Solar stills of inclined evaporating cloth

Abstract

This article describes various solar stills with inclined evaporating surfaces. It also discusses theoretical studies of maximum annual solar energy absorbed in fastened inclined plane surfaces or in plane surfaces with adjustable slope, which have been performed at the University of Santa Maria, Valparaiso, Chile. The University has studied the efficiency of solar stills with the evaporating cloth oriented to the sun in several ways. The relation of the cloth arrangement to solar radiation: transfer and absorption coefficient of the solar rays, thermal insulation, distances between evaporating surface and transparent cover, vapor leaks, enthalpy loss due to brine output, and wind were determined. The influence of time on the various still material is discussed. Factors included are aging of the plastic covers (Oro T polyethylene, polystyrene, metacrylic polyester, etc.), alterations suffered by different types of evaporating cloths (yute, malva, canamo, etc.), insoluble salt deposition, and seals (organic and inorganic cement, neoprene, etc.). The economics of solar stills with inclined evaporating cloths developed in Chile are considered. This includes annual costs of the materials, construction and maintenance costs of the stills, and specific production and cost of the distilled water in several locations.