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Dissertation/Thesis Abstract

Confinement of Nucleation Sites in Nucleate Pool Boiling Using Atomic Layer Deposition and Constrictive Heaters
by Stehle, Gregory Raymond, Ph.D., University of Pittsburgh, 2017, 112; 10645783
Abstract (Summary)

Boiling heat transfer is a powerful cooling mechanism used in a variety of industries to efficiently dissipate heat by taking advantage of latent heat. Nucleation site interactions have been demonstrated to affect behaviors in the bulk fluid, in the solid substrate and coalescence. Despite extensive studies of multi-site interactions, the conclusions of these studies are not in agreement. Namely, hydrodynamic effects are explained by some studies to promote nucleation while other studies find that, even with thermally isolated heat supplies, the presence of nearby sites diminishes nucleation. The present study identifies superheated fluid as a possible explanation for this variability. Hydrodynamic factors are determined to only promote single site nucleation if there is an appreciable thermal boundary layer present. Even with a thermal boundary layer, the presence of other sites causes competition over the superheated fluid; thus, diminishing the promotive effects of hydrodynamic factors. There have also been studies that have characterized the changing dimensions of the microlayer and the heat transfer that occurs beneath it. However, there is not a complete study of bubble behavior resulting from varying heater areas; specifically heater areas smaller than the microlayer. The present study quantifies the effect of heater diameter on vapor effectiveness and determines the optimal heater diameter. A metric for the coincidence of vapor production and microlayer coverage is proposed. Vapor effectiveness and the coincidence metric are shown to have similar relationships with heater diameter.

Indexing (document details)
Advisor: Kimber, Mark
Commitee: Aumiller, David, Lee, Jung-Kun, Schmidt, David
School: University of Pittsburgh
Department: Mechanical Engineering
School Location: United States -- Pennsylvania
Source: DAI-B 79/01(E), Dissertation Abstracts International
Subjects: Chemical engineering, Mechanical engineering, Nuclear engineering
Keywords: Atomic layer deposition, Bubble growth, Bubble interaction, Constrictive heaters, Microlayer, Pool boiling
Publication Number: 10645783
ISBN: 978-0-355-19032-8
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