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Surface Engineering in Heat-Transfer Applications
thesisposted on 2021-12-01, 00:00 authored by Georgios Damoulakis
The purpose of this dissertation is to show the effectiveness of surface engineering (wettability patterning) in thermal management applications. The study is centered on redesigning an existing thermal-management system, the vapor chamber, using an innovative concept to improve its performance. The study was inspired by the tremendous potential of surface-energy patterning to provide a platform for harnessing surface-tension forces to transport fluids in a pumpless and rapid manner, which resulted in the development of a pattern combination that improves the condensation heat transfer of a metallic surface. The following steps were taken to accomplish this goal; initially, the conventional vapor-chamber heat-spreader was modified by replacing a portion of the totally wick-lined system (condenser) with a wickless and wettability patterned one, resulting in a hybrid vapor chamber. Furthermore, the hybrid vapor-chamber's capacity to serve as a passive thermal diode was demonstrated. Moreover, an attempt was made to completely reap the benefits of the wettability-patterning process by fabricating a quite effective wick-free vapor chamber. This system constitutes the first completely wick-free thermal-management apparatus. Additionally, femtosecond laser processing technology was applied on the wick-free system to develop a wickless and laser-fabricated vapor-chamber thermal diode, which takes advantage of the extreme limits of wettability. Finally, in order to further investigate the condensation phenomena that occur on the novel vapor-chamber's wickless and wettability-patterned condenser, a unique experimental setup was developed that focuses solely on steam dropwise condensation on metallic surfaces in an environment similar to the vapor chamber’s interior.