An Ultrathin Nanoporous Membrane Evaporator

Lu, Zhengmao; Wilke, Kyle L.; Preston, Daniel J.; Kinefuchi, Ikuya; Chang-Davidson, Elizabeth; Wang, Evelyn N.

doi:10.1021/acs.nanolett.7b02889

Cited by 66 publications

(46 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the application of nanopores to evaporative wicking structures yields significant improvements in CHF, heat transfer coefficients and pumping power consumption, it also introduces challenges with respect to membrane clogging 30 . The duration of experiments at low heat flux (<100 W/cm 2 ) was more than 20 min, but at high heat flux (>500 W/cm 2 ) experiments were limited to 20 s due to clogging.…”

Section: Discussionmentioning

confidence: 99%

Nanoporous membrane device for ultra high heat flux thermal management

et al. 2018

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

Nanoporous membrane device for ultra high heat flux thermal management

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…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: 94%

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

View full text Add to dashboard Cite

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.

show abstract

“…We pattern thin (22 ± 1 µm thick) IO structures into a bridge area (2.0 × 0.27 mm) that connects with two electrical contact pads, supported by a glass substrate (thermal conductivity < 1 Wm −1 K −1 ) to minimize conduction heat losses ( Figure a). The active IO bridge serves as both a resistive temperature detector (RTD) and a heater . This configuration allows us to measure wall superheat with high spatial accuracy due to the proximity of the RTD to the evaporation/boiling interface.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Capillary‐Fed Boiling in Copper Inverse Opals via Template Sintering

Zhang

Palko

Barako

et al. 2018

Adv Funct Materials

View full text Add to dashboard Cite

Capillary-fed boiling of water from microporous metal surfaces is promising for low thermal resistance vapor chamber heat spreaders for hot spot management. Vapor transport through the void spaces in porous metals enables high heat fluxes at low evaporator superheat. In this work, the critical heat fluxes of capillary-fed boiling in copper inverse opal (IO) wicks that consist of uniform pores with 3D periodicity is investigated. Template sintering is used to enlarge the "necks", or hydraulic vias, that bridge adjacent IO pores of diameters from 0.6 to 2.1 µm. The enhanced neck size increases the hydraulic permeability for vapor extraction by an order of magnitude, and subsequently the CHF from 100 to 1100 W cm −2 . Modeling of the boiling limit accounts for the vapor pressure drop through an IO wick using Darcy's law at a given bubble departure rate. This work links the effect of wick structure design on the boiling crises phenomenon in microporous surfaces and demonstrates material capabilities for ultrathin and low superheat thermal management solutions for high-power-density electronic devices.

show abstract

An Ultrathin Nanoporous Membrane Evaporator

Cited by 66 publications

References 25 publications

Nanoporous membrane device for ultra high heat flux thermal management

Nanoporous membrane device for ultra high heat flux thermal management

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

Enhanced Capillary‐Fed Boiling in Copper Inverse Opals via Template Sintering

Contact Info

Product

Resources

About