Effect of design and operating parameters on solar still productivity

Water desalination processes have become of prime importance due to the increasing demands for fresh water. Due to the rapidly increasing prices of fossil fuel and caring about environmental safety, use of solar energy has drawn the interest of many researchers in the last few years as a means of an environmentally-friendly process for water desalination. The present study is an investigation of the effects of operating and design parameters on the performance of single-slope basin-type passive solar stills. A series of stills with the same external dimensions are used. Modifications are limited to the still basin by changing either the water depth or the shape of the still basin. The amount of water distillate, ambient temperature, vapor temperature, basin temperature, glass temperature and solar intensity were recorded. The results showed that water depth 0.4 cm gives the highest productivity of 2096 ml /m2/day. The effect of the material of construction was studied. The results showed that the productivity of the stills increases by 16.7% when using metal as a construction material; compared to glass. Use of energy absorbing materials in the basin of the solar still increased the still productivity by 4.1%. Using a corrugated metal sheet in the bottom of solar still reduced the active area of evaporation to half its original value but the productivity was higher than half the productivity of the reference still.