Performance enhancement of single-slope solar still using phase change materials.

Abstract

Freshwater scarcity appears clearly in coastal areas of Egypt despite the existence of a large amount of seawater around. Solar still is the cheapest and oldest way to desalinate seawater and brackish water. In the proposed study, single-slope solar still was examined in the climatic conditions of Qena, Egypt (Latitude: 26.16°, longitude: 32.71°). The purpose of the study was to analyze the energy storage behavior inside the phase change materials and to enhance the solar still productivity during both daytime and nighttime operation. The performance of the proposed solar still was tested under the use of phase change material (RT42PCM) with different quantities of 2, 4, and 6 kg in weight, which was placed inside the basin area. Furthermore, the optimum phase change material quantity was compared with simple conventional solar still without phase change material. The results showed that the productivity of the proposed solar still in the case of using 4-kg phase change material was higher than that for using 2-kg phase change material and 6-kg phase change material by about 18.6 and 27.7%, respectively. Moreover, the average daily efficiency is 68, 57.2, and 53.6%, respectively. The use of 4-kg phase change material in the basin caused an enhancement in the proposed solar still productivity by about 29.7% and the average daily efficiency was 66.7 and 51.5%, respectively, in comparison with simple solar still without phase change material. It was additionally seen that in the case of using phase change material, more yield was gotten over during the nighttime and the average basin water temperature was increased due to its high ability to store thermal energy inside. Furthermore, the produced freshwater could be used in different life applications, because of its appropriate ranges of total dissolved solids, pH, hardness, and water clarity.