GAS AND VAPOR TRANSPORT THROUGH MICROPOROUS MEMBRANES .2. MEMBRANE DISTILLATION

Experimental membrane distillation (MD) fluxes were increased by up to 50% by deaeration. A new theoretical model shows that under these conditions, membrane permeability increased by around seven-fold, but temperature polarisation decreased the thermal driving force by five-fold. Greater flux increases are predicted using higher film heat transfer coefficients. Heat loss by conduction across the membrane was shown to decrease with deaeration. Results indicate that the membrane is rarely the controlling resistance and that future developments should be towards improved MD modules rather than specialised MD membranes. © 1990.