Water nanofilm boiling on a copper surface in the presence of dissolved air

Boiling is an effective and critical energy transfer process in energy, aerospace, and electronic applications. With the rapid development of nanotechnologies, the development of a highly efficient thermal management system for high flux energy applications from microscale to nanoscale become a promising topic. The dissolved air in water nanofilms has adverse effects on the boiling process due to the size effects, but the boiling mechanism at the nanoscale has not been well clarified. Therefore, non-equilibrium molecular dynamics (NEMD) simulations are employed to investigate the behavior of water boiling on a nanoscale copper surface in the presence of air. We observe that the interfacial air layer adsorbed on the copper surface increases the boiling time by 73, 20, and 7 times at a pressure of 1bar, 20bar, and 100bar, respectively. We propose a theoretical model based on the heat conduction differential equation to predict the time evolution of water temperature at atmospheric pressure. The results indicate that the boiling process at the nanoscale only manifests into Leidenfrost phenomenon rather than bubble nucleation, along with the negative effects of air dissolved in water nanofilm. By revealing the boiling process on a copper surface at the nanoscale, this work provides useful insights for broad applications in nanoscale thermal management and energy conversion.