Date of Award

Spring 5-25-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Arden L. Moore

Abstract

Micro- and nano-scale surface modifications have been a subject of great interest for enhancing the pool boiling heat transfer performance of immersion cooling systems due to their ability to augment surface area, improve wickability, and increase nucleation site density. However, many of the surface modification technologies that have been previously demonstrated show a lack of evidence concerning scalability for use at an industrial level. In this work, the pool boiling heat transfer performance of nanoporous anodic aluminum oxide (AAO) films, copper oxide (CuO) nanostructure coatings, and 1D roll-molded microfin arrays has been studied. Each of these technologies possess scalability in production, thus making them a subject of great interest to industry. To evaluate each surface modification technology, a custom pool boiling setup filled with 3MTM NovecTM HFE-7100 dielectric fluid was utilized. The pool boiling setup was autonomously operated by computer control using a custom LabVIEWTM program. Compared to natively oxidized aluminum samples, AAO samples showed improvements in surface area, but not in wickability or nucleation site density, allowing for the isolated study of the influence of increased surface area on pool boiling performance. Serving as an inverse analogue to nanoporous AAO films, protrusive CuO nanostructure coatings were shown to offer improvements in critical heat flux (CHF), wettability, and nucleation activity over their natively oxidized copper counterparts. At the micro-scale, 1D roll- molded microfin arrays were shown to have improved CHF and nucleation activity over their planar counterparts. Following the initial pool boiling evaluation of each surface finish, the practical applicability of 1D roll-molded microfin arrays was demonstrated through a comparative study of cooling solutions for a field-programmable gate array (FPGA). In this study, the junction-to-ambient thermal resistance for an immersion cooling configuration that utilized a mounted 1D roll-molded microfin array surface was found to be lower than that of both a conventional forced-air cooling system and an immersion cooling configuration with no mounted surface. This finding highlights the significance of 1D roll-molded microfin array surfaces as an industrially acceptable means of improving the capabilities of immersion cooling systems.

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