Visualization study on bubble dynamical behavior in subcooled flow boiling under various subcooling degree and flowrates

Cao, Yang; Kawara, Zensaku; Yokomine, Takehiko; Kunugi, Tomoaki

doi:10.1016/j.ijheatmasstransfer.2015.10.053

Cited by 35 publications

(17 citation statements)

References 22 publications

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“…After that, those bubbles began shrinking while slightly shifting from the nucleate site and, finally, they departed from the probe surface collapsing in the bulk flow, near the probe surface. This dynamic behavior is in good agreement with that reported by other researchers [5][6][7][8][9][10] and is related to the inverse boiling curve as the dynamics of the bubbles at or near the wetting front produce the maximum heat extraction. Images of a bubble below the wetting front are shown in Fig.…”

Section: Resultssupporting

confidence: 92%

“…To improve the understanding of the boiling mechanisms, in particular during the nucleate boiling stage, the characteristics of the bubbles and their dynamic behavior must be studied. Most of the research conducted in this field has been carried out through heating experiments [5][6][7][8][9][10] and provide information related to bubble parameters such as size distribution, departure diameter, lifetime, growth rate, etc., as function of system variables such as heat flux, pressure, subcooling or quenchant velocity.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Boiling Phenomena during Laboratory-Scale Forced Convection Quenching

Cruces¹,

Hernández²,

Novas³

2018

World Congress on Mechanical, Chemical, and Material Engineering

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An experimental investigation was conducted to correlate heat extraction with boiling phenomena at the liquid-probe interface during forced convective quenching of a steel probe in a laboratory-scale facility. A conical-end probe made of AISI 304 stainless steel instrumented with two type-K thermocouples was rapidly cooled from 850 °C in water at 60°C, flowing with a free-stream velocity of 0.2 m/s. Bubble formation, growth and detachment at the probe surface was recorded with a high-speed video camera. Using the experimental cooling curves measured with the sub-surface thermocouple, the surface heat flux was estimated by solving a onedimensional inverse heat conduction problem (IHCP) without phase change. The inverse boiling curve obtained showed that the maximum peak on heat extraction was reached during the nucleate boiling stage and is associated with the time at which the wetting front passed though the thermocouple axial location. From image analysis, two regions can be distinguished as the wetting front travels through the probe: the wetting front, formed by small bubbles that grew rapidly and coalesced due to the large bubble population; and a region trailing the wetting front, where the size, population and dynamic behavior of the bubbles was quite different. These bubbles grew conserving a spheroidal shape until they reached their maximum size; when they were decreasing, a concave deformation was observed at the interface due to condensation caused by the quench media rewetting the surface and, finally, the bubble departed from the probe surface, collapsing in the bulk flow near the probe surface.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Characterization of Boiling Phenomena during Laboratory-Scale Forced Convection Quenching

Cruces¹,

Hernández²,

Novas³

2018

World Congress on Mechanical, Chemical, and Material Engineering

View full text Add to dashboard Cite

show abstract

“…To handle the complexity of the flow boiling, many researchers have recently studied and developed the individual mechanistic models based on the physical bubble behaviours, for instance, a sliding before lift-off, coalescence with neighbours to later become a mushroom bubble and also a reduction in the size while attaching to the wall due to its exposure to a cooler bulk liquid. 3,[17][18][19][20][21][22][23][24][25] To the best of author's knowledge, there is no existing combination of empirical correlations which is able to predict a wide range of boiling flow conditions. Also, as mentioned by Warrier and Dhir, 26 using the correlation without physical mechanisms of bubbles could also sometimes lead to a significant difference between the prediction and experimental data.…”

Section: Introductionmentioning

confidence: 99%

“…breakup, coalescence 30,31 and the condensation. 24 Consequently, through consideration of real fluid properties, a more precise prediction of vapour bubble size and its distribution could be expected.…”

Section: Introductionmentioning

confidence: 99%

CFD investigation of sub-cooled boiling flow using a mechanistic wall heat partitioning approach with Wet-Steam properties

Promtong

Cheung

Yeoh

et al. 2018

The Journal of Computational Multiphase Flows

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In this paper, the mechanistic wall heat partitioning approach was used to capture the complex heat and mass transfer in sub-cooled boiling flows. In order to accommodate the changes of local variables to be relevant to the physical properties of sub-cooled fluids, the Wet-Steam (IAPWS-IF97) is used as the working fluid. Currently, the approach is evaluated based on the bubble sliding along the wall before lifting-off, which is usually found in the flow boiling situations. In the simulation, the closure mechanistic models, including the fractal analysis, the force balance and the mechanistic frequency, were coupled with the Eulerian-Eulerian two-fluid framework, while the Shear Stress Transport model was used as a turbulent modelling closure. The Multiple Size Group model was introduced to handle the bubble interactions and predict the bubble size distribution. Moreover, the effect of adopting the sub-cooled liquid properties into the modelling was investigated and compared with the experiments over a wide range of flow conditions. Specifically, the predicted void fraction and the sub-cooling temperature near the heated wall were precisely compared with the cases of using the constant-property liquid. Overall, the satisfactory agreements were found between the experiments and the predictions of the liquid temperature, void fraction, interfacial area concentration, Sauter mean diameter and bubble and liquid velocities with the exception of the case of high heat and mass fluxes. To enhance the current prediction accuracy for a situation of having a high superheating temperature, more bubble interactions on the boiling wall, such as merging of the bubbles while sliding, need to be considered. Furthermore, to assess the model capability, this mechanistic approach will be introduced to elucidate the sub-cooled boiling flow in situations of using different fluids in the near future.

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“…At the beginning, the manual process was slow and tedious, but current technology brings the opportunity for turning the bubble recognition into a mass and automatized process. In the last few years, many research papers have tackled bubble size measurement and tracking procedures by the use of high speed filming as a valuable aid even with some other techniques, such as the infrared thermometry [ 31 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ], ultrasound technologies [ 40 ] or particle image velocimetry [ 41 , 42 ]. However, only a few authors briefly explain the processing image steps [ 43 , 44 , 45 , 46 ], and almost none fully described the computational steps of the recognition process.…”

Section: Introductionmentioning

confidence: 99%

On the Application of Image Processing Methods for Bubble Recognition to the Study of Subcooled Flow Boiling of Water in Rectangular Channels

Paz

Conde

Porteiro

et al. 2017

Sensors

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This work introduces the use of machine vision in the massive bubble recognition process, which supports the validation of boiling models involving bubble dynamics, as well as nucleation frequency, active site density and size of the bubbles. The two algorithms presented are meant to be run employing quite standard images of the bubbling process, recorded in general-purpose boiling facilities. The recognition routines are easily adaptable to other facilities if a minimum number of precautions are taken in the setup and in the treatment of the information. Both the side and front projections of subcooled flow-boiling phenomenon over a plain plate are covered. Once all of the intended bubbles have been located in space and time, the proper post-process of the recorded data become capable of tracking each of the recognized bubbles, sketching their trajectories and size evolution, locating the nucleation sites, computing their diameters, and so on. After validating the algorithm’s output against the human eye and data from other researchers, machine vision systems have been demonstrated to be a very valuable option to successfully perform the recognition process, even though the optical analysis of bubbles has not been set as the main goal of the experimental facility.

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Visualization study on bubble dynamical behavior in subcooled flow boiling under various subcooling degree and flowrates

Cited by 35 publications

References 22 publications

Characterization of Boiling Phenomena during Laboratory-Scale Forced Convection Quenching

Characterization of Boiling Phenomena during Laboratory-Scale Forced Convection Quenching

CFD investigation of sub-cooled boiling flow using a mechanistic wall heat partitioning approach with Wet-Steam properties

On the Application of Image Processing Methods for Bubble Recognition to the Study of Subcooled Flow Boiling of Water in Rectangular Channels

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