National Center for Hydrogen Research

Faculty Projects

Silicon based hydrogen sensors

Team Members:

  • Chris Lowrie
  • Charudatta Mandhare
  • Mohammed Nazer
  • Kanthi Yalamanchili

Project Information:

 

Overview of Primary Project

Improvement of current silicon based hydrogen sensors using standard CMOS processing techniques

PEM Fuel Cell Flow Modeling

Team Members:

  • Manish Jindal
  • Christopher Jojola
  • Crisen McKenzie

Project Information:

Dr, Archambault's research interests primarily lie in the field of propulsion and combustion, with special emphasis on rocket engine applications. Specific areas of interest inclufe fuel injector modeling (gas and liquid), injector/chamber compatibility, multi-phase fluid flow, spray and particulate dynamics, combustion efficiency, rocket engine performance analysis, electric and laser propulsion, and solid rocket motors. Dr. Archambault's research is currently focused on fuel cell efficiency.

Mathematical Model of a Polymer Electrolyte Membrane Fuel Cell

Project Information:

 

Team Members:

Graduate Student Katie Pentas investigates the effect of gas diffusion layer fiber size distribution and diffusion regime on the PEM Fuel Cell performance.

Overview of Primary Project:

A mathematical model for a polymer electrolyte membrane fuel cell (PEMFC) is being developed, accounting for viscous flow, heat and mass transfer and electrochemical reactions within the gas channels, gas diffusion layers, the anode and cathode catalyst layers and the polymer electrolyte membrane. Special emphasis is placed on investigating the effect of the gas diffusion layer transport properties on the fuel cell performance, recognized as a “key need in fuel cell modeling” in the 2004 Fuel Cell Workshop at the University of Florida, sponsored in part by the NASA Glenn Research Center.

Description of Project:

Synopsis of Year-1 Project Outcome:
The effective diffusivity and viscous permeability of the anode and cathode Gas Diffusion Layers (GDL) of a PEM fuel cell are key parameters that determine the rate of mass transport and viscous flow of hydrogen, oxygen, and water vapor through the cell, thereby influencing the supply of reactants to the catalyst layers and the overall performance of the fuel cell. However, a review of recent literature shows that these critical parameters have not received the deserved attention in most fuel cell modeling studies. Experimentally supported numerical predictions for these properties are presented and used in our two-dimensional PEMFC mathematical model. Our results suggest that the GDL permeability values routinely used in the literature may lead to significant errors in the fuel cell modeling predictions, overestimating the current and power density by 100% or more. Additional deviations up to 15% are due to the commonly used effective diffusivity approximations.

High feed pressure and humidification levels were found to enhance the fuel cell performance considerably.  The humidification effect is due primarily to the resulting high membrane hydration and ionic conductivity, while the pressure effect is caused mainly by the increased reactant concentrations and the resulting high rates of electrochemical reactions in the catalyst layers.

Results presented at the 2006 AIChE Spring National Meeting.  Paper and presentation attached. 

Synopsis of Year-2 Project Outcome:
The PEMFC mathematical model developed in Year 1 was modified to account for anisotropic transport through the Gas Diffusion Layers (GDL), then used to investigate the effect of the GDL electrical conductivity on the fuel cell performance.  The model predicts that the fuel cell current and power density may be over-estimated or under-estimated by up to 15% when popular literature approximations or assumptions are used for the electrical conductivity, or when the anisotropic nature of the gas diffusion layers is overlooked.  Energy balance equations have been developed for all seven zones of the fuel cell, and are currently being incorporated into our model.  Random-walk simulation algorithms were developed for the computation of the effective diffusivity and thermal and electrical conductivity of alternative PEMFC GDL materials, namely bimodal fiber structures reported recently to improve fuel cell performance.  Our simulation results suggest a considerable effect of the bimodal fiber size distribution of such structures on their transport characteristics at low porosities.  These results will be incorporated into our PEMFC model to investigate the effect of using such media as gas diffusion layers in the fuel cell.

Results presented at the 2006 NCHR Review meeting. 

Results to be presented at the 2007 International Conference on Porous Media and its Applications in Science, Engineering, and Industry, Kauai, Hawaii, June 2007.

Timeline for Project

The project originated in 2004 and is currently in its 3rd year