Mathematical modeling and simulation of carbon dioxide stripping from water using hollow fiber membrane contactors

• A mathematical model was used to predict transfer of CO2 in stripping process.
• The stripping is a strong function of liquid velocity and is less dependent to gas velocity.
• The CO2 stripping was improved by increasing the liquid phase temperature and velocity.
• The liquid phase resistance controls mass transfer in desorption process.
• The Wilke–Chang equation predicts DAB better than the Versteeg equation.

In the present investigation, removal of carbon dioxide from water was examined theoretically using a hollow fiber membrane contactor. A 2D mathematical model with axial and radial diffusions in the membrane contactor was developed. The finite element method was used to solve the governing equations. The results of modeling were in good agreement on the wide range of liquid velocity and temperature with experimental data. The results indicated that, as liquid phase velocity and carbon dioxide concentration in liquid phase increased, the carbon dioxide stripping increased significantly. Also by the increment of the liquid temperature, carbon dioxide stripping flux increased because of carbon dioxide solubility decrement. By increasing gas velocity from 0.02 to 0.07, CO2 stripping flux increases by 7.5%. The diffusion coefficient was computed through the equations of Versteeg and Wilke–Chang. The results revealed that since concentration does not change through the tube and diffusion coefficient is a function of concentration in liquids, the Wilke–Chang equation could better predict the diffusion coefficient than the Versteeg equation. The maximum error in this regard was 6% with solution time of 20 second.