Enhancement of evaporation of a liquid drop using EHD effect

This paper reports that it was confirmed, in the preceding study, that evaporation of a liquid drop on a heated plate was enhanced to a great extent by applying an electric field. Visual observation of the evaporation process indicated that small columns of the liquid were formed underneath the bottom of the drop, causing direct contact between the liquid and the solid surface. In this study, an experiment was carried out to investigate the effect of electric field on the onset of instability of a liquid surface. The static electric potential was imposed between the liquid surface and a horizontal planer electrode placed over the surface. The imposed voltage was raised gradually until the liquid surface became unstable. The threshold voltages were measured for different distances between the electrode and the liquid surface and for different liquids. Criteria for the onset of instability were derived analytically using a modified Rayleigh-Taylor instability equation and it was found that the theoretical results agreed very well with the experimental data. In addition, the temperature of the heat-transfer surface above which the drop evaporation was enhanced was predicted using the result of the instability analysis