Surface charge enhanced kinetically-limited evaporation in nanopores

Understanding the fundamentals of the kinetically-limited water evaporation in nanopores is of signifi-cant importance to improve the performance of modern evaporation-based thermal management devices. However, the ubiquitous existence of ions in aqueous solutions and charged function groups on solid walls have been ignored traditionally and the effect of surface charges on nanopore evaporation remains elusive. Herein, we consider the effect of surface charges on disjoining pressure and solve the system of equations governing the heat and mass transfer during the evaporation process from single nanopores numerically to yield the ultimate evaporation under various working conditions. Our results reveal that the surface charge, along with pore radius, wall temperature, and the relative humidity of ambient air, plays a critical role in determining the overall performance of the system. As the surface charge density increases, or as the pore radius decreases, the extended meniscus leads to a higher net rate of evapora-tion per unit pore area. Increasing the pore wall temperature increases the driving force for evaporation and results in a better performance despite the meniscus contracted. Results of this work provide new understanding of nanoscale phase-change heat transfer and is beneficial to applications requiring inten-sive evaporation, such as electronic cooling, forward osmosis, and membrane distillation. (c) 2023 Elsevier Ltd. All rights reserved.