EVAPORATION DYNAMICS OF LIQUID BRIDGE FORMED BETWEEN TWO HEATED HYDROPHILIC AND HYDROPHOBIC FLAT SURFACES

A small amount of liquid bounded by two surfaces forms a liquid bridge between them. The dry out during phase change in porous media filled with liquid is also dependent on the evaporation time scales of the liquid bridges. To mimic practical situations, the evaporation of liquid bridge between heated glass substrates of different wettability is analyzed in this work. Both side and base profiles of the liquid bridge are photographed during evaporation. The evaporation of the bridge between hydrophobic surfaces is somewhat slow compared to the hydrophilic substrates. Evaporation dynamics with a hydrophobic surface is similar to hydrophilic surfaces after some time duration has elapsed. There is a change in the interface curvature with a hydrophobic surface due to pinning. The breaking of the liquid bridge at the end of process is identical for both hydrophilic and hydrophobic surfaces. The evaporation modes are predominantly constant-contact radius (CCR) and mixed mode (MM) with hydrophilic surfaces, while it is MM with hydrophobic surfaces. The evaporation time reduces non-linearly with an increase in heat flux. This understanding will help in designing porous media, wherein the dry out can be mitigated.