CFD Modeling of Mass and Momentum Transfer in Sea Water Desalination by Direct Contact Membrane Distillation

The computational fluid dynamics (CFD) approach was employed to model the direct contact membrane distillation (DCMD) process for desalination of water by Polytetrafluoroethylene (PTFE), Polypropylene (PP) and Polyvinylidene fluoride (PVDF) membranes. Various thermodynamic equations of state including Peng-Robinson (PR), Redlich-Kwong (RK), Soave–Redlich–Kwong (SRK), and van der Waals (VdW) are considered to calculate the partition coefficient for the water concentration in liquid and gas phase adjacent to the membrane. The Peng-Robinson equation of state best fits experimental data. The effects of feed flow rate, feed temperature, cold stream flow rate, and flow direction on membrane performance are examined. The results show that the increase in feed flow rate, and feed temperature decrease the partition coefficient so, increase the permeation flux. An increase in cold stream flow rate results in decreases in temperature polarization and it enhances water permeation. The mathematical model results show that cross-current flow arrangement results in a higher permeation flux in comparison with co-current and counter-current flow arrangements.

Keywords:

Computational Fluid Dynamics (CFD) , Direct Contact Membrane Distillation (DCMD) , Thermodynamic , Peng-Robinson Equation , Cross-current Flow