Rational Design and Salt Resistance Study of 3D Conical Solar Evaporators via Gravity-Enhanced Water Supply

Developing robust strategies to prevent salt precipitation during the treatment of high-salinity and complex brines is essential for achieving stable solar desalination. On the basis of desirable energy management, a gravity-enhanced water transport strategy was rationally designed on a 3D conical evaporator to ingeniously realize a dynamic equilibrium between water supply and evaporation for salt resistance under various complex brine conditions. Through systematic investigation of the critical factors in the salt precipitation behavior through experimental testing and multiphysics simulation, our conical evaporator with optimized composition, dimensions, and morphology could operate stably in not only high-concentration NaCl solution (25 wt % NaCl) but also complex ion composition brine (10 wt % artificial concentrated seawater). Thanks to the water transfer improvement of the photothermal cone via gravity, the evaporation rate could be maintained at 2.06 kg m^-2 h^-1 during continuous 100 h measurement on 10 wt % artificial concentrated seawater without observable salt precipitation. In outdoor experiments, the evaporator was assembled into an application array, achieving a freshwater output of 7.92 L m^-2 d^-1 with a total photothermal projection area of 0.037 m² (using 10 wt % artificially concentrated seawater). Gravity-enhanced water transport has been demonstrated as an effective strategy for salt resistance during solar-driven desalination toward high-salinity water, which can be extensively applicable to various 3D evaporator designs.