Solar-Powered Water Distillation System

Abstract

Future water demand is predicted to increase while current resources are continuously depleted. In this paper, a standalone off-the-grid water purification system is designed to provide an economically sustainable model for delivering clean drinking water is presented. This system utilizes concentrated heat generated by solar parabolic troughs to boil brackish water for the distillation process. The water vapor is then condensed into clean drinkable water in a water collection tank. The process of designing and optimizing the solar-powered distillation system (Heat exchanger, boiler, parabolic troughs, tracking and control system, photovoltaic panels and vapor and the heat transfer fluid pumps) and specifically the process of fabricating the parabolic trough is presented and discussed in details. Two troughs were designed and fabricated each with an area of 1.5 m2 (16 ft2). Each trough provides approximately 125 watts/ft. Duratherm 450, a non-toxic, non-hazardous heat transfer fluid (HTF) is selected for the solar trough hot loop. Additional system performance analysis was conducted through experimental testing and through a virtual system model utilizing the Engineering Equation Solver (EES). EES is used to model the heat transfer process of the overall distillation system and a range of optimum HTF flow rates were determined. The experimental results show an increase in water temperature within the boiler for the new range of HTF flow rates. In addition, the results show that the solar troughs are more robust, less expensive to manufacture, operate at a higher temperature and provide a higher performance when compared to a system that utilizes thermal panels. The overall system manufacturing cost is approximately $6000, which includes tracking, a control system and other required distillation components. This system is designed to fit into a standard 20-foot shipping container for ease of transportation worldwide.