SEPARATION EFFICIENCY IN VACUUM MEMBRANE DISTILLATION

Vacuum membrane distillation has been analyzed as a separation process for aqueous mixtures. The total permeate flux obtained is affected by two simultaneous resistances, those due to the heat and mass transfer processes which take place through the liquid phase and through the membrane respectively. On the other hand, the separation factor is highly sensitive to the mass transfer resistance existing within the liquid phase. Different applications have been considered such as extraction of organic components, degassing of water and evaporation of pure water. In all cases appropriate design equations for shell and tube equipment have been obtained and solved. In parallel, appropriate criteria for a priori recognition of the principal resistances have been formulated.