Experimental and Numerical Analysis of a PCM-Supported ...

seawater desalination, upgrading water quality of surface and contaminated
underground water, and intensification of wastewater regeneration and reuse.
1.2 Desalination option
Water desalination is the process that removes dissolved minerals and other
pollutants from seawater, brackish water, or treated wastewater to produce fresh
potable water. Water desalination is a technically mature technology to provide
renewable and reliable water supplies and has been practiced regularly over the last
50 years in different parts of the world. Most of the desalination plants in operation
are located in the driest part of the world; Middle East and North Africa (MENA)
region. Nearly more than 15 thousand desalination plants (of a unit size of 100
m 3 /day or more) with cumulative capacity of approximately 65.2 Million m 3 /day have
been installed or contracted around the world by the end of 2010.
The three factors that have the
largest effect on the cost of
desalination per unit of fresh water
produced are the feed water
salinity level, energy cost, and
plant size which show economies
of scale [65]. Intensive energy
requirement stands as a major
contributor to -the relatively- high
cost of desalinated water. It has
been estimated by Kalogirou [66]
that the production of 1000 m 3 per
day of fresh water requires 10000
tons of oil per year.
Figure 1.1: Cost breakdown of desalinated
water, adopted from Abdel Gawad [5]
Fortunately, desalination cost declines steadily over time and becomes more
competitive compared with conventional water resources. Nevertheless there are still
some potential and necessity for bringing the cost down. While cost cannot be
overlooked, there is compelling evidence that desalination will have to be adopted as
the only acceptable way to provide potable water in some developing countries,
particularly in the MENA region [68]. Reducing the cost of desalinated water,
therefore, has been and will continue to be a crucial issue to be explored.
1.3 Overview on desalination processes
Depending on the transport phenomena involved in the separation process,
desalination systems are broadly categorized under two main groups, which
survived the crucial evolution of desalination technology, namely; thermal (or phase
change) and membrane techniques. Several treatment and desalination
technologies that vary in nature, efficiency, and energy requirements are
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