Magnetic photo-thermal evaporator with joule-assisted heating for stable vapour generation

Abstract

Solar energy has the potential to be applied in the production of vapour that relies on high-temperature liquids in conventional ways because it is one of the reproducible energy sources. In this work, a magnetic photo-thermal evaporator (MPE) based on nickel foam coated with reduced-graphene-oxide is used to produce vapour. The increase of thermal conversion efficiency can be implemented by a solar absorbed structure that promotes the vaporization of generated water. MPE has its optimal energy conversion efficiency of 98 %. Due to the coupling joule heat and solar thermal processes, the efficient and stable interfacial evaporated performance could be controlled, which is to optimize the multi-process coupling and multi-energy complementary process and promote the actual applications of MPE. Under the solar power of 1000 W·m−2, the evaporation rates obtained were 1.75 kg·m−2·h−1 and 1.81 kg·m−2·h−1 for the coupled continuous and segmented magnetic fields for the 90 s, which are much higher than the theoretical evaporation rate limit for two-dimensional interfacial photo-thermal evaporator. In case of extreme water shortage, the magnetic field can be used to assist in the rapid extraction of fresh water. The advantages of rapid fabrication and lower cost of the MPE have made the developments of solar evaporator applications possible such as desalination and wastewater treatment.