The effect of phase difference between adjacent channels of fluctuating air intake on the performance improvement of multi-channel fuel cells

Abstract

The concentration of reactants directly affects the electrochemical performance of fuel cells. This study aims to improve mass and heat transfer within the gas diffusion layer by introducing pressure fluctuations at the cathode inlet and enhancing lateral velocities under the rib region by setting phase differences between adjacent channels. A three-dimensional, two-phase, four-channel PEMFC model was established. The results indicate that when a 90-degree phase difference exists between adjacent channels, the max average current density increases by 6.7 % compared to that at steady state. The potential reason is that the phase difference creates a pressure gradient on both sides of the rib, promoting the conversion of internal energy to kinetic energy. Consequently, the peak pressure in GDL-rib region decreases to 1500 Pa, and the peak lateral velocity increases to 0.6 m/s. Lower fluctuation frequencies not only result in larger regions of high lateral velocity but also have longer velocity maintenance times, thereby facilitating material exchange in the deeper GDL-rib regions and significantly increasing the oxygen concentration. Additionally, the results show that increasing the amplitude of fluctuations helps enhance fuel cell performance but also significantly increases the pressure difference, thereby increasing parasitic power.