Increasing the freshwater productivity of a solar still loaded with CuO nanofluids using vibration motion and cover cooling techniques

Abstract

The performance of a single-slope solar still system has been improved with the addition of copper oxide (CuO) nanopowder in water as nanofluid and thermoelectric glass cover cooling combination. The use of vibration further enhances the performance of distillate water as a result of the accelerated heat transfer. In this study, CuO nanofluids loaded the solar still system at volume concentrations of 0.5%, 1%, and 1.5%. The design, fabrication, and testing of the single still were conducted under the local weather conditions of Alexandria, which is located in the northwest of Egypt. The proposed solar still had a base area of 1 m2 and fitted with four coiled springs, a DC motor, and a photovoltaic (PV) solar panel. The vibration generator was a three-phased, with a 1-HP power motor (220 V, 50 Hz, and 1380 rpm maximum speed) fixed to a compact disk with a small punch for adding masses to generate the un-mass balance forces. The power source for the DC motor was a 250-W PV. The daily output of fresh water during the experimental period was empirically measured under the same climate conditions, and the results were compared with those of a conventional solar still. The daily rates of freshwater productivity were investigated in two cases: (a) under vibration without cover cooling and (b) under vibration with cover cooling at the three given nanofluid volume concentrations. Based on the results, the highest daily freshwater productivity attained with the vibration and cover cooling (at the 1.5% nanofluid volume concentration) 7.13, 4.97, and 3.36 kg/day, and the daily efficiency increases by 54%, 43% and 36% compared to the conventional case at the water depths of 10, 20, and 30 mm, respectively, with a maximum estimated cost of 0.027653$/L/m2.