Solar-powered adsorption desalination utilizing composite silica gel with a humidification-dehumidification desalination system

This work comes in light of addressing crises of freshwater scarcity, energy demand, and climate change to investigate innovative configurations of hybrid adsorption desalination integrated with a humidification dehumidification system powered by solar energy or waste heat in four operation modes. The investigation includes economic cost analysis and system performance using raw silica gel and silica gel/CaCl₂ adsorbents under the weather data of Assiut-Egypt. System performance has been evaluated regarding daily water production, gain output ratio, and cooling effect using TRNSYS and MATLAB software. The combined configuration with heat recovery (the fourth mode) using silica gel/CaCl₂ gives a relatively high freshwater production (69 m³/ton.day in June) compared with the basic adsorption desalination system using raw silica gel (7.1 m³/ton.day in June). Silica gel/CaCl₂ in the first mode presented the highest cooling effect (555 W/kg) in June compared with silica gel in the primary system (197 W/kg). The third configuration's solar-powered silica gel/CaCl₂ system shows a clear superiority of 1.8 in gain output ratio, compared with the basic system with and without heat recovery (0.54 and 0.4, respectively). The third configuration also provided the cheapest freshwater production among all configurations at 2 $/m³ in June.