Droplet Evaporation on Hot Micro-Structured Superhydrophobic Surfaces: Analysis of Evaporation from Droplet Cap and Base Surfaces

In this study, evaporation of sessile water droplets on hot micro-structured superhydrophobic surfaces is experimentally and theoretically investigated. Water 4 µL are placed micro-pillared silicon substrates with the substrate temperature heated up to 120°C. A comprehensive thermal circuit model developed analyze effects roughness droplet evaporation. For first time, two components heat mass transfer, i.e., one from cap surface other base surface, during distinguished systematically studied. As such, transfer rates both interstitial liquid-vapor interface between micropillars at calculated in various conditions. range 40°C – 80°C, predicted matches well experimental results. During constant contact radius mode evaporation, decrease rate contributes most continuously decreasing overall rate, whereas dominant angle mode. The influence internal fluid flow considered for above 100°C, an effective conductivity adopted as a correction factor account effect convection inside droplet. Temperature differences estimated be about 2°C, 5°C, 8°C, 13°C 18°C 40°C, 60°C, 120°C, respectively, elucidating delayed or depressed boiling rough due evaporative cooling.