Advancing solar-assisted air gap membrane distillation through multi-short-channel module innovation

• CFD model for solar-assisted AGMD module is validated with literature data (<5% error) • Novel multi-short-channel AGMD delivered up to 26% higher permeate flux than single-long channel modules. • CPV-integrated solar absorber increased feedwater temperatures, with higher concentration ratios significantly enhancing productivity. • Air gap optimization showed thinner gaps boost flux, while thicker gaps improve thermal efficiency, indicating a performance trade-off. • Economic analysis revealed up to ∼25% lower freshwater production cost, reaching 18 $/m³ under optimal solar and hydraulic conditions. This research analyzes the performance and economic viability of a solar-assisted air gap membrane distillation (AGMD) system, comparing a conventional single long-channel module with an optimized multi-short-channel configuration. A computational fluid dynamics (CFD) model, validated against published literature data (<5% error), was developed to evaluate the effects of Reynolds number, solar irradiance, air gap thickness, and concentration ratio (CR) on thermal and mass transfer characteristics. The multi-short-channel design consistently outperformed the single-channel module, achieving up to 26% higher permeate flux and marginally improved thermal efficiency due to reduced temperature polarization, enhanced flow uniformity, and sustained high membrane surface temperatures. Parametric analysis revealed that thinner air gaps and lower flow rates favored higher flux, whereas thicker gaps improved thermal efficiency, indicating a trade-off between productivity and energy utilization. Integration with a concentrator photovoltaic (CPV) solar absorber further elevated feedwater temperatures, with higher CR values significantly boosting system output. Economic analysis demonstrated that the multi-short-channel configuration reduced freshwater production costs by up to ∼25% compared to the single-channel design, reaching as low as (5-18) $/m³ under optimal solar and hydraulic conditions. These findings highlight the potential of advanced channel geometries and solar-thermal integration to deliver cost-effective, energy-efficient desalination solutions, particularly for remote and off-grid regions.