Systematic exploration of direct solar absorption potential to enhance direct contact membrane distillation

Abstract

Increasing concerns about global freshwater scarcity and the growing demand for renewable energy are stimulating the exploration of innovative technological solutions for sustainable water management. Thanks to an experimentally validated model, here we systematically assess the effectiveness of distributed solar heat in enhancing the productivity of direct contact membrane distillation (DCMD) for seawater desalination. The proposed study investigates the impact of various configurations and operating parameters, analyzing more than 1000 cases, focusing on optimizing heat and mass transfer, hence water flux, in counter-current and co-current channel designs. Our findings indicate that integrating solar heat can significantly improve DCMD performance, with productivity enhancements potentially exceeding 200%, especially at low cross-flow rates, by alleviating temperature polarization and enhancing vapor flux. The detailed analysis further reveals that the counter-current configuration consistently outperforms the co-current design under optimal conditions, achieving higher water fluxes and reduced polarization effects. Moreover, sensitivity studies underscore that fine-tuning channel dimensions and flow parameters is critical for maximizing energy efficiency and ensuring robust desalination performance. The results highlight the potential of solar-powered MD systems to provide sustainable and cost-effective freshwater solutions, particularly for off-grid and remote areas. By optimizing solar heat utilization and MD configurations, this study advances both theoretical understanding and practical applications in water desalination, promoting energy efficiency, operational cost reduction, and environmental sustainability.