Abstract
During cloudy or rainy days, a solar still (SS) cannot work in its normal state. So, improving the yield of low-cost solar-powered desalination technologies such as the SS is essential to ensuring sustained access to freshwater for remote area. This study aims at improving the potable water from saline water via stepped solar stills. Experimental work for different sand beds stepped SS was conducted to improve its performance, the sand was used as thermal storage materials. The effects of sand type (black and yellow) and sandy bed height on the performance of stepped SS were studied. Also, the effect of internal reflectors and cooling coil on the sand stepped SS performance was investigated. Experimental results revealed that the sandy layer improves the stepped SS productions. The maximum increase in accumulated production of sandy stepped SS with internal mirrors and cooling coil was obtained at sand beds height of 1 cm and black sand. The yield was increased by 136% over conventional solar still (CSS) with thermal efficiency of 54.4%. The costs of 1 L of the freshwater for black SSS and CSS were around 0.016$ and 0.026$.