الفهرس 
Chapter one: IntroductionOnly 14 pages are availabe for public view
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Abstract
Water is the most important element for life. Water covers about 70% of earth, but only about 0.5% of this water is valid for human usage. Increasing human numbers and uses increases the need for water, so, the water sources used in human usage must be increased [1]. Sea water is not valid for usage because of high content of salts. The removal of sea water salts is known as desalination process. Saline water desalination processes which are used around the world can be broadly classified as either thermal or membrane. Both technologies need energy to operate and produce fresh water. Within those two broad types, there are sub-categories (processes) using different techniques. The method of desalination used in this research is a membrane desalination usingair gab method AGMD.This thesis introduces a theoretical and experimental study for air gab membrane desalination process AGMD using low pressure membrane type. The experimental unit was designed and fabricated according to the theoretical study and the data collected from the literature review.The unit used experimentally is a double feed desalination unit. A simulation study using CFD (ANSYS 16.2) program is created to this study to determine the affecting conditions for operating this desalination unit. Also, an experimental study had been done using the sameconditions used in the theoretical study to validate both theoretical and experimental results. The study consists of two categories: the first one studies desalination unit as a parallel feed unit, the two feed have the same temperature, the second one studies desalination unit as a forward fee unit, the feed to second stage is the recycled outlet of first stage.Mansoura University Faculty of Engineering Mechanical power Eng. Dept.Both theoretical and experimental study show that the most effecting parameters in AGMD are; thickness of air gab, membrane pore size, inlet feed temperature, inlet feed velocity, inlet coolant temperature and inlet coolant velocity. According Simulation, the best thickness of air gab to be used to get best results is 3mm and the best membrane to be used was of thickness 0.175 µm and 0.45 µm pore size.The operating conditions which give maximum permeate flux according to theoretical and experimental results are; inlet feed temperature of 70 0C, inlet feed velocity of 0.8 m/s, inlet coolant temperature of 10 0C, inlet coolant velocity of 0.65 m/s.Using the previous operating conditions lead to permeate flux amount of 55.657 L/m2h from each feed chamber, about 110 L/m2h total permeate flux when operating the unit as the two feed chambers has the same feed temperature. The maximum permeate flux recorded at these conditions was achieved through operating time of 50 h. In the recycled feed method, forwardfeed, the maximum permeate flux was found to be 105.483 L/m2h from both chambers together.The decrease found in permeate flux in the forward operating method is due to heat losses because of condensation and contact with membrane in the first feed chamber.