الفهرس 
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Abstract
Water plays a significant role in all daily activities and its consumption is
increasing day by day as a result of the increased living criterions of humankind.
Up to half of the world’s population is facing water crisis that are growing at an
alarming rate, especially in arid and semi-arid regions of the world. During the
past decade, there has been a significant reduction in the annual per capita share
of freshwater in Egypt. This is indicated by an increase in population with the
same freshwater sources. Future forecasts indicate that by 2025; the annual per
capita of freshwater will fall to 500 cubic meters, half of the international normal
level. The freshwater needs of mankind can be only met if the saltwater available
in large quantities is diverted to drinking water by desalination. Thus, with the
potential of solar energy available in Egypt (2100-2400 kWh/m”) and large
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saltwater resources from the Mediterranean Sea in the north and the Red Sea in
the east, desalination has been found as an attractive and promising solution
towards freshwater availability.
Among many indirect non-membrane water desalination systems, a system
based on the multi-effect evaporation (MEE) process consumes low thermal
energy and is highly competitive with desalination systems driven by
conventional energy. It can be used to provide clean water to more than a billion
people who do not have water access or have water shortages, and prevent their
health and economies threaten. The solar desalination system consists of solar
evacuated tube collectors (ETC) and the MEE desalination unit which consist of
horizontal tube, falling-film effects (heat exchangers) in sequential order, to
produce fresh water through repeated steps of evaporation and condensation.
Solar evacuated tube collectors provide sufficient thermal energy to heat up solar
fluid which will then transfer its thermal power to the seawater in the first effect
across the desalination unit and would raise it to the desired temperature then the
solar fluid would be pumped back into the solar field for further heating. MEE
desalination system performance depends on the weather conditions of the
implementation location. This indicates the urgent needs for a design tool that
could help in predicting the performance parameter of the desalination system at
certain location before implementation decision.
The essential standards for understanding the performance of the
desalination system are; the productivity (rrr’zday), the performance factor (PF)
which is the amount of fresh water produced specified to unit mass of heating
source, the specific heat transfer surface area (SA) (m2/(kg/s)), which is the