Experimental and Theoretical Investigation of Nucleation Site Density and Heat Transfer During Dropwise Condensation on Thin Hydrophobic CoatingsSource: Journal of Heat Transfer:;2022:;volume( 144 ):;issue: 006::page 61601-1Author:Sablowski, Jakob
,
Galle, Lydia
,
Grothe, Julia
,
Roudini, Mehrzad
,
Winkler, Andreas
,
Unz, Simon
,
Beckmann, Michael
DOI: 10.1115/1.4053922Publisher: The American Society of Mechanical Engineers (ASME)
Abstract: Dropwise condensation (DWC) has the potential to enhance heat transfer compared to filmwise condensation (FWC). The heat transfer rates achieved by DWC depend on the drop size distribution, which is influenced by nucleation processes of newly formed drops. In DWC modeling, the nucleation site density Ns is used as an input parameter to obtain the drop size distribution of small drops. However, due to the small scale of the condensate nuclei, direct observation is difficult, and experimental data on the nucleation site density are scarce. In the literature, values in the range of 109 m−2 to 1015 m−2 can be found for Ns. In this paper, we report DWC experiments on SiO2 and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) thin hydrophobic coatings that show significantly different nucleation site densities. Nucleation site densities are estimated from high-speed imaging of small drops during initial condensation and from model calibration using established DWC theory. We have found the values for Ns to be in the range from 1.1×1010 m−2 to 5.1×1011 m−2 for the SiO2 coating and 1011 m−2 to 1013 m−2 for the PFDTES coating. Our results show that there can be large differences in the nucleation site density under similar conditions depending on the surface properties. This underlines the importance of investigating nucleation site density specifically for each surface and under consideration of the specific process conditions used for DWC.
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contributor author | Sablowski, Jakob | |
contributor author | Galle, Lydia | |
contributor author | Grothe, Julia | |
contributor author | Roudini, Mehrzad | |
contributor author | Winkler, Andreas | |
contributor author | Unz, Simon | |
contributor author | Beckmann, Michael | |
date accessioned | 2022-05-08T09:25:03Z | |
date available | 2022-05-08T09:25:03Z | |
date copyright | 4/5/2022 12:00:00 AM | |
date issued | 2022 | |
identifier issn | 0022-1481 | |
identifier other | ht_144_06_061601.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl1/handle/yetl/4285115 | |
description abstract | Dropwise condensation (DWC) has the potential to enhance heat transfer compared to filmwise condensation (FWC). The heat transfer rates achieved by DWC depend on the drop size distribution, which is influenced by nucleation processes of newly formed drops. In DWC modeling, the nucleation site density Ns is used as an input parameter to obtain the drop size distribution of small drops. However, due to the small scale of the condensate nuclei, direct observation is difficult, and experimental data on the nucleation site density are scarce. In the literature, values in the range of 109 m−2 to 1015 m−2 can be found for Ns. In this paper, we report DWC experiments on SiO2 and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) thin hydrophobic coatings that show significantly different nucleation site densities. Nucleation site densities are estimated from high-speed imaging of small drops during initial condensation and from model calibration using established DWC theory. We have found the values for Ns to be in the range from 1.1×1010 m−2 to 5.1×1011 m−2 for the SiO2 coating and 1011 m−2 to 1013 m−2 for the PFDTES coating. Our results show that there can be large differences in the nucleation site density under similar conditions depending on the surface properties. This underlines the importance of investigating nucleation site density specifically for each surface and under consideration of the specific process conditions used for DWC. | |
publisher | The American Society of Mechanical Engineers (ASME) | |
title | Experimental and Theoretical Investigation of Nucleation Site Density and Heat Transfer During Dropwise Condensation on Thin Hydrophobic Coatings | |
type | Journal Paper | |
journal volume | 144 | |
journal issue | 6 | |
journal title | Journal of Heat Transfer | |
identifier doi | 10.1115/1.4053922 | |
journal fristpage | 61601-1 | |
journal lastpage | 61601-11 | |
page | 11 | |
tree | Journal of Heat Transfer:;2022:;volume( 144 ):;issue: 006 | |
contenttype | Fulltext |