Colloquium: Dr. Yun Wang
Dynamic Modeling of Polymer Electrolyte Membrane Fuel Cells
Dr. Yun Wang
Dept. of Mechanical and Aerospace Engineering
University of California, Irvine
Polymer electrolyte membrane (PEM) fuel cell has been widely regarded as a potential power source for portable and mobile applications due to its noteworthy features of high efficiency and zero emission. During operation, hydrogen and air are fed into anode and cathode gas channels, respectively, and distributed over the porous electrodes. Reactant molecules transport to the catalyst sites via the pore passage of diffusion media. Hydrogen dissociation occurs at the TPB (triple phase boundary) of the anode catalyst layer and produces protons and electrons which travel, via the ion-conductive membrane and external circuit respectively, to the cathode to electrochemically react with oxygen molecules.
In this talk, several aspects of fundamental modeling of electrochemical and transport processes occurring in PEM fuel cells will be discussed. The focus will be placed on modeling the processes vital to fuel cell performance, such as transport of electrons, protons, heat, and species (oxygen, water, and hydrogen), which take place in various regions of fuel cells, e.g. proton transport occurs in the membrane and porous catalyst layers. Detail of fuel cell transients and associated various dynamic processes, such as electrochemical double-layer discharging/charging, species transport, heat transfer, and membrane water uptake will be introduced in detail. Efforts are also made to explore the complex dynamic response of fuel cells that involves various time scales and transient operation relevant to severe degradation of MEAs, such as fuel/oxidant starvation, membrane dryout, electrode flooding, and voltage reversal. In addition, physical phenomena occurring during cold-start will be investigated and the key parameters governing fuel cell subzero start-up will be presented.
Yun Wang obtained his B.S. and M.S. degrees in China (Peking University, Beijing) in 1998 and 2001, respectively. He then went to the Pennsylvania State University where he received his Ph.D degree in Mechanical Engineering in 2006. Right after obtaining his PhD, Wang joined the MAE (Mechanical and Aerospace Engineering) faculty at the University of California, Irvine in the summer of 2006. Prior to arriving at UC Irvine, Wang conducted research at the Electrochemical Engine Center at the Pennsylvania State University, and at the State Key Laboratory for Turbulence Research in China. Wang's research interests include electrochemical energy systems, such as fuel cells and batteries, and internal combustion engines, specializing in multiphase multi-component transport, heat transfer, electrochemistry, microfluidics, parallel computations, and turbulent combustion.