Velocity field measurement in micro-bubble emission boiling

Ito, Daisuke; Jun, Natazuka; Saitō, Yasushi

doi:10.1299/transjsme.16-00428

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…It would be thus rather impossible to detect the precise variations of the surface temperature and heat flux. It is noticed that the quasi-heat flux q ′′ is evaluated regardless of the development of the heat flux q (Ando et al, 2016;Ito et al, 2017;Horiuchi et al, 2021) in the present study.…”

Section: Methodsmentioning

confidence: 79%

Hysteresis in microbubble emission boiling (MEB) under highly subcooled conditions

KOBAYASHI

Hayashi

Kurose

et al. 2022

Mechanical Engineering Journal

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Hysteresis in so-called 'microbubble emission boiling (MEB)' in a pool is investigated experimentally. Correlation among the heat transfer characteristics, the behavior of the vapor bubbles over the horizontal circular heat-transfer surface, and the induced boiling sound is indicated under various highly subcooled conditions for the processes of increasing and decreasing the power input to the heaters. Variations of the boiling sound is depicted by monitoring the spectrogram. Spatio-temporal variation of the vapor bubbles' oscillation and their synchronous behavior in the MEB are illustrated. It is indicated that the variation of the fundamental frequency of the vapor bubbles' oscillation almost coincides in the increasing and decreasing processes of the power input to the heaters, whereas the heat transfer characteristics becomes worse in the decreasing process in the MEB regimes.

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Section: Methodsmentioning

confidence: 79%

Hysteresis in microbubble emission boiling (MEB) under highly subcooled conditions

KOBAYASHI

Hayashi

Kurose

et al. 2022

Mechanical Engineering Journal

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“…Ando et al (2016) tracked several microbubbles above the heating surface to show the near-wall liquid flow, and found that the local liquid might be drawn towards the heating surface in MEB. Ito, Natazuka & Saito (2017) also used microbubbles as tracer particles to measure the flow field and discussed the temporally averaged velocity characteristics in MEB. The tracked microbubbles formed via bubble collapse, resulting in their uneven spatial distribution in the bulk, and temporal variations in their sizes.…”

Section: Introductionmentioning

confidence: 99%

Bubble-induced oscillating flow in microbubble emission boiling under highly subcooled conditions

Tang

et al. 2023

J. Fluid Mech.

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Microbubble emission boiling (MEB), a phenomenon that occurs under highly subcooled boiling conditions, can achieve a high heat flux beyond critical heat flux. MEB has been observed to differ from nucleate boiling and is always accompanied by the emission of microbubbles from an oscillating bubble. The heat transfer mechanism of MEB differs from that of nucleate boiling and remains elusive. In this study, we measure the behaviour of a vapour bubble and its induced liquid flow simultaneously during subcooled boiling using the high-speed two-phase particle image velocimetry method. Different from nucleate boiling, we observe a rapid oscillating flow outside the bubble that constantly attaches on the heating surface in MEB. The spatially and temporally averaged velocity magnitude values under this oscillating flow, and their dependency on liquid subcooling and heat flux, are quantified. Then we derive a scaling law for the heat transfer of MEB as a function of Péclet and Jacob numbers. With such correlations, we suggest that the oscillating flow induced by bubble oscillations is important to MEB, thus elucidating a different heat transport process from nucleate boiling.

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“…Several studies have considered the instability of the liquid-vapor interface of coalesced bubbles, with an emphasis on the condensation disappearance process of coalesced bubbles in the subcooled region, as the main factor for inducing a high heat flux (Ueno, et al, 2015;Tang, et al, 2017;Tang, et al, 2018;Tang, et al, 2019a). To elucidate the effect of a subcooled liquid supply to the heat transfer surface, velocity field measurements near the heat transfer surface have been performed via a particle image velocimetry (PIV) (Ito, et al, 2017). It is interesting to note that the disappearance of coalesced bubbles which creates a rapid flow of subcooled water to the heat transfer surface initiates the transition to MEB (Ando, et al, 2016).…”

Section: Introductionmentioning

confidence: 99%