Pool-boiling CHF enhancement by modulated porous-layer coating: theory and experiment

Liter, S. G.; Kaviany, Massoud

doi:10.1016/s0017-9310(01)00084-9

Cited by 439 publications

(220 citation statements)

References 11 publications

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“…Submerged pool boiling from porous surfaces has been extensively characterized for a number of surface geometries, working fluids, and flooded porous wick structures often found in heat pipes [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The fundamental mechanism of heat transfer during boiling from a porous surface submerged in a liquid pool differs from that from a wick that is passively fed by capillary action.…”

Section: Nucleate Boiling In Porous Wick Structuresmentioning

confidence: 99%

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

Weibel

Garimella

2013

Advances in Heat Transfer

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Owing to their high reliability, simplicity of manufacture, passive operation, and effective heat transport, flat heat pipes and vapor chambers are used extensively in the thermal management of electronic devices. The need for concurrent size, weight, and performance improvements in high-performance electronics systems, without resort to active liquid-cooling strategies, demands passive heat spreading technologies that can dissipate extremely high heat fluxes from small hot spots. In response to these daunting application-driven trends, a number of recent investigations have focused on the design, characterization, and fabrication of ultra-thin vapor chambers for proximate heat spreading away from these hot spots. The predominant transport mechanisms and operational limits have been found to be different under these conditions relative to conventional low-power heat pipes. Noteworthy advances in the fundamental understanding of evaporation and boiling from porous microstructures fed by capillary action, and improvements in vapor chamber characterization, modeling, design, and fabrication techniques are reviewed. Characterization of evaporation and boiling from idealized and realistic wick structures, observation of vapor formation regimes as a function of operating conditions, assessment of fluid dryout limitations, design of novel multi-scale and nanostructured wicks for enhanced transport, and incorporation of these high heat flux transport phenomena into device-level models are discussed. These recent developments have successfully extended the maximum operating heat flux limits of vapor chambers.2

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Section: Nucleate Boiling In Porous Wick Structuresmentioning

confidence: 99%

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

Weibel

Garimella

2013

Advances in Heat Transfer

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“…15 The basic idea is that the hydrodynamic limit model based on Rayleigh-Taylor instability wavelength ͑ RT,c ͒ on the plain surface originally proposed by Zuber 16 can be extended to a surface with microstructure coating and the capillary limit. The onset of CHF based on the hydrodynamic limit is due to the instability of vapor columns.…”

mentioning

confidence: 99%

“…The wavelength can be a geometrically determined factor according to the surface condition. 15 As the result, the change in wavelength prolongs the wetting of the surface by allowing the liquid to break through which means the enhancement of CHF. Recognizing that the CHF enhancement and wavelengths reported in the literature are not exactly matched with the prediction of Eq.…”

mentioning

confidence: 99%

Effects of nanofluids containing graphene/graphene-oxide nanosheets on critical heat flux

Park

Lee

Kang

et al. 2010

Applied Physics Letters

174

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The superb thermal conduction property of graphene establishes graphene as an excellent material for thermal management. In this paper, we selected graphene/graphene oxide nanosheets as the additives in nanofluids. The authors interestingly found that the highly enhanced critical heat flux (CHF) in the nanofluids containing graphene/graphene-oxide nanosheets (GON) cannot be explained by both the improved surface wettability and the capillarity of the nanoparticles deposition layer. Here we highlights that the GON nanofluid can be exploited to maximize the CHF the most efficiently by building up a characteristically ordered porous surface structure due to its own self-assembly characteristic resulting in a geometrically changed critical instability wavelength.

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“…A similar analysis has been employed by others with satisfactory predictions [17,34]. Using a volumetric porosity ε of 0.5±0.02, an average breakthrough bubble diameter d br of 42 μm (determined from the average pore diameter ), and thermophysical properties of water at saturation temperature (100 °C), the hydrodynamic limit of the bare sample is estimated to be 906±102 W/cm 2 using: …”

Section: Mechanism Of Dryoutmentioning

confidence: 92%

“…The hydrodynamic instability limit is reached when the interfaces of the liquid-vapor counterflow columns become Helmholtz-unstable. Liter and Kaviany [34] demonstrated that the hydrodynamic limit can be significantly increased using modulated porous structures which provide preferential flow paths for liquid and vapor, thereby reducing the liquid/vapor counterflow situations and aiding non-hydrodynamical determination of the critical instability wavelength. Various other studies also report a significant increase in critical heat flux (CHF) of uniformly coated porous surfaces compared to plain surfaces investigated under natural convection boiling conditions [17,35].…”

Section: Mechanism Of Dryoutmentioning

confidence: 99%

Metal functionalization of carbon nanotubes for enhanced sintered powder wicks

Kousalya

Weibel

Garimella

et al. 2013

International Journal of Heat and Mass Transfer

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Phase change cooling schemes involving passive heat spreading devices, such as heat pipes and vapor chambers, are widely adopted for thermal management of high heat-flux technologies. In this study, carbon nanotubes (CNTs) are fabricated on a 200 μm thick sintered copper powder wick layer using a microwave plasma enhanced chemical vapor deposition technique. A physical vapor deposition process is used to coat the CNTs with a varying thickness of copper to promote surface wetting with the working fluid, water. Thermal performance of the bare sintered copper powder sample (without CNTs) and the copper-functionalized CNT-coated sintered copper powder wick samples is compared using an experimental facility that simulates the capillary fluid feeding conditions of a vapor chamber. A notable reduction in the boiling incipience superheat is observed for the nanostructured samples. Additionally, nanostructured samples having a thicker copper coating provided a considerable increase in dryout heat flux, supporting heat fluxes up to 457 W/cm 2 from a 5 mm × 5 mm heat input area, while maintaining lower surface superheat temperatures compared to a bare sintered powder sample; this enhancement is attributed primarily to the improved surface wettability. Dynamic contact angle measurements are conducted to quantitatively compare the surface wetting trends for varying copper coating thicknesses and confirm the increase in hydrophilicity with increasing coating thickness.

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Pool-boiling CHF enhancement by modulated porous-layer coating: theory and experiment

Cited by 439 publications

References 11 publications

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

Effects of nanofluids containing graphene/graphene-oxide nanosheets on critical heat flux

Metal functionalization of carbon nanotubes for enhanced sintered powder wicks

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