Nanotexturing-enhanced heat transfer and interfacial evaporation for energy-efficient solar-thermal water desalination

Abstract

Seawater desalination based on nano-interface-enhanced evaporation is one of the promising energy-effective solutions to alleviate global clean water scarcity. However, the heat and mass transfer mechanisms from the absorber surface to the surrounding liquid, which is critically significant to improve the evaporation performance in practical applications, are still unclear. Here, we develop an all-carbon hierarchical architecture via engineering of vertically oriented graphenes on a graphite felt monolith, and simultaneously, gain new insights into the effects of the surface morphology on the heat and mass transfer at the absorber/liquid interface by manipulating the graphene texturing from microscale to nanoscale. In the visualization experiments, compared with the microstructured and smooth surfaces, a higher-density bubble distribution with a smaller departure diameter on the nanostructured surface is observed, leading to the significant enhancement of heat transfer through the micro-convection and transient conduction mechanisms. Specifically, the heat transfer coefficient value of the nanostructured surface is more than 1.5 times that of the microstructured surface, thus achieving an increment of ∼5% in freshwater productivity.