Microwave-assisted desorption of CO2 from ethanolamine solvent in a porous hollow fiber membrane - numerical modeling

In our previous work, microwave regeneration of 30 wt% ethanolamine solvents in a hollow fiber gas-liquid contactor was studied. In this system, the solvent was heated by microwaves as it traversed a microwave applicator while passing through the lumen of the hollow fiber. Experimental results do not provide insight into the operation of microwave regeneration. The aim of this study is therefore to develop a model to simulate the microwave solvent regeneration in the single fiber system. The numerical approach is based on coupling 3D microwave heating of solvent flow, and 1D chemical desorption of CO 2 applicable to non-isothermal conditions along the fiber. The model was successful in reproducing with reasonable accuracy the global desorption data from the regeneration experiments, assuming a low wetting fraction of the membrane. The effects of operating conditions were explored: results show that increasing the solvent flow rates induces higher temperature gradients at the boundary of the fiber lumen thus increasing desorption rates. It has been found that increased fiber radius leads to better desorption rates at the expense of lowering the interfacial surface density. On another note, numerical results show that isothermal regeneration performs better than microwave mode although the latter is able to outperform where hotspots persist along the fiber. With regards to flow configurations during microwave regeneration, counter-current mode performed better than co-current one: the sweeping gas in the former mode passes from the hot solvent side to the cold solvent side which encourages reabsorption of the desorbed CO 2 .