Performance Analysis and Optimization Study of a Desiccant wheel Enhanced Condensation Atmospheric Water Harvesting Hybrid System

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ObjectiveIn arid regions， the low dew-point temperature of ambient air significantly limits the water-harvesting efficiency of conventional condensation-based atmospheric water-harvesting （AWH） systems. To address this limitation， this study proposes a desiccant-wheel-enhanced condensation AWH hybrid system that elevates the dew-point temperature of the incoming air prior to condensation， thereby enhancing the condensation potential. The primary objective of this study was to investigate the performance of three hybrid system configurations featuring different desiccant-wheel partition structures （WFS-1， WFS-2， and WFS-3） under various environmental and operational conditions as well as identify the optimal configuration and operating parameters for efficient water production in arid environments.MethodsA comprehensive mathematical model describing coupled heat and mass-transfer processes in a hybrid system was developed. The model integrates desiccant-wheel dehumidification and regeneration processes with the subsequent cooling condensation process. Numerical simulations were performed to evaluate the effects of key parameters on system performance， including the ambient humidity ratio， ambient temperature， regeneration temperature， and cooling-source temperature. Three system configurations—WFS-1， WFS-2， and WFS-3—were compared. Performance metrics included water harvesting rate （WHR， kg/h） and water harvesting efficiency （WHE， kg/（kW·h））. All simulations were conducted under steady-state assumptions， and model accuracy was validated against experimental data from the literature.Results and DiscussionThe simulation results revealed several key findings. First， the ambient humidity ratio showed a strong positive correlation with the water yield. When the humidity ratio exceeded 3 g/kg（dry air）， WFS-1 achieved the highest WHR owing to its lower pressure decrease and simpler heat-transfer characteristics. However， under extremely dry conditions （humidity ratio <3 g/kg（dry air））， WFS-3 outperformed the other two configurations owing to its enhanced moisture adsorption efficiency in low-humidity environments.ConclusionThis study demonstrated that integrating a desiccant wheel with condensation-based atmospheric water harvesting is a viable strategy for improving the water yield in arid regions. The hybrid system performance was highly sensitive to the ambient humidity ratio， and ambient， regeneration， and cold-source temperatures. Among the three configurations， WFS-1 is recommended for moderately humid arid conditions （humidity ratio >3 g/kg（dry air））， whereas WFS-3 performs better in extremely dry environments （humidity ratio <3 g/kg（dry air））， and offers superior energy efficiency under high-temperature regeneration conditions. These findings provide theoretical guidance for the design and optimization of energy-efficient atmospheric water-harvesting systems tailored to arid and semiarid regions.

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