Effect of shading and evaporative cooling of glass cover on the performance of evacuated tube-augmented solar still

Solar still is a promising device used worldwide for water distillation due to its simple design, easy construction and low cost. However, the freshwater output from a solar still is moderate. Several active techniques have been emerged over the years to solve this problem. In this paper, an experimental study is carried out on a single-slope solar still augmented with an evacuated tube collector (ETC) and a heat exchanger working on thermosyphon. The effects of shading and evaporative cooling of glass cover on the active solar still performance were explored and analyzed on separate days under the meteorological conditions of Kurukshetra, India. The experiments were conducted at a constant water depth of 4 cm. The main aim of this study is to enhance the productivity and efficiency of ETC-coupled solar still by increasing the condensation rate. The experimental results showed remarkable increment in freshwater productivity of the still with a maximum of 2114 ml/day achieved for the case of ½ shading and cooling of glass cover. An increase of 16.4% and 3.8% in freshwater productivity and overall efficiency was achieved with ½ shading and cooling of glass cover in comparison with solar still without glass cover shading and cooling. The solar still performance was decreased when the shading and cooling are done on more than half the area of glass cover.