Investigation of a solar-powered desalination system employing regeneration Original Research Article

The objective of this research project was to develop a process that makes use of low-grade heat provided from solar irradiation to drive a distillation-desalination process. An optimized distillation process re-uses 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 MEH device — GORMEHi” is described and used. In contrast to other projects investigating low temperature distillation devices employing regeneration, 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 CFD-optimized 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 (≈23,000 ppm) to very low levels (≈17 ppm) of dissolved salt content at thermal efficiencies comparable to the theoretically possible.