Research Papers

Heat Transfer From Novel Target Surface Structures to a Normally Impinging, Submerged and Confined Water Jet

[+] Author and Article Information
Nicholas M. R. Jeffers

Department of Mechanical and Aeronautical Engineering, Stokes Institute, University of Limerick, Limerick, Irelandnick.jeffers@ul.ie

Jeff Punch1

Department of Mechanical and Aeronautical Engineering, CTVR, Stokes Institute, University of Limerick, Limerick, Irelandjeff.punch@ul.ie

Edmond J. Walsh, Marc McLean

Department of Mechanical and Aeronautical Engineering, Stokes Institute, University of Limerick, Limerick, Ireland


Corresponding author.

J. Thermal Sci. Eng. Appl 1(3), 031001 (Dec 03, 2009) (9 pages) doi:10.1115/1.4000564 History: Received June 03, 2009; Revised September 14, 2009; Published December 03, 2009; Online December 03, 2009

Contemporary electronic systems generate high component-level heat fluxes. Impingement cooling is an effective way to induce high heat transfer coefficients in order to meet thermal constraints. The objective of this paper is to experimentally investigate the heat transfer from five novel target surface structures to a normally impinging, submerged, and confined water jet. The five target structures were: 90 deg vane, a 2×2 pin fin array, and three geometries, which turn the flow away from, and back towards, the surface to be cooled to create an annular jet. The experiments were conducted for inlet Reynolds numbers of 500Re22,000, based on the mean velocity and jet tube diameter. The confined impinging jet was geometrically constrained to a round 8.5 mm diameter, square edged nozzle at a jet exit-to-target surface spacing of H/D=0.5. The heat transfer characteristics of the five target surfaces were nondimensionally compared to a flat surface, and surface effectiveness of up to 2.2 was recorded. Enhancements of up to 45% were noted when the wetted surface area of the target surface structures was considered. The pressure drop attributed to the target surfaces is also considered. The findings of the paper are of practical relevance to the design of primary heat exchangers for high-flux thermal management applications, where the boundaries of cooling requirements continue to be tested.

Copyright © 2009 by American Society of Mechanical Engineers
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Figure 1

Surface impingement of a single round jet

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Figure 2

Bulk heat transfer setup

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Figure 3

Normalized axial velocity profiles at the nozzle exit, with a particle image velocimetry (PIV) subplot image showing a full field velocity magnitude plot of the stagnation zone

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Figure 4

Six jet impingement target surfaces: (a) 90 deg vane, (b) 2×2 pin fin array, (c) turn-up profile dish, (d) turn-up square edge dish, (e) pedestal, and (f) flat surface

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Figure 5

Turn-up turn-down configuration

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Figure 6

Comparison for a flat target surface tested between 500<Re<20,000

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Figure 7

Comparison between the pedestal, the turn-up dishes, and the effect of the addition of the turn-down dishes

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Figure 8

Local Nu/Pr distribution of a jet with a polycarbonate turn-up and turn-down dishes at Re=12,000

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Figure 9

Effect of the 90 deg vane and the 4×4 pin fin array augmentations compared to a flat surface and a pedestal with the turn-down dish

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Figure 10

Comparison between the target structures using h⋆ to calculate Nu

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Figure 11

Pressure drop as a function of Re for all the target surfaces tested




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