Pool boiling CHF enhancement by micro/nanoscale modification of zircaloy-4 surface

Ahn, Ho Seon; Lee, Chan; Kim, Hyungdae; Jo, HangJin; Kang, SeongTae; Kim, Joonwon; Shin, Jonghwa; Kim, Moo Hwan

doi:10.1016/j.nucengdes.2010.07.006

Cited by 167 publications

(57 citation statements)

References 32 publications

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“…The liquidspreading effect of nanoscale rods on a micro/nanoscale surface changed the surface wettability and produced a greater increase in the CHF than did other factors. Ahn et al [12] used zircaloy-4 (Zerlo, zirconium alloy) as a test material for pool-boiling CHF experiments. Their results are valuable because zirconium alloy is often used as cladding for nuclear fuel rods.…”

Section: Surface Modifications To Enhance the Chf During Pool Boilingmentioning

confidence: 99%

The Effect of Micro/Nanoscale Structures on CHF Enhancement

Ahn¹,

Kim

2011

Nuclear Engineering and Technology

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Section: Surface Modifications To Enhance the Chf During Pool Boilingmentioning

confidence: 99%

The Effect of Micro/Nanoscale Structures on CHF Enhancement

Ahn¹,

Kim

2011

Nuclear Engineering and Technology

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“…This is largely due to the limited current state-of-the-art technologies for functionalizing such surfaces. Functionalization of Zircaloy surfaces has been accomplished with the use of an anodization process and was shown to result in critical heat fluxes up to about 200 W/cm 2 , 19,20 however with relatively low microstructures height. Surface enhancement techniques for stainless steel and similar metals are limited to coatings and deposition techniques.…”

mentioning

confidence: 99%

Secondary pool boiling effects

Kruse

Tsubaki

Zuhlke

et al. 2016

Applied Physics Letters

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A pool boiling phenomenon referred to as secondary boiling effects is discussed. Based on the experimental trends, a mechanism is proposed that identifies the parameters that lead to this phenomenon. Secondary boiling effects refer to a distinct decrease in the wall superheat temperature near the critical heat flux due to a significant increase in the heat transfer coefficient. Recent pool boiling heat transfer experiments using femtosecond laser processed Inconel, stainless steel, and copper multiscale surfaces consistently displayed secondary boiling effects, which were found to be a result of both temperature drop along the microstructures and nucleation characteristic length scales. The temperature drop is a function of microstructure height and thermal conductivity. An increased microstructure height and a decreased thermal conductivity result in a significant temperature drop along the microstructures. This temperature drop becomes more pronounced at higher heat fluxes and along with the right nucleation characteristic length scales results in a change of the boiling dynamics. Nucleation spreads from the bottom of the microstructure valleys to the top of the microstructures, resulting in a decreased surface superheat with an increasing heat flux. This decrease in the wall superheat at higher heat fluxes is reflected by a “hook back” of the traditional boiling curve and is thus referred to as secondary boiling effects. In addition, a boiling hysteresis during increasing and decreasing heat flux develops due to the secondary boiling effects. This hysteresis further validates the existence of secondary boiling effects.

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“…For both cases, the nanowires are 40-50 µm long. Both the CHF and boiling HTC of the nanowires are more than doubled compared [28][29][30][31]33] to plain Si surfaces. Such enhancement can be attributed to the unique properties of nanowires, including high nucleation site density, superhydrophilicity, and enhanced capillary pumping effect.The insight obtained from this study indicates that further enhancement of the CHF and HTC is possible by rational design and synthesis of nanowire arrays.…”

Section: Surface Modification Technology (Nanotechnology)mentioning

confidence: 99%

“…In the case of the MWCNTs with 9 µm height, they obtained a similar BHT and 10% enhancement of CHF. <Coarse nano/micro-structures> Ahn et al [33] prepared Zirconium alloy nanostructure and micro/nanostructures (so-called mountain-like structures) through an anodic oxidation process. They reported higher CHF values and lower boiling heat transfer compared to bare substrates and substrates with the microstructures.…”

Section: Surface Modification Technology (Nanotechnology)mentioning

confidence: 99%