Theoretical and experimental studies on air gap membrane distillation

Air gap membrane distillation (AGMD) is an innovative membrane separation t echnique for pure water extraction from aqueous solutions. In this study, b oth theoretical and experimental investigations are carried out on AGMD of- different aqueous solutions, namely, tap water, salted water, dyed solution s, acid solutions, and alkali solutions. A simple mechanistic model of heat and mass transfer associated with AGMD is developed. Simple relationships of permeate flux, total heating or cooling load and thermal efficiency of A GMD with respect to the membrane distillation temperature difference are ob tained. Effects of solution concentration and the width of the air gap in A GMD are analyzed. In the experimental study, the experiments were conducted using 1 mu m PTFE membrane with a membrane distillation temperature differ ence up to 55 degrees C. The AGMD system yields a permeate flux of pure wat er of up to 28 kg/m(2) h. Direct comparison of the experimental results wit h the proposed modeling predictions shows a fairly good match.