Experimental analysis of the effect of a wettability gradient on condensation heat transfer coefficient

The use of surfaces with wettability gradient aims to cover the surface with drops of small size to allow a large heat exchange. Thus, the action of the wettability gradient on the surface of the substrate is twofold: on the one hand, it allows the preservation of a dropwise condensation regime for which the heat exchange coefficient is particularly important and, on the other hand it allows the evacuation of the dispersed phase, thus promoting a renewal of the surface with very important heat exchanges during the nucleation phase. Thereby, a heat transfer enhancement factor up to 3.4 has been experimentally measured.Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .International centre for heat and mass transfer.American society of thermal and fluids engineers