Investigation the performance of new designed solar still of rhombus shaped based on new model

Abstract A theoretical study on the performance of new design solar still of rhombus shape is presented. The rhombus solar still shape is composed of two glass cover walls of Λ shape while the still basin is of V shape including wood fibers porous material saturated with saline water. A complete new theoretical model is presented for the solar still including still basin and walls and humid air region. The radiation exchange between still walls is considered in the theoretical model. The study is performed under different climate conditions of Upper Egypt in summer, winter, and spring at different inclination angles of the still basin with the horizontal of 70°, 45o, and 30°. The theoretical model is validated with an experimental work and shows a good agreement between the theoretical and experimental results. The findings show that the solar still performance (solar still temperatures, freshwater production, and solar still efficiency) rises with decreasing the inclination angle of the solar still while the energy loss decreases with decreasing the inclination angle. The radiation exchange between the glass walls and the basin surfaces is negligible compared to the radiation exchange between the glass walls and their faced basin surfaces. The maximum daily solar still freshwater yield is 2.9 kg/m2.day in winter, 4.8 kg/m2.day in spring, and 5.4 kg/m2.day in summer while, the maximum solar still efficiency is 29% in winter, 42% in spring, and 47% in summer.