Experimental investigation of the effect of thermal properties of the substrate in the wetting and evaporation of sessile drops

Abstract

An experimental investigation on the evaporation of sessile drops is reported in this paper. The effect of thermal properties of the substrate is investigated by studying the evaporation of sessile drops on substrates with various thermal conductivities. The results show that the evaporation rate of drops is limited by thermal properties of the substrate especially for high evaporation rates. Furthermore the temperature of the evaporating drop is measured to show that it is dependent on both the evaporation rate and the thermal conductivity of the substrate. Preliminary results on the evaporation of water droplets under a reduced pressure environment show clearly that as evaporation is increased the gap between substrates having different thermal conductivities is widened. The results of this investigation demonstrate the crucial role played by the nature of the substrate in the process of spontaneous evaporation of sessile drops.