Improvement of glass solar still performance using locally available materials in the southern region of Algeria

Abstract

Limited resources and increased water demand associated with fast socio-economic development and expansion in the irrigated land in southern Algeria have led to overexploitation of groundwater and caused a significant water table drawdown as well as groundwater quality degradation due to saline water intrusion. Solar distillation is an interesting alternative source for producing drinking water from brackish water for the purpose of supplying isolated communities in remote areas. The present seeks to improve the performance of a glass solar still through increasing the productivity of freshwater by the use of different new absorbers, such as gravel, polyethylene, and sand, as heat storage systems. The solar distiller under study was fabricated with cheap glass and healthy materials, and was tested under the climatic conditions of the City of Adrar, in the Southern part of Algeria, where solar energy and underground saline water are abundant. The experimental results show that, gravel produces the highest quantity of fresh water, i.e. 5 L per m2 per day, followed by black polyethylene with 4.48 l/m2/d and then sand with 3.84 l/m2/d. It is interesting to note that the daily freshwater productivities of gravel and black polyethylene are, respectively, 32.20% and 16.67% higher than that of sand. In addition, it was found that gravel is the best absorber and has the highest productivity as compared to the other absorbers. The solar radiation intensity is quite high; the maximum value was found equal to 1131.013 W/m2. Moreover, the quality of water is reflected in its Total Dissolved Salts (TDS) level which is of the order of 21.247 mg/l from feed water with a TDS content of about 3062.60 mg/l. Hence, the efficiency of the solar still is approximately 99.30%.