Mechanical Engineering Ph.D. Dissertation

Abstract

As industrialization and fossil fuels have dominated the power sector for decades, electricity generation is one of the most significant anthropogenic carbon dioxide (CO2) releasing activities. Nonetheless, fossil fuel power plants constitute CO2-emitting infrastructure with high socio-technical inertia and, as of today, no carbon-free alternative stands out. Therefore, a shift will unlikely be immediate and abrupt: long-distance net-zero targets must be coupled with rapid mitigation of the environmental impact. Hence the present work. Finite volume computational fluid dynamics (CFD), in the nuance of OpenFOAM, was chosen as Swiss knife to secure short and medium-distance targets and to bridge between fundamentals research and industrial applications. In detail, the present thesis aims to describe turbulent and multiphase flow for sustainable energy applications.

The first part of the thesis deals with fundamental aspects regarding current technologies related to power generation. They are in order: the nature of the high turbulence level in a well-studied premixed burner (HiPilot), the break up of a viscous jet in a gasifier and the liquid injection in a compression ignition engine. Specifically, large eddie simulation could isolate scale separation and intermittency in the HiPilot burner; adaptive grid refinement and dynamic load balance allowed us to replicate the dynamics of long viscous ligament and the dominance of the turbulent boundary layer in a high Reynolds liquid jet break-up.

The second part of the thesis focuses on novel and promising technologies, such as Ultrasonically Induced Cavitation (UIC) for oil conversion and Cryogenic Carbon Capture (CCC) for carbon dioxide removal. Whether -currently- no alternative is the silver bullet, the lack in fully comprehending the phenomena hides potential to approach the net-zero target. Therefore, a step further is made in this work, successfully predicting bubbles dynamics and frost formation in non-trivial configuration.

Bio

Alberto is a Ph.D. candidate in the Mechanical Engineering program, in PSE division,  in Professor Im’s group. He obtained his B.Sc. and M.Sc. degrees in Chemical Engineering at Politecnico di Milano. He is passionate about modelling multiphase flows and world energy challenges.