Numerical study of PCM-integrated solar still efficiency enhancement

Abstract This research paper provides a detailed comparison of three types of solar stills: the conventional passive solar still (still-I), the solar still with paraffin wax as a phase change material (PCM) (still-II) and the solar still with PCM coupled to a storage tank (still-III). The study involves a numerical investigation across six regions of Morocco during typical days of each season of the year. The paper formulates and solves the thermal energy balance equations for the different components of the solar stills and storage tank. The numerical simulation is validated by comparing the results with existing experimental and numerical data. The study shows that a portion of the energy produced during the day is stored in the PCM, which can be utilized at night. In addition, the storage tank plays an active role in improving the yield of the passive solar still, indicating the advantage of the new configuration. Thus, the productivity of still-III during typical days of spring, summer and autumn exceeds that of still-II and still-I. The maximum value of still-III was obtained in region five of Morocco (Marrakech) in spring with 8.6 kg ${\mathrm{m}}^{-2}$. However, the highest energy efficiency was achieved in region 1 (Agadir) with 76.05%, while the maximum exergy was reached in region five (Marrakech) in spring with 7.09%.