Establishing a transient model of double-layer porous media interfacial evaporation system to reveal the relationship between porous media parameters and evaporation performance

Abstract

The solar interfacial evaporation system can generate steam efficiently by localizing solar thermal energy to heat air–water interface, which has great application potential in seawater desalination, sewage treatment, and other fields. At present, the solar absorption layer and substrate of the interfacial evaporation system are mainly made of carbon materials, sponges, foams, and other porous media materials. However, the transient interfacial evaporation heat and mass transfer model and the influence of the physical parameters of porous media on evaporation performance have rarely been investigated. Based on heat and mass transfer theory of porous media, a transient theoretical model of porous media interfacial evaporation system is established in this paper. Moreover, the effects of physical parameters such as the porosity and thermal conductivity of porous media on evaporation performance are analyzed, and the accuracy of the model is verified through outdoor experiments. Based on the model calculation, as the porosity of the substrate increases, the evaporation rate and efficiency of the evaporator first increase and then decrease. The lower the thermal conductivity of the substrate and the higher the porosity and thermal conductivity of the solar absorption layer are, the better the evaporation performance is, but the growth rate gradually decreases. Therefore, the relationship between the improvement of evaporation performance and the increased cost caused by the improvement of material properties needs to be considered. The model and related theoretical analysis results can provide a theoretical basis for system structure optimization, material selection and other aspects of future research on double-layer porous media interfacial evaporation system.