Abstract: Hydrogen is an energy carrier that, if produced through decarbonized methods, can serve as a key solution for reducing emissions in hard-to-decarbonize industries such as long-haul trucking, cement and steel production, and aviation. Proton Exchange Membrane (PEM) fuel cells are a class of energy conversion devices that use hydrogen as fuel. Their byproducts are water and heat. Effective water management is critical for achieving durable and reliable PEM fuel cell performance. While part of the produced water helps maintain membrane hydration, excess water must be efficiently removed from the cell. The transport phenomena associated with water removal are complex and span multiple length scales ranging from a few micrometers in the pores of the porous layers to several hundred micrometers (or even millimeters, depending on design) across the flow channels. A common feature across these scales is the dominant role of capillary effects, arising from surface tension forces, which significantly influence mass and momentum transport.This talk summarizes over a decade of research on transport phenomena in PEM fuel cells, with a primary focus on liquid water transport in different components of the cell. Particular emphasis will be placed on two-phase flow in flow channels and novel, yet simple, techniques for eliminating liquid water buildup. The presentation highlights outcomes from both experimental and theoretical investigations and briefly exemplifies how machine learning could help resolve some decades-long questions in two-phase flow pressure drop modeling.Bio: Mehdi Mortazavi is a faculty member in the Department of Mechanical and Materials Engineering at WPI. His research focuses on thermo-fluids systems, where he combines experimental and theoretical approaches to uncover the physics of transport phenomena in multiphase flows. He deeply values the process of discovery through collaboration with students. His current projects involve droplet dynamics, bubble actuation for enhanced hydrogen production, and workforce development in hydrogen energy systems. He earned his PhD in Mechanical Engineering from Michigan Technological University in 2014 and spent two years in the HVAC industry before joining Western New England University for his first academic appointment in 2016. In 2023, he joined WPI to expand his research activities through access to advanced infrastructure and graduate student mentorship.