Design, development and effects of operational conditions on the performance of concentrated solar collector based desalination system operating in Iraq

Abstract

Fresh water is the most essential basic need in daily life, while its sources are shrinking rapidly due to global warming and climate change. Desalination of sea water is seen as the potential solution to meet the scarcity of fresh water. In this article, a concentrated solar collector-based distillation (evaporation and condensation) plant has been presented that desalinates brackish water in three consecutive stages. In the first stage, solar energy is absorbed by the solar collector and raises the heat transfer fluid (HTF) temperature that in turn heats up brackish water through heat exchanger and upon reaching the boiling point it starts boiling. The vapour rises to the tilt surface of the second still and gets condensed, condensate droplets being collected in a trough. On the other hand, evaporation and condensation in the second and third stages occur by reason of their latent heat. Performance of the three-stage solar water still has been analysed and optimized numerically in MATLAB; thereafter, outdoor experimental investigation is carried out from January to May 2018 in Tikrit, Iraq. Distillate production is found to depend on irradiation level, number of collectors and, operating and weather conditions. Experimental results show that average yield of distillate is 11.85 L/day and 30.97 L/day for the average irradiation of 358 W/m2 and 720 W/m2 respectively. The quality of distilled water totally complies with WHO standards. Detailed mathematical model of a solar desalination system has been proposed in this study that allows further extension and variation of such scheme. Such distillation plants can play an important role in supplying fresh water in remote arid places that are out of the reach of electrical grid.