AN EXPERIMENTAL STUDY ON SINGLE BASIN SOLAR STILL AUGMENTED WITH EVACUATED TUBES

The productivity of the solar still is determined by the temperature of water in the basin and the glass temperature. Various active methods have been adopted to increase the temperature of the basin, so as to improve the productivity of solar still. Most of the previous research works have been focusing on flat plate collector and concentrating collector. In this experimental study, a single slope solar still directly augmented with evacuated tubes was used to increase the daily productivity by reducing heat losses. Evacuated tubes were directly coupled to the lower side of the single slope solar still with an area of lm(2). Black gravel is used to increase the productivity by means of reducing quantity of water in the basin. Extensive experiments were conducted to explore the performance of solar still in several modes namely still alone, still with black stones, still with evacuated tubes, and still with evacuated tubes and black gravel. The experimental set-up was designed and installed at Solar Energy Park, Tamilnadu College of Engineering, Coimbatore (77 degrees E, 11 degrees N), Tamil Nadu, India. These experiments were conducted using tap water as feed. It was found that, after augmentation of the evacuated tubes, the daily production rate has increased by 49.7% and it increased by 59.48% with black stones. Economic analysis was also done and payback period of this experimental setup is 235 days.