Effect of wind speed on some designs of solar stills

The effect of wind speed V on the daily productivity P-d Of some designs of basin type and vertical solar stills is investigated by computer simulation. Numerical calculations have been performed on typical summer and winter days in Tanta in order to correlate P-d With V for different masses of basin water m(w) for basin type stills and various thicknesses of flowing water d(w) for the vertical still. It is found that P-d increases with the increase of wind speed up to a typical velocity V-t beyond which the increase in P-d becomes insignificant. For the present stills, V-t was found to be 10 and 8 m/s on typical summer and winter days, respectively. The value of V-t is independent of the still shape and heat capacity of the brine. The wind is more effective in summer and at higher water masses. Further, the maximum daily productivity can be obtained at the lowest heat capacity of the brine and the rate of still productivity decreases with increased water mass. This effect is more pronounced in winter than in summer due to the lower solar radiation. (C) 1999 Elsevier Science Ltd. All rights reserved.