Identification of operational parameter levels that optimize the production in solar stills with plain, corrugated,...

Researchers integrate various operational parameters in the conventional type solar still to improve the distillate production. But maximum production can be obtained only when the optimum parameter levels which suit the solar still design are identified and incorporated. In this study, an attempt has been taken to identify the optimum level of four operational parameters-Mass of Heat Storage Material, Basin Water Depth, Basin Cover Thickness, and External Mirror Position, which suit well in plain basin, corrugated basin, and compartmental basin solar still. The parameter levels were combined as per L₉ orthogonal array and the distillate production obtained under different combinations of operational parameter levels was 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 side). 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.