The Red Sea area wind-driven mechanical vapor compression desalination system

Abstract

Egypt confinement governorates suffer a big shortage in water resources. In a previous study, the problem has been resolved for North Sinai, South Sinai and Matrouh governorates. Meanwhile, the problem still stands for the Red Sea Governorate. In this region, the population is less than 0.2% of Egypt total population; while its area is more than 20% of Egypt's area, which makes investments difficult to exist. In addition, there is a chain of mountains expanding along the Red Sea shore making the piping works and fuel transportation expensive, especially because of the lack of railways. In addition, the National Electric Grid is also not connected. Fortunately, there are locations where high wind speed is steady all over the year allowing electricity generation by wind, with consequent water production. Among the seawater desalination techniques adapted for remote areas is the mechanical vapor compression desalination system (MVC). The main drawbacks for wind driven units is the variable wind speed. This problem is resolved through a proposed electrical and mechanical system, which is interconnected to the local electrical grid. In the present work the equation for determining the yearly electric power generated from a wind turbine as a function of the wind speed and turbine rotor diameter is obtained. An improved simple realistic working formula for determining the compressor specific work needed for the desalination system has been improved from a previous work by the author. In addition, a correlation for determing the wind driven MVC system water productivity at different design parameters has been deduced, enabling design curves to be obtained. The study has indicated that at the operating evaporator temperature and temperature difference recommended are 50°C and 3°C respectively. The average prevailing wind speed in these areas is 7 m/s, the system productivities are 203, 398, and 938 m 3/d, at wind turbine diameters 20, 28 and 43 m respectively. These productivities are adequate for communities around 510, 1000 and 2350 capita/unit respectively (for specific water consumption of 400 l/d per capita for domestic, tourism and/or small industries).