An Electrochemical Performance Characterization Method for Comparing PEFCs of Varying Channel Dimensions

Abstract

A method which allows for the comparison of polymer electrolyte fuel cell (PEFC) bipolar plates (BPs) with various channel dimensions is outlined here. It is applied to data from an experiment with different channel and land width and channel depth combinations for interdigitated and parallel designs. Channel and land width and channel depth varied from 0.25 mm to 1 mm on six different BP designs, and two stoichiometries were tested. Each condition was performed three times for repeatability. The method calculates the performance of each condition after accounting for reversible voltage and overpotential changes due to varying pressure and after eliminating ohmic resistance as a variable. In these data, the interdigitated flow field outperformed the parallel flow field. Designs are compared using the BP permeability as a benchmark metric. The method then calculates the area-specific ohmic resistance (ASR) of the cell. It was difficult to draw hard conclusions about changes in the ASR between flow field designs, but there may be more consistent liquid water removal from the gas diffusion layer (GDL) with smaller channel dimensions. It was found that concentration losses seem to be primarily a result of channel width, rather than channel depth.

Liquid water transport and management for fuel cells

“…Channel geometry, including land width, channel width, and channel depth, significantly influences two-phase flow behavior and impacts PEMFC performance. Extensive in-situ experimental testing over a wide range of channel dimension combinations with depths and widths ranging from 0.25 mm to 1 mm has shown that optimal performance, accounting for pumping power at higher pressures, is achieved at a hydraulic diameter of ~0.4 mm for certain ranges of stoichiometry (59,60). Other results focusing on channel and rib widths (in parallel designs) have…”