Model of PEM Fuel Cell Cathode Sarah Hipple

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Model of PEM Fuel Cell Cathode Sarah Hipple EGEE 520 May 3, 2007

Model of PEM Fuel Cell Cathode Sarah Hipple EGEE 520 May 3, 2007

Introduction PEM Fuel Cell Structure Platinum Electrodes Very effective at splitting hydrogen at the

Introduction PEM Fuel Cell Structure Platinum Electrodes Very effective at splitting hydrogen at the anode Less effective at splitting oxygen at the cathode This Analysis: Focuses on transport of species through the Cathode Species Distribution Velocity of molecules

Governing Equations Darcy's Law Conservation of mass & momentum balance Equation: Maxwell-Stephan Equation Mass

Governing Equations Darcy's Law Conservation of mass & momentum balance Equation: Maxwell-Stephan Equation Mass Balance Equation: where and

Boundary Conditions (1) (2) (3)

Boundary Conditions (1) (2) (3)

Solution Parameters Basic Operating Conditions: T=80°C Atmospheric Pressure

Solution Parameters Basic Operating Conditions: T=80°C Atmospheric Pressure

Solution: Velocity:

Solution: Velocity:

Solution: Oxygen and Water Distribution From the left: • Graph of oxygen mass fraction

Solution: Oxygen and Water Distribution From the left: • Graph of oxygen mass fraction at 5 x values; • Image of Oxygen mass fraction distribution; • Image of water mass fraction distribution

Validation Comparison to work of Yi and Nguyen & He, Yi, and Nguyen On

Validation Comparison to work of Yi and Nguyen & He, Yi, and Nguyen On the left: Pressure On the right: Velocity Field

Parametric Study Oxygen Concentration at the Interface with the Polymer Electrolyte Membrane Air as

Parametric Study Oxygen Concentration at the Interface with the Polymer Electrolyte Membrane Air as the cathodic feed (left image) Pure oxygen as the cathodic feed (right image) Importance Drying out of the membrane (too much oxygen/air) Reduction of power output (too little oxygen/air) Carbon monoxide poisoning prevention

Conclusions This model agrees with other authors’ models This model can help determine species’

Conclusions This model agrees with other authors’ models This model can help determine species’ distributions and flow paths through the cathode in: The existing model A model with modified pressure, temperature, porosity, dimensions, or cathodic feed

Image Sources Aguirre, Lauren. (2005, July). Nova: science. NOW: How Fuel Cells Work: PBS.

Image Sources Aguirre, Lauren. (2005, July). Nova: science. NOW: How Fuel Cells Work: PBS. URL www. pbs. org/wgbh/nova/sciencenow/3210/01 -fcw. html (visited 2007, January 30) Yi, Jung Seok, & Nguyen, Trung Van. (1998, April). An along-thechannel model for proton exchange membrane fuel cells. Journal of The Electrochemical Society, 145 (4), 1149 -1159. He, Wensheng, Yi, Jung Seok, & Nguyen, Trung Van. (2000, October). Two-phase flow model of the cathode of PEM fuel cells using interdigitated flow fields. American Institute of Chemical Engineers. AICh. E Journal, 46 (10), 2053 -2064.