Investigation of a solar-powered desalination system employing regeneration

The objective of this research project was to develope a process that makes use of low-grade heat pfovided from solar irradiation to drive a distillation-desalination process. An optimized distillation process rebuses input heat, by using the heat-of-condensation as the heat source for pre-heating the incoming cold saline water. This research project was concerned with examining the physical and thermodynamic characteristics Of this process so as to optimize the efficiency of a solar powered water distiller employing heat recovery. The study Was primarily concerned with understanding the natural convection driving the evaporation-condensation process and the other physical and geometric considerations that affect the distillation process in multi effect humidification (MEH) systems. A new term, coined "GOR of an ideal MM device-GOR(MEHi)'' is described and used. In contrast to other projects investigating low temperature distillation devices employing regenefdtion, this research project incorporated a CFD analysis that formed the base for the optimization process. By using such an analysis the optimum geometry for a distillation enclosure was determined to be an "ovalized rectangle''. This basic geometry with CVD-optimiized dimensions, along with some additional features was incorporated into a fully operational laboratory distillation system. The distillation system was tested for its functionality and thermal efficiency. The device tested is capable of distilling salty water (similar to 23,000 ppm) to very low levels (similar to 17 ppm) of dissolved salt content at thermal efficiencies comparable to the theoretically possible.