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

Ahmed Jassim Shkarah,Md Razali Bin Hj Ayob,Mohd Yusoff Bin Sulaiman

doi:10.1155/2015/369581

Abstract

Physical and mathematical model has been developed to predict the two-phase flow and heat transfer in a microchannel with evaporative heat transfer. Sample solutions to the model were obtained for both analytical analysis and numerical analysis. It is assumed that the capillary pressure is neglected (Morris, 2003). Results are provided for liquid film thickness, total heat flux, and evaporating heat flux distribution. In addition to the sample calculations that were used to illustrate the transport characteristics, computations based on the current model were performed to generate results for comparisons with the analytical results of Wang et al. (2008) and Wayner Jr. et al. (1976). The calculated results from the current model match closely with those of analytical results of Wang et al. (2008) and Wayner Jr. et al. (1976). This work will lead to a better understanding of heat transfer and fluid flow occurring in the evaporating film region and develop an analytical equation for evaporating liquid film thickness.

Highlights

Over the last decade, micromachining technology has been increasingly used to develop highly efficient heat sink cooling devices due to advantages such as lower coolant demands and smaller machinable dimensions
A better understanding of the evaporation mechanisms governed by the disjoining pressure in the thinfilm region, especially for high heat flux, is very important in the development of highly efficient heat transfer devices
Analytical and numerical solutions are obtained for the heat flux distribution, total heat transfer rate per unit length, location of the maximum heat flux, and ratio of the conduction to convection thermal resistance in the evaporating film region

Summary

Introduction

Over the last decade, micromachining technology has been increasingly used to develop highly efficient heat sink cooling devices due to advantages such as lower coolant demands and smaller machinable dimensions. A better understanding of the evaporation mechanisms governed by the disjoining pressure in the thinfilm region, especially for high heat flux, is very important in the development of highly efficient heat transfer devices. Stephan and Busse [7] developed a mathematical model based on the theoretical analysis presented by Wayner Jr. et al [5, 8] to investigate the heat transfer coefficient occurring in small triangular grooves and found that the interface temperature variation plays an important role in the thinfilm evaporation. A mathematical model is established and its analytical solutions are obtained to evaluate the heat flux, total heat transport per unit length along the thinfilm profile, thin-film thickness, and location for the maximum heat evaporation in the thin-film region and maximum heat transfer rate per unit length by thin-film evaporation

Theoretical Analysis

Results and Discussion

Conclusions