Survey of solar desalination systems and system selection

The most common sea water desalination systems available today are described. These are divided into two broad categories, namely, direct and indirect collection systems. In the former, solar energy is absorbed and used in the same piece of equipment whereas in the latter, two separate sub-systems are used, one for solar energy conversion and one for desalination. Various systems are analysed with respect to their primary energy consumption, sea water treatment requirement, cost, and suitability for solar energy utilisation. Of the various types of processes that are analysed, the multiple-effect boiling (MEB) system and, in particular, the multiple-effect stack (MES) type evaporator, is the most suitable for solar energy utilisation since it can be used under varying energy supplies without upset. In addition, this system has a low specific energy requirement, low equipment cost and also requires the simplest sea water treatment.