UTILIZATION OF SOLAR EARTH-WATER STILLS FOR DESALINATION OF GROUNDWATER

Three solar earth-water stills of single-sloped type, designed for producing drinking water in remote areas, have been investigated. These stills were installed over an insulated hole, a hole with insulated base, and a hole with insulated walls. Multiple linear regression equations, relating to ambient air temperature, wind speed, and solar radiation, were developed to estimate the productivity of these stills. The study showed that condensation process inside these stills is achieved during the period between sunset and sunrise. Results showed also that the average wall's contribution in supplying fresh water is about 56%, whereas base contribution is about 31%. It is concluded, therefore, that setting many stills on a number of separated holes will give higher output rather than setting a single still on one large hole of the same volume.