A Transient Two‐Dimensional Finite Difference Model for the Simulation of Solar Still Enhanced With Glass Cover Cooling System

Solar stills provide a simple, low‐cost, and sustainable solution for freshwater production in arid and water‐scarce regions. However, their widespread adoption remains constrained by low freshwater productivity. The present study numerically investigates the effect of film cooling on the thermal performance and freshwater productivity of a conventional solar still. A transient two‐dimensional finite‐difference model is developed to solve the coupled energy equations governing the system components, providing high‐fidelity spatial and temporal representations of the temperature field and the freshwater productivity. The numerical model is validated against experimental data available in the literature. The results show that the glass‐cover cooling technique increases the maximum water‐to‐glass temperature difference from 8.31°C to 18.15°C. In addition, the daily freshwater productivity increases from 2.69 to 3.20 kg.m −1 .day −1 , representing an improvement of 18.95%. The average energy efficiency also increases from 24.24% to 29.18%. Furthermore, a parametric analysis identifies an optimal cooling‐water film thickness of 5 mm and a volumetric flow rate of 0.1 L.s −1 .