Solar water desalination using plate-like desalination unit enhanced by air flow

A solar water desalination unit was built and tested. The unit mainly consists of an inclined black plate, glass cover, and condenser. On the black plate, metallic strips were attached, which act as heating fins in order to increase water residence time and increase evaporation area. The evaporation was enhanced by blowing air through the unit carrying the water vapor. The water vapor-air mixture was passed through a condenser, in which fresh water was obtained. The unit productivity, defined as the volume of fresh water obtained per unit area times unit time, was measured and presented. The results showed that the unit is capable of producing 0.2 l/m²-hr with an average water electrical conductivity of 52 mS/cm and hot water of about 60oC. It was found that the productivity drops by 21% when the feed water salinity is increased to 20000 ppm. The experimental results showed that the countercurrent mode of operation enhances the unit productivity by 30%. Recycling the air out of the condenser to the unit improved its productivity by 3.6-fold (360%). Performing mass and energy balance around the condenser to predict the productivity of the unit showed an excellent agreement between the theoretical and the experimental results.