Speaker

Dr. Nicolò Varallo 
Postdoctoral researcher, Department of Energy, Politecnico di Milano, Italy

Title 

Experimental and numerical characterization of multiphase flows for CO₂ capture in bubble columns: from local dynamics to global flow behaviour

Abstract

With increasing atmospheric CO₂ concentrations driving climate change, efficient carbon capture technologies are receiving growing attention. Ionic liquids have emerged as attractive solvents for CO₂ capture due to their negligible vapor pressure, high thermal stability, and high CO₂ solubility. Bubble columns are particularly suitable gas–liquid contactors for these applications because they provide efficient gas–liquid contact, enhancing CO₂ absorption into ionic liquid solvents. However, bubble column fluid dynamics is inherently characterized by complex multiscale phenomena that are not yet fully understood. A deeper understanding of these phenomena across scales is essential for the rational design and optimization of next-generation CO₂ capture technologies. Experimental investigations alone are often insufficient to study industrial-scale bubble columns due to their large size and complex operating conditions. Consequently, numerical models have become essential tools for reactor design and scale-up. However, their predictive capability relies on closure relations and model parameters that must be developed and validated using experimental data. Therefore, a combined experimental and numerical approach is crucial for the reliable prediction of bubble column performance.

Short bio 

Nicolò Varallo is a postdoctoral researcher at the Department of Energy of Politecnico di Milano. He received his M.Sc. in Energy Engineering in 2022 and completed his Ph.D. in Energy and Nuclear Science and Technology in 2026. His research focuses on multiphase flows, combining experimental and numerical approaches. His work includes the characterization of bubble columns, mass transfer in CO₂–ionic liquid systems for carbon capture applications, and CFD modeling of gas–liquid reactors. He has gained international research experience at the Helmholtz-Zentrum Dresden-Rossendorf (Germany), where he contributed to the development and validation of morphology-adaptive CFD models for complex multiphase flows, and at IFP Energies Nouvelles (France), where he worked on CFD simulations of industrial-scale bubble columns. His research interests include multiphase fluid dynamics, mass transfer, carbon capture technologies, and the development of modelling tools for energy and chemical engineering applications. In addition to his research activities, he has served as a Teaching Assistant in Thermodynamics at Politecnico di Milano.