Fabrication and Testing of Small Capacity Solar Desalination System Using Humidification-Dehumidification Method

Abstract

Water is an essential and unique natural resource that provides life support for plants and animals. The world's water consumption rate is doubling every 20 years, outpacing by two times the rate of population growth. It is projected that by the year 2025 water demand will exceed supply by 56%, due to persistent regional droughts, shifting of the population to urban coastal cities, and water needed for industrial growth. . Lack of fresh water reduces economic development and lowers living standards. Clearly, there is a critical worldwide need to better manage this increasingly valuable resource. Desalination is a water treatment process that converts brackish or saline water to fresh water by removing dissolved minerals from the water. Solar desalination with humidification - dehumidification process seems to be an efficient means of utilizing solar energy for production of fresh water from saline water. The study has been conducted in KCAET campus, Tavanur, Malappuram district. It is situated at 10°52'30'' north latitude and 76° east longitude. Flat plate solar collector is used as the heat source. The study was conducted during 2011 in successive days to ensure the same climatic conditions for all tests. The yield of the system with different temperatures and flow rates were noted. Temperature was within a range of 55 to 75 o C and flow rates were in between 3000 to 6000 ml/min. Three concentration of saline water was used for the study. It has been observed that temperature have a great influence on the yield of desalinated water in the Humidification-dehumidification unit. A change of hot water temperature from 55°C to 75°C showed the yield to rise from 17 ml/min to 36 ml/min., which clearly indicate that a rise of temperature of saline water will increase the yield of the system. The maximum yield obtained was about 36 ml/min with a flow rate of 6000 ml/min. The comparison of quality of saline and desalinated water shown that the quality of desalinated water is improved and nearly matches with the BIS standard for drinking water.