Experimental and Computational Study of Direct Contact Membrane Distillation

Experimental and computational studies of direct contact membrane distillation (DCMD) are conducted. The permeate flux is measured in a module containing a flat sheet membrane. Polytetrafluoroethylene (PTFE) hydrophobic membrane (Membrane Solutions, FPB045A16) with a nominal pore size of 0.45 μm, the thickness of 179∼239 μm, the porosity of 80% is used in the experiments. The feed solution is a binary mixture of water and NaCl. The inlet feed temperature is fixed at 70°C, and the feed Reynolds number is varied between 500 and 2000. Two inlet feed concentrations, 0 and 35g/L, are considered. The permeate flow rate was kept constant at Re of 1300 and temperature of 20°C. Three-dimensional steady-state computational fluid dynamics (CFD) simulations are performed using the laminar model. The Navier’s Stokes, energy, and mass transport equations in each channel coupled with flux boundary conditions imposed at the membrane surface are solved. The predicted module-averaged flux is compared to measured data for all operating conditions. Measured and predicted flux agrees well; validating both experiments and model, Temperature polarization in the feed and permeate channel and concentration polarization in the feed channel are characterized by validated CFD simulations.