CO2 absorption into absorbents is a widely used method to reduce carbon emissions,in which the con-centration gradient near the gas-liquid interface may induce Rayleigh convection(RC).Once RC occurs,the mass transfer rate will be significantly enhanced.Therefore,it is necessary to explore the mass trans-fer enhancement mechanism further and develop a penetration/surface divergence hybrid mass transfer model.In this study,we conduct research on the process of CO2 absorption into ethanol with RC.Firstly,we use a multi-relaxation time lattice Boltzmann method to simulate the absorption process and obtain the flow and concentration fields.And we also verify the reliability of the numerical simulation results by comparing with the experimental results.Then,we analyze the characteristics of non-uniform flow and concentration fields in RC.Moreover,we divide the near-interface region into diffusion-dominated and convection-dominated mass transfer zones by checking whether the horizontal average velocity is greater than 1.0 x 10-4 m·s-1.Furthermore,based on the differences in mass transfer mechanisms of the aforementioned two zones,we propose a penetration/surface divergence hybrid model to predict the instantaneous mass transfer coefficient.The prediction results demonstrate that the hybrid model can precisely predict the instantaneous mass transfer coefficient of the entire CO2 absorption process.Our proposed hybrid model provides a promising way to deal with the complex mass transfer problems with non-uniform flow and concentration fields.

Longyun Zheng;Kai Guo;Hongwei Cai;Bo Zhang;Hui Liu;Chunjiang Liu

School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China;State Key Laboratory of Chemical Engineering,Tianjin University,Tianjin 300072,China

中国化学工程学报（英文版）

[1]Longyun Zheng;Kai Guo;Hongwei Cai;Bo Zhang;Hui Liu;Chunjiang Liu-.Investigation of mass transfer model of CO2 absorption with Rayleigh convection using multi-relaxation time lattice Boltzmann method)[J].中国化学工程学报（英文版）,2022(10):130-142

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