Identification of Optimum Operational Parameter Levels for Plain Basin, Corrugated Basin and Compartmental Basin Solar Stills

Abstract

This study aimed at optimizing or maximizing the distillate production in plain basin, corrugated basin and compartmental basin solar stills by integrating them with optimum level of the four operational parameters - Mass of Heat Storage Material, Basin Water Depth, Basin Cover Thickness and External Mirror Position. The efficiency of the parameters is not uniform and it differs from still to still due to variation in the structure of the basin. Further, the most efficient level in a parameter differs from still to still. A particular basin water depth which is highly productive in plain basin still may not suit well for corrugated or compartmental basin still. To find out the optimum parameter levels, the 4 operational parameters and the four levels of each parameter were combined as per L16 orthogonal array and the distillate production under different combination of operational parameter levels were analyzed using S/N ratio analysis, mean response method, analysis of variance and regression analysis. The analysis revealed that the optimum mass of heat storage material was 16 kg in plain basin, 12 kg in corrugated basin and 10 kg in compartmental basin still. The efficiency of corrugated basin and compartmental basin solar stills was maximum at a lower basin water depth of 15 mm and 10 mm respectively. But plain basin still efficiency was maximum at a higher basin water depth of 20 mm. The optimum basin cover thickness was 4 mm in all the solar stills, in spite of a difference in the structure of the basin. In the same way, the distillate production was maximum when the external mirrors were positioned on the two sloping sides of the solar still (east and west direction). The expected production from the solar stills integrated with the optimum parameter levels was estimated using regression analysis and mean response method. The average distillate production which was 3304, 3493 and 3629 ml/m2.day in the modified (not with optimum parameter levels) plain basin, corrugated basin and compartmental basin solar stills respectively, improved to 6414, 7153 and 7629 ml/m2.day respectively when they were modified with optimum parameter levels and the increase in production was 94 %, 105 % and 110 % respectively.