Enhancing nanoscale phase-change heat transfer by collaborative roles of surface functionalization and external electric field

Abstract

Understanding the mechanism behind phase-change heat transfer and designing new strategies to improve the heat transfer coefficient is crucial for numerous applications, such as heat engines, cooling, and steam generators. Here, we demonstrate the heat transfer coefficient at the Au surface can be improved by 113 % utmost via applying an external electric field (EEF) and modifying the surface with functional groups (FGs). This enhancement is found to be resulting from the fast vapor-liquid transition and high thermal conductance across the solid-liquid interface. On the one hand, the EEF decreases water-vapor phase transition activation energy and therefore increases the evaporation rate. On the other hand, introducing the FGs at the Au surface increases the interfacial adhesion and bridges the interfacial inter-medium vibrational couplings, leading to an increasing thermal conductance of Au/water interfaces. The vibrational coupling between water and the FGs is further increased by the EEF which complements the decreased influence of EFF on the water-vapor phase transition activation energy at high temperatures. Our work here provides a collaborative strategy to enhance phase-change heat transfer on surfaces which could be beneficial to its related applications.