Thermal models of solar still-A comprehensive review

Water is vital to life and supplying of potable water can hardly be overstressed in recent years. The conventional desalination processes require significant amount of energy to convert brackish water into potable water for human consumption and industry. With an extensive research on various desalination systems over the last few decades, solar desalination is one of the most promising methodologies to provide high quality water to the human community by using sustainable source. The demand for a small scale self-contingent desalination device is the need of the hour. Solar still is an innovative device that utilizes solar energy to produce distilled water from brackish water. Numerous experimental research works have been reported in the literature to analyze the performance of various types of solar stills under local climatic conditions. Thermal models have also been presented based on energy balances and the theoretical results have been validated through experimental data by many researchers. Thermal models have a great advantage of predicting the performance of virtually designed solar stills without spending much cost and time. Accordingly, the usage of most recent theoretical attempts and proposed ideas tackling this point is limited. An attempt has been made in this article to provide a comprehensive review on thermal models developed for various types of solar stills and modifications done to improve their performance over the years. Our findings indicate that few more parameters and design aspects to be considered while designing new solar still. The efficacy of this study is that it provides energy researchers' insights into solar still design for clean water production and, thus, it promotes commercialization of this product in rural development. Finally, some general course of action are given for the selection of solar still with flexible, consistent and robust design. Suggestions for further research are also incorporated. (C) 2015 Elsevier Ltd. All rights reserved.