A numerical and experimental investigation on an aerogel-based solar interfacial evaporation system

In this work, a multiphase transport model was developed based on the surface evaporation assumption (SEA) or distributed evaporation assumption (DEA) in simulating the solar interfacial evaporation (SIE). A starch-based aerogel was prepared and used for the SIE experiments in a lab-scale SIE apparatus with a cuboid chamber and closed sidewalls under 1-sun irradiance to validate the developed model. Compared with the SEA-based model, the DEA-based model achieved excellent agreement with the measured mass-change and surface temperature evolutions with NRMSE s being 1.05% and 4.16%, respectively. Based on the validated DEA-based model, the transport mechanisms governing the SIE were systematically investigated. The results revealed that a vapor shield formed above the aerogel suppressed evaporation despite sufficient heat and water supply. Together with the sensitivity analyses, vapor removal was thus targeted as the primary rate-limiting factor of the SIE under the closed sidewall configuration. To enhance the SIE performance, open sidewall configuration with a chimney were numerically analyzed. The results showed that an air inlet height of 10 mm at the chimney bottom could effectively disrupt the vapor shield. The highest evaporation rate reached 2.17 kg·m –2 ·h –1 under the optimal chimney configuration and investigated operating conditions. Finally, the developed model was extended to local meteorological conditions to perform a first-order estimation. The optimal chimney configuration significantly improved the annual evaporation yield by 12.0% compared with the closed sidewall configuration. The fundamental research provided guidance for the industrial implementation of high-efficiency SIE systems.