Modeling and simulation absorption of CO2 using hollow fiber membranes (HFM) with mono-ethanol amine with computational fluid dynamics

In these papers, the computational fluid dynamics technique is used to simulation a Hollow fiber membrane contactor to absorb carbon dioxide from the air by absorbing Mono-ethanol amine. The governing equations of this process include the equations of continuity, momentum and mass transfer in areas related to the shell membrane and tube and taking into account the relevant boundary conditions and assumptions, using the software COMSOL were solved. By examining and comparing the results with experimental data presented in the papers, the accuracy of simulation results was confirmed. The influence of important parameters in the process including wetness of membrane, the volumetric flow rate of gas, liquid volumetric flow rate and temperature effects were studied. The results showed that by increasing the volumetric flow rate of liquid absorption 73-83, the mass transfer rate of carbon dioxide to absorption increases because of the carbon dioxide concentration gradient in the gas phase and liquid increases. Because of the reduced residence time 86 to 20 in the membrane contact, by increasing the volumetric flow rate of gas the amount of removed CO2 in contact reduced so that by increasing the gas flow rate 0.6-1.4, the CO2 removal rate will be only 18 % decreased. The CO2 concentration is decreased along the tube since it penetrates the tube where the highest concentration of carbon dioxide is in the contact surface of the membrane and absorbent solution. In doing so, due to the reactions done in the tube between Carbon dioxide and Monoethanolamine, the CO2 concentration is decreased and reaches zero at the center of the tube. The other factors are the solvent temperature and wetness. With increasing the absorption solvent temperature, carbon dioxide removal efficiency is significantly increased. Wettability has a strong negative effect on the efficiency of the membrane contactor. So with increase wettability, the efficiency of the membrane suddenly finds a sharp decrease. In some cases with increased wettability efficiency is close to zero.