Accelerating vapor condensation with daytime radiative cooling

TL;DR

This paper introduces daytime radiative condensers that reflect solar radiation to enable vapor condensation and dew formation in sunlight, significantly boosting water production in solar purification systems.

Contribution

Development of daytime radiative condensers that operate under direct sunlight, doubling water production compared to existing condensers.

Findings

Dew water can be produced in sunlight using the new radiative condensers.

Water production rate increased from 0.4 to over 1 L/m²/hour.

The system is compatible with existing solar water-purification technologies.

Abstract

Vapor condensation plays a crucial role in solar water-purification technologies. Conventional condensers in solar water-purification systems do not provide sufficient cooling power for vapor condensation, limiting the water production rate to $0.4 L m^{-2} hour^{-1}$. On the other hand, radiative dew condensation, a technique used by existing radiative dew condensers, only works at nighttime and is incompatible with solar water-purification technologies. Here, we develop daytime radiative condensers that reflect almost all solar radiation, and can thus create dew water even in direct sunlight. Compared to state-of-art condensers, our daytime radiative condenser doubles the production of purified water over a 24-hour period. The integration of our daytime radiative condenser with solar water-purification systems can increase the water production rate in sunlight from $0.4 L m^{-2} hour^{-1}$ to more than $1 L m^{-2} hour^{-1}$.