Solar distillation using a blackened mixture of Portland cement and alluvial sand as a heat storage medium

Abstract Solar energy is one of renewable energies source to produce drinkable water to supply isolated low-density population areas such as those located in southern Algeria. Alluvial sand and Portland cement are composed by several metal oxides which some of them can play a role of photocatalysts. In aim to increase the yield of conventional solar still, different mixture layers of equal masses of Portland cement and alluvial sand have been used to observe both of the heat storage system amount and the photocatalysts effects on the output of distillate. Experimental results conducted at Ouargla University showed that: - The gain is 39.70% after adding 300 g of adhered layer i.e. 1.811 (kg of mixture/m 2 of absorber area) - 200 g of mixture i.e. 1.207 (kg of mixture/m 2 of absorber surface) improves the yield by 31.61%. - 100 g of adhered layer i.e. 0.604 (kg of mixture/m 2 of absorber area) increases the yield by 25.49%. - However, a layer of 400 g i.e. 2.414 (kg of mixture/m 2 of absorber surface) enhances the yield by only 33.08%. Physical analysis of distillate shows that not only the layers improve the still production, but also enhance the quality of distilled water produced because of the photocatalysts effect.