Visualization study of flow boiling characteristics in open microchannels with different wettability

Zhao, Qi; Qiu, Juncheng; Zhou, Jianhong; Lu, Mingxiang; Li, Qiang

doi:10.1016/j.ijheatmasstransfer.2021.121808

Cited by 45 publications

(4 citation statements)

References 52 publications

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“…The dynamic viscosity characteristic can make the working fluid perform periodic disturbances to enhance convective boiling heat transfer. A study showed that modulating the wettability of microchannels is an effective method to improve flow boiling [10]. Soleimani et al [11] used computational fluid dynamics (CFD) to simulate the subcooled flow boiling inside the microchannel.…”

Section: Introductionmentioning

confidence: 99%

Parametrical Study on the Capillary Flowing Characteristics of the Parallel Microchannel Array

et al. 2022

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The flow mechanism within a silicon-based micro heat sink plays a crucial role in two-phase thermal dissipation technology. In this study, the effect of geometrical properties on the flow behavior within a silicon-based array parallel microchannel as the evaporator of a silicon-based micro loop heat pipe (s-mLHP) is experimentally and numerically investigated. Here, three arrayed microchannels with different aspect ratio (AR) parameters (depth of 180 μm and AR of 6, 9, and 15) are specially fabricated. A visual experiment platform is established to observe and measure capillary properties of microchannels characterized by the suction distance. In addition, a validated numerical model (the maximum deviation less than 38.3%) is applied to simulate the flow characteristics of microchannels with different ARs. Numerical solutions show that the microchannel with ARs taken between 3 and 4 achieves the best capillary pumping performance within the studied range (suction distance up to 0.8 mm), which provides a theoretical basis for further exploration of silicon-based microchannel array with the optimal flow and thermal performance.

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Section: Introductionmentioning

confidence: 99%

Parametrical Study on the Capillary Flowing Characteristics of the Parallel Microchannel Array

et al. 2022

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“…The comparison between the flow boiling in closed microchannels and that in open microchannels was conducted. Zhao et al 34 also experimentally explored the flow boiling in open microchannels, where the three various wetting property surfaces were fabricated. The surface wettability determined the bubble nucleation and liquid delivery, which significantly affected the flow pattern, pressure drop, and boiling heat transfer.…”

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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“…Surface wettability is one of the most important parameters affecting two-phase heat transfer due to modifications in the three phase contact line as well as the number of active nucleation sites (Basu et al, 2002). Experimental studies proved that hydrophobic substrates provide higher heat transfer coefficients in flow boiling in micro- (Choi et al, 2011;Kim and Lee, 2019) and minichannels (Phan et al, 2011;Zhao et al, 2021) in comparison with hydrophilic ones. Generally, low energy surfaces (hydrophobic) remarkably augment the onset of nucleate boiling and bubble departure, while high energy surfaces (hydrophilic) enhance liquid replenishment and raises the critical heat flux (Motezakker et al, 2019;Sadaghiani et al, 2020a;Tan et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…The heat transfer performance and visualization were investigated for different biphilic surfaces in the following sections. It should be noted that since the hydrophobic surfaces typically provide higher heat transfer coefficients (Choi et al, 2011;Phan et al, 2011;Kim and Lee, 2019;Zhao et al, 2021), the heat transfer coefficients obtained from the biphilic surfaces are compared with a hydrophobic surface, which acts as a better reference in this study for comparison purposes.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Biphilicity on FC-72 Flow Boiling in a Rectangular Minichannel

et al. 2021

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Flow boiling is one of the most effective mechanisms in heat transfer thanks to the latent heat of vaporization. Surface modifications such as mixed-wettability have a considerable effect on the boiling heat transfer performance in terms of enhancement in boiling heat transfer as well as critical heat flux. This study introduces a new method of fabrication of biphilic surfaces, where C4F8 (Octafluorocyclobutane) islands are surrounded by silicon. Two different biphilic surfaces were fabricated and compared with the entirely uniform hydrophobic surface taken as a reference,. Each of the biphilic surfaces has three different sections, namely inlet, middle and outlet regions. The first region is mainly hydrophobic (inlet), while the third region is mainly hydrophilic (outlet). The heat transfer coefficients were obtained at different heat fluxes. Compared to the entirely uniform hydrophobic surface, the results show that biphilic surfaces enhance the boiling heat transfer performance by up to 50%. The visualization results revealed that the biphilic surfaces lead to more nucleation sites in the bubbly flow regime and break up the elongated bubbles in the slug flow regime.

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Visualization study of flow boiling characteristics in open microchannels with different wettability

Cited by 45 publications

References 52 publications

Parametrical Study on the Capillary Flowing Characteristics of the Parallel Microchannel Array

Parametrical Study on the Capillary Flowing Characteristics of the Parallel Microchannel Array

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

Effect of Surface Biphilicity on FC-72 Flow Boiling in a Rectangular Minichannel

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