All-weather solar desalination enabled by phase-change microcapsules with high photothermal conversion efficiency
摘要
The intermittent nature of solar radiation prevents interfacial evaporation systems from operating continuously around the clock. To overcome the limitation, this study developed a phase change microcapsule material (MPCMs) with excellent comprehensive performance for water evaporators. In this work, nano-tungsten carbide (nano-WC) hybrid melamine-urea–formaldehyde (MUF) resin was used as the shell to wrapped capric acid core material to prepare hybrid MPCMs. The MPCMs and EP (epoxy resin) were mixed and solidified by ultrasonic stirring to form a composite material for seawater evaporation test. At a 6 wt.% nano-WC loading, the microcapsules achieved optimal performance with an encapsulation efficiency of 66.0% and a 76.40% improvement in thermal conductivity. Specifically, the microcapsule sample achieved a photo-thermal conversion efficiency of 75.96% in photo-thermal conversion experiments. The composite sample showed excellent durability, maintaining an evaporation efficiency of 98.70% in six circulating water evaporation tests, and the average evaporation rate was 1.41 kg m−2 h−1. The evaporation efficiencies for samples were 82.30%. Compared with the traditional sample without phase change material, the evaporated water of the developed phase change microcapsule composite plate sample increased by 25.30 g m−2 within 10 min after the light stopped. This photo-thermal conversion and energy storage composite material provides a viable strategy for developing uninterrupted solar-thermal water evaporators, showcasing broad application prospects in sustainable desalination and energy-efficient water purification.
Graphical Abstract