Enhancing solar steam generation using a highly thermally conductive evaporator support

Abstract

Interfacial solar steam generation is an efficient water evaporation technology which has promising applications in desalination, sterilization, water purification and treatment. A common component of evaporator design is a thermal-insulation support placed between the photothermal evaporation surface and bulk water. This configuration, common in 2-dimensional (2D) evaporation systems, minimizes heat loss from evaporation surface to bulk water, thus localizing the heat on the evaporation surface for efficient evaporation. This design is subsequently directly adopted for 3-dimensional (3D) evaporators without any consideration if it is appropriate. However, unlike 2D solar evaporators, the 3D evaporators can also harvest additional energy (other than solar light) from the air and bulk water to enhance evaporation rate. In this scenario, the use of thermal insulator support is not proper since it will hinder energy extraction from water. Here, the traditional 3D evaporator configuration was completely redesigned by using a highly thermally conductive material, instead of a thermal insulator, to connect evaporation surfaces and the bulk water. Much higher evaporation rates were achieved by this strategy, owing to the rapid heat transfer from the bulk water to the evaporation surfaces. Indoor and outdoor tests both confirmed that evaporation performance could be significantly improved by substituting a thermal insulator with thermally conductive support. These findings will redirect the future design of 3D photothermal evaporators.