Multi Solar Desalination Plant
Abstract
MSS pervaporation (known as membrane distillation) is a membrane separation process which allows gas or vapor molecules to permeate but which blocks the passage of liquids. When two liquids with different vapor pressures are separated by a membrane having this property, the vapor evaporating from the liquid with higher vapor pressure passes through the pores of the membrane and condenses. This is why fresh (distilled) water can be separated from sea water. In order to create two liquids with different vapor pressures the sea water needs to be heated to a temperature between 60ºC-70ºC. At this temperature, the molecules of the salt water and the fresh water can easily be separated. There are two types of membrane distillation: The direct contact system and the diffusion gap system (see Figure 2). The direct contact system needs coolers to cool fresh water which is used as a cooling liquid to condense the water vapor. The diffusion gap system uses cold sea water as a cooling liquid and doesn't require coolers; it recovers the latent heat of the water vapor, and is consequently relatively high in efficiency.