Synchronously managed water and heat transportation for highly efficient interfacial solar desalination

Abstract

Interfacial photothermal water evaporation technology has shown great potentials in the fields of water resource exploitation and solar energy utilization. The trade-off between rapid evaporation and salt accumulation has been continuously explored in recent years. Herein, a two-stage evaporator (TSE) that synchronously manages the water and heat transportation is introduced. The TSE is designed to improve the evaporation rate by harvesting the dissipated heat including the radiative and convective heat losses on the surface of the solar absorber together with the conductive heat loss to the insulator. The surface temperature of the upper solar absorber is lower than that of a conventional single-stage evaporator (SSE) with a thermal insulator because energy from the upper evaporation surface is partially transferred to the secondary evaporation surface. Importantly, the typical TSE configuration improves the evaporation rate of the traditional SSE from 1.39 to 1.57 kg m−2 h−1, which excludes the contribution of the ambient energy-assisted heating to evaporation. Importantly, by introducing a unilateral water supply channel, the TSE maintains a high evaporation flux of 1.48 kg m−2 h−1 in saline water with a concentration of up to 20% (w/w). The synchronous scheme of water and heat management provides an effective way to overcome the contradiction between rapid evaporation and salt accumulation.