Membrane contactor as degasser operated under vacuum for ammonia removal from water: A numerical simulation of mass transfer under laminar flow conditions

The system studied in this work is a membrane contactor (hollow fibre module) based removal of NH3 from its aqueous solution. Aqueous solution of NH3 flows through the membrane contactor (lumen side) and vacuum is being applied on the shell side to create a concentration gradient across the membrane for the purpose of mass transfer of ammonia by diffusion from lumen side to shell side. A mathematical model has been developed by using the resistances-in-series mass transfer system that takes into account boundary layers, membrane porosity, phenomenological considerations and mass balances of the membrane contactor. The model equations are solved and simulated on MATLAB for laminar conditions in the lumen side. Velocity and concentration profiles are obtained. Simulation result shows the variation of concentration in both axial and radial directions. The effect of operating conditions on the removal process shows an increase in flow results in lower removal rate.