Enhancing the sustainability of interfacial evaporation to mitigate solar intermittency via phase change thermal storage

Solar-driven interfacial water evaporation is a low-carbon footprint strategy for addressing global water scarcity. However, the operation of the evaporator requires continuity of solar radiation. Herein, the key to overcoming the intermittency of sunlight lies in utilizing the heat storage/release cycle of phase change materials. Additionally, the synergistic effect of high thermal conductivity materials and increased heat transfer area addresses the nonuniform spatial temperature within the heat storage device caused by the low thermal conductivity of molten paraffin. Although the heat transferred to the paraffin reduces the evaporation rate under illumination, the thermal storage/release capacity of paraffin increases the evaporation mass by 171.5% in darkness. Ultimately, after one light-dark cycle, the total evaporation mass over the entire period increased by 11.5%. Finally, although paraffin undergoes sensible and latent heat absorption and release across various temperature ranges during multiple light-dark cycles and prolonged operation, the phase change delays at different internal locations still ensure stable dark-state evaporation compensation for the evaporator, thereby enhancing the sustainability of the evaporation process.