Design, Fabrication and Performance Evaluation of a Semi-Cylindrical Solar Still Working in Medina Region

The exponential population growth has led to severe fresh water availability issues around the world. Saudi Arabia is one of the countries that mostly rely on desalination process to satisfy their fresh water needs in desert regions. The distillation process has become too expensive due to the sharp rise in oil prices. Renewable energy is a promising source for the water distillation process. This work aims to design, fabricate, and test a solar still for purification of salty and brackish water. A semi-cylindrical solar still was designed and tested under Medina climatic conditions. The semi-cylindrical solar still connected with a parabolic trough solar concentrator was supposed to enhance the system performance and the system productivity by warming up the brackish or saltwater before it was directed to the basin. To calculate system efficiency, the temperatures of water in the basin, glass outside and inside surface, inside of the still, and the ambient were measured. It was found that the average intensity of solar radiation was about 729.8W/m2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$729.8 \mathrm{W}/{\mathrm{m}}^{2}$$\end{document} per hour and the average system efficiency was found to be 23.38% without a parabolic trough. The system efficiency reached 29.5% by connecting the solar still with a parabolic trough. The maximum productivity of the solar still was found to be 1.8 L/h at peak time, with an average value of 0.9 L/h in May.