Dr. H. Uchtmann | email: uchtmanh@mailer.uni-marburg.de
A solar driven thermal desalination plant was developed and successfully installed at an agricultural centre in the outskirts of Sfax/Tunesia. The aim of the project was to provide the farm completely with water for the drip-irrigation system that was implemented too for effective use of the water. Special emphasis was laid on the implementation of a technology which requires very little maintenance and repair.
The scheme of the desalination plant is shown in the figure above. It consists of the distillation module, in which the hot brackish water is distilled, and the solar unit, which provides the required thermal energy by use of flat plate collectors. The essential improvement was the implementation of a heat storage tank in combination with a thermally controlled mixing valve that enables a 24 hour operation under optimum quasi steady-state conditions for distillation.
The water production is 600 ± 50 l/d. The specific energy consumption is 105 kWh/m3, which is equivalent to a gained output ratio of 6.4. The GOR is a measure of the effectiveness of heat recovery.