04. Boiling and Multi-Phase Flow

Liquid hydrogen has been recently focused as one of the useful storages or transportations of the clean energy source in industrial fields, and the detailed understanding of its liquid-vapor two-phase flow characteristics including boiling and cavitation phenomenon is becoming important because hydrogen is easily vaporized. However, in the microscopic point of view, the bubble inception or nucleation mechanisms have not been fully understood due to the related few experimental data. In this study, by using path integral Centroid Molecular Dynamics (CMD) method, we evaluated the liquid-vapor interfacial thickness and the surface tension as the basic interfacial properties, and discussed the quantum influence of liquid hydrogen, which is known as an important factor for defining the liquid-vapor coexisting state. Resultingly, it was confirmed that the quantum influence of hydrogen enlarges the liquid-vapor interfacial thickness while that of hydrogen weakens the surface tension. In addition, the quantum influence could be roughly scaled by using a characteristic length and intermolecular potential energy depth, both of which are the parameters of the effective intermolecular potential reflecting the quantum nature. Note that the present insight above the liquid-vapor interfacial properties would be also useful for the modelling of the nucleation work, which is a dominant factor of the bubble nucleation rate in liquid hydrogen.

Prof.

Shin-ichi Tsuda