Evaporative spray cooling of plain and microporous coated surfaces

Kim, J.H.; You, Seungkwon; Choi, Seok Jin

doi:10.1016/j.ijheatmasstransfer.2004.01.018

Cited by 91 publications

(31 citation statements)

References 14 publications

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“…The CHF was reached at the highest contact line density. Kim et al [14] investigated evaporative spray cooling on a microporous coated surface using water at very low flow rates up to 0.025 cm 3 /cm 2 /s. The low thermal conductivity (estimated to be ~0.95 W/mK) porous layer was fabricated using a mixture of methylethylketone, epoxy, and aluminum powder, and its maximum thickness was 500 µm.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Heat Transfer with Pool and Spray Impingement Boiling on Microporous and Nanowire Surface Coatings

Thiagarajan¹,

Wang²,

Yang³

et al. 2010

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The National Renewable Energy Laboratory (NREL) is leading a national effort to develop next-generation cooling technologies for hybrid vehicle electronics, as part of the Advanced Power Electronics and Electrical Machines program area in the U.S. Department of Energy's (DOE's) Vehicle Technologies Program. The overarching goal is to reduce the size, weight, and cost of power electronic modules that convert direct current from the batteries to alternating current for the motor, and vice versa. Aggressive thermal management techniques help in achieving the goals of increased power density and reduced weight and volume, while keeping the chip temperatures within acceptable limits. The viability of aggressive cooling schemes such as spray and jet impingement in conjunction with enhanced surfaces is being explored as part of the program. In this work, we present results from a series of experiments with pool and spray boiling on enhanced surfaces, such as a microporous layer of copper and copper nanowires, using HFE-7100 as the working fluid. Spray impingement on the microporous coated surface showed an enhancement of 100%−300% in the heat transfer coefficient at a given wall superheat with respect to spray impingement on a plain surface under similar operating conditions. The critical heat flux also increased by 7%−20%, depending on the flow rates. Heat transfer coefficients obtained on the nanowire-grown surface are considerably better than those obtained on the plain surface, although the enhancement is lower than those obtained on the microporous surface. The critical heat flux is also considerably lower for the nanowire surface than for the plain surface.

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Section: Introductionmentioning

confidence: 99%

Enhancement of Heat Transfer with Pool and Spray Impingement Boiling on Microporous and Nanowire Surface Coatings

Thiagarajan¹,

Wang²,

Yang³

et al. 2010

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“…Uncertainty in the heat flux measurements were found using the the same method as Chang and You [11] and Kim et al [2] due to the similarities in the test heater and procedure. This uncertainty was estimated to be ± 6% for heat fluxes between 0-50 W/cm².…”

Section: Uncertainty Analysismentioning

confidence: 99%

Evaporative Cooling Performance of a Brazed Microporous Coating on an Aluminum Surface

King

Amaya

You

2012

Volume 7: Fluids and Heat Transfer, Parts A, B, C, and D

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The effect of an aluminum microporous coating on evaporative cooling performance of water was studied. The coating consisted of aluminum powder brazed to a flat aluminum substrate. Coatings of average thicknesses of 175 μm, 270 μm, 900 μm, and of average aluminum particle sizes of 27 μm, 70 μm and 114 μm were tested. A hot water treatment of the coating insured repeatability of thermal performance. Wickability was measured and compared to Washburn’s equation for capillary flow. Evaporative cooling tests were then performed on coated and plain surfaces. The test surfaces were uniformly heated while kept vertically dipped in an isothermal pool of water. All microporous coatings increased evaporative heat transfer relative to that of the plain surface by their ability to wick fluid to the entire heated area. With particle size increase from 27 μm to 70 μm both the wickability and heat transfer were significantly increased, but no further significant gains in either were obtained with increase to 114 μm. The maximum heat transfer coefficient was increased ∼11 times and the temperature limit (dry-out) heat flux increased ∼10 times with the two larger particle sizes (70 μm and 114 μm). The heat transfer coefficient and dry-out heat flux similarly increased with thickness increase.

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“…Kim et al [15] conducted spray cooling experiments with water on the microporous coating surfaces and observed that these surfaces enhanced the heat removal rate due to the capillary pumping action through the microporous cavities connecting each other. Apart from this, the evaporative spray cooling increased the heat transfer coefficient up to 400% relative to that of the uncoated surface cooled by dry air, and this enhancement was maintained at high heat fluxes by using microporous surfaces.…”

Section: Steady Flow Spray Coolingmentioning

confidence: 99%