A recent study has provided insights into why solar radiation is particularly effective at evaporating water compared to other energy forms. The research highlights the role of the oscillating electric field inherent in sunlight.
“It’s well established that the sun is exceptionally good at causing water to evaporate – more efficient than heating water on the stove, for instance,” stated Saqlain Raza, a Ph.D. student at North Carolina State University and first author of the paper. “However, it has not been clear exactly why. Our work highlights the role that electric fields play in this process.”
Jun Liu, co-corresponding author and associate professor of mechanical and aerospace engineering at NC State, explained that this study is part of broader research efforts aimed at understanding this phenomenon with potential applications in developing more efficient water-evaporation technologies.
The researchers utilized computational simulations to investigate how different parameters associated with sunlight affect evaporation. Liu noted, “Light is an electromagnetic wave, which consists – in part – of an oscillating electric field. We found that if we removed the oscillating electric field from the equation, it takes longer for sunlight to evaporate water. But when the field is present, water evaporates very quickly. And the stronger the electric field, the faster the water evaporates.”
Raza further explained that during evaporation, either individual water molecules or clusters are freed from liquid water. Liu added that their findings showed that “the oscillating electric field is particularly good at breaking off water clusters,” making it a more efficient process.
The team demonstrated these findings by simulating evaporation in models of pure water and hydrogel-saturated water. Raza observed that while pure water had fewer surface-level clusters for evaporation, hydrogel-saturated models had more clusters near surfaces where evaporation occurs faster due to their presence.
“This work substantially advances our understanding of what’s taking place in this phenomenon since we are the first to show the role of the water clusters via computational simulation,” said Liu.
The paper titled “Oscillations in Incident Electric Field Enhances Interfacial Water Evaporation” was published in Materials Horizons and co-authored by Cong Yang from NC State and Xin Qian from Huazhong University of Science and Technology. The study received support from the American Chemical Society’s Petroleum Research Fund under award ND5-65609.
