الفهرس 
صفحة العنوانOnly 14 pages are availabe for public view
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Abstract
The present thesis shows the water problem especially in Egypt then discusses the different water production techniques that are used to overcome this problem. A new water
production technique called ”Water Recovery from Atmospheric Air” is introduced as a beneficial solution for providing remote regions with fresh water. This system depends on
extraction of water vapor from atmospheric air by using desiccant material. The desiccant material (calcium chloride solution or, silica gel) absorbs water from humid air during night time then, it evaporates the absorbed water during the day time by solar energy. The evaporated water condensates on the solar collector sides and the condensed water droplets
are collected.
In order to investigate the system performance theoretically, a new mathematical model for the egeneration process is introduced. The new model presents 15% improvement in heoretical results compared with other published models. This work aims to evaluate the effect of different operation conditions (initial desiccant concentration,initial mass of solution and host materials) on the system performance characteristics (system efficiencies, evaporation rate and water productivity). Moreover, the simulation model investigates the system performance for different Egyptian weather conditions
(Cairo and Alexandria). The results revealed that Cairo’s water productivity is higher than that of Alexandria’s. The total produced water from the system in spring is about 3.11 Iit/day.m/ and 3.02 lit/day.rn/ in Cairo and Alexandria, respectively. The most effective parameter in regeneration process is desiccant concentration, for 25% increasing in initial desiccant concentration, the total produced water and system efficiency are decreased by
38% and 40 %, respectively.
A trapezoidal prism solar collector with four fiberglass sides is used for experimental study. This collector has multi-shelves used as beds in order to maximize bed surface area inside the collector. Thus, the absorption and evaporation surfaces are increased. Also, this design allows the condensation process over the four sides of the collector. Experimental
work shows the effect of weather conditions on system operation for both day and night times. The regeneration and absorption processes are discussed for different operation
conditions (collector tilt angle, initial desiccant concentration, bed layers number/area density, desiccant mass and, natural/forced convection). Also, the system is studied for different desiccant materials (calcium chloride aqueous solution and, silica gel) and, the calcium chloride solution is investigated with two host materials (Cloth and sand).
Furthermore, an illustrative omparison between different bed types is presented in this work. The experimental results revealed that the total evaporated water for cloth bed can reach to 2.32 lit/day.m/ at cacl, initial saturated concentration of 30%. For saturation initial
cacl, concentration, the cloth and sand beds efficiencies are 29.3 and 17.76 %, respectively. The variation of initial cacl, concentration sharply affects the system performance characteristics. The cacl, initial concentration increases by 40%, the system efficiency decreases by 45% for cloth bed. For silica gel, the total evaporated water is 0.64 lit/day.m/ at 6 kg/m ’ area density. The increasing in area density by 66% enhanced the
system efficiency by 28.5%, and raised the initial cost of the system by 6%. For normal absorption and regeneration processes in Cairo, the system efficiencies are 10, 8.2 and 4.8
% for cloth, silica and sand beds, respectively.