Experimental Study of Preheating Enhancing the Evaporation Performance of Solar Interfacial Evaporator

Solar interfacial evaporation is a promising technology for steam preparation to solve the global shortage of freshwater resources. Existing research has achieved significant enhancement through the development of photothermal materials, but the spatial utilization efficiency of solar energy remains suboptimal. To improve the utilization efficiency of solar energy, this study has designed a new interfacial evaporator with preheating enhancement. It couples the 3D hydrogel with a preheating structure composed of a light-absorbing coating and a copper sheet. The experiment has investigated the effects of solar irradiance intensity and preheating structure on evaporation. According to the experimental results, under the solar radiation intensity of only 1 sun, the steam generation amount increases to a maximum of 2.37 kg·m^{− 2}·h^{− 1}. In addition, the preheating structure has a significant effect on improving the evaporation efficiency of the evaporator. Compared with the evaporator without a preheating structure, the maximum enhancement effect can reach 40.1% under the solar radiation intensity of 1 sun. Under a higher radiation intensity, the enhancement effect increases to 43.4%. The enhancement mechanism primarily involves intensified heat transfer, enhancing the wettability of the water transport layer and reducing the enthalpy of water evaporation, which jointly improves the evaporation effect.