Development of a variable-porosity metal-foam model for the next fuel cells flow-distributors

Enhancing volumetric power density (VPD), for fuel cell vehicles or combined heat and power systems, has always been a determined desired goal. To give an idea, the present VPD = 5.5 kW L-1 for 2020 Toyota-MIRAI, is targeted to 9.0 kW L-1 by 2040 by Japan. The present research proposes that the conventional GDL + ribbed/channel setup, e.g. in parallel-serpentine (PS) bipolar-plates (BPPs), to be replaced by functionally graded porous material (FGPM) or variable-porosity metal-foam (VPMF) flow distributors. For the present comparative study, at cell current density 1 A/cm(2), the fuel cell with FGPM flow-distributor provides over 80% enhancements in VPD, w.r.t. the PS cases. The enhancement is even higher at higher currents densities. The present manuscript contains three parts: (1) development of a novel protocol to design FGPMs for flow distributors. Through several examples, it has been shown that the designed FGPM reduces the flow resistances towards, and from-the concave corner areas. Hence, flow can reach-to, and leave-from these corners effectively; (2) application of the noted FGPM protocol to fuel cells, in which a three-dimensional and two-phase computational fluid dynamics model has been used to compare the performances of the FGPM flow-distributors with conventional channel/ribbed PS cases; and finally (3) guidelines are proposed on how to manufacture the FGPM flow-distributor. The present model opens a new era in designing flow-distributors for FCs and can be applied to both graphite and metallic BPPs. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study proposes using functionally graded porous material (FGPM) or variable-porosity metal-foam (VPMF) flow distributors to enhance the volumetric power density (VPD) of fuel cells. Comparative studies show that fuel cells with FGPM flow distributors provide over 80% enhancements in VPD compared to conventional setups. This research opens a new era in flow distributor design for fuel cells and provides important guidelines for manufacturing FGPM flow distributors.