Effect of specific height on productivity and thermal efficiency of a solar still: An experimental approach under indoor environment

A novel experimental approach is presented where studies have been conducted on a solar still at four specific heights in the range of 0.266-0.341 m (in steps of 0.025 m) keeping other dimensions constant. Performance of solar still is established under indoor environment to suppress meteorological factors. Uniform heat was supplied to the solar still through flat plate-type electrical heaters. For each specific height, the performance of the solar still was evaluated at five heat fluxes (600-1000 W/m(2) in steps of 100 W). Performance of solar still at different specific heights was compared in terms of operating temperatures, productivity, and efficiency. It was found that reduction in specific height enhances distillate productivity as well as thermal efficiency of the solar still due to reduction in cavity volume and an increase in average operating temperature. An increase of in daily distillate yield of 89.44% (at 600 W/m(2)), 56.07% (at 700 W/m(2)), 28.50% (at 800 W/m(2)), 38.60% (at 900 W/m(2)), and 37.38% (at 1000 W/m(2)) between Case 1 to Case 4 was observed. Further, between Case 1 and Case 4, the thermal efficiency increased from 27.29 to 46.18%, 32.73 to 51.06%, 36.82 to 52.17%, 41.25 to 56.79%, and 42.55 to 57.50% at 600, 700, 800, 900, and 1000 W, respectively. Results demonstrate that for a particular specific height the total daily productivity increases linearly with heat flux. Correlation for estimating thermal efficiency of solar still is proposed in terms of the aspect ratio and input power. (c) 2019 American Institute of Chemical Engineers Environ Prog, 38: e13227, 2019