ANALYSIS OF ROOF TYPE SOLAR STILLS WITH ASSISTING EXTERNAL CONDENSERS

Abstract

A simple solar still coupled to an external condenser, to enhance the yield, is modeled and analytically investigated. The analysis is general in nature and not limited to a particular condenser features. The present analysis, based on actual meteorological data, shows that the yield improvement depends upon both brine level and the surface area provided for heat removal. For an ideal still with negligible thermal inertia (water depth approaches zero) an auxiliary condensing surface at a temperature below the glass temperature decreases the daily yield. The still yield is improved for brine levels up to 10 cm above this level additional heat removal from the still does not significantly improve the daily productivity. The productivity for the limiting condition when the auxiliary condensing surface is maintained at the ambient temperature is also presented and discussed.