Bubble column fluid dynamics: a multi-scale perspective
The Clean Energy Processes lab hosts a seminar from Dr Giorgio Besagni of Ricerca sul Sistema Energetico in Milan.
Abstract
Bubble columns are widely used as contacting devices and multiphase reactors. Their baseline layout consists of a vessel where the gas phase is introduced into a stagnant liquid phase in the form of “dispersed bubbles” or “coalescence-induced structures”. Even in the baseline layout, the coupling between the phases gives rise to rich, fascinating and mysterious fluid dynamics phenomena.
Since the pioneering work in the 80s, it is recognized that the “global-scale” is imposed by the “local-scale” and that the coupling between the two scales emerges in the flow regimes. In particular, the “bubble-scale” (i.e., the bubble motion) influences the medium-scale (i.e., turbulent eddies that transport the dispersed phase) and the large-scale (i.e., circulation cells and central plume oscillations) circulation, which characterize the “reactor-scale”.
Unfortunately, a precise and analytical description of the connections between the “local-scale” parameters as well as their upscaling towards the “reactor-scale”, in the different flow regimes, is elusive to date. The common approach is to study separately the different scales and subsequently consider the flow regimes as outcome of the operating conditions, with no a precise interpretation of the underlying physics.
In this lecture, starting from the comprehensive dataset gathered in the last years of research, a multi-scale perspective is proposed.
Biography
Dr. Giorgio Besagni obtained a M.S. degree (cum laude, 2012), in energy engineering, and a Ph.D (cum laude, 2016), in Energy and Nuclear Science and Technology, at Politecnico di Milano. After his post-doctoral activities he moved in the innovation-centre of a commercial-refrigeration company where he studied, experimentally and numerically, innovative refrigeration systems.
Since July 2017 he has been a Researcher at Ricerca sul Sistema Energetico, a publicly-controlled research center focused on national strategic projects. In April 2018, he obtained the Associate Professor Qualification in Technical Physics and Nuclear Engineering. During his Ph.D, Post-Doctoral and Reseracher activities he was teaching assistance at Politecnico di Milano, he spent guest stays at HZDR (2015) and at TU Eindhoven (2019), he collaborated with Eni Spa and he was involved in different nationally-founded projects.
He is author of more than 70 publications among international journals, book chapters and conference proceedings, focusing on (i) renewable energy-based technologies (i.e., ejector systems, multi-source heat pumps, PCM storage systems), (ii) experimental and numerical investigations of multiphase flows, (iii) multi-scale modeling of the residential sector. He is associate editor for Applied Thermal Engineering and Journal of Cleaner Production, International Journal of Energy and Environmental Engineering, and Energy, Ecology and Environment. He is on the editorial board of Renewable Energy and ENERGY Journals, assistant editor of Renewables: Wind, Water, and Solar.