Miniaturization has been the hallmark of electronic and photonic instruments in the last few decades. The miniaturization efforts span an enormous range of dimensions from nanoscale transistors to thumbnail-sized chips, smartphone, vehicle electronics, and server farms. This miniaturization accompanied by enhanced functional density necessitates enhanced heat dissipation, which has been the bottleneck of further advancement in these technologies. Among the cooling methods, thin-film evaporation with nanometer fluid thickness is one of the most promising approaches. In this method, momentum transport is the current limit to enhance dissipiated heat flux and one can enhance evaporative heat flux by transcending the momentum transport within the nanoscale confinement. Here, we study physics of fluid flow in small confintments and discuss unexpected phenomena occurs in these scales. We use slip concept at solid-liquid interface to overcome the momentum limit and achieve unprecedented heat fluxes in nanochannels with the depth of \< 20 nm.  We report fabrication of sub 20 nm graphene coated nanochannels and study of wicking and evaporation inside these nanochannels. Our results indicate that slip boundary condition of graphene walls boost the liquid-vapor interface velocity by an order of magnitude compared to Si nanochannels, thereby achieving ultra-high heat fluxes in these channels. The physics of wicking and evaporation in these channels are discussed and rational direction for future thermal management technologies are elucidated.


On Physics of Fluid Flow in Sub-20 Nm Channels

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.