Second Two Years' Progress on Study and Field Evaluation of Solar Sea-Water Stills

摘要

The solar distillation project discussed is concerned primarily with the simple single-effect type of solar still in which sea water is heated by solar radiation, evaporates from a basin or wick, and condenses on the underside of a transparent cover over the basin or wick. A new deep-basin still was built at a cost of $2.00 per square foot, as compared to $7.50 for the first deep-basin still. In addition, the new design is expected to have a longer useful life. Performance of the two stills has been approximately the same. The tilted-wick stills are more efficient than the basin stills. However, their life is shorter and they are more difficult to operate. The four vertical-envelope stills have been unsatisfactory, because of the poor wettability of their wicks and their susceptibility to wind damage. A small all-plastic inflated-tube still has operated successfully, with a productivity near that of the basin stills. Three basin liner materials are being evaluated in the materials-evaluation stills: Butyl rubber sheeting, asphalt-impregnated jute, and a prefabricated asphalt mat. Asphalt paving was tried but was found to leak excessively. In addition, new distillate trough materials, new glass-sealing methods, and single-strength glass covers are being studied. Slime growth in the basins has been a problem. Control methods investigated have been unsuccessful. (Author)