Scale Effects and Slip Microflow Characteristics of Evaporating Thin Films in a MicroChannel

摘要

Micro flow, phase change and heat transfer characteristics of an evaporating thin film in a microchannel was investigated using an augmented Young-Laplace model and the kinetic theory for transverse flow in a solid-liquid-vapor triple contact line region. A model considering both wall slip and wall temperature jump was developed to explore scale effects of channel width. The results show that the average heat transfer coefficient and Reynolds number in thin film regions decrease with decreasing channel width, indicating worse flow and heat transfer characteristics. The scale effects are caused by increased far-field liquid film curvature and film thickness and consequently lower liquid superheat and lower evaporation pumping capability.Original models describing wall-affected ordered adsorbed flowing liquid microlayer and variable slip coefficient were established to give the solid-liquid interfacial resistance and wall temperature jump. Microflow and microlayer near a wall increase wall thermal resistance and thus leads to worse film spreading and heat transfer characteristics, which are significant in thin film regions. The microflow model with variable slip coefficient is logical, more reasonable in results and better than the microflow model with constant slip coefficient.