Slip and Micro Flow Characteristics near a Wall of Evaporating Thin Films in a Micro Channel

摘要

The microscopic liquid flow and heat transfer characteristics near the solid-liquid interface in the evaporating thin film region of a mini channel were investigated based on the augmented Young-Laplace equation and kinetic theory. A physical model using the boundary layer approximation and a constant slip length was devel-oped to obtain the solid-liquid interfacial thermal resistances and interfacial tempera-tures. The results show that the ordered micro layer and micro flow near the wall reduce the effective liquid superheat and the liquid pressure difference mainly due to the reduced capillary pressure gradient. The solid-liquid interfacial thermal resistances and U-shaped temperature drops tend to reduce the thin film spreading and heat transfer. The effects of the solid-liquid interfacial thermal resistances on the thin film evaporation outweigh the effects of the thermal conductivity enhancement due to the liquid ordering. The concepts of the micro flow and ordered adsorbed flowing micro layer are clarified to express the Kapitza resistance analytically in terms of the slip length and micro layer thickness.