CHBE Seminar Series: Yossef A. Elabd
Tuesday, February 8, 2011
11:00 a.m.-12:15 p.m.
Room 2110 Chemical and Nuclear Engineering Bldg.
Professor Srinivasa Raghavan
Transport Phenomena in Polymer Electrolyte Membrane Fuel Cells
Yossef A. Elabd
Department of Chemical and Biological Engineering
Fuel cells offer an innovative alternative to current energy sources with higher power densities and efficiencies at a lower environmental cost. Specifically, polymer electrolyte membrane (PEM) fuel cells can produce energy for a variety of applications ranging from portable electronics (with methanol or ethanol fuel) to transportation (with hydrogen fuel). The critically important PEM serves as an electrolyte, exchanging protons from the anode to the cathode enabling the direct conversion of chemical energy to electrical energy. However, the less than ideal performance of typical PEMs contributes to significant power losses and low efficiencies due to both low proton conductivities at higher temperatures (hydrogen fuel cells) and high fuel crossover rates (methanol fuel cells). For both issues, the transport of molecules and ions in the PEM plays a critical role in the performance of a fuel cell.
Our laboratory has designed a number of new polymer electrolyte membranes. Our approach has been motivated by developing a more in depth understanding of transport phenomena in PEMs. In addition to using numerous conventional transport measurement techniques, we have utilized a new technique to this field, in situ time-resolved Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy, to investigate transport in PEMs on a molecular scale. These results provide real-time dynamic information regarding multicomponent diffusion and the diffusion of different states of water and solvated ions in the PEM. In conjunction with new transport models, these results provide insights into the fundamental mechanisms behind the critical issues in fuel cells and have guided our development of new PEMs with improved fuel cell performance.