporation were compared with the bare silicon surface. The results show that, for a mat thickness of 14 mu m and higher, the maximal imbibed area as well as the drying time depend only on the drop volume and are nearly independent of mat thickness. However, for the thinnest mat tested, the imbibed area was significantly smaller and the drying time was longer than for thicker coatings.

Journal or Publication Title: Colloids and Surfaces A: Physicochemical and Engineering Aspects
Journal volume: 631
Publisher: Elsevier
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institute for Technical Thermodynamics (TTD)
DFG-Collaborative Research Centres (incl. Transregio)
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 1194: Interaction between Transport and Wetting Processes
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 1194: Interaction between Transport and Wetting Processes > Research Area A: Generic Experiments
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 1194: Interaction between Transport and Wetting Processes > Research Area A: Generic Experiments > A04: Flow and Evaporation of Pure Liquids and (Nano)-Suspensions from Structured Coatings
TU-Projects: DFG|SFB1194|TP A04 Gambaryan-Roi
Date Deposited: 12 Nov 2021 07:43
DOI: 10.1016/j.colsurfa.2021.127450
Official URL: https://www.sciencedirect.com/science/article/abs/pii/S09277...
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