Improving the performance of solar still by using PCM as a thermal storage medium under Egyptian conditions

• The impact of PCM on the behavior of still was investigated experimentally under Egyptian conditions
• The improvement in the productivity for still with PCM is 67.18% higher than that for conventional still
• The amount of distillate water reaches approximately 7.54 L/m2 day for still with PCM

The objective of the present work is to improve the performance of a solar still through increasing the productivity of freshwater. In order to improve the performance of a solar still, a phase change material (PCM) was added as a heat storage medium. Two solar stills were designed, constructed and tested in the present experimental study to compare the productivity of the solar desalination system. One of them is a solar still with PCM and the other is the conventional solar still. The experimental results show that, the daily freshwater productivity for solar still with PCM is higher than that of conventional solar still. The daily freshwater productivity approximately reached 7.54 L/m2 day for solar still with PCM, while its value is recorded 4.51 L/m2 day for the conventional solar still. The results show that the daily freshwater productivity for solar still with PCM is 67.18% higher than that of the conventional solar still. Also, the solar still with PCM is superior in daily freshwater productivity (67%–68.8% improvement) compared to a conventional solar still in the period from June to July 2015 under the ambient conditions of Tanta city (Egypt). In this case study the estimated cost of 1 L of distillate water reached approximately 0.24 LE (0.03 $) and 0.252 LE (0.032 $) for solar still with PCM and conventional solar still, respectively.