Full metadata
Title
Microchannel flow boiling enhancement via cross-sectional expansion
Description
The heat transfer enhancements available from expanding the cross-section of a boiling microchannel are explored analytically and experimentally. Evaluation of the literature on critical heat flux in flow boiling and associated pressure drop behavior is presented with predictive critical heat flux (CHF) and pressure drop correlations. An optimum channel configuration allowing maximum CHF while reducing pressure drop is sought. A perturbation of the channel diameter is employed to examine CHF and pressure drop relationships from the literature with the aim of identifying those adequately general and suitable for use in a scenario with an expanding channel. Several CHF criteria are identified which predict an optimizable channel expansion, though many do not. Pressure drop relationships admit improvement with expansion, and no optimum presents itself. The relevant physical phenomena surrounding flow boiling pressure drop are considered, and a balance of dimensionless numbers is presented that may be of qualitative use. The design, fabrication, inspection, and experimental evaluation of four copper microchannel arrays of different channel expansion rates with R-134a refrigerant is presented. Optimum rates of expansion which maximize the critical heat flux are considered at multiple flow rates, and experimental results are presented demonstrating optima. The effect of expansion on the boiling number is considered, and experiments demonstrate that expansion produces a notable increase in the boiling number in the region explored, though no optima are observed. Significant decrease in the pressure drop across the evaporator is observed with the expanding channels, and no optima appear. Discussion of the significance of this finding is presented, along with possible avenues for future work.
Date Created
2013
Contributors
- Miner, Mark (Author)
- Phelan, Patrick E (Thesis advisor)
- Baer, Steven (Committee member)
- Chamberlin, Ralph (Committee member)
- Chen, Kangping (Committee member)
- Herrmann, Marcus (Committee member)
- Arizona State University (Publisher)
Topical Subject
Resource Type
Extent
x, 134 p. : ill. (some col.)
Language
eng
Copyright Statement
In Copyright
Primary Member of
Peer-reviewed
No
Open Access
No
Handle
https://hdl.handle.net/2286/R.I.16463
Statement of Responsibility
by Mark Miner
Description Source
Viewed on Oct. 29, 2013
Level of coding
full
Note
thesis
Partial requirement for: Ph.D., Arizona State University, 2013
Includes bibliographical references (p
Field of study: Mechanical engineering
System Created
- 2013-03-25 02:40:34
System Modified
- 2021-08-30 01:43:04
- 3 years 2 months ago
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