Taguchi-based optimization of solar desalination with porous medium application and geometry modifications

A stationary solar desalination system is commonly utilized for purifying seawater and brackish water. However, its primary drawback is the limited freshwater output. To address this challenge, this study aims to enhance the performance of solar desalination by numerically investigating the application of a porous foam gradient across different absorber geometries. The research examines the impact of various factors, including absorber surface temperature, glass cover temperature, glass slope, absorber and glass geometries, porous medium, and foam gradient, on the system's energy and exergy efficiencies. A detailed analysis was conducted to evaluate the system's efficiency concerning absorber plate thickness, absorber temperature, and glass temperature. The Taguchi optimization method was employed to determine the optimal configuration. Among the investigated geometries, the solar desalination unit with a spherical glass cover demonstrated the highest efficiency. The incorporation of a porous layer significantly enhanced the system's energy efficiency. The increase in productivity was found to depend on factors such as porous layer thickness, porosity, permeability, and the thermal conductivity ratio of the solid to the fluid within the porous layer. The application of a porous layer with variable porosity in different spatial directions resulted in an efficiency improvement of up to 350 % for the P2 case. Furthermore, a minimal difference of only 2.1 % was observed between the Taguchi-based predictions and the CFD simulation results.