Visualization of convective boiling heat transfer in single microchannels with different shaped cross-sections

Yen, Tzu-Hsiang; Shoji, Masahiro; Takemura, Fumio; Suzuki, Yuji; Kasagi, Nobuhide

doi:10.1016/j.ijheatmasstransfer.2005.12.024

Cited by 77 publications

(36 citation statements)

References 18 publications

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“…Yen et al [10] reported that for a square microchannel crosssection, bubbly, slug, and annular flow patterns were typically observed, and capillary flow pattern was rarely observed. Here, the dryout of the liquid film was initiated at the center of the inner walls in an annular flow pattern.…”

Section: Introductionmentioning

confidence: 99%

Two-Phase Flow Pressure Drop Characteristics in Trapezoidal Silicon Microchannels

Singh

Bhide

Duttagupta

et al. 2009

IEEE Trans. Comp. Packag. Technol.

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Abstract-This paper focuses on experimentally studying the pressure drop characteristics for two-phase flow in microchannels of hydraulic diameter 109 μm, over a relatively large range of heat flux of (0-30 W/cm 2 ) and mass flow rate values (44-1114 kg/m 2 -s). Three fluid flow regimes (single-phase, twophase, and dryout) have been covered in this paper, with deionized water as the working fluid. For a given heat flux, the variation of average pressure drop with flow rate can be classified into three distinct regimes. In the first regime (higher flow rate), the pressure drop decreases linearly with decrease in flow rate. In the second regime (lower flow rate), pressure drop increases with decreasing flow rate and reaches a maximum (with a minimum on either side). Finally, in the very low flow rate regime, pressure drop increases rapidly with decreasing flow rate. The average pressure drop in the two-phase regime is predicted well by the annular flow model. In addition to absolute pressure drop values, we also report pressure fluctuations. The magnitude of pressure fluctuations appears to be correlated to the underlying flow regime, such as bubbly, slug, and annular regimes, which have been identified through the flow visualization. An important outcome of this study is the identification of as many as four operating points with similar pressure drop penalty. This may help to choose the right operating conditions for a microchannelbased heat sink for use in cooling electronics. These detailed experimental results are also expected to be useful for modeling two-phase flow in microchannels.

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Section: Introductionmentioning

confidence: 99%

Two-Phase Flow Pressure Drop Characteristics in Trapezoidal Silicon Microchannels

Singh

Bhide

Duttagupta

et al. 2009

IEEE Trans. Comp. Packag. Technol.

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“…Furthermore, they suggested that annular flow model is good for approximately square cross-sections but poor for large aspect ratio rectangular cross-section microchannels. Yen et al (2006) studied convective boiling of HCFC-123 in transparent microchannels of same hydraulic diameter of 214 µm but different cross-sections. They observed that the heat transfer coefficient was higher for square microchannel (because of corners which acted as active nucleation sites) as compared to circular shaped microchannel.…”

Section: Frontiers In Heat and Mass Transfermentioning

confidence: 99%

Pressure Drop Measurements With Boiling in Diverging Microchannel

Agrawal

Duryodhan²,

Singh³

2012

Frontiers in Heat and Mass Transfer

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An experimental study of flow boiling through diverging microchannels has been carried out in this work, with the aim of exploring reduction in flow instabilities during boiling in diverging microchannels. Effect of mass flux, heat flux and divergence angle on two phase pressure drop has been studied using deionized water as the working fluid. The experiments are carried out on three test sections with divergence angle of 4, 8 and 12 deg with nearly constant hydraulic diameter (146, 154 and 157 µm respectively), for inlet mass flux and heat flux range of 117 -1197 kg/m 2 -s and 2.5 to 19.7 W/cm 2 respectively. Pressure drop with respect to mass flux is linear and non-linear in single and two phase regimes, respectively. There are up to three points in single/two-phase regime having the same pressure drop, which is similar to uniform cross section microchannel. However, unlike uniform cross section microchannel, the slope of demand curve at the point of onset of flow boiling is less steep in diverging microchannel; further, the slope is an inverse function of the divergence angle. Preliminary study suggests that diverging microchannel can reduce the flow instabilities.

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“…Flow boiling of H CFC123 in micro-channels with different shaped cross-sections was carried out by Yen et al (2006). They reported that at low vapour quality region, bubbly flow and annular flow were observed in the square micro-channel having hydraulic diameter of 214 µm.…”

Section: Fl Ow Visualizationmentioning

confidence: 99%

“…Yen et al (2006) e xperimentally studied flow boiling heat transfer characteristics of H CFC123 in circular and square microchannels with the same hydraulic diameter of a round 210 µm. The heat transfer coefficient for t he square channel was relatively high in low vapour quality region when compared with that for t he circular channel.…”

Section: Two-phase Heat Transfermentioning

confidence: 99%

A Critical Review of Recent Investigations on Flow Pattern and Heat Transfer During Flow Boiling in Micro-Channels

Saisorn¹

2012

Frontiers in Heat and Mass Transfer

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Visualization of convective boiling heat transfer in single microchannels with different shaped cross-sections

Cited by 77 publications

References 18 publications

Two-Phase Flow Pressure Drop Characteristics in Trapezoidal Silicon Microchannels

Two-Phase Flow Pressure Drop Characteristics in Trapezoidal Silicon Microchannels

Pressure Drop Measurements With Boiling in Diverging Microchannel

A Critical Review of Recent Investigations on Flow Pattern and Heat Transfer During Flow Boiling in Micro-Channels

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