An Alternative Energy Technology Topic Advisors: Dr. E Caglan Kumbur & Dr. Minjun Kim Peter Carrion Dean Galarowicz Karl Gutwein-Guenther Anthony Salvatore Trevor Smith

Overview Introduction Fuel Cell Background Problem Statement Method of Solution Task 1: FIB/SEM Imaging of MPL Task 2: Resin Impregnation of GDL Task 3: MicroCT Imaging of GDL Summary of Results FIB/SEM Imaging of MPL MicroCT Imaging of GDL Other Considerations Environmental and Societal Impacts Economic Analysis Project Management and Timeline Questions

Electrochemical devices – convert chemical energy directly to electrical energy Used for power generation Stationary Mobile Different Types Alkaline Phosphoric Acid Solid Oxide Molten Carbonate Polymer Electrolyte (PEFC) Introduction Fuel Cells

Gas Diffusion Layer (GDL) Fuel Oxidizer Exhaust GDL MPL CL Structure: PTFE coated carbon fibers. (5- 30% by wt) Weave and Paper Conductive ( S/cm) Function: Reactant transport to CL Thermal insulation for CL Mechanical support for electrolyte/CL Properties: Porosity: Pore Size: μm Thickness: μm (BAZYLAK – Water Visualization in Fuel Cells – A Review) Cloth Paper Introduction Fuel Cell Components

Microporous Layer (MPL) Fuel Oxidizer Exhaust GDL MPL CL Structure: Carbon PTFE slurry Conductive Function: Serves as moisture barrier between CL and the GDL Improves conductivity Highly hydrophobic Properties: Pore Size: μm Thickness: μm 5-20% PTFE content SEM image showing profile of MPL (Kumbur) Introduction Fuel Cell Components

Figure 1 Polarization Curve for PEM fuel cell with and without flooding losses (Mench 2008) Introduction Polarization Curve Voltage Current

Problem Statement The exact water transport mechanism within the GDL and MPL is not fully understood. There are prohibitive limitations to real time visualization of these components during steady-state operation.

Method of Solution Task 1: FIB/SEM Imaging of MPL

Selection of resin: Procedure 1: Large tube encompassing entire sample Procedure 2: Small tube centralized injection Procedure 3: Heated flexible pressure vessel Method of Solution Task 2: Resin Impregnation of GDL

Quantifying resin Calculations: Resin ρ (g/mm^3) GDL ρ (g/mm^3) MPL ρ (g/mm^3) Sample Volume = Length * Height * Thickness Sample wo/ MPL = sample volume *.86 MPL Weight = (sample volume-sample wo/ MPL)*MPL ρ GDL Weight = weight-MPL Weight Resin Surface V = Length * Height * (thickness after resin-thickness before resin) Resin Volume = ((weight after resin-weight before resin)/Resin ρ)-resin surface volume Void Volume = sample wo/MPL*.8 % void filled = resin volume/void volume Method of Solution Task 2: Resin Impregnation of GDL Large Tube Large Tube w/ heated resin (30˚c) Large tube w/ heated resin (89.4) Heated pressure chamber Trial 1Trial 2Trial 3Trial 5Trial 4Trial %54.8%60.6%67.2%64.4%67.3%

The plan: Selection of the wetting fluid The wetting fluid chosen will have similar material properties to water A small specimen of carbon paper will be impregnated with the selected wetting fluid Use of MicroCT to provide a full 3D internal structure and composition of specimens Method of Solution Task 3: MicroCT Imaging of GDL

Summary of Results FIB/SEM Imaging of MPL

Summary of Results MicroCT Imaging of GDL

Improvements in fuel cell efficiency could lead to acceptance of fuel cell technology in automobiles Reduction of greenhouse gases Increase of on-site or local energy production Building a hydrogen economy to support fuel cell demand ElectraGen-System2.asp cleDetails.php?articleID=300 Other Considerations Societal and Environmental Impact

Increased durability and reliability Enable PEFC use in vehicles Greater efficiency than ICE, lower cost of energy vs useful work Minimum Cost Resource CostTimeTotal Cost FIB/SEM $85/hr 6 hrs $ MicroCT - Imaging $82.90/use 4 hrs $82.90 MicroCT - Reconstruction $ hrs $16.58 Resin $50.00 N/A $50.00 Hard Drive $ N/A $ Total $ Additional Costs MicroCT Total $ Times$ Misc Expenses $ Total $1, Other Considerations Economic Analysis

Other Considerations Time Line