Bubble dynamics and induced flow in a subcooled nucleate pool boiling with varying subcooled temperature

Kim, Hyunsup; Park, Hyungmin

doi:10.1016/j.ijheatmasstransfer.2021.122054

Cited by 16 publications

(11 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based on the error propagation method, the relative heat flux and wall temperature uncertainties were found to be 10.7 % and 2 %, respectively. The bubble behaviours and liquid flow field were recorded simultaneously using the high-speed two-phase PIV technique (Maeng & Park 2021;Kim & Park 2022). The PIV system consisted of a high-speed video camera (Photron: Fastcam AX100), a continuous-wave laser (OEM-V-532, CNI) with wavelength 532 nm, and an LED light with a long-pass optical filter (with a 680 nm cut-on wavelength).…”

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The heat transfer mechanisms of nucleate boiling and MEB are distinguishable due to the significantly different bubble behaviours. In nucleate boiling under subcooled conditions, vapour bubbles experience growth, coalescence, departure, rising and condensation (Kim & Park 2022). Lakkaraju et al (2013) reported that the buoyancy of detached bubbles in nucleate boiling drove the liquid near the wall to enhance natural convection, especially under subcooled conditions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Tang

et al. 2023

J. Fluid Mech.

View full text Add to dashboard Cite

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.

show abstract

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Tang

et al. 2023

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…Understanding the mechanisms behind bubble growth, detachment, coalescence, and rising is important in various fields such as chemical, energy, and environmental engineering. − This understanding is essential for accurately predicting and optimizing gas holdup in a bubble column, , heat transfer performance in boiling, , and hydrogen production efficiency during water electrolysis . In recent years, there has been a growing interest in studying bubble formation on small-scale nozzles or orifices due to the development of microreaction and two-phase microchannel heat sink and the need for fine bubble preparation.…”

Section: Introductionmentioning

confidence: 99%

Shape Oscillation-Induced Early Detachment of Bubble from a Submerged Microcapillary Nozzle

Tang,

Hu,

et al. 2023

Langmuir

View full text Add to dashboard Cite

Bubble growth and detachment are basic phenomena in boiling and water splitting processes and are essential for their heat transfer performance and hydrogen production efficiency. In this study, we investigate the formation and detachment of bubbles from a submerged capillary nozzle. Here, we report a new bubbling regime and term it unstable bubbling, where early and normal bubble detachments coexist. The early detachment leads to the generation of many finer bubbles, ranging from one-fifth to one-half of the volume of the permanently detached bubbles driven by buoyancy. The occurrence conditions for unstable bubbling are identified by developing a regime map. The visualization of bubble-induced liquid flow and energy analysis suggest that the oscillating detached bubble provides excess surface and kinetic energies to the growing bubble, supporting early bubble detachment. Two dimensionless numbers are derived considering the effect of these energies, which can be applied to successfully predict the occurrence of early detachment. The present results not only provide physical insight into bubble interactions but also offer potential techniques for generating fine bubbles.

show abstract

“…Interfacial momentum exchange between continuous and dispersed phases is very important in understanding the physics of multiphase flows, in particular, for the gas-liquid two-phase flows, where the gas-liquid interface deforms in a complex manner and the mutual interaction between the phases are correlated [1][2][3][4][5][6][7][8][9][10] . Since the interfacial forces (e.g., drag, lift, added mass and basset history forces) acting on the rising bubbles in a liquid flow [11][12][13] and the bubbleinduced agitation (pseudo-turbulence) to the liquid flow [5,8,[14][15][16][17][18][19] are strongly determined by the bubble velocity (motion) relative to the liquid-phase, it is critical to have the detailed information of bubble velocities.…”

Section: Introductionmentioning

confidence: 99%

Bubble velocimetry using the conventional and CNN-based optical flow algorithms

Park

Choi

2022

Preprint

Self Cite

View full text Add to dashboard Cite

In the present study, we introduce new bubble velocimetry methods based on the optical flow, which were validated (compared) with the conventional particle tracking velocimetry (PTV) for various gas-liquid two-phase flows. For the optical flow algorithms, the convolutional neural network (CNN)-based models as well as the original schemes like the Lucas-Kanade and Farnebäck methods are considered. In particular, the CNN-based method was retrained (fine-tuned) using the synthetic bubble images produced by varying the density, diameter, and velocity distribution. While all models accurately measured the unsteady velocities of a single bubble rising with a lateral oscillation, the pre-trained CNN-based method showed the discrepancy in the averaged velocities in both directions for the dilute bubble plume. In terms of the fluctuating velocity components, the fine-tuned CNN-based model produced the closest results to that from PTV, while the conventional optical flow methods under-or overestimated them owing to the intensity assumption. When the void fraction increases much higher (e.g., over 10%) in the bubble plume, the PTV failed to evaluate the bubble velocities because of the overlapped bubble images and significant bubble deformation, which is clearly overcome by the optical flow bubble velocimetry. This is quite encouraging in experimentally investigating the gas-liquid two-phase flows of a high void fraction. Furthermore, the fine-tuned CNN-based model captures the individual motion of overlapped bubbles most faithfully while saving the computing time, compared to the Farnebäck method.

show abstract

Bubble dynamics and induced flow in a subcooled nucleate pool boiling with varying subcooled temperature

Cited by 16 publications

References 66 publications

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

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

Shape Oscillation-Induced Early Detachment of Bubble from a Submerged Microcapillary Nozzle

Bubble velocimetry using the conventional and CNN-based optical flow algorithms

Contact Info

Product

Resources

About