Pool boiling enhancement and a method of bubble diameter determination on surfaces with deep minichannels

Pastuszko, Robert; Kaniowski, Robert; Dadas, Norbert; Bedla-Pawlusek, Milena

doi:10.1016/j.ijheatmasstransfer.2021.121713

Cited by 19 publications

(8 citation statements)

References 43 publications

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“…It could be observed that the augmentation potential decreases with rising temperature of the heater. This observation is backed by other researchers, albeit for slightly different microstructural coatings (Kaniowski and Pastuszko, 2018;Pastuszko et al, 2021).…”

Section: Resultssupporting

confidence: 78%

Application of laser treatment technology for boiling heat transfer augmentation

Orman,

Radek,

Honus

et al. 2024

Production Engineering Archives

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Boiling heat transfer can be enhanced when the heater’s surface morphology is altered. The paper discusses the use of the laser beam to produce efficient heat exchangers. Two types of samples were investigated with distilled water and ethyl alcohol as boiling agents. The specimens differed with the height of the microfins: 0.19 mm and 0.89 mm. It was observed that both of them enhanced boiling heat transfer in comparison to the smooth reference surface. However, the sample with higher microfins performed better, especially in the region of low temperature differences, where the heat flux was about three times higher than in the case of the smaller microfins. The comparison of the experimental data with selected models of boiling heat transfer revealed significant differences with regard to the heat flux. The laser-made samples dissipated larger heat fluxes than it could be anticipated according to the models. It might be linked with high surface roughness of the area between the microfins, generated as a result of the laser beam interaction with the surface.

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Section: Resultssupporting

confidence: 78%

Application of laser treatment technology for boiling heat transfer augmentation

Orman,

Radek,

Honus

et al. 2024

Production Engineering Archives

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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: 51%

“…Boiling curves and heat transfer coefficients comparison at saturation with and without electric field. The VDI correlation is also showed [3].…”

Section: Figurementioning

confidence: 88%

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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“…9 kW m −2 K −1 using open microchannels. Recently, Pastuszko et al [68] investigated the use of deep microchannels for boiling enhancement and found that the best results for Novec™ 649 were obtained at a depth of 10 mm with the highest recorded HTCs exceeding 25 kW m −2 K −1 . Ghaffari et al [69] measured the CHF of Novec™ 649 to be 195 kW m −2 on bare copper surface under pool boiling conditions.…”

Section: Boiling Heat Transfer With Dielectric Fluidsmentioning

confidence: 99%

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

et al. 2021

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Increasing heat dissipation requirements of small and miniature devices demands advanced cooling methods, such as application of immersion cooling via boiling heat transfer. In this study, functionalized copper surfaces for enhanced heat transfer are developed and evaluated. Samples are functionalized using a chemical oxidation treatment with subsequent hydrophobization of selected surfaces with a fluorinated silane. Pool boiling tests with water, water/1-butanol mixture with self-rewetting properties and a novel dielectric fluid with low GWP (Novec™ 649) are conducted to evaluate the boiling performance of individual surfaces. The results show that hydrophobized functionalized surfaces covered by microcavities with diameters between 40 nm and 2 µm exhibit increased heat transfer coefficient (HTC; enhancements up to 120%) and critical heat flux (CHF; enhancements up to 64%) values in comparison with the untreated reference surface, complemented by favorable fabrication repeatability. Positive surface stability is observed in contact with water, while both the self-rewetting fluids and Novec™ 649 gradually degrade the boiling performance and in some cases also the surface itself. The use of water/1-butanol mixtures in particular results in surface chemistry and morphology changes, as observed using SEM imaging and Raman spectroscopy. This seems to be neglected in the available literature and should be focused on in further studies.

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Pool boiling enhancement and a method of bubble diameter determination on surfaces with deep minichannels

Cited by 19 publications

References 43 publications

Application of laser treatment technology for boiling heat transfer augmentation

Application of laser treatment technology for boiling heat transfer augmentation

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

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

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