Slip and micro flow characteristics near a wall of evaporating thin films in a micro channel

Abstract

The microscopic liquid flow and heat transfer characteristics near the solidliquid 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 developed to obtain the solid-liquid interfacial thermal resistances and interfacial temperatures. 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.

Analytical Solutions of Heat Transfer and Film Thickness with Slip Condition Effect in Thin-Film Evaporation for Two-Phase Flow in Microchannel

“…Our numerical and analytical solutions are compared to the ones of Wang and Schonberg and Wayner. It shows good agreement for moderate superheat temperatures; however, our analytical solution tends to underestimate total heat flux at large [5] o x x x Moosman and Homsy [15] o o x x Schonberg and Wayner [9] o o x x Stephan and Busse [7] o x x x Schonberg et al [16] o o x x Shikhmurzaev [17] x o x x Ma and Peterson [10] o x x x Pismen and Pomeau [18] x o x x Catton and Stroes [19] o o x x Choi et al [20] o x x o Qu and Ma [21] o o x x Choi et al [22] o x x o Park and Lee [23] o x x x By Morris [24] x o x x Demsky and Ma [25] o x x x Jiao et al [26] x o x x Na et al [27] o o x x Sultan et al [28] x o x x Wang et al [14] o x x x Ma et al [29] o x x x Wang et al [13] o o x x Zhao et al [30] o x x o Zhao et al [31] o x x o Benselama et al [32] x o x x Biswal et al [33] o x x o Liu et al [34] x o x x Bai et al [35] o o x x Biswal et al [36] o x x x Thokchom et al [37] o x x x Yang et al [38] o x x x Current study o o o o superheat temperatures. In addition, the model presented herein can be used to predict analytically and numerically all of the equilibrium film thickness, heat flux distribution, film thickness variation of evaporating film region, maximum total heat transfer rate through the evaporating film region, and ratio of the conduction to convection thermal resistance.…”