Effect of Electric Field on Internal Heat-Flow Characteristics During Evaporation of a Sessile Droplet

Electric-field-enhanced evaporation is an innovative approach to reducing the energy consumption of evaporation processes. To investigate the effect of an electric field on droplet heat-flux characteristics during evaporation, this study numerically simulated the evaporation of pinned sessile droplets on a solid substrate under a parallel-plate electrode configuration. The results show that increasing the plate voltage (from 2 kV to 4 kV) can significantly enhance the surface flow velocity, with the maximum increase reaching 157% in the early stage of evaporation; however, this enhancement diminishes as evaporation progresses. At higher voltages, the internal flow field of the droplet transitions from a single circulation to a double-circulation structure, and the influence of voltage on the droplet's bulk internal temperature gradient is limited, with the maximum temperature difference remaining below 1 K. When the ambient temperature is below 308.15 K, the electric field enhancement of evaporation is most pronounced: compared with natural (no-field) evaporation, the drying time is reduced by approximately 15.5%. However, when the ambient temperature exceeds 308.15 K, the electric field enhancement decreases markedly. These findings provide a theoretical basis for electric-field-assisted evaporation technologies and inform directions for parameter optimization.