Performance analysis of a PEM fuel cell with indented flow channels under various operating conditions

There are situations where using indented flow channels can enhance the Performance of Polymer Electrolyte Membrane Fuel Cells (PEMFCs). The present article aims to introduce and assess a new parameter that has a crucial role in determining these situations. As a novelty, the influence of the binary mass diffusivity of the species on the performance gain caused by indented channels is investigated. A numerical analysis is carried out using an in-house finite volume code to simulate the cathode of a PEMFC with conventional and indented flow channels. An innovative implementation of the Mirroring Immersed Boundary (MIB) technique is employed to impose semi-circular cross-section dents on a fixed background Cartesian grid. The results demonstrate that the channel indentation boosts the cell performance just when the mass diffusion resistance towards the catalyst layer (CL) is high. That is, under high operating pressures, while the current density is also high. As an illustration of this point, under the operating pressure of 5 bar, channel indentation of the cathode side enhances the cell performance by 3.3%, whereas under the operating pressure of 1 bar, the indented bed not only does not improve the cell performance, but reduces it. The outcomes of the study highlight the role of the binary mass diffusivity coefficient of the species and show that the smaller the mass diffusivity coefficients, the more effective indented channels are in improving cell performance. Therefore, channel indentation on the anode side is not profitable since the mass diffusivity coefficient of hydrogen is typically large.

Automated summary

The use of indented flow channels can enhance the performance of Polymer Electrolyte Membrane Fuel Cells, especially when there is high mass diffusion resistance, operating pressures, and current densities. The study found that the binary mass diffusivity coefficient of the species plays a crucial role in determining the effectiveness of indented channels in improving cell performance.