Solar still with rotating parts: a review

Access to freshwater is narrowed down every day in the world. Many diseases of human beings are related to water supplies contaminated or unpurified. Nowadays, there are massive water shortages in developed and developing nations due to unplanned mechanisms and water pollution caused by human behavior. Water desalination with no impact on the environment is the necessity of the hour. The distillation of saline or brackish water using free solar energy such as solar still is one of the techniques of water purification providing ultrapure distilled water. Besides, solar still is an economical and eco-friendly method, particularly in arid areas. Solar distillers also provide renewable equipment for freshwater productivity. The still design was affected by several operating and environmental factors. The low productivity of the solar still is its major drawback, so many researchers have studied various models to enhance solar still productivity. This paper aims to review the numerous studies of solar still incorporated with rotating parts that are deemed to be effective and efficient design because rotating parts break water surface tension, increase evaporation area, and improve the still performance. Throughout this detailed review, the scholars intend to present, clarify, and analyze the status of several solar distillers with various rotary component arrangements such as a fan, rotating wick, shaft, drum, disc... etc. In addition, based on the entire work, it was confirmed and recommended that the solar still with rotating parts should be continuously followed to supply potable water efficiently and economically. Different results showed the importance of part rotation (best daily yield & improvement) such as vertical disc distiller (16.5 L/m²/d & 617.4%), drum distiller (9.22 L/m²/d & 350%), moving wick solar still (9.17 L/m²/d & 315%), shaft still (0.83 L/m²/d & 39.49%), and vibratory distiller (5.8 L/m²/d & 132%). These important results obtain the importance of embedding rotating parts into the solar stills.