A two-phase analysis of the use of water-aluminum nanofluid in a solar still with a layer of phase change materials

Abstract

This study employed the finite element method to simulate a solar still three-dimensionally. Aluminum nanoparticles were used in the still's tank, at the bottom of which was a layer of the N-auxin Phase Change Material (PCM). The variables of the problem included the degree of solar radiation for 12 different hours a day, the 10–45˚ angle of the front glass plate of the still, and the ambient temperature ranging from 293˚K to 330˚K. The effects of these variables on the air temperature, glass, PCM, and PCM volume fraction were examined. A two-phase method was used to analyze the nanofluid in the tank. The results showed that solar radiation generally had the highest effect on the maximum PCM temperature, maximum air temperature, and PCM volume fraction. However, the drop in the ambient temperature had the maximum impact on the maximum glass temperature. The PCM inside the solar still made the maximum air temperature slightly higher in the evenings than in the mornings. As a result, the maximum glass temperature could reach 330˚K at the ambient temperature of 330˚K and maximum solar radiation. In the last hours of the study, a decline in the angle of the solar still's front plate reduced the volume fraction of the molten PCM. Besides, at the 10˚ angle of the still's front plate, a drop in the outside temperature led the PCM to freeze faster.