Stehle, Gregory
(2017)
Confinement of Nucleation Sites in Nucleate Pool Boiling Using Atomic Layer Deposition and Constrictive Heaters.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
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 created. Vapor effectiveness and the coincidence metric are shown to have similar relationships with heater diameter.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
14 June 2017 |
| Date Type: |
Publication |
| Defense Date: |
6 December 2016 |
| Approval Date: |
14 June 2017 |
| Submission Date: |
31 October 2016 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
111 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
microlayer, artificial, nucleation, interaction, wettability, constricted, heater, single |
| Date Deposited: |
14 Jun 2017 19:02 |
| Last Modified: |
14 Jun 2017 19:02 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/30080 |
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