CHARACTERIZATION OF INTERFACIAL STRUCTURE IN PEFCS: WATER STORAGE AND CONTACT RESISTANCE MODEL
Open Access
- Author:
- Swamy, Tushar
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 09, 2010
- Committee Members:
- Clinton Matthew Mench, Thesis Advisor/Co-Advisor
Matthew M Mench, Thesis Advisor/Co-Advisor
Dr Emin C Kumbur, Thesis Advisor/Co-Advisor - Keywords:
- Micro Porous Layer
Interface
Polymer Electrolyte Fuel Cell
Catalyst Layer
Water Management - Abstract:
- In this work, an analytical model of the micro porous layer (MPL) and the catalyst layer (CL) interface under elastic compression is developed to investigate the effects of the MPL|CL interfacial morphology on the ohmic and mass transport losses at the MPL|CL interface in a polymer electrolyte fuel cell (PEFC). The model utilizes experimentally measured surface profile data as input. Results indicate that the uncompressed surface morphology of mating materials, elasticity of PEFC components and local compression pressure are the key parameters that influence the characteristics of the MPL and CL contact. The model predicts that a 50% drop in the MPL and CL surface roughness may result in nearly a 40% drop in the MPL|CL contact resistance. The model also shows that the void space along the MPL|CL interface can potentially store significant amount of liquid water (0.9 to 3.1 mg/cm2), which could result in a performance loss and reduced durability. A 50% drop in the MPL and CL surface roughness is expected to yield nearly a 50% drop in the water storage capacity of the MPL|CL interface. The results of this work provide key insights that enhance understanding regarding the complex relation between MPL|CL interfacial structure and cell performance. Additionally, an upgraded (fractal) model is formulated to simulate the bi-polar plate (BP)| diffusion media (DM) interface. The fractal model can potentially provide a better estimate of the aforementioned results when applied to the MPL|CL interface. Either model is capable of digitally reconstructing the MPL|CL interfacial morphology via control volume allocation, which can be incorporated into a macroscopic fuel cell model to facilitate a more accurate prediction of PEFC performance.