The effect of pulsating pressure on the performance of a PEM fuel cell with a wavy cathode surface

Abstract

In the context of attempts to improve the performance of Proton Exchange Membrane (PEM) fuel cells with a heterogeneous porous gas diffusion layer (GDL) consisting of carbon paper, we investigated whether - and to which degree - pulsating the pressure in a single waveform cathode channel affects the flow field in the channel and the performance of the fuel cell. In this 2-D study, the GDL was modeled by a stochastic arrangement of circular solid obstacles the macroscopic transport properties of which, such as permeability and tortuosity, were numerically simulated and found to compare favorably with experimental data. The focus of this paper is on the effects of varying amplitude and frequency of the pressure pulsations on cell performance. The results obtained show that a pulsating pressure enhances the convective species transport to the reaction sites and thereby increases cell performance. We found that in a waveform channel a pulsatile pressure with an amplitude as high as 0.7 times the pressure drop over the cathode channel improves the fuel cell performance by around 7%, while the effect of pulsation frequency on output power is marginally small only.