Numerical Simulation of Mass Transfer of Slug Flow in Microchannel

Abstract

Computational fluid dynamics (CFD) is used to investigate mass transfer characteristics of gas-liquid two- phase slug flow in microchannel. Simulation results illustrates liquid volumetric mass transfer coefficient kLa is proportional to the square root of diffusion coefficient D and gas bubble velocity uB, and inversely proportional to the length of slug unit cell. Moreover, kLa shows a similar tendency to Higbie penetration model, but has a large deviation. In this paper, an improved expressions including two contributions of the caps and liquid film is presented based on Higbie penetration model. The effect of Fo on mass transfer of liquid film contribution is discussed. The predicted kLa with the new correlation agree well with the simulated kLa, the average relative error is within 20%. The control variables which determine slug flow mass transfer in microchannel such as gas bubble velocity uB? liquid film thickness dF?liquid film length LF and unit cell length LUC can be deduced from superficial gas velocity uG ? superficial liquid velocity uL and liquid physical properties. Thus, the developed correlation not only reflects the characteristics of mass transfer process, but also has simplicity andpracticality as empirical correlations.