Effect of Depth of Water on the Performance of Stepped Type Solar Still

Samir Deshmukh; S. Gawande; Lalit B. Bhuyar
The research work carried out so far in the field of solar desalination is related to the single basin type solar still only. The effect of changes in design, climatic and operational parameters on the distillate yield has been studied but limited to the single basin type solar still. The increase in productivity by connecting a flat plate collector which is called as active solar desalination has also been studied but limited to the single basin type solar still. Present study deals with a stepped type solar still to improve the performance of single basin type solar still by increasing the production rate of distilled water. The modifications in the design of single basin type solar still are introduced by replacing the flat basin by a stepwise structure. The stepped type solar still selected in this case has 8 number of steps of size 620 mm(L) x 100 mm(W) and total absorber area equal to 0.5093 m2. The characteristic feature of stepped type solar still is that it provides an additional 40% absorber area as compared to the single basin type solar still. In this work, three number of stepped type solar stills with varying depth of water and other design parameters like thickness of glass cover, insulation thickness, condensing cover material, shape of the absorber surface, absorbing material provided over the basin surface, angle of inclination of the still etc. being fixed have been selected for experimentation. The depth of water provided in solar stills A, B and C was 5 mm, 7.5 mm and 10 mm respectively. After conducting experiments for the varying depths of water, it has been observed that the distillate yield of solar still A is greater than solar still B and C by 14.15% and 22.64% respectively. Thus, as depth of water goes on increasing, the distillate yield produced per unit area of absorber surface goes on decreasing. Also, an economic analysis was made. The payback period of solar still A, B and C is 823 days, 958 days and 1064 days respectively. Thus, the solar still A with 5 mm depth of water gives the returns within the least possible time as compared to other two types of stepped solar stills.
Stepped Type Solar Still; Depth of Water; Distillate Yield; Thermal Performance
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