Computational fluid dynamics investigation of CO2 absorption using ionic liquids in hollow-fiber membrane contactors

Abstract

This study integrates computational fluid dynamics (CFD) modeling with previously obtained experimental data to investigate the CO2 absorption process using hollow fiber membrane contactors (HFMCs) and ionic liquids (ILs). Two types of HFMCs, polysulfone (PS) and polypropylene (PP), were tested in combination with two ILs: [emim][Ac] and [emim][EtSO4]. The CFD models, developed using COMSOL Multiphysics, were validated against laboratory-scale experimental data. A strong correlation between the experimental and simulated results was observed, as indicated by high R2 values (0.9208 to 0.9844) and low RMSE values (1.4657 to 2.1479), confirming the model's accuracy in representing the actual process. Among the ILs studied, [emim][Ac] showed superior CO2 absorption efficiency due to its higher CO2 solubility compared to [emim][EtSO4]. Velocity and concentration profiles of both gas and liquid phases were determined, showcasing the ability of CFD modeling to predict key process parameters across the system geometry. Sensitivity analyses identified the optimal absorption temperature, membrane length, and gas velocity to achieve CO2 absorption efficiency exceeding 90 %. Results showed that increasing the absorption temperature and membrane length significantly enhances the process performance. Additionally, incorporating shell baffles improved absorption efficiency by approximately 5 %, though it resulted in a notable increase in liquid pressure drop across the shell.