Experimental and Simulation Study of Solar-Powered Air-Gap Membrane Distillation Technology for Water Desalination.

This work aimed to investigate temperature polarization (TP) and concentration polarization (CP), which affect solar-powered air-gap membrane distillation (SP-AGMD) system performance under various operating conditions. A mathematical model for the SP-AGMD system using the experimental results was performed to calculate the temperature polarization coefficient (τ), interface temperature (T fm ), and interface concentration (C fm ) at various salt concentrations (C f ), feed temperatures (T f ), and flow rates (M f ). The system of SP-AGMD was simulated using the TRNSYS program. An evacuated tube collector (ETC) with a 2.5 m 2 surface area was utilized for solar water heating. Electrical powering of cooler and circulation water pumps in the SP-AGMD system was provided using a photovoltaic system. Data were subjected to one-way analysis of variance (ANOVA) and Spearman's correlation analysis to test the significant impact of operating conditions and polarization phenomena at p < 0.05. Statistical analysis showed that M f induced a highly significant difference in the productivity (P r ) and heat-transfer (h f ) coefficients ( p < 0.001) and a significant difference in τ ( p < 0.05). Great F -ratios showed that M f is the most influential parameter. P r was enhanced by 99% and 146%, with increasing T f (60 °C) and M f (12 L/h), respectively, at a stable salt concentration (C f ) of 0.5% and a cooling temperature (T c ) of 20 °C. Also, the temperature increased to 85 °C when solar radiation reached 1002 W/m 2 during summer. The inlet heat temperature of AGMD increased to 73 °C, and the P r reached 1.62 kg/(m 2 ·h).