A Microstructure-Driven Approach to Characterize Transport Phenomena in Porous Media of Polymer Electrolyte Fuel Cells

The polymer electrolyte fuel cell (PEFC) is an electrochemical device which holds great promise as an alternative power source for use in a wide range of applications. However, improvements in cell performance are necessary for the commercialization of PEFCs. Recently, significant research effort has been placed on understanding the influence of the internal structure (i.e., microstructure) of fuel cell materials on the transport of water and reactant gases in PEFC systems. One component of interest is the porous diffusion media (DM), which has been shown to be vital for achieving necessary water management to maintain efficient fuel cell operation. However, current modeling efforts rely primarily on bulk correlations or idealized/randomly selected structures for these porous materials, which may misrepresent the true morphology of the DM and potentially fail to accurately capture the related effects on transport within this component. The objective of this dissertation work is to establish a framework which combines recent advances in 3-D microstructure quantification and pore-scale analysis to evaluate the structure and related transport characteristics of fuel cell DM. The presented framework includes the following features: i) the microstructures of the materials of interest are quantified rigorously in 3-D; ii) small representative volume elements (RVEs) are selected which capture the important features of the measured microstructure datasets to within high accuracy, for reliable and computationally efficient modeling of transport behavior; and iii) a suite of microstructure analysis tools is developed to determine several difficult-to-measure key structure-related transport properties. Using this approach, an in-depth understanding of the structure-related transport characteristics of a fuel cell DM sample is achieved.Ph.D., Mechanical Engineering and Mechanics -- Drexel University, 202