Nanoporous evaporative device for advanced electronics thermal management

Hanks, Daniel F.; Lu, Zhengmao; Narayanan, Shankar; Bagnall, Kevin R.; Raj, Rishi; Xiao, Ran; Enright, Ryan; Wang, Evelyn N.

doi:10.1109/itherm.2014.6892295

Cited by 22 publications

(12 citation statements)

References 24 publications

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“…By supplying liquid from the cross-plane direction of the membrane and reducing the membrane thickness, the liquid transport flow length is decreased to lower the viscous drag without significantly affecting the heat transfer and capillary force. Enhanced heat transfer performances have been predicted [33,34] and demonstrated [35][36][37].…”

Section: Introductionmentioning

confidence: 96%

Transition between thin film boiling and evaporation on nanoporous membranes near the kinetic limit

Wang

Shi

Chen

2020

International Journal of Heat and Mass Transfer

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Nanoporous structures including single nanopores and nanoporous membranes have beenutilized as a platform to study fundamental liquid-vapor phase change heat transfer (PCHT) processes as well as a promising candidate for high flux heat dissipation. Previously, we implemented nanoporous membranes to support a thin liquid film for boiling, which was termed "thin film boiling", and realized high heat transfer performance. Besides thin film boiling, thin film evaporation through nanoporous structures have also been demonstrated to achieve high heat flux, but these two mechanisms are usually considered two mutually exclusive regimes operated under vastly different conditions, and the factors dictating how close the PCHT process is to the kinetic limit are elusive. In this work, we utilized a unique transition between thin film boiling and evaporation through nanoporous membranes to clarify the factors determining the heat flux and heat transfer coefficient (HTC) with respect to the kinetic limit conditions. We unambiguously showed the controllable transition from boiling to evaporation, when the liquid receded into the nanopores and provided additional driving force from capillary pumping sustained in the nanoscale pores. We showed that this transition is universal and can be understood from a simple fluid transport model for all the four types of fluids we studied, which cover a wide span of surface tension (water, ethanol, IPA, FC-72). More importantly, PCHT conditions at the transition points between boiling and evaporation were close to those of the kinetic limit of all these fluids. However, further increase of the heat flux beyond the transition points led to decreasing HTC and deviation from the kinetic limit, which can be attributed to the increasing vapor resistance in the vapor space and inside the nanopores. This increasing vapor resistance was also confirmed by experiments on IPA with different vapor pressures. Our work could shed light on PCHT on nanoporous structures with respect to the kinetic limit, and could advance the development of high heat-flux heat dissipation devices, especially using dielectric fluids.

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Section: Introductionmentioning

confidence: 96%

Transition between thin film boiling and evaporation on nanoporous membranes near the kinetic limit

Wang

Shi

Chen

2020

International Journal of Heat and Mass Transfer

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“…The industry has called for innovative cooling technologies to respond to these issues . Integrated microfluidics and two-phase cooling have been proposed as potential solutions; however they require a cooling fluid and complicated changes to current layouts and manufacturing processes. The inherent compatibility and simplicity of solid-state thin-film thermoelectric devices with conventional CMOS makes μTECs a promising alternative.…”

Section: Introductionmentioning

confidence: 99%

Electrodeposited Thin-Film Micro-Thermoelectric Coolers with Extreme Heat Flux Handling and Microsecond Time Response

Corbett

Gautam

Lal

et al. 2021

ACS Appl. Mater. Interfaces

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Thin-film thermoelectric coolers are emerging as a viable option for the on-chip temperature management of electronic and photonic integrated circuits. In this work, we demonstrate the record heat flux handling capability of electrodeposited Bi 2 Te 3 films of 720(±60) W cm −2 at room temperature, achieved by careful control of the contact interfaces to reduce contact resistance. The characteristic parameters of a single leg thin-film devices were measured in situ, giving a Seebeck coefficient of S = −121(±6) μV K −1 , thermal conductivity of κ = 0.85(±0.08) W m −1 K −1 , electrical conductivity of σ = 5.2(±0.32) × 10 4 S m −1 , and electrical contact resistivity of ∼10 −11 Ω m 2 . These thermoelectric parameters lead to a material ZT = 0.26(±0.04), which, for our device structure, allowed a net cooling of ΔT max = 4.4(±0.12) K. A response time of τ = 20 μs was measured experimentally. This work shows that with the correct treatment of contact interfaces, electrodeposited thin-film thermoelectrics can compete with more complicated and expensive technologies such as metal organic chemical vapor deposition (MOCVD) multilayers.

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“…Evaporation from nanopores is essential for plant transpiration , and has inspired a variety of technologies in diverse areas including electronics cooling, − steam generation, − water desalination, − and power generation. , To further develop nanopore-evaporation-based technologies and achieve their ultimate performance, it is critical to understand the ultimate mass-transport-limited process involved. Evaporation from nanopores consists of three mass transport processes, i.e., liquid/vapor transport to/from the liquid–vapor interface, as well as liquid vaporization at the liquid–vapor interface.…”

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confidence: 99%

Ultrafast Diameter-Dependent Water Evaporation from Nanopores

Chen

Xiao

et al. 2019

ACS Nano

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Evaporation from nanopores plays an important role in various natural and industrial processes that require efficient heat and mass transfer. The ultimate performance of nanopore-evaporation-based processes is dictated by evaporation kinetics at the liquid–vapor interface, which has yet to be experimentally studied down to the single nanopore level. Here we report unambiguous measurements of kinetically limited intense evaporation from individual hydrophilic nanopores with both hydrophilic and hydrophobic top outer surfaces at 22 °C using nanochannel-connected nanopore devices. Our results show that the evaporation fluxes of nanopores with hydrophilic outer surfaces show a strong diameter dependence with an exponent of nearly −1.5, reaching up to 11-fold of the maximum theoretical predication provided by the classical Hertz–Knudsen relation at a pore diameter of 27 nm. Differently, the evaporation fluxes of nanopores with hydrophobic outer surfaces show a different diameter dependence with an exponent of −0.66, achieving 66% of the maximum theoretical predication at a pore diameter of 28 nm. We discover that the ultrafast diameter-dependent evaporation from nanopores with hydrophilic outer surfaces mainly stems from evaporating water thin films outside of the nanopores. In contrast, the diameter-dependent evaporation from nanopores with hydrophobic outer surfaces is governed by evaporation kinetics inside the nanopores, which indicates that the evaporation coefficient varies in different nanoscale confinements, possibly due to surface-charge-induced concentration changes of hydronium ions. This study enhances our understanding of evaporation at the nanoscale and demonstrates great potential of evaporation from nanopores.

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Nanoporous evaporative device for advanced electronics thermal management

Cited by 22 publications

References 24 publications

Transition between thin film boiling and evaporation on nanoporous membranes near the kinetic limit

Transition between thin film boiling and evaporation on nanoporous membranes near the kinetic limit

Electrodeposited Thin-Film Micro-Thermoelectric Coolers with Extreme Heat Flux Handling and Microsecond Time Response

Ultrafast Diameter-Dependent Water Evaporation from Nanopores

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