Enhancing double-slope solar still performance through integrated channel shape variations: An experimental and numerical simulation investigation

The solar still system effectively addresses water scarcity concerns by adopting suitable methods for enhancing yields. Incorporating a preheating system, such as channels within solar still leads to an increased yield from the conversion of saline water. This research integrates various channel shapes (square, rectangular, triangular, and trapezoidal) into double-slope solar stills (DSSS) and their internal properties using numerical simulation and experimental processes under similar climatic conditions. A three-dimensional, multi-phase computational fluid dynamics (CFD) model of solar still was developed using Ansys Fluent 18.1 to compare simulation results with experimental data under the atmospheric conditions of Chengalpattu. The simulation predicted a maximum water yield of 0.44 kg/m²/h, while experimental data showed a peak yield of 0.41 kg/m²/h between 1 p.m. and 2 p.m. There is a 6.82 % variation between the simulations and the experiments. According to the experimental results, the modified system shows a maximum variation of 8.13 % in influence parameter; the yield rate differences for the square, rectangular, triangular, and trapezoidal channels are 8.13, 7.24, 6.73, and 6.52 %, respectively. Trapezoidal channels are superior to other shapes due to their large evaporation capacity, higher wall temperatures due to increased solar absorption area, and superior base resistance. The simulation further explains the heat and mass transfer mechanics into the channel due to resistance from the feed water surface. The research suggests that varying channel shapes inside solar still enhance evaporation and yield rates compared to DSSS systems.