Thin-film evaporation from micropillar wicks in ambient environment

We characterize thin-film evaporation of water from well-defined silicon micropillar arrays under ambient conditions (≈24 °C and ≈100 kPa). We compare the dryout heat fluxes from these experiments with the corresponding heat fluxes for experiments conducted at saturated conditions for water (≈24 °C and ≈3 kPa). Dryout heat fluxes for the experiments at 100 kPa were higher (τ2×) when compared to the corresponding values at 3 kPa. The dryout heat fluxes were found to be in good agreement with a semi-analytical thermal-fluidic model which accounts for the favorable change in the figure of merit of water when the vapor pressure changes from ≈3 kPa to ≈100 kPa. The experimental results show that self-regulated capillary-fed fluidic transport is vital for delaying nucleate boiling and achieving higher heat fluxes.