UBC Theses and Dissertations
New methodologies to characterize PEMFC performance losses Flick, Sarah
As fuel cells reach the early stages of commercialization, the need for effective research methods and efficient characterization tools is increasing. Industrial demands allowing for serial production require methods for standardized testing and efficient quality control while developing new materials and production methods. This thesis work presents two methodologies: Design of Experiments (DoE) applied to Polymer Electrolyte Membrane Fuel Cells (PEMFCs) to analyze for sparsity of effects and performance mapping; and a systematical Voltage Loss Breakdown (VLB) method based on experimental polarization featuring anodic contributions. Both concepts were validates and the effects of commercial porous transport layer (PTL) material on the fuel cell’s voltage under galvanostatic conditions were investigated. The results of this work demonstrate the use of DoE to assess the differences and parameter dependencies of different materials in the PTL of PEMFC. Split-plot and general blocked design models were used to analyze the voltage and pressure drop of PEMFC at different current densities of 1.0 A cm^-², 1.4 A cm^-² and 1.6 A cm^-². The empirical models show good fit and prove that these methodologies based on experimental designs can be useful to predict and analyze fuel cell performance within this design space. The use of designed experiments allows a scientifically objective analysis of the data compared to one-factor-at-a-time (OFAT) testing while reducing the overall required test runs. Our results show, that this analysis can capture and model the effects of PTL materials and operating conditions as statistically and physically significant. The VLB method developed in this work systematically analyzes the different dominant loss contributions and shows the relevance of the anode under varying operating conditions. A reference electrode system was designed and validated in order to measure the anodic and cathodic contributions to the cell’s polarization separately. A mathematical approach was developed to break down the polarization curve into the individual contributing losses, distinguishing between anode and cathode and the individual kinetic, ohmic and mass-transport overpotentials. Based on this study it can be concluded, that a micro-porous layer (MPL) leads to reduced mass-transport losses inside the cathode electrode and decreases the ohmic losses.
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Attribution-NonCommercial-NoDerivs 2.5 Canada