Enhanced performance of a direct contact membrane distillation (DCMD) system with a Ti/MgF₂ solar absorber under actual weather environments

In this study, we report on a solar membrane distillation (MD) system with a 5-stack Ti/MgF₂ solar absorber adapted as a heat source under actual weather conditions. The 5-stack Ti/MgF₂ solar absorber showed light absorption of 85% over the wavelength range from 0.3 to 2.5 μm. This consequently induced greater heat and a two-fold greater water heating capability up to 80 °C for water in a closed water tank without insulation under a 1-sun illumination. The enhanced solar absorption of the Ti/MgF₂ solar absorber showed a 12% improvement in permeate flux of the integrated MD system compared with a system without a solar absorber. Under actual weather conditions, the solar DCMD system with the Ti/MgF₂ solar absorber successfully produced distillate water in the range of 0.51–4.78 L/m²·day depending on weather conditions. Despite unfavorable solar irradiance conditions in autumn, the integrated DCMD system with the Ti/MgF₂ solar absorber proved superior to a conventional commercial evacuated-tube solar collector in terms of daily production of distillate water and solar energy requirements for certain amounts of distillate.