Abstract:
Membrane processes are used widely to desalinate water. Major techniques for this
purpose include Reverse Osmosis (RO), Multi-stage Flash Distillation (MSD), Membrane
Distillation (MD) and Multi-effect Distillation (MED) with RO being most used. Higher salt
rejection rate of MD (99%) than that of RO (96%) makes it a better option for water
desalination. Direct Contact Membrane Distillation (DCMD) is the easiest configuration
among others for MD at low temperature and pressure conditions thus reducing cost.
CFD study of impact of spacer in feed and permeate channels has been conducted by
considering the effect of velocity, membrane thickness, spacer filament distance and their
arrangement variants. Temperature Polarization Index (TPI) and Vapor Flux are used as the
evaluation criteria for performance of a combination. Study shows that TPI is lower and thus
performance of DCMD setup is better for a combination of high feed and permeate velocity,
larger filament diameter arranged mid channel using a thicker membrane in a counter flow
arrangement. This can be used to design an effective hybrid desalination system to attain
maximum flux.
