Effects of Microchannel/Macrochannel Configurations on the Evaporation Performance of Internal Vertical/External Radial Hydrogel Solar Evaporators: Experiments and Simulations Insights

Abstract Hydrogel evaporators with combined vertical/radial channel are demonstrated to synergistically leverage the advantages of each individual structural mode to achieve superior evaporation performance compared to single‐structured counterparts. However, in such composite structures, the dimensions of micro‐ and macro‐scale channels simultaneously influence both water transport and thermal transfer, and the underlying mechanisms governing the balance between water supply and heat loss remain insufficiently understood. Herein, a series of composite alkali‐treated polyacrylonitrile/MXene@sodium alginate (PMS) hydrogel evaporators featuring controllable vertical channel dimensions is fabricated. Through adjusting the dimensions of interior channels of evaporators, it is investigated how varying the vertical channel size affects convective water flow, heat confinement, and overall evaporation performance. The systematic experiments and numerical simulations show that vertical microchannels significantly enhance convective water transport, while the surrounding radial structure effectively confines heat. Under one‐sun illumination, this optimized vertical/radial composite achieves an evaporation rate of 5.01 kg m −2 h −1 at 165.13% energy efficiency. Further upscaling the microchannel to the macroscale amplifies convective effects, boosting the evaporation rate to 8.60 kg m −2 h −1 . These findings highlight the importance of finely balancing micro‐ and macro‐scale channel architectures to simultaneously optimize water supply and heat loss, providing new guidelines for designing high‐performance hydrogel evaporators.