Abstract

Highly efficient water evaporation under solar illumination is of key importance for the performance of seawater desalination stills. Thermal vapor generation efficiency increases markedly through thermal insulation of the irradiated water surface layers from the underlying bulk water. Recent studies have shown that the use of nanomaterials with plasmonic surface properties lead to additional thermal efficiency boosts. We present experimental results of in situ water evaporation experiments performed under normal ambient conditions. The use of floating sandwich-layered structures (SLS), can increment water evaporation rates of up to 43% when compared to the rates obtained for plain water surfaces with an underlying light-exposed bulk. The importance of water transport to the light-exposed SLS surface, and hence the SLS design is crucial, as we demonstrate with an additional set of experiments. Evaporation efficiency increases when water impregnated powder layers of strong light absorbers are present at the illuminated SLS surface. Comparative results obtained with wet powder layers of graphite and igneous rock compounds show that, under same experimental conditions, the water evaporation rate can be boosted by as much as 470% compared to bare water surfaces.

Authors and Affiliations