Capillary-Limited Evaporation From Well-Defined Microstructured Surfaces
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v001t11a006-mnhmt2013-22120.pdf
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1.12 MB
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Author(s)
Adera, Solomon
Raj, Rishi
Wang, Evelyn
Date Issued
December 2013
Journal
ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer
Publisher
American Society of Mechanical Engineers
Citation
Adera, Solomon, Rishi Raj, and Evelyn N. Wang. “Capillary-Limited Evaporation From Well-Defined Microstructured Surfaces.” ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer, 11-14 December, 2014, Hong Kong, China, ASME, 2014. © 2013 by ASME
Version
Final published version
Abstract
Thermal management is increasingly becoming a bottleneck for a variety of high power density applications such as integrated circuits, solar cells, microprocessors, and energy conversion devices. The performance and reliability of these devices are usually limited by the rate at which heat can be removed from the device footprint, which averages well above 100 W/cm[superscript 2] (locally this heat flux can exceed 1000 W/cm[superscript 2]). State-of-the-art air cooling strategies which utilize the sensible heat are insufficient at these large heat fluxes. As a result, novel thermal management solutions such as via thin-film evaporation that utilize the latent heat of vaporization of a fluid are needed. The high latent heat of vaporization associated with typical liquidvapor phase change phenomena allows significant heat transfer with small temperature rise. In this work, we demonstrate a promising thermal management approach where square arrays of cylindrical micropillar arrays are used for thin-film evaporation. The microstructures control the liquid film thickness and the associated thermal resistance in addition to maintaining a continuous liquid supply via the capillary pumping mechanism. When the capillary-induced liquid supply mechanism cannot deliver sufficient liquid for phase change heat transfer, the critical heat flux is reached and dryout occurs. This capillary limitation on thin-film evaporation was experimentally investigated by fabricating well-defined silicon micropillar arrays using standard contact photolithography and deep reactive ion etching. A thin film resistive heater and thermal sensors were integrated on the back side of the test sample using e-beam evaporation and acetone lift-off. The experiments were carried out in a controlled environmental chamber maintained at the water saturation pressure of ≈3.5 kPa and ≈25 °C. We demonstrated significantly higher heat dissipation capability in excess of 100 W/cm[superscript 2]. These preliminary results suggest the potential of thin-film evaporation from microstructured surfaces for advanced thermal management applications.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1115/MNHMT2013-22120
