Low-temperature multi-effect evaporation desalination systems coupled with salinity-gradient solar ponds

As part of a project investigating the productive use of saline land and the development of sustainable desalination systems, the production of potable water from seawater or brackish water using desalination systems powered by low-temperature solar-thermal sources, including salinity-gradient solar ponds, has been studied. A Visual Basic computer model of solar-powered multi-effect evaporation (MEE) desalination processes was developed to determine the technical and economic feasibility of the system. A small-scale three-effect evaporation desalination system powered by a solar pond, capable of producing up to 2,300 litres of fresh water per day, has been designed using the model. The system has been manufactured and commissioned, and has operated effectively at a first-effect vapour temperature of about 68 degrees C, which is ideal for heat delivery from a solar pond. The key design and operating parameters controlling the cost of fresh water - distillate production, recovery ratio, thermal energy and solar collection area-are determined from the computer simulation and compared with experimental results.