Investigations on performance Enhancement of solar stills

Abstract

The availability of potable water is not sufficient to meet the growth of human population and industrial developments. The water available in sea is not possible to use directly due to high salt concentrations. Moreover, the water available from rivers and lakes are polluted with industrial wastes, which are not possible to drink directly. Thermal desalination is the established technology for purifying the saline and sewage water. However, the thermal desalination is the energy intensive process, which uses low grade heat energy obtained during combustion of fossil fuel to evaporate the water. The fast depletion of fossil fuel and its negative impact to environment have created a research motivation to use renewable energy resources for evaporating the saline water (brackish water). Solar still desalination is the one of the established water purifying technology, which produces 2-3 kg/m2 per day only. Hence, attempts have been made in this research to improve the productivity of solar stills. newlineIn this research work, the performance of solar still has been improved by integrating with gravel coarse aggregate bed, use of magnets to improve the evaporation rate, integrating with crushed gravel sand and biomass evaporator to preheat the saline water and integrating with heat pump water heater to improve water evaporation and condensation. The thermodynamic performances of each configuration have been assessed to study the technical feasibility. The economic feasibility was estimated using payback analysis. The environmental benefits of the system have been assessed using enviro-economic analysis. The experimental observations have been made for the period of 12 hours (9.00 hours 21.00 hours) in the modified solar stills and for the period of 10 hours (9.00 hours 19.00 hours) in the conventional solar still. The experimental observations were used for thermodynamic performance assessments newline