University of Delaware Department of Mechanical Engineering Fuel Cell Research Laboratory



   
 
Water Management in PEM Fuel Cells
Dusan Spernjak, PhD student

Co-advisors:

Professor Suresh Advani
Professor Ajay K. Prasad

Humidification has to be carefully optimized in PEM fuel cells. Extremes in humidity levels at both the low end (membrane dehydration) and the high end (cathode flooding) of the range can seriously reduce PEMFC performance. Due to the conflicting requirements for a PEMFC operation, the region of suitable operating conditions is very narrow. The cell is usually operated at the flooding limit, and some areas of the catalyst layer can easily become flooded by condensed water. Since flooding has been identified as one of the main current-limiting processes, understanding and optimizing liquid water transport throughout the cell is critical to improving PEMFC performance. Moreover, flooding can also take place at lower current densities, if the gas flow rate and/or temperature (i.e. equilibrium vapor pressure) are low.

The gas diffusion layer (GDL) on the cathode side must remove product water from the catalyst layer while still maintaining sufficient membrane hydration. It is therefore vital to characterize the GDL material’s ability to reach a steady state for mass transport and hydration level of the polymer membrane after step changes in cell current draw. This is important in load-following applications, as well as during startup and shutdown. Further, insight into liquid water transport within the GDL pores and through the channels is needed to optimize the design parameters and prevent electrode flooding.

One of our research goals has been to examine the properties of the porous GDL media, and to evaluate their influence on the water and gas transport. Furter, we are studying the effect of the microporous layer (MPL) as well as the water dynamics in different flow field configurations. We have designed an operational transparent PEM fuel cell, which enables optical access to the flow field channels. We are therefore able to visually characterize flooding in a working fuel cell, while varying operating conditions, flow field design and GDL material properties. The ultimate goal is to improve the cell performance and durability through the efficient water management.

For more information, please visit Dusan Spernjak's personal webpage.

Operation Transparent Fuel Cell
Operational transparent PEM fuel cell.


Flow Visualization in and Operational PEM Fuel Cell
Flow visualization in an operational transparent PEM fuel cell.


Polarization Curve
Performance of the transparent cell with different GDL materials at same operating conditions.
Flow field visualization was performed simultaneously with the cell testing.

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Principal Investigators
Dr. Ajay Prasad
Dr. Suresh Advani
  126 Spencer Laboratory - Newark, DE - 19716 - phone: 302-831-2421
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