ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
COMPUTATIONAL STUDY ON BREAK-UP MECHANISMS OF ISOLATED VAPOUR SLUGS DURING SATURATED FLOW BOILING CONDITIONS
摘要
In the present paper, an enhanced Volume Of Fluid (VOF) based numerical simulation framework is applied for the conduction of parametric numerical experiments, aiming to investigate break-up phenomena of elongated vapour slugs, within circular mini-channels. The effect of fundamental controlling parameters, in the resulting break-up characteristics, is examined. In more detail, four different series of parametric numerical experiments of isolated liquid slugs within a mini-channel were performed, investigating the effects of Applied Pressure Drop
(APD), Surface Tension Coefficient (STC), Initial Liquid Film Thickness (ILFT) and Applied Heat Flux (AHF), on the vapour slug dynamics. Such break-up phenomena have been observed experimentally, in the past, within mini-channel branches of a hybrid thermosyphon/pulsating heat pipe device, under micro-gravity conditions. The simulation results identify three prevailing regimes. A "full break-up" regime, a "partial break-up" regime and a "no break-up" regime. It is characteristic that an entrainment of liquid droplets at the trailing edge of the vapour slugs, is responsible for their subsequent "full break-up", into a leading and a trailing bubble in each case, as it is identified from the numerical simulations. Moreover, it is quite interesting that the value of the AHF, does not
seem to influence the resulting break-up regime and its main characteristics.