Calla lily-inspired 3D evaporator: A dual interface design for enhanced solar water evaporation

Abstract

Due to the exponential growth of the global population, groundwater resources have long been insufficient to meet the escalating demand for potable water. In recent years, interfacial solar stream generation (ISSG) technology has emerged as a pivotal approach in generating clean water. The paramount performance factors of solar thermal evaporators encompass their exceptional light absorption capacity, efficient water transport, and effective thermal management. Among these factors, the 3D interface evaporator stands out due to its inherent advantages and ingenious structural design that enhances overall performance. In this study, the structure of calla lilies was used as inspiration, we propose a novel design featuring a 3D inverted conical double-sided evaporator (3D-ASIE) which effectively traps sunlight within its core, thereby augmenting light absorption capabilities while simultaneously forming a dual-evaporation interface. The inverted conical structure comprises two cellulose/TiN aerogel films with superior light absorption and heat insulation properties along with a polytetrafluoroethylene (PTFE) hydrophilic film that is skillfully bent and assembled together. To ensure continuous water supply during evaporation, the tail end of the hydrophilic membrane is immersed in water. During interfacial evaporation process, activation of the outer photothermal layer of our 3D-ASIE facilitates steam diffusion along both inner and outer surfaces of the inverted cone structure concurrently resulting in an impressive dual-evaporative effect. Under sunlight intensity level at 1 kW m−2, our 3D-ASIE exhibits remarkable performance with an evaporation flux reaching up to 2.97 kg m−2 h−1 alongside an efficiency as high as 94.7 %, thus demonstrating immense potential for large-scale solar desalination applications.