Effect of Nanostructures of Different Sizes on Boiling and Nucleation: A Molecular Dynamics Study

Abstract With the development of technology, the energy needs of today’s society are gradually increasing, and methods that can improve heat transfer efficiency within limited volumes are becoming increasingly important. Among various heat transfer methods, boiling is considered an effective way to improve spatial heat transfer efficiency due to its ability to fully utilize phase change latent heat. The design of nanostructures enables further enhancement of boiling heat transfer efficiency, and numerous studies indicate that nanostructures facilitate bubble nucleation and growth during boiling, thereby increasing critical heat flux (CHF). However, existing studies mostly analyze the influence of surface nanostructures on bubbles independently of the heat transfer and potential energy aspects. Possible synergistic or mutually inhibiting effects between the two are hardly taken into account. In addition, boiling heat transfer in a reactor not only improves the efficiency of heat transfer, but can also affect the reactivity and safety of the reactor due to the uneven distribution of bubbles in time and space. Therefore, it is also necessary to consider the influence of nanostructures on the bubble nucleation positions. The entire bubble growth process was directly observed by using molecular dynamics simulations. Furthermore, a detailed discussion was conducted on the influence of nanostructures on nucleation positions, nucleation times, and CHF. The results suggested that not all nanostructures contribute to bubble nucleation; Instead, when the nanostructure size is smaller, bubble nucleation was delayed and CHF is reduced. The mechanism of this phenomenon is revealed by the inhibitory effect between heat transfer and potential energy.