Scaling factors for channel width variations in tree-like flow field patterns for polymer electrolyte membrane fuel cells - An experimental study

Marco Sauermoser,Bruno G Pollet,Natalya Kizilova,Signe Kjelstrup

doi:10.1016/j.ijhydene.2021.03.102

Abstract

To have a uniform distribution of reactants is an advantage to a fuel cell. We report results for such a distributor with tree-like flow field plates (FFP). Numerical simulations have shown that the width scaling parameters of tree-like patterns in FFPs used in polymer electrolyte membrane fuel cells (PEMFC) reduces the viscous dissipation in the channels. In this study, experimental investigations were conducted on a 2-layer FF plate possessing a tree-like FF pattern which was CNC milled on high-quality graphite. Three FF designs of different width scaling parameters were employed. I–V curves, power curves and impedance spectra were generated at 70%, 60% and 50% relative humidity (25 cm2 active area), and compared to those obtained from a conventional 1-channel serpentine FF. It was found that the FF design, with a width scaling factor of 0.917 in the inlet and 0.925 in the outlet pattern, exhibited the best peak power out of the three designs (only 11% - 0.08 W/cm2 lower than reference serpentine FF). Results showed that a reduction of the viscous dissipation in the flow pattern was not directly linked to a PEMFC performance increase. It was found that water accumulation, together with a slight increase in single PEMFC resistance, were the main reasons for the reduced power density. As further improvements, a reduction of the number of branching generation levels and width scaling factor were recommended.

Highlights

Polymer electrolyte membrane fuel cell (PEMFC) systems already contribute to the rapidly growing transition from a fossil fuel-based to a green and renewable energy-based society
A PEMFC stack consists of a series of single cells in which membrane electrode assemblies (MEA) are sandwiched between flow field plates or bipolar plates
The results of the three tests carried out on the four flow field plates setups will be reported in the same order as described above

Summary

Introduction

Polymer electrolyte membrane fuel cell (PEMFC) systems already contribute to the rapidly growing transition from a fossil fuel-based to a green and renewable energy-based society. The increase in Rct reported for Design 1 to 3 could be indicative of water flooding restricting the reactant flow to the catalyst layer, according to Fouquet et al [26] and agreeing with the reduction in PEMFC performance compared to the serpentine pattern.

Objectives

Results

Conclusion