Surface Structure Enhanced Microchannel Flow Boiling

Zhu, Yangying; Antao, Dion S.; Chu, Kuang‐Han; Chen, Siyu; Hendricks, Terry J.; Zhang, Tiejun; Wang, Evelyn N.

doi:10.1115/1.4033497

Cited by 135 publications

(41 citation statements)

References 48 publications

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“…While liquid-vapor phase-change techniques such as flow boiling in microchannels have been investigated for conductive 7,8 as well as dielectric fluids [9][10][11] , significant limitations associated with flow instabilities and power consumption prohibit practical implementation 8,12 .…”

Section: Introductionmentioning

confidence: 99%

Nanoporous membrane device for ultra high heat flux thermal management

et al. 2018

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High power density electronics are severely limited by current thermal management solutions which are unable to dissipate the necessary heat flux while maintaining safe junction temperatures for reliable operation. We designed, fabricated, and experimentally characterized a microfluidic device for ultra-high heat flux dissipation using evaporation from a nanoporous silicon membrane. With~100 nm diameter pores, the membrane can generate high capillary pressure even with low surface tension fluids such as pentane and R245fa. The suspended ultra-thin membrane structure facilitates efficient liquid transport with minimal viscous pressure losses. We fabricated the membrane in silicon using interference lithography and reactive ion etching and then bonded it to a high permeability silicon microchannel array to create a biporous wick which achieves high capillary pressure with enhanced permeability. The back side consisted of a thin film platinum heater and resistive temperature sensors to emulate the heat dissipation in transistors and measure the temperature, respectively. We experimentally characterized the devices in pure vaporambient conditions in an environmental chamber. Accordingly, we demonstrated heat fluxes of 665 ± 74 W/cm 2 using pentane over an area of 0.172 mm × 10 mm with a temperature rise of 28.5 ± 1.8 K from the heated substrate to ambient vapor. This heat flux, which is normalized by the evaporation area, is the highest reported to date in the pure evaporation regime, that is, without nucleate boiling. The experimental results are in good agreement with a high fidelity model which captures heat conduction in the suspended membrane structure as well as non-equilibrium and sub-continuum effects at the liquid-vapor interface. This work suggests that evaporative membrane-based approaches can be promising towards realizing an efficient, high flux thermal management strategy over large areas for high-performance electronics.

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Section: Introductionmentioning

confidence: 99%

Nanoporous membrane device for ultra high heat flux thermal management

et al. 2018

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“…A variety of heat sink designs have been employed to dissipate larger heat fluxes by delaying CHF or reducing the pressure drop in two-phase operation compared to a conventional design with straight, parallel channels fed by a single header. These designs have implemented one or more of features such as vapor venting [10], pin-fins and interrupted channels of various shapes and configurations [10][11][12], wick structures to aid in thin film evaporation [13][14][15], microchannels with reentrant cavities and/or inlet restrictors [16], microgaps [17], arrays of jets [18][19][20][21], diverging channels [22,23], microchannels fed with tapered manifolds [24], and stacked heat sinks [25]. Heat fluxes as high as 1127 W/cm² have been dissipated with dielectric fluids [26] using a 10 mm × 20 mm copper heat sink that incorporated both flow boiling in microchannels and jet impingement.…”

Section: Introductionmentioning

confidence: 99%

A hierarchical manifold microchannel heat sink array for high-heat-flux two-phase cooling of electronics

Drummond

Back

Sinanis

et al. 2018

International Journal of Heat and Mass Transfer

268

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High-heat-flux removal is necessary for next-generation microelectronic systems to operate more reliably and efficiently. Extremely high heat removal rates are achieved in this work using a hierarchical manifold microchannel heat sink array. The microchannels are imbedded directly into the heated substrate to reduce the parasitic thermal resistances due to contact and conduction resistances. Discretizing the chip footprint area into multiple smaller heat sink elements with high-aspect-ratio microchannels ensures shortened effective fluid flow lengths. Phase change of high fluid mass fluxes can thus be accommodated in micron-scale channels while keeping pressure drops low compared to traditional, microchannel heat sinks.A thermal test vehicle, with all flow distribution components heterogeneously integrated, is fabricated to

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“…The experiments were conducted on a stainless steel (13 mm × 30 mm × 0.25 mm) using micro wire EDM with multi-process micro machine tools, DT-110 (Mikrotools Inc., Singapore) as shown in Figure 1a. Stainless steel is one of the commonly used materials in fabricating miniaturized parts especially micropillars for cooling purposes in electronic components [32][33][34]. Tungsten wire with 70 µm was used as the tool electrode since it has high tensile strength and load-carrying capability [35].…”

Section: Methodsmentioning

confidence: 99%

Dimensional Accuracy in Dry Micro Wire Electrical Discharge Machining

Ali¹,

Banu²,

Salehan³

et al. 2018

J. MECH. ENG. SCI.

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Dimensional accuracy is important in fabricating miniaturized product in order to reduce the material waste and machining cost as well as to achieve a better quality product. This paper presents the analysis and modelling of dimensional accuracy in dry micro wire electrical discharge machining with control parameters of gap voltage and wire tension. The investigation was performed on stainless steel using integrated multi-process micro machine tools DT 110 with compressed air as the dielectric fluid and tungsten as the wire electrode. The dimensional accuracy was determined through kerf width differences of the machined slots. The kerf width was measured using scanning electron microscope. Full factorial was used to design the experiment while analysis of variance (ANOVA) was used to analyse the results as well as to evaluate the adequacy of the developed model. Based on ANOVA, both parameters; gap voltage and wire tension have high influence on kerf width differences. The optimum machining parameters for minimum kerf width differences were found to be 85 V gap voltage and 10 % wire tension. The developed model is adequate since the percentage error (2.13 %) is relatively small. It is recommended that different type of gases should be used for further investigation in order to determine the accuracy of the dry micro wire EDM.

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Surface Structure Enhanced Microchannel Flow Boiling

Abstract: ABSTRACT

Cited by 135 publications

References 48 publications

Nanoporous membrane device for ultra high heat flux thermal management

Nanoporous membrane device for ultra high heat flux thermal management

A hierarchical manifold microchannel heat sink array for high-heat-flux two-phase cooling of electronics

Dimensional Accuracy in Dry Micro Wire Electrical Discharge Machining

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