Microstructured Ceramic-Coated Carbon Nanotube Surfaces for High Heat Flux Pool Boiling

Zhao, H and Dash, S and Dhillon, NS and Kim, S and Lettiere, B and Varanasi, KK and Hart, AJ (2019) Microstructured Ceramic-Coated Carbon Nanotube Surfaces for High Heat Flux Pool Boiling. In: ACS Applied Nano Materials, 2 (9). pp. 5538-5545.

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Abstract

Stable surfaces with high boiling heat flux are critical to many thermal and energy conversion systems, and it is well-known that the microscale texture and wettability of a surface influences its critical heat flux (CHF). We investigate pool boiling on microstructured ceramic-coated carbon nanotube (CNT) surfaces. CNT microstructures are patterned with precise dimensions over large areas, and a ceramic coating by atomic layer deposition (ALD) imparts stability in the presence of capillary forces and thermal stresses that occur during boiling, achieving a measured CHF as high as 245 W cm-2. We also show that the nanoporosity of the ceramic-CNT microstructures has a negligible influence on the CHF because surface rewetting is dominated by microscale imbibition. The high CHF values achieved on our surfaces are attributed to the micropatterning and the nanoscale surface texture of the CNTs, which accelerate liquid imbibition upon bubble departure. Our findings also suggest further enhancements in CHF can be made by optimizing the microstructure pattern and improving its wettability. Therefore, micropatterned ceramic-CNT composites are a potentially attractive substrate for industrial applications of pool boiling.

Item Type:	Journal Article
Publication:	ACS Applied Nano Materials
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society
Keywords:	Atomic layer deposition; Boiling liquids; Carbon nanotubes; Ceramic coatings; Ceramic materials; Energy conversion; Microstructure; Surfaces; Textures; Wetting, Boiling heat flux; Critical heat flux(CHF); Energy conversion systems; Liquid imbibition; Micro patterning; Nano-porous; Nano-scale surfaces; Surface influences, Heat flux
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	18 Feb 2020 09:11
Last Modified:	18 Feb 2020 09:11
URI:	http://eprints.iisc.ac.in/id/eprint/64560

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