Local heat transfer to an evaporating superhydrophobic droplet

The heat flux distribution beneath a superhydrophobic evaporating droplet has been explored. High speed, high resolution infrared thermography was employed to measure the heat transfer characteristics of the evaporating droplet. Optical imaging and analytical techniques were used the capture droplet dynamics over the course of its evaporation. The droplet evaporated with a receding contact line predominantly in the constant contact angle regime. The peak local convective heat transfer was located at the triple contact line over the entire evaporation period. Peak and average heat fluxes were shown to increase as the evaporation proceeded due to the increasing contact line length density and liquid-gas interface temperature. The total thermal power across the solid-liquid interface decreased due to the decreasing solid-liquid surface area. The average heat flux to the evaporating droplet was shown to vary linearly with contact line length density.