Effect of bubble coalescence on two-phase flow boiling heat transfer in raccoon microchannel - A numerical study

Bhuva, Vatsal Jayantilal; Jani, Jash; Patel, Abhay; Tiwari, Nishant

doi:10.1016/j.ijheatmasstransfer.2021.121943

Cited by 20 publications

(5 citation statements)

References 48 publications

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“…Wavy microchannels Bhuva et al (2021) numerically investigated the effect of flow boiling instabilities and bubble behavior in a racoon and straight microchannels. Both Eotvos and Weber numbers were estimated to analyze the bubble's behavior for different waviness (0 to 0.267 mm) and mass fluxes (118 to 590 kg/m 2 .s).…”

Section: Introductionmentioning

confidence: 99%

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Thermal performance improvement in wavy microchannels using secondary channels

Paramanandam,

Srinivasan

et al. 2024

HFF

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Purpose This study aims to minimize the pressure drop across wavy microchannels using secondary branches without compromising its capacity to transfer the heat. The impact of secondary flows on the pressure drop and heat transfer capabilities at different Reynolds numbers are investigated numerically for different wavy microchannels. Finally, different channels are evaluated using performance evaluation criteria to determine their effectiveness. Design/methodology/approach To investigate the flow and heat transfer capabilities in wavy microchannels having secondary branches, a 3D conjugate heat transfer model based on finite volume method is used. In conventional wavy microchannel, secondary branches are introduced at crest and trough locations. For the numerical simulation, a single symmetrical channel is used to minimize computational time and resources and the flow within the channels remains single-phase and laminar. Findings The findings indicate that the suggested secondary channels notably improve heat transfer and decrease pressure drop within the channels. At lower flow rates, the secondary channels demonstrate superior performance in terms of heat transfer. However, the performance declines as the flow rate increased. With the same amplitude and wavelength, the introduction of secondary channels reduces the pressure drop compared with conventional wavy channels. Due to the presence of secondary channels, the flow splits from the main channel, and part of the core flow gets diverted into the secondary channel as the flow takes the path of minimum resistance. Due to this flow split, the core velocity is reduced. An increase in flow area helps in reducing pressure drop. Practical implications Many complex and intricate microchannels are proposed by the researchers to augment heat dissipation. There are challenges in the fabrication of microchannels, such as surface finish and achieving the required dimensions. However, due to the recent developments in metal additive manufacturing and microfabrication techniques, the complex shapes proposed in this paper are feasible to fabricate. Originality/value Wavy channels are widely used in heat transfer and micro-fluidics applications. The proposed wavy microchannels with secondary channels are different when compared to conventional wavy channels and can be used practically to solve thermal challenges. They help achieve a lower pressure drop in wavy microchannels without compromising heat transfer performance.

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Section: Introductionmentioning

confidence: 99%

“…Bhuva et al. (2021) numerically investigated the effect of flow boiling instabilities and bubble behavior in a racoon and straight microchannels.…”

Section: Introductionmentioning

confidence: 99%

Thermal performance improvement in wavy microchannels using secondary channels

Paramanandam,

Srinivasan

et al. 2024

HFF

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“…Our team has previously obtained models that accurately predict common surface microchannels in pressure drop prediction studies but has not explored surface-modified microchannels [ 26 ]. In addition, raccooning or hybrid waving of the microchannel is also an effective way to enhance heat transfer [ 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Flow Pattern Study and Pressure Drop Prediction of Two-Phase Boiling Process in Different Surface Wettability Microchannel

Zhang

Zhang³

et al. 2023

Micromachines

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An experimental study of two-phase flow pressure drop using R-134a is conducted on three types of different surface wettability microchannels with superhydrophilic (contact angle of 0°), hydrophilic (contact angle of 43°) and common (contact angle of 70°, unmodified) surfaces, all with a hydraulic diameter of 0.805 mm. Experiments were conducted using a mass flux of 713–1629 kg/m2s and a heat flux of 7.0–35.1 kW/m2. Firstly, the bubble behavior during the two-phase boiling process in the superhydrophilic and common surface microchannel is studied. Through a large number of flow pattern diagrams under different working conditions, it is found that the bubble behavior shows different degrees of order in microchannels with different surface wettability. The experimental results show that the hydrophilic surface modification of microchannel is an effective method to enhance heat transfer and reduce friction pressure drop. Through the data analysis of friction pressure drop and C parameter, it is found that the three most important parameters affecting the two-phase friction pressure drop are mass flux, vapor quality, and surface wettability. Based on flow patterns and pressure drop characteristics obtained from the experiments, a new parameter, named flow order degree, is proposed to account for the overall effects of mass flux, vapor quality, and surface wettability on two-phase frictional pressure drop in microchannels, and a newly developed correlation based on the separated flow model is presented. In the superhydrophilic microchannel, the mean absolute error of the new correlation is 19.8%, which is considerably less than the error of the previous models.

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“…To date, the flow boiling in heated micro/mini channels has also received much attention due to its unique merits comparing with single-phase flow, where the heat transfer enhancement effect, pressure drop, temperature uniformity, and flow stabilities were recognized as the key performance indicators. [20][21][22] Several important affecting parameters such as geometric structure, [23][24][25] mass flow rate, [26][27][28] heating condition, 29,30 surface wettability, 31 and working fluid 32 determined the bubble nucleation and liquid delivery, which significantly affected the flow pattern, pressure drop, and boiling heat transfer. Aside from the above experimental studies, the numerical methods have also been extensively employed, which could reveal the heat and mass transport details that are not easily measurable in experiments.…”

Section: Introductionmentioning

confidence: 99%

“…To date, the flow boiling in heated micro/mini channels has also received much attention due to its unique merits comparing with single‐phase flow, where the heat transfer enhancement effect, pressure drop, temperature uniformity, and flow stabilities were recognized as the key performance indicators 20–22 . Several important affecting parameters such as geometric structure, 23–25 mass flow rate, 26–28 heating condition, 29,30 surface wettability, 31 and working fluid 32 were investigated by means of experiment and simulation. Yin et al 33 performed visualization experiments on the flow boiling in open straight microchannels and found different types of confined bubbles.…”

Section: Introductionmentioning

confidence: 99%

Bubble breakup and boiling heat transfer in Y‐shaped bifurcating microchannels

2022

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Three-dimensional simulations are performed to study the bubble breakup and boiling heat transfer in Y-shaped bifurcating microchannels with different heat fluxes and bifurcating angles. Results show that the breakup regime for continuously growing bubble changes from tunnel breakup to obstructed breakup as the heat flux increases. Interestingly, the pinch-off stage of bubble breakup becomes inconspicuous in small acute-angle bifurcating microchannel. The flow structure changes from smooth mode to twining mode as the bifurcating angle increases. The bubble transit leads to the shrink or disappearance of vortex. The heat transfer is tightly associated with bubble dynamics. The negative heat transfer enhancement is observed at low heat flux and it is eliminated at high heat flux. The heat transfer is enhanced with the increase in heat flux, while the effect of bifurcating angle is relatively complex. The present study provides new insights into the two-phase flow in bifurcating structures.

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Effect of bubble coalescence on two-phase flow boiling heat transfer in raccoon microchannel - A numerical study

Cited by 20 publications

References 48 publications

Thermal performance improvement in wavy microchannels using secondary channels

Thermal performance improvement in wavy microchannels using secondary channels

Flow Pattern Study and Pressure Drop Prediction of Two-Phase Boiling Process in Different Surface Wettability Microchannel

Bubble breakup and boiling heat transfer in Y‐shaped bifurcating microchannels

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