Numerical and experimental analyses of a transparent solar distiller for an agricultural greenhouse

Solar distillers are the simplest desalination equipment used to produce fresh water using the most sustainable source of energy. In this research, a new fully transparent solar distiller is designed to be integrated into the roof of an agricultural greenhouse using the excess solar radiation to produce desalinated water for plant irrigation. A numerical technique is proposed to analyse the performance of the distiller. This technique couples a lumped model based on transient mass and energy balance equations for different components of the distiller with a computational fluid dynamics (CFD) model to simulate the flow, heat transfer, and phase change of humid air and water with a free surface inside the distiller. The predicted temperature variations of the glass and basin by the lumped model are used as boundary conditions for the CFD model to improve the accuracy of the water production estimations. The results of the lumped model and the coupled lumped-CFD model are compared with the experimental data from a transparent distiller test performed at Alexandria, Egypt. The same average daily efficiency of 12.4% for both the experimental measurements and the coupled lumped-CFD model is shown. The results of the validated numerical model indicate that the daily yield can be increased by approximately 22% by increasing the basin insulation. Additionally, the predicted maximum yield is 618.2 mL/day in August. Integrating transparent distillers into a greenhouse roof can provide 37.5% of irrigation water and reduce the power consumption of the greenhouse cooling system by 60%.