Enhanced solar evaporation of water from porous media, through capillary mediated forces and surface treatment

TL;DR

This study investigates how surface treatments and pore size influence solar water evaporation from porous media, highlighting the roles of capillary and surface forces in enhancing efficiency for solar energy applications.

Contribution

It demonstrates that nitric acid surface treatment enhances evaporation by mimicking the effects of smaller pore sizes and capillary forces, providing a new approach to optimize solar evaporation systems.

Findings

Hydrophilic surface treatment improves evaporation efficiency.

Lower Capillary number correlates with higher efficiency.

Surface modification can replace pore size reduction effects.

Abstract

The relative influence of the capillary, Marangoni, and hydrophobic forces in mediating the evaporation of water from carbon foam based porous media, in response to incident solar radiation, are investigated. It is indicated that inducing hydrophilic interactions on the surface, through nitric acid treatment of the foams, has a similar effect to reduced pore diameter and the ensuing capillary forces. The efficiency of water evaporation may be parameterized through the Capillary number (Ca), with a lower Ca being preferred. The proposed study is of much relevance to efficient solar energy utilization.