Near-Wall Liquid Layering, Velocity Slip, and Solid-Liquid Interfacial Thermal Resistance for Thin-Film Evaporation in Microchannels

Heat transfer and liquid flow near solid-liquid interfaces for evaporating thin films in microchannels were investigated based on the augmented Young-Laplace equation and kinetic theory. A wall-affected nanolayer was used to correlate the Kapitza resistance with the liquid layering and velocity slip for both hydrophilic and hydrophobic surfaces. This nanolayer physical model was developed to show the combined effects of the solid-liquid interfacial temperature slip and the velocity slip on the thin-film evaporation. The results show that the liquid velocity slip elongates the thin-film region and enhances the evaporation. A minimum slip length exists for the extremely wetting case. The Kapitza resistance and nanolayer disordering for hydrophobic surfaces tend to reduce the thin liquid film superheat and overall heat transfer, leading to a larger U-shaped temperature drop. The nanolayer ordering enhances the thin-film evaporation but cannot entirely counteract the Kapitza resistance.