A multichannel photothermal rod for antigravity water transportation and high-flux solar steam generation

Abstract

Solar-driven interfacial evaporation is a promising technology to produce clean water from seawater or polluted water. However, the evaporation rate in existing photothermal materials is normally limited to 5 kg m⁻² h⁻¹ or below, which makes it hard to fulfil the daily water demand of a family, let alone the enormous water requirements in agricultural and industrial sectors. Herein, under the guidance of computational fluid dynamics (CFD) simulations, a multichannel photothermal rod (MCPR) is proposed as a solar interfacial material for evaporative disposal of real municipal sewage and concurrent production of freshwater. The production rate of the freshwater over a 10 centimetre-high MCPR is 18.8 kg m⁻² h⁻¹ under 1 sun, with water quality equivalent to that of commercial pure water. When the light is incident at oblique angles, faster evaporation rates are obtained (e.g., 31.3 kg m⁻² h⁻¹ at a 30° angle). Furthermore, the evaporation rate can even be raised to 126.5 kg m⁻² h⁻¹ in an outdoor environment via a magnified evaporation system constructed of a 35 centimetre-high MCPR array. These values were achievable due to a series of properties of the MCPR, including antigravity water transport, omnidirectional collection of solar energy, minimization of heat dissipation, and maximization of the evaporation interface.