Cain Department of Chemical Engineering SEMINAR
“Transport Processes in Energy Conversion and Storage Devices:
X-ray Computed Tomography Approach”
Iryna V. Zenyuk
Department of Mechanical Engineering, Tufts University
200 Boston Ave. 2600, Medford, MA 02155, USA
Understanding transport processes in thin porous carbon materials is critical for electrochemical energy applications. However, tools that are designed for characterization of porous media on a large scale are not always applicable for thin (< 500 um) layers. Moreover, it is essential to bridge nano- and micro-scale transport processes, as fine nano-structures of carbon materials are desirable for high surface area and the features of a larger size are needed for high hydraulic permeation. To characterize transport on nano and micro-scales synchrotron X-ray computed tomography (CT) is well-fit due to its fast, non-intrusive measurements that allows quantification of morphological properties of porous media.
For polymer-electrolyte fuel cells (PEFCs) and anion exchange membrane fuel cells (AEMFCs) effective water management remains a hurdle, especially at lower operating temperatures. During start-up and operation liquid water formed as a byproduct of electrochemical reaction can block gas (reactant) delivery to a catalyst, resulting in flooding, mass-transport losses, and low cell power densities. Using synchrotron X-ray CT we have previously shown morphology and transport dependencies on material structure, compression and chemical composition. These ex- and in-situ studies are useful and shed light on an isolated transport phenomena. Continuum, pore-network and direct meshing models are used to explain the observed phenomena and to guide the fuel cells components design. Addressing and understanding water transport issues, however, is made possible by introducing the capabilities for operando X-ray CT. This presentation focuses on operando techniques for understanding water management in PEFCs and AEMFCs and examples of various operating conditions will be presented. Furthermore, two more applications of X-ray CT will be presented: batteries characterization and water transport in electrolyzers.
Friday October 13, 2017
1221 Patrick Taylor Hall
Coffee will be served at 1:30pm