568 HEAT AND TRANSFER ANALYSIS IN A CONICAL SOLAR STILL: AN EXPERIMENTAL STUDY

ABSTRACT In this paper, an attempt is made to estimate the heat transfer coefficients of a conical solar still. Many researches and development works tried to enhance the productivity of solar stills using different methods. So in this study the productivity enhancement of solar still by decreasing the shadow effect and maximize utilization of solar radiation is discussed. A new conical solar still was designed and manufactured at faculty of engineering Sheben El-Kom -Egypt (latitude 30.56 N and longitude 31.01 E). The still base area was 0.8 m 2 , and the glass (acrylic) cover of still inclined at 31 o which equal to the latitude of Sheben El-Kom. The experimental results of conical solar still were compared with a conventional type solar still which have the same dimensions. The results showed that, the daily productivity for conical and conventional solar stills was 3.38 and 1.93 L/m 2 .day respectively. Heat and mass transfer coefficients were evaluated and the Nusselt and Sherwood numbers were calculated with the aid of both evaporation measurements and Chilton-Colburn analogy. The maximum value of the total heat transfer coefficient were 66 and 32 W/m 2 . o C for conical and conventional solar stills respectively.The analogy between heat and mass transfer coefficients was also investigated