Boiling on Enhanced Surfaces

Antao, Dion S.; Zhu, Yangying; Wang, Evelyn N.

doi:10.1007/978-3-319-26695-4_43

Cited by 1 publication

(2 citation statements)

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“…It is also relevant to point out that Hsu proposed a model for the size range of effective nucleation cavities on boiling surfaces based on a transient heat transfer analysis, and demonstrated that the size range of effective nucleation cavities on boiling surfaces is ∼1–100 μm, which is orders of magnitude larger than the effective nucleation cavities for gas-evolving surfaces (∼0.01–1 μm) determined by our proposed model. This explains why the nucleation site densities on boiling surfaces (10 4 –10 6 sites/m 2 ) − are far lower than electrochemical gas-evolving surfaces (10 7 –10 9 sites/m 2 ). − The orders of magnitude difference on the sizes of effective nucleation cavities can be attributed to the fact that the typical thermal boundary layer thickness on boiling surfaces (∼25 to 250 μm) is much larger than the concentration boundary layer thickness (∼0.2 to 5 μm).…”

Section: Resultsmentioning

confidence: 99%

“…This explains why the nucleation site densities on boiling surfaces (10 4 −10 6 sites/m 2 ) 43−45 are far lower than electrochemical gas-evolving surfaces (10 7 −10 9 sites/m 2 ). 46−48 The orders of magnitude difference on the sizes of effective nucleation cavities can be attributed to the fact that the typical thermal boundary layer thickness on boiling surfaces (∼25 to 250 μm 49 ) is much larger than the concentration boundary layer thickness (∼0.2 to 5 μm 24 ).…”

Section: Effects Of the Contact Angle And Cone Angle On The Size Rang...mentioning

confidence: 99%

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Size Ranges of Effective Nucleation Cavities on Gas-Evolving Surfaces

Zhao,

Zhang,

Gong

2023

Langmuir

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Bubble nucleation has a significant influence on mass transfer and energy conversion in electrochemical gas-evolving reactions. In this work, we establish a theoretical model for bubble nucleation from gas cavities on gas-evolving surfaces. Based on analyses of transient gas diffusion within the concentration boundary layer and supersaturation equation for stable bubble nuclei, we determined the size ranges of effective nucleation cavities on gas-evolving surfaces under different levels of supersaturation conditions. In addition, a criterion for the incipience of bubble nucleation on gasevolving surfaces is proposed. We investigate the effects of the contact angle, cone angle, concentration boundary layer thickness, ambient pressure, and temperature on the size ranges of effective nucleation cavities, respectively. We demonstrate that a larger contact angle or a smaller cone angle can broaden the size range of effective cavities, thereby promoting bubble nucleation from cavities. We also show that increasing the concentration boundary layer thickness causes larger cavities to become effective nucleation sites, which significantly expands the size range of effective cavities. In contrast, increasing the ambient pressure enables smaller cavities to become effective nucleation sites, resulting in an expansion in the size range of effective cavities. Results of this work will contribute to the manipulation of bubble nucleation densities and the optimal design of gas-evolving electrodes in various electrochemical gas-evolving reactions.

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