الفهرس 
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Abstract
A solar desalination system was designed, manufactured and developed in Zagazig town, (30° 2’ N latitude and 31°12’ E longitude), during the period from June 2009 to February 2011. The components of solar desalination system were: a basin solar still (Triangular solar still), flat plate solar collector (FPSC), external condenser, raw water tank and connection piping connects these parts. The present research clarified that desalination of ground, sea and brackish water by solar powered systems is a practical and promising technology for producing potable water in the regions which suffers from water scarcity especially in arid areas. The solar desalination method was chosen to be the topic of this research because the recent sharp increase in energy prices makes the solar desalination technique a more attractive method for obtaining fresh water. In addition, the process includes the use of clean and abundant energy which is friendly to the environment, and concurrence of periods of high sunshine with high water demand.
The productivity of the solar desalination system was measured under the following parameters: 1- Operational parameters: four different basin water depths (1, 2, 3 and 4 cm), four different water salinities (irrigation water of 1.4, ground water of 4.5, Mediterranean seawater of 35.5 and Red seawater of 44.50 dS/m) and two cover cooling treatments: a. Continuous flow with different rates (2.5, 5 and 7.5 l/h). b. Flash flow with 2.5 l/h every 5 minutes (five minutes on and five minutes off), every 10 minutes (ten minutes on and ten minutes off) and every 15 minutes (fifteen minutes on and fifteen minutes off). 2- Design parameters: three different thicknesses of glass cover (0.3, 0.4 and 0.5 cm), three different inclination angles of solar still glass cover 0.436, 0.611 and 0.785 rad (25, 35 and 45 deg), the effect of integration the solar still with the flat plate solar collector on the productivity, three different inclination angles of the flat plate solar collector 0.436, 0.524 and 0.611 rad (25, 30 and 35 deg) and the effect of coupling an external condenser with the flat plate solar collector on the productivity. 3- Climatic conditions: ambient temperature, wind speed and solar insolation.
The experimental investigations showed that, during summer, the highest productivity is 10.06 l/m2.d. when the flat plate solar collector is 0.436 rad (25 deg), the glass cover inclination is 0.436 rad (25 deg), the water basin depth is 1cm and applying solar still cover cooling (active solar still). Without applying cover cooling, the highest productivity is 8.52 l/m2.d. For passive solar still, the highest productivity is 7.80 l/m2.d. when the glass cover inclination is 0.436 rad (25 deg), the water basin depth is 1cm (by applying solar still cover cooling), without applying cover cooling, the highest productivity is 6.38 l/m2.d. For condenser, the highest productivity is 7.93 l/m2.d. when coupling it with the flat plate solar collector. During winter, the highest productivity is 5.52 l/m2.d. when the flat plate solar collector is 0.524 rad (30 deg), the glass cover inclination is 0.611 rad (35 deg), the water basin depth is 1cm and without applying solar still cover cooling (active solar still). For passive solar still, the highest productivity is 3.95 l/m2.d. when the glass cover inclination is 0.611 rad (35 deg), the water basin depth is 1cm (without applying solar still cover cooling). For condenser, the highest productivity is 4.26 l/m2.d. when coupling it with the flat plate solar collector. It was observed that the productivity of active mode is 1.34 the productivity of the passive mode during the day hours. The desalination system produces water has salinity of 0.67 dS/m from 44.50 dS/m of seawater. Four days of winter and summer seasons, 10 December 2009 and 16 August 2010 (for passive solar still) and 11 December 2009 and 17 August 2010 (for active solar still), were taken as examples to show the effect of all parameters of the study.