Vapor generation via porous nanochannel wicks

Abstract

Vapor generation rate in nano/microstructured-based interfacial vapor generation devices is limited by water supply. Here, we report an innovative design for enhancement in vapor generation using porous nanochannel wicks. Vapor generation rate of 1.18 kg m − 2 h -1 is achieved in a dark environment (without heat input) and of 17.12 kg m − 2 h -1 is achieved with a heat input of 5.08 W at low temperature of 62°C, significantly higher than a typical vapor generation rate reported for interfacial solar vapor generation systems. We also demonstrate our wick’s performance under solar heat flux of 1.25 sun and attain a vapor generation rate of 4.87 kg m − 2 h -1 at surface temperature below 35°C. Thus, we present an unconventional approach of separating surfaces of vapor generation and heat supply that would provide additional flexibility in the choice of energy source, such as solar energy and waste heat from exhaust gases. This approach can be consequential in low-grade waste heat recovery. • Wick made of cross-connected buried nanochannels with micropores at intersections • Capillary-induced passive water supply with simultaneous evaporation at micropores • Thin film evaporation causes high vapor generation rate at low surface temperature Vapor generation rates are limited in passive nano/microstructure-based interfacial vapor generation devices. Ranjan et al. report the performance of a porous nanochannel wick design that can achieve high vapor generation rate with solar heat flux, with waste heat, and even in the absence of heat supply.