Desalination of brackish water using indigenous dual acting solar still system

Water scarcity in Pakistan is multifaceted and increasing day by day. Beside energy crisis, Pakistan is facing severe water scarcity challenges and has lowest fresh water availability per capita in the region. About a quarter to a third of Pakistan's population (40 million) does not have access to fresh water. Desalination of the brackish water is a very suitable approach to augment the exponentially increasing fresh water demand due to uncontrolled population growth in the country. Desalination of saline water is highly energy intensive process. Conventional methods of desalination are not suitable for the countries like Pakistan. Solar desalination is very feasible method as sun light is a continuous, natural resource of energy and the technology is also free from emission of smoke and other greenhouse gases that is a serious detriment to the environment. This research work is carried to design and develop an indigenized dual acting (passive & active) solar still desalination system. The system comprised of flat plate solar collector (FPC) of 1 m2 area used as a primary heat source, desalination chamber having 1 m2 area and made of galvanized iron sheet of 1.6 mm thickness, heating fluid circulation mechanism using 5 mm copper tubes with thermal conductivity of 385 W/(m.K) for the efficient desalination of brackish water. The roof of the evaporation chamber is made pyramidal shape using glass of 5 mm thickness. The effect of vital parameters on the production of fresh water is studied. The average FPC inlet and outlet temperature is observed to be 46.4 degree C and 71.5 degree C respectively. The mean heat energy recovered by the water in evaporation chamber to produce vapors is 198.6 kJ/kg. The performance evaluation of solar still is carried out under local climatic conditions and it is found that the efficiency and productivity of the desalination system are strongly affected b) the direct solar radiation, flow rate and inlet hot water temperature. The experimental results show that peak fresh water production from the designed system reaches to 3.8 1/m2 in 8 hours and water quality test of the fresh water proves the effectiveness of the desalination system. Fresh water shows excellent results having EC, pH, TDS, Na1+, Ca2+ and Mg as 0.15 dSm-1, 6.1, 105 ppm, 0.47 mg/l, 0.65 mg/l and 0.54 mg/l respectively. The results show that solar desalination system can be used to produce the desalinated water for drinking applications.