Modeling of Solar Still Enhanced with Evacuated Tube Collectors for Brine Volume Reduction from Reverse Osmosis Plants

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Date
2017-08-09
Authors
حمد, أفنان فواز
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An-Najah National University
Abstract
 In the last years and as a result of continuous increasing in world demand for potable water, shortage of fresh water became a major challenge for human society. Desalination seems to be a suitable solution for water production. Oon other hand, shortage of conventional energy needed for desalination technologies is considered as the second challenge for human society, in addition to the growing concern of brine disposal problem.  Solar still is the best alternative to convert brackish water or saline water into potable water, this technology became popular among the scientific community because of its simple working principle, its low costs and the dependence on a free and abundantly available energy. Main disadvantage of conventional still is the production rate.  This research aims at to studying the effect of coupling a single slope solar still with an evacuated tube collectors (E.T.C) through mathematical modeling. For this purpose, different models for hybrid systems were investigated, a model for a conventional still, a model for conventional still enhanced with E.T.C and model for evaporation and drying (no glass model). For all models two different were considered, the first was considering constant parameters (properties are not function of temperature), while parameter changing with temperature are considered in the other case.  The results were obtained from solving the models numerically were analyzed and different parameters were plotted as a function of time. All obtained results showed that solar still coupled with E.T.C have as superiority over the conventional still, the potable water increased by 48% and 73% when constant and variable parameters were considered, respectively.  The effect water depth and wind speed were on water temperature, glass temperature and the output from the still were also studded. The results showed that increasing water depth decrease the fresh water productivity while increasing wind speed increases the productivity.  Removing the glass cover for brine volume reduction, showed that the evaporation rate increases by 100%.  It was concluded that the idea of using solar still enhanced with evacuated tube collectors for brine volume reduction in our study area is effective because it reduces brine volume and produces fresh water at the same time.
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