Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649

Može, Matic; Vajc, Viktor; Zupančič, Matevž; Golobič, Iztok

doi:10.3390/nano11123216

Cited by 28 publications

(25 citation statements)

References 108 publications

(191 reference statements)

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“…Novec 649 showed slightly higher heat transfer coefficient but moderately lower Critical Heat Fux (CHF). More recently, other authors compared the two fluids using enhanced surfaces such as copper surfaces with deep minichannels [3], microporous copper surfaces and hydrophilic and hydrophobic nanostructured surfaces [4]. The results are similar to the ones by [1], i.e., similar performances between the two fluids were observed.…”

Section: Introductionsupporting

confidence: 52%

Pool boiling performances comparison of FC-72 and Novec 649 in the presence of a DC electric field

Garivalis,

Fanani,

Di Marco

2024

J. Phys.: Conf. Ser.

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Electronics cooling by direct immersion of the components in a dielectric liquid to obtain pool boiling is a valuable solution to dissipate the high heat fluxes of latest and increasingly challenging requirements. In the last decades, perfluorocarbons such as FC-72 were intensively studied and used. However, such fluids will be replaced by other refrigerants with lower Global Warming Potential. The Novec 649 is a suitable alternative to FC-72 as most of the thermophysical properties are similar. Enhanced boiling of FC-72 due to electric fields has been a subject of studies in the past years, for ground and space applications. The aim of this work is to compare the boiling performances of the two fluids in the presence of a DC electric field. Boiling curves were obtained at ambient pressure with fully degassed fluids and at different subcooling levels. Results showed that the performances of the two fluids are comparable in the absence of the electric field, but there are some differences when the electric field is on: electric field enhances the heat transfer coefficient of Novec 649 at low heat fluxes and the Critical Heat Flux at high subcooling. Boiling patterns and bubbles dynamics appear quite different between the two fluids in the presence of the electric field. These observations are explained with the fact that while FC-72 behaves as an electric insulator, while Novec 649 is a leaky-dielectric in the examined conditions. Thus, Novec 649 is a valid replacement of FC-72 and further investigations are needed to better quantify its boiling performances under the action of an electric field.

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Section: Introductionsupporting

confidence: 52%

Pool boiling performances comparison of FC-72 and Novec 649 in the presence of a DC electric field

Garivalis,

Fanani,

Di Marco

2024

J. Phys.: Conf. Ser.

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“…The enhancement of heat transfer in the nucleate boiling regime can be achieved in various ways, including by (i) changing the characteristics of the boiling surface, (ii) modifying the surface-fluid interaction, (iii) modifying the working fluid, or (iv) changing the operating conditions [ 10 , 11 ]. The aim of these methods is generally to lower the ONB and increase both the CHF and the HTC [ 11 , 12 , 13 ]. Most approaches to boiling enhancement only consider one technique, meaning that possible combinations and synergies between more techniques are largely unexplored.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, researchers have thoroughly studied different techniques for intensifying boiling heat transfer, such as adding nanoparticles to the base fluid or modifying the surface characteristics of the boiling surface, namely its roughness, porosity, wettability, wickability, etc. [ 13 , 14 , 15 , 16 , 17 , 18 ]. Surface modification may be performed on the macro-, micro- or nanoscale [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Nanoparticle Size and Concentration on Pool Boiling Heat Transfer with TiO2 Nanofluids on Laser-Textured Copper Surfaces

et al. 2022

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The enhancement of boiling heat transfer has been extensively shown to be achievable through surface texturing or fluid property modification, yet few studies have investigated the possibility of coupling both enhancement approaches. The present work focuses on exploring the possibility of concomitant enhancement of pool boiling heat transfer by using TiO2-water nanofluid in combination with laser-textured copper surfaces. Two mass concentrations of 0.001 wt.% and 0.1 wt.% are used, along with two nanoparticle sizes of 4–8 nm and 490 nm. Nanofluids are prepared using sonification and degassed distilled water, while the boiling experiments are performed at atmospheric pressure. The results demonstrate that the heat transfer coefficient (HTC) using nanofluids is deteriorated compared to using pure water on the reference and laser-textured surface. However, the critical heat flux (CHF) is significantly improved at 0.1 wt.% nanoparticle concentration. The buildup of a highly wettable TiO2 layer on the surface is identified as the main reason for the observed performance. Multiple subsequent boiling experiments using nanofluids on the same surface exhibited a notable shift in boiling curves and their instability at higher concentrations, which is attributable to growth of the nanoparticle layer on the surface. Overall, the combination of nanofluids boiling on a laser-textured surface proved to enhance the CHF after prolonged exposure to highly concentrated nanofluid, while the HTC was universally and significantly decreased in all cases.

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“…Many researchers have focused on an exploration of the basic physical principle and practical meaning as related to liquid-solid interaction, including drop impact on micro-and nano-structured surfaces [16][17][18][19][20][21][22][23][24][25][26][27][28]. Bird et al [16] studied that superhydrophobic surfaces with macrotextures could decrease the contact time of millimeter-sized water drops by means of center-assisted retraction.…”

Section: Introductionmentioning

confidence: 99%

“…Besides the head-on impact on macrotexture, Han et al [18] presented fin-stripe non-wettable surfaces for spatial offset maximization and temporal contact minimization of bouncing drops. Other methods have been developed to functionalize the surfaces and modify the performance: vitrimer thin films for durable hydrophobicity [19], functionalized copper surfaces [20], and biphilic surfaces [21] for enhanced heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the Bounce and Separation Dynamics of Janus Drop on Macrotextured Surface

Choi

Yun

2022

Polymers

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Janus drops are thermodynamically stable when a high-viscosity fluid is imposed on a low-viscosity fluid. To understand physical mechanisms in Janus drop impact on macrotextured surfaces, several challenges in finding parameters or strategies still remain. Here, this study investigates the asymmetric bounce and separation of impinging Janus drops on non-wettable surfaces decorated with a macroridge to explore the effect of the drop size, viscosity ratio, and ridge size on the dynamics. Through numerical simulations, we determine the threshold Weber number, above which separation occurs, by varying drop diameters and viscosity ratios of the Janus drops. We investigate the initial bouncing directions of separated drops as a function of the impact velocity and viscosity ratio. We also predict how the separation efficiency is affected by the ridge’s height and width. The asymmetric impact dynamics of Janus drops on macrotextured surfaces can provide new strategies to control drop bouncing in applications, such as liquid separation and purification.

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Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649

Cited by 28 publications

References 108 publications

Pool boiling performances comparison of FC-72 and Novec 649 in the presence of a DC electric field

Pool boiling performances comparison of FC-72 and Novec 649 in the presence of a DC electric field

Effect of Nanoparticle Size and Concentration on Pool Boiling Heat Transfer with TiO2 Nanofluids on Laser-Textured Copper Surfaces

Characterizing the Bounce and Separation Dynamics of Janus Drop on Macrotextured Surface

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