Multi-scale study of turbulent mass transfer process in different shaped-adsorbent packed bed

Abstract

Insufficient consideration of the coupled effect of multi-scale and turbulent mass transfer impedes thorough understanding of the dynamic adsorption process in the fixed bed. To solve this problem, a novel PR-CMT model, integrated particle resolution method and computational mass transfer theory, is proposed and verified to simulate the gas adsorption process on particles by combining the computational mass transfer method and the particle dissolution method. The proposed model not only rigorously accounts for the turbulent diffusion by incorporating the equation of concentration variance c2‾ and concentration variance dissipation εc, but also establishes connections between different scales of fixed-bed particle-fluid systems. Through this work, it is found that there is a preferred fluid path in the particle filling structure, which can lead to significant changes in local mass transfer performance. Additionally, the turbulent diffusion enhances the mass and heat transfer between the gas and particles, resulting in a more uniform distribution in the radial direction. Using the proposed model, the effects of the adsorbent characteristics on the multi-scale adsorption process, such as the adsorbent porosity and shape, are further examined. The results indicate that increasing the adsorbent porosity leads to enhanced overall adsorption rate in the fixed bed, and the turbulent diffusion is strongest in the fixed bed with cylinder adsorbents.