A three-dimensional folded multistage distillation device with enhanced air convection for efficient solar interface evaporation

Solar interface evaporation technology is widely used as an effective method of vapor generation. However, the convection and condensation processes that follow vapor generation have received little attention, limiting the actual freshwater output. In this study, we designed an innovative 3D folded structure with enhanced light absorption and air convection for the multistage distillation device. It is demonstrated that the 3D folded structure increases the average air flow velocity by 3 orders of magnitude compared to the conventional flat structure. As a result, the device achieves higher evaporation efficiency with less energy input, with a 7-stage device achieving an evaporation rate of 3.22 kg m−2 h−1 at 1 kW m−2 light intensity. In addition, we have designed an effective salt tolerance strategy for the new structure, with zero liquid discharge and easier salt collection. The experiment proved the stable operation of the device in high concentration brine at 20 wt%. This new structure provides a new idea for the interface evaporator to improve fresh water production and practicality.