Stable and uniform heat dissipation by nucleate-catalytic nanowires for boiling heat transfer

Kim, Beom Seok; Shin, Sangwoo; Lee, Donghwi; Choi, Geehong; Lee, Hwanseong; Kim, Kyung Min; Cho, Hyung Hee

doi:10.1016/j.ijheatmasstransfer.2013.10.061

Cited by 84 publications

(35 citation statements)

References 49 publications

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“…Advanced techniques, such as fabrication of nano/micro hierarchical structures, 2-4 and functionalization of interfaces allowed the synthesis of finer structures for limitless manipulation of interfaces, and secured the advantages of rough morphology and by-productive wetting characteristics for activating nucleation, areal pin-fin effects, and favorable surface re-wetting. [5][6][7][8] Despite the promise of these approaches, the interfacial physics governing the thermo-hydraulic criteria on critical heat flux (CHF), which is the maximum heat dissipation capacity, remains poorly understood. When vigorous nucleation and its coalescence break the hydrodynamic stability, CHF will occur causing the burnout of the interface.…”

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confidence: 99%

Interfacial wicking dynamics and its impact on critical heat flux of boiling heat transfer

Kim

Lee

Shin

et al. 2014

Applied Physics Letters

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138

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Morphologically driven dynamic wickability is essential for determining the hydrodynamic status of solid-liquid interface. We demonstrate that the dynamic wicking can play an integral role in supplying and propagating liquid through the interface, and govern the critical heat flux (CHF) against surface dry-out during boiling heat transfer. For the quantitative control of wicking, we manipulate the characteristic lengths of hexagonally arranged nanopillars within sub-micron range through nanosphere lithography combined with top-down metal-assisted chemical etching. Strong hemi-wicking over the manipulated interface (i.e., wicking coefficients) of 1.28 mm/s0.5 leads to 164% improvement of CHF compared to no wicking. As a theoretical guideline, our wickability-CHF model can make a perfect agreement with improved CHF, which cannot be predicted by the classic models pertaining to just wettability and roughness effects, independently.

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mentioning

confidence: 99%

Interfacial wicking dynamics and its impact on critical heat flux of boiling heat transfer

Kim

Lee

Shin

et al. 2014

Applied Physics Letters

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138

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“…On one hand, Gerardi et al 21 investigated pool boiling of water and nanofluids with an infrared camera and found a strong dependence of the bubble departure frequency on the wall superheat. Additional confirmation of the heat flux strong effect on the departure frequency in pool boiling is seen from the experimental results conducted by Dong et al 22 On the other hand, Kim et al 23 incorporated nanowires to the boiling surface and their results show a small to no significant effect of heat flux on the bubble detaching frequency on the plain or enhanced silicon surface. Similar results of the bubble nucleation frequency with small dependence on the wall superheat in pool boiling was presented in Hutter et al 24 A small effect of the heat flux on the nucleation frequency during vertical subcooled flow boiling was encountered by Chu et al 25 The employment of numerical analysis to flow boiling in microchannels is being studied by various research groups, however a fully functional numerical model is still far from being reached due to the complexity of the boiling phenomena.…”

Section: Introductionmentioning

confidence: 72%

Oscillations During Flow Boiling in Single Microchannels

Sitar¹,

Lebar²,

Crivellari³

et al. 2018

ACSi

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Flow boiling of degassed double-distilled water in a single 50 × 50 μm and 100 × 50 μm microchannel was investigated on the basis of experimental measurements and high-speed visualization. The visualized events during boiling were analyzed in terms of the bubble frequencies and boiling front oscillations in microchannels. A digital image sequence analysis algorithm was composed to determine the time dependence of bubble and meniscus locations. The results show (i) the dynamic characteristics of boiling in microchannels, (ii) the increase of fundamental oscillation frequencies with increasing heat flux and temperature of the microchannel bottom, (iii) the amplitudes of the flow boiling oscillations are inversely proportional to the fundamental frequencies. The outcomes of the study are important as the oscillations during boiling in single microchannels are experimentally confirmed to be predictable in terms of oscillation frequencies and amplitudes trends and dependencies. This knowledge is especially significant at constructing efficient two-phase micro heat exchangers, micro mixers or micro reactors, as the cross section and the length of the channel become exceedingly important design parameters in micro devices with boiling.

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“…As the length of the nanopillars is diminished by 64% (2.5 μm), which efficiently decreases aspect ratio of structures, relative to that of SiNWs, they are more favorable for guaranteeing jet access by preventing the conglomeration of nanostructures. In the case of SiNWs, which have a high aspect ratio of 46.7, they should be distributed densely and be readily conglomerated with each other at the tip due to van der Waals forces2250. Although this is one of the advantageous aspects in order to reinforce catalytic ebullitions in boiling heat transfer, the conglomerated feature is just an obstacle to single-phase convection, especially in terms of the direct accessibility of the jet towards a stagnant point51.…”

Section: Resultsmentioning

confidence: 99%

“…The roughened morphology offers a prerequisite for strong capillary force, i.e. , hemi-wicking, especially for liquids13141516, and thus leads to favorable static hydrophilicity and dynamic refreshing towards the surface171819202122. Based on these concepts, forested silicon nanowires and analogous vertically standing nanostructures have been adopted to enhance heat transfer.…”

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confidence: 99%

Nano-inspired smart interfaces: fluidic interactivity and its impact on heat transfer

Kim

Lee

et al. 2017

Sci Rep

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Interface-inspired convection is a key heat transfer scheme for hot spot cooling and thermal energy transfer. An unavoidable trade-off of the convective heat transfer is pressure loss caused by fluidic resistance on an interface. To overcome this limitation, we uncover that nano-inspired interfaces can trigger a peculiar fluidic interactivity, which can pursue all the two sides of the coin: heat transfer and fluidic friction. We demonstrate the validity of a quasi-fin effect of Si-based nanostructures based on conductive capability of heat dissipation valid under the interactivity with fluidic viscous sublayer. The exclusive fluid-interface friction is achieved when the height of the nanostructures is much less than the thickness of the viscous sublayers in the turbulent regime. The strategic nanostructures show an enhancement of heat transfer coefficients in the wall jet region by more than 21% without any significant macroscale pressure loss under single-phase impinging jet. Nanostructures guaranteeing fluid access via an equivalent vacancy larger than the diffusive path length of viscid flow lead to local heat transfer enhancement of more than 13% at a stagnation point. Functional nanostructures will give shape to possible breakthroughs in heat transfer and its optimization can be pursued for engineered systems.

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Stable and uniform heat dissipation by nucleate-catalytic nanowires for boiling heat transfer

Cited by 84 publications

References 49 publications

Interfacial wicking dynamics and its impact on critical heat flux of boiling heat transfer

Interfacial wicking dynamics and its impact on critical heat flux of boiling heat transfer

Oscillations During Flow Boiling in Single Microchannels

Nano-inspired smart interfaces: fluidic interactivity and its impact on heat transfer

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