الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Water scarcity is one of the most critical challenges in many developing countries in Middle East. Seawater desalination techniques that are driven by solar energy are promising solutions in Egypt where long coasts and high solar intensities are available. The present research aims at designing, fabricating, and assessing a mobile desalination unit that relies on successive evaporation-condensation stages with localized condensation heat recovery. This unit can be driven by solar energy or other waste heat sources, while the evaporation will be enhanced using wicks. The condensate will be collected on aluminum sheets aligned in front of the wicks with narrow gaps. The multi-stages of evaporation-condensation process significantly improve freshwater production. The operation of the present module does not necessitate the availability of electricity; hence it can be classified among the passive techniques of seawater desalination. Setting the sheets and wicks in vertical position enables the evaporation to take place while the wicks are always wetted with the saline water by the capillary effect. Passive multi-stage solar still for seawater desalination technology has a very high production rate compared with the classical solar still. Although till now this technique cannot afford the amounts of clean water needed in agriculture or industry, but for sure it can provide drinking water especially in rural areas far away from electricity and water grid. Also, in emergency cases like wars and dry out, it may be the only source available at this time. It’s simple, cheap, and easy-to-maintain parts giving it the advantage to be installed and operate with no previous experience. The main objective is to develop a mathematical model that can analyze the performance of the desalination unit under various operating conditions. A lab-scale prototype was built to validate the theoretical modeling and a very good agreement was obtained. The mathematical model can be modified to predict the production rate for various configurations and operating conditions aiming at proposing an optimum design for large scale units that can be adopted in rural areas far from the grid. Parameters such as air gap thickness between successive plates, number of stages, and front wall insulation thickness were changed to study their effects on both production and the Gain Output Ratio (GOR) of the multi-stage desalination unit. Studying the single stage desalination unit via changing the air gap thickness enabled designers to find the optimum air gap thickness, which is 4.5 mm. Also, optimum number of stages is 7 stages based on the multi-stages study, which produces 6 𝐿 𝑚2 ⁄ ℎ𝑟 and a GOR of 3.