Multi-artery, heat-pipe spreader

Min, Da-Hye; Hwang, Gisuk; Kaviany, Massoud

doi:10.1016/j.ijheatmasstransfer.2008.07.021

Cited by 36 publications

(4 citation statements)

References 8 publications

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“…The proposed top-down feeding approach decouples the liquid-feeding structure (i.e., the wick cap layer) from the capillary-fed boiling region in the evaporator; the complete evaporator footprint area is made available to the wick cap layer for capillary supply. Prior top-down feeding approaches [20] consisted of vertical posts covered by a uniform porous wick, directly connected from the condenser side to the evaporator. These long arteries spanning the entire thickness of a vapor chamber incur an increased pressure drop that negates any improvement over lateral feeding [9].…”

Section: Two Layer Evaporator Wick Conceptmentioning

confidence: 99%

Design of an Area-Scalable Two-Layer Evaporator Wick for High-Heat-Flux Vapor Chambers

Sudhakar

Weibel

Garimella

2019

IEEE Trans. Compon., Packag. Manufact. Technol.

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A hybrid two-layer evaporator wick is proposed for passive, high-heat-flux dissipation over large areas using a vapor chamber heat spreader. For such applications, the evaporator wick layer must be designed to simultaneously minimize the device temperature rise and minimize the flow resistance to capillary feeding of the wick. This requires a strategy that exploits the benefits of a thin wick for reduced thermal resistance and a thick wick for liquid feeding. In the present design, a thick cap layer of wick material evenly routes liquid to a thin, low-thermal-resistance base layer through an array of vertical liquid-feeding posts. This twolayer structure decouples the functions of liquid resupply (cap layer) and capillary-fed boiling heat transfer (base layer), making the design scalable to heat input areas of ~1 cm 2 for operation at 1 kW/cm 2. A reduced-order model is developed to demonstrate the potential performance of a vapor chamber incorporating such a two-layer evaporator wick design. The model comprises simplified hydraulic and thermal resistance networks for predicting the capillarylimited maximum heat flux and the overall thermal resistance, respectively. The reduced-order model is validated against a higher fidelity numerical model and then used to analyze the performance of the vapor chamber with varying two-layer wick geometric feature sizes. The two-layer wick design is found to sustain liquid feeding at higher heat fluxes, without reaching the capillary limit, compared to single-layer evaporator wick designs.

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Section: Two Layer Evaporator Wick Conceptmentioning

confidence: 99%

Design of an Area-Scalable Two-Layer Evaporator Wick for High-Heat-Flux Vapor Chambers

Sudhakar

Weibel

Garimella

2019

IEEE Trans. Compon., Packag. Manufact. Technol.

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“…The first type of novel liquid return structures investigated were columnar cylindrical arteries distributed over the heated area that fed fluid directly from the opposing condenser surface [40]. The artery geometry tested was optimized using a fluidthermal resistance network model [67]. While the columnar arteries act to provide local fluid delivery, the performance regimes are determined by evaporation from the thin monolayer of particles.…”

Section: Efficient Liquid Feeding and Vapor Extraction Featuresmentioning

confidence: 99%

“…Several wick structures were considered based on preliminary sub-device testing, viz. biporous sintered powder [36], lateral converging liquid return arteries [41], and vertical columnar arteries [67], but lateral arteries were ultimately chosen for their mechanical robustness [42]. A 100 mm × 100 mm prototype vapor chamber was constructed to accommodate an array of four 10 mm × 10 mm heat input areas for the potential thermal management of vertical cavity surface emitting laser (VCSEL) arrays, as shown in Figure 29c.…”

Section: Planar Vapor Chambers With Hybrid Evaporator Wicksmentioning

confidence: 99%

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

Weibel

Garimella

2013

Advances in Heat Transfer

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Owing to their high reliability, simplicity of manufacture, passive operation, and effective heat transport, flat heat pipes and vapor chambers are used extensively in the thermal management of electronic devices. The need for concurrent size, weight, and performance improvements in high-performance electronics systems, without resort to active liquid-cooling strategies, demands passive heat spreading technologies that can dissipate extremely high heat fluxes from small hot spots. In response to these daunting application-driven trends, a number of recent investigations have focused on the design, characterization, and fabrication of ultra-thin vapor chambers for proximate heat spreading away from these hot spots. The predominant transport mechanisms and operational limits have been found to be different under these conditions relative to conventional low-power heat pipes. Noteworthy advances in the fundamental understanding of evaporation and boiling from porous microstructures fed by capillary action, and improvements in vapor chamber characterization, modeling, design, and fabrication techniques are reviewed. Characterization of evaporation and boiling from idealized and realistic wick structures, observation of vapor formation regimes as a function of operating conditions, assessment of fluid dryout limitations, design of novel multi-scale and nanostructured wicks for enhanced transport, and incorporation of these high heat flux transport phenomena into device-level models are discussed. These recent developments have successfully extended the maximum operating heat flux limits of vapor chambers.2

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“…Microscale porous and modulated surface coatings have been shown to offer enhanced heat transfer efficiencies [1][2][3][4][5][6][7][8][9][10]. Various fabrication methods to achieve such surfaces were considered and experimented with as published in previous studies [11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Microscale-modulated porous coatings: fabrication and pool-boiling heat transfer performance

Cora

Min

Koç

et al. 2010

J. Micromech. Microeng.

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The manufacture of microscale-modulated coatings (periodic, porous stacks with a thin base layer) under mass-production conditions was investigated experimentally to establish robust process parameters. Copper powders (average diameter of 100 μm) were compacted on a copper substrate under controlled pressure, temperature, surface geometry and processing sequences (e.g., sintering before and after compaction). Porosity, stack height, pitch and base thickness of coatings were measured. Results show that a minimum temperature of 350 • C and pressure of 25 MPa are required for permeable coatings, when sintering is carried out after compaction. When 'sintering before compaction' is followed, pressure values in excess of 100 MPa are needed and surfaces from this approach block the pores and diminish permeability. Pool boiling heat transfer experiments were conducted on selected coatings, showing that the best enhancement is by low-pressure compation coatings.

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Multi-artery, heat-pipe spreader

Cited by 36 publications

References 8 publications

Design of an Area-Scalable Two-Layer Evaporator Wick for High-Heat-Flux Vapor Chambers

Design of an Area-Scalable Two-Layer Evaporator Wick for High-Heat-Flux Vapor Chambers

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

Microscale-modulated porous coatings: fabrication and pool-boiling heat transfer performance

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