Mechanisms of Heat and Mass Transfer for Thin-Film Evaporation With Velocity Slip and Temperature Jump

Abstract

Velocity slip and temperature jump at the solid-liquid interface are important phenomena in microchannel heat transfer. A comprehensive mathematical model considering both velocity slip condition and temperature jump at the solid-liquid interface is developed to understand the mechanisms of heat and mass transfer during thin-film evaporation in this paper. The model structure is established based on the lubrication theory, Clausius-Clapeyron equation and Young-Laplace equation. To better formulate the film evaporation process, three dimensionless parameters representing the effects of slip length coefficient, temperature jump and wall superheat degree respectively, are introduced in the present model. The analytical solution provides insight of film thickness and heat transfer characteristics for the evaporating thin film. It shows that as the slip length and temperature jump coefficient decrease, the length of evaporating thin film region is shortened and the location of maximum heat flux moves closer to the initial evaporating point. The effect of slip condition on heat flux is small, but the increase of temperature jump can reduce the peak heat flux significantly. Furthermore, the analysis on the three thermal resistances which are caused by temperature jump, conduction through liquid film and evaporation on liquid-vapor interface result in a better understanding for effective heat transfer during thin-film evaporation.