Design optimisation of pillar-mounted sun tracking solar-water purifiers for large households

Abstract

This study was conducted to design a pillar-mounted sun tracker for solar-water purifiers for large households. The main reason for doing this research was to reduce the ground space taken up by solar-water purifiers when used by large households and increase yields. No previous work has been done by researchers to address this problem. Moreover, most people in sub-Saharan Africa and in other developing countries do not have access to clean water. There is need for a solar water purification method to be used by households to purify water for human consumption. Research on the following four different types of solar water purification methods was conducted: Solar-water disinfection, Solar-water pasteurization, Solar-water distillation and Solar-water reverse osmosis. At the university, research work has been done by two students on water purifiers by distillation for small households in rural areas. Their work focused on ground-mounted single basin type design solar water purifiers units that do not track the sun. Larger families would need multiple units of the type developed by these students. These would occupy much space in the compounds, and therefore necessitate to look upward without having to compromise performance or effort to refill the purifiers., Additionally, the effectiveness of the purifiers is to be improved increasing its yields by allowing them to rotate to track the sun since they will all be mounted off the ground. A single axis pillar sun tracker was designed, constructed and tested at the roof top of the Mechanical Engineering at the Cape Peninsula University of Technology. The tracking system consists of a compound gearbox and a stepper motor driven by an Arduino Uno powered by 2 DC 12V batteries. The stepper motor was programmed to rotate intermittently at 15 degrees per hour in the East-West direction. Four Engohang-Kanyarusoke solar water purifier's were mounted on the tracking system and another unit was ground-mounted. Experiments were performed from the 29th of May 2018 to the 07th of June 2018 for 10 connective days at Bellville; Cape Town; South Africa. An area of 30 m2 was saved by mounting four purifiers on the pillar this could however go up to 35 m2 if the full potential of the designed pillar is utilised. The pillar-mounted tracking solar water purifies out-performed the ground mounted still by about 31% in terms of daily water yield.