Direct effect of solvent viscosity on the physical mass transfer for wavy film flow in a packed column

TL;DR

This paper investigates how solvent viscosity influences mass transfer in packed columns, revealing that wavy film flow enhances this effect compared to uniform films, supported by analytical, experimental, and numerical evidence.

Contribution

It introduces a new mechanism involving wavy films and eddy effects to explain viscosity's impact on mass transfer, validated through multiple methods.

Findings

Mass transfer coefficient varies steeply with viscosity for wavy films.

Theoretical and experimental data show a power-law relation $k_L \,\propto\, \mu_L^{-0.38}$.

Wavy film flow significantly enhances mass transfer compared to uniform films.

Abstract

The interphase mass transfer plays a critical role in determining the height of packed column used in the absorption process. In a recent experiment (Song D. Ind. Eng. Chem. Res. 2018, 57, 718), the direct impact of viscosity ($\mu_L$) on the physical mass transfer coefficient ($k_L$) was observed to be higher in a packed column as compared to the wetted wall column. We offer a plausible mechanism involving the wavy film and eddy enhanced mass transfer in a packed column to explain the underlying physics via analytical and numerical studies. The analytically derived mass transfer coefficient matches well with experimental observation in a packed column. The countercurrent flow simulations in a packed column with both uniform and wavy films also confirm this behavior. The predicted $k_L$ shows steep variation with $\mu_L$ for a wavy film than a uniform film and further confirms the proposed theory. A similar relation ($k_L \propto \mu_L^{-0.38}$) for a wavy film is also observed in theoretical, experimental, and numerical studies.