ENHANCED HEAT AND MASS TRANSFER IN A SOLAR STILL WITH A POROUS-FIN LATTICE BASIN

Abstract

An analysis of the internal and external heat and mass transfer in an improved solar still is presented. The improved design is obtained by modifying a conventional single-sloped basin-type solar still by placing blackened cotton cloth porous fins in the basin water of the still. The experimental study revealed that the wet porous fins, which were partially extended above the basin water surface, received a major part of the solar radiation, particularly during the morning and evening hours. Moreover, the low thermal inertia and increased evaporation area in the modified design led to quicker start-up, and the higher operating temperatures resulted in better performance. The basin water remained relatively cooler, resulting in less base heat loss. The theoretical study showed higher internal heat and mass transfer coefficients and less base heat loss. Heat loss from the glass cover temperature to ambient temperature by convection and radiation is also analyzed. The basin water of the improved still primarily serves as an energy storage medium, which supplies warm water to the porous fins during low insolation and off sunshine hours, giving nocturnal output. Sound agreement between the theoretical and the experimental results was observed.