Modelisation of Membrane Distillation: Mass and Heat Transfer in Air Gap Membrane Distillation

In the early of 1980 with the growth of membrane engineering, MD claims to be a cost effective separation process that can utilize low-grade waste and alternative energy sources such as solar and geothermal energy. Membrane distillation is ahybrid process that uses membranes and operates based on evaporation. Unlike most other membrane process, MD does not require a mechanical pressure pump and is not limited by the osmosis pressure.

A variety of methods may be employed in MD, such as direct contact membrane distillation (DCMD) in which the membrane is in direct contact with liquid phases in both sides. Then, air gap membrane distillation (AGMD) in which an air layer is interposed between the membrane and the condensation surface. At that time, avacuum membrane distillation (VMD) where, a vacuum is applied to increase orestablish the vapor pressure difference between the membrane sides and the condensation takes place in an external condenser. At that point, sweeping gas membrane distillation (SGMD) in which a stripping gas is used on the cold side to sweep the permeate away, with Condensation in a separate device.