Thermal analysis, experimental validation, and performance evaluation of a single slope passive solar desalination...

Bahrain faces increasing pressure on freshwater resources and relies heavily on energy-intensive desalination. This study investigates the performance of a passive single-slope solar still designed for Bahrain climatic conditions through analytical modelling and prototype testing. An energy-balance model based on Dunkle's heat and mass transfer correlations was developed to predict water production under representative summer conditions. The model predicted a freshwater yield of 2.05 L/m²/day with a thermal efficiency of 34%. Experimental testing of a fabricated prototype showed good agreement with the model, with a mean absolute percentage error of approximately 4%. The influence of key design and environmental parameters, including water depth, glass-cover inclination, humidity, wind speed, solar irradiance, optical properties, and feedwater salinity, was also examined. In addition, three enhancement options, namely latent heat recovery, basin fins, and an external air-cooled condenser, were evaluated analytically. When combined, these measures were analytically predicted (not yet experimentally verified) to increase productivity to 2.93 L/m²/day, an improvement of about 43% over the baseline design. The results indicate that passive solar desalination can provide a practical small-scale water-production solution under Bahrain conditions. However, annual productivity estimates and performance enhancements remain model-based predictions requiring further experimental validation.