Heat Transfer in a Channel with Dimples and Protrusions on Opposite Walls

Mahmood, Gazi I.; Sabbagh, Mounir Z.; Ligrani, Phillip M.

doi:10.2514/2.6623

Cited by 120 publications

(38 citation statements)

References 8 publications

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“…However, the pressure drop increased from a minimum of 60% up to a maximum of 160% in the same range of Re. The use of dimpled/protrusion channels used by Mahmood et al [18] or Elyaan et al [19], yielded increases in Nu of up to 150% at a Re Dh = 5,000. Similarly, the increase in friction coefficient of the dimpled-augmented channel with respect to the baseline channel was found to be between 3.5 and 5.5 times larger.…”

Section: Heat Transfer Enhancementmentioning

confidence: 97%

Direct actuation of small-scale motions for enhanced heat transfer in heated channels

Hidalgo

Glezer

2014

2014 Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)

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Flow-effected, enhanced heat transfer in a high aspect ratio rectangular mm-scale channel that models a segment of a high-performance, air-cooled heat-sink is characterized. The present investigation reports a novel approach to enhanced cooling without increasing the channel's characteristically low Reynolds number. Heat transport that is governed by the local heat transfer from the fin surface and by subsequent mixing with the core flow is significantly increased by deliberate shedding of unsteady small-scale vortices that are induced by the vibration of a miniature, planar self-oscillating reed. The present investigation focuses on the heat transfer and fluid mechanics that are associated with the small-scale motions induced by the reed. Performance enhancement by reed actuation is quantified in terms of increased power dissipation over a range of flow rates compared to the baseline flow in the absence of the reed. It is demonstrated that the channel's coefficient of performance can be increased by a factor of 4 while accounting for all the losses associated with the reed actuation.

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Section: Heat Transfer Enhancementmentioning

confidence: 97%

Direct actuation of small-scale motions for enhanced heat transfer in heated channels

Hidalgo

Glezer

2014

2014 Semiconductor Thermal Measurement and Management Symposium (SEMI-THERM)

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“…Mahmood et al [9] describe the mechanisms responsible for local and spatially-averaged heat transfer augmentations on flat channel surfaces with an array of dimples on one wall for one channel height equal to 50 percent of the dimple print diameter. Other recent investigations consider flow and heat transfer in single spherical cavities [10], effects of dimples and protrusions on opposite channel walls [11,12], the effects of dimple depth on vortex structure and surface heat transfer [13,14], the effects of deep dimples on local surface Nusselt number distributions [15], the combined influences of aspect ratio, temperature ratio, Reynolds number, and flow structure [16], and the flow structure due to dimple depressions on a channel surface [17].…”

Section: Dimpled Test Surfacementioning

confidence: 99%

Flow characteristics along and above dimpled surfaces with three different dimple depths within a channel

Won

Ligrani

2007

J Mech Sci Technol

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The effects of dimples in altering time-averaged flow behavior occur mostly within one-half of one dimple print diameter from the surface, and the dimples within the arrays periodically eject a primary vortex pair from each dimple, which exists in conjunction with edge vortex pairs that form along the spanwise edges of staggered dimples regardless of three dimple depths. As the dimple depth increases, deeper dimples eject stronger primary vortex pairs, with hig her levels of turbulence transport due to larger deficits of time-averaged, normalized total pressure and streamw ise velocity as the surfaces with deeper dimples are approached. Primary vortex pair ejection frequencies range about 7-9 Hz, and edge vortex pair oscillation frequencies range about 5-7 Hz for RelJ=20,OOO, regardless of dimple depths.

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“…Experimental work for dimples and protrusions in an internal cooling channel has been reported by Hwang and Cho [4] whose result shows that the dimples on both surfaces of the channel are better than the dimples on the single surface or protruded surface in terms of pressure drop or Nusselt number enhancement. Mahmood et al [5] have presented heat transfer characteristics when dimples and protrusions are placed on opposite walls. Experimental study of staggered arrays of dimples on a single surface has been reported by Burgess and Ligrani [6] and Burgess et al [7].…”

Section: Introductionmentioning

confidence: 99%

Optimum design of a channel roughened by dimples to improve cooling performance

Samad

Lee

Kim

et al. 2010

Front. Energy Power Eng. China

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Staggered arrays of dimples imprinted on opposite surfaces of an internal flow channel have been formulated numerically to enhance turbulent heat transfer compromising with pressure drop. The channel is simulated with the help of three-dimensional Reynoldsaveraged Navier-Stokes (RANS) analysis. Three nondimensional design variables based on dimple size and channel dimensions and two objectives related to heat transfer and pressure drag have been considered for shape optimization. A weighted-sum method for multi-objective optimization is applied to integrate multiple objectives into a single objective and polynomial response surface approximation (RSA) coupling with a gradient based search algorithm has been implemented as optimization technique. By the present effort, heat transfer rate is increased much higher than pressure drop and the thermal performance also has shown improvement for the optimum design as compared to the reference one. The optimum design produces lower channel height, wider dimple spacing, and deeper dimple as compared to the reference one.

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Heat Transfer in a Channel with Dimples and Protrusions on Opposite Walls

Cited by 120 publications

References 8 publications

Direct actuation of small-scale motions for enhanced heat transfer in heated channels

Direct actuation of small-scale motions for enhanced heat transfer in heated channels

Flow characteristics along and above dimpled surfaces with three different dimple depths within a channel

Optimum design of a channel roughened by dimples to improve cooling performance

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