Design parameters and preliminary experimental investigation of an indirect vertical solar still

Obtaining water is one of the major occupations of rural peoples in the desert of Algeria. In some zones of desert, the available water is too salty for humans to consume without serious consequences. The only reliable source is groundwater accessible through foggara or the well. The introduction of solar distillation in arid areas of Algeria promises to enhance the quality of life and to improve health standards. An indirect vertical solar still consisting of a flat plate collector, an evaporation chamber and condensation chamber, forms a compact unit. The principle of operation of such a still, the main design parameters and the results of solar still preliminary performance tests are presented in this paper. The present discussion is restricted to the design parameters and preliminary performance testing of the solar still with a nominal flat plate collecting area of 0.942 m2 and an evaporation area of 0.869 m2, utilizing solar energy as source of heat. The daily productivity of the solar still during winter period, December 2005 to January 2006, varied from 0.863 to 1.323 l/m2.d, when the solar radiation intensity was in the range 19.15-26.08 MJ/m2, under daily ambient temperature that varied from 10.68 to 15.19°C, maximum hourly efficiency ranged from 47.69 to 57.85%.