Break-up Mechanisms and Conditions for Vapour Slugs Within Mini-Channels

In the present investigation an enhanced Volume Of Fluid (VOF) based numerical simulation framework is applied for the conduction of parametric numerical simulations, aiming to investigate observed break-up phenomena of vapour slugs, within circular mini-channel branches of a hybrid thermosyphon / pulsating heat pipe device, during microgravity experiments. The simulation results identify three prevailing break-up regimes. The effect of fundamental controlling parameters in the resulting break-up characteristics is also examined. An entrainment of a liquid droplet at the trailing edge of the vapour slug, that is responsible for its subsequent “full” break-up, is identified from the simulations. Moreover, it is quite interesting that the value of the applied heat flux, does not seem to influence the break-up regime and its main characteristics.