Technical Brief

Confinement Effects on FKE-774 Critical Heat Flux in Buoyancy-Driven Microgap Channels

[+] Author and Article Information
Karl J. L. Geisler

Mail Stop 0235-03-E-66
St. Paul, MN 55144
e-mail: kjgeisler@mmm.com

Shweta Natarajan

Department of Mechanical Engineering,
Georgia Institute of Technology,
222 14th Street NE, Apt#305,
Atlanta, GA 30309
e-mail: shwetan@gatech.edu

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received May 5, 2015; final manuscript received October 22, 2015; published online December 8, 2015. Assoc. Editor: Mohamed S. El-Genk.

J. Thermal Sci. Eng. Appl 8(2), 024502 (Dec 08, 2015) (4 pages) Paper No: TSEA-15-1141; doi: 10.1115/1.4031931 History: Received May 05, 2015; Revised October 22, 2015

Critical heat flux (CHF) of the fluoroketone fluid FKE-774 in vertical microgap channels is explored, with a focus on submillimeter spacings. Experiments were conducted using a 20 mm × 20 mm heated aluminum surface. Microgap channel spacings were decreased down to 0.3 mm, providing channel aspect ratios (height/spacing) as high as 67. In the limit where channel spacing is large, CHF was found to be 140 kW/m2 for saturated boiling at atmospheric pressure. A reduction in CHF of 55% was observed for the largest channel aspect ratio investigated. Results for degradation of the CHF limit with decreasing microgap spacing are compared to a correlation available in the literature and show a roughly hyperbolic dependence on channel aspect ratio (height/spacing) for aspect ratios larger than 10.

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Grahic Jump Location
Fig. 1

Experimental apparatus

Grahic Jump Location
Fig. 2

Illustrated top view of heater assembly

Grahic Jump Location
Fig. 3

Relative degradation of CHF with increasing microgap aspect ratio (i.e., decreasing microgap spacing)




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