Exploring Ultimate\nWater Capillary Evaporation in\nNanoscale Conduits

Abstract

Capillary evaporation\nin nanoscale conduits is an efficient heat/mass\ntransfer strategy that has been widely utilized by both nature and\nmankind. Despite its broad impact, the ultimate transport limits of\ncapillary evaporation in nanoscale conduits, governed by the evaporation/condensation\nkinetics at the liquid–vapor interface, have remained poorly\nunderstood. Here we report experimental study of the kinetic limits\nof water capillary evaporation in two dimensional nanochannels using\na novel hybrid channel design. Our results show that the kinetic-limited\nevaporation fluxes break down the limits predicated by the classical\nHertz–Knudsen equation by an order of magnitude, reaching values\nup to 37.5 mm/s with corresponding heat fluxes up to 8500 W/cm². The measured evaporation flux increases with decreasing\nchannel height and relative humidity but decreases as the channel\ntemperature decreases. Our findings have implications for further\nunderstanding evaporation at the nanoscale and developing capillary\nevaporation-based technologies for both energy- and bio-related applications.