Numerical simulation of condensation in microchannels between spherical particles

Dongren Liu,Xiang Ling,Hao Peng,Yan Wang,Lingjun Zhou

doi:10.1177/1687814016679310

Abstract

In this article, a numerical investigation of vapor condensation in a two-dimensional ordered microchannel was conducted with computational fluid dynamics software Fluent. A simplified physical model was built up to simulate a rectangular channel filled with particles. A constant wall heat flux was added to the side walls of the rectangular channel. Volume of fluid model was adopted to pursue the interface of the gas and liquid. The results showed that a better heat transfer performance could be obtained with the porous structure. The local heat transfer coefficient obtained from simulation was in good accordance with the former experimental data, which increased with the increase in fluid velocity and decreased along the flow direction. Parametric analyses were conducted concerning the effects of initial vapor velocity u0, initial temperature T0, and wall heat flux qw on local heat transfer coefficient. The velocity u0 played a significant role during the process of condensation. Temperature distributions along the porous channel and side walls were also analyzed. The results showed that the temperature decreased along the flow direction and increased with the increase in fluid velocity.

Highlights

The porous structure can intensify the heat transfer process effectively
At the beginning of the condensation, the toluene vapor enters the channel with a temperature higher than the saturate temperature, and when it passes through the microchannels between the particles, the temperature of the fluids begins to decrease due to the cooling heat flux from the side walls, so the fluid temperature near the inlet is much higher than the temperatures at the outlet
In Barletta and Nield’s34 research of the effect of viscous dissipation on forced and free convection, the temperature distribution of the fluid was obtained by solving the equations with mathematical method, and the results suggested that in the channel filled with the particles and under a constant heat flux acting on the wall, one has a decreasing temperature and a decreasing temperature gradient in forced convection along the flow direction

Summary

Introduction

The porous structure can intensify the heat transfer process effectively. With this property, it has been widely used in many fields such as chemical engineering, oil recovery, and nuclear energy. Numerous studies have been carried out to understand the mechanism of the heat and mass transfer in it. Theoretical analyses and experimental investigations were performed extensively on heat transfer process in the porous media, the problem concerning the phase change is still a difficult area that people rarely involved with.

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Discussion

Conclusion