Time-Resolved Water Measurement in a PEM Fuel Cell Using High-Resolution Neutron Imaging Technique

Author(s):  
P. Quan ◽  
M.-C. Lai ◽  
D. S. Hussey ◽  
D. L. Jacobson ◽  
A. Kumar ◽  
...  

The dynamic process of water transport along the through-plane direction in the membrane electrode assembly of a proton exchange membrane fuel cell was investigated using the high-resolution neutron imaging. Four different membrane/gas diffusion layer or membrane/gas diffusion electrode assemblies were tested by measuring the through-plane water thickness profiles. The results indicate that proper design and assembly of the test fixture are critical for accurate water measurement; the accumulation speed of liquid water inside an assembly varies with time; the ionomer in catalyst layers could facilitate water management in the membrane; the time constants for wetting and drying processes are functions of gas diffusion layer thickness, inlet flow rate, and gas dew point; and the time constant for the wetting process is about 1.4 times longer than the corresponding drying process.

Author(s):  
Angelo Esposito ◽  
Cesare Pianese ◽  
Yann G. Guezennec

In this work, an accurate and computationally fast model for liquid water transport within a proton exchange membrane fuel cell (PEMFC) electrode is developed by lumping the space-dependence of the relevant variables. Capillarity is considered as the main transport mechanism within the gas diffusion layer (GDL). The novelty of the model lies in the simulation of the water transport at the interface between gas diffusion layer and gas flow channel (GFC). This is achieved with a phenomenological description of the process that allows its simulation with relative simplicity. Moreover, a detailed two-dimensional visualization of such interface is achieved via geometric simulation of water droplets formation, growth, coalescence and detachment on the surface of the GDL. The accomplishment of reduced computational time and good accuracy makes the model suitable for control strategy implementation to ensure PEM fuel cells operation within optimal electrode water content. Furthermore, the model is useful for optimization analysis oriented to both PEMFC design and balance of plant.


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