Analysis of mass and thermal transport characteristics in a novel honeycomb stack layout of high-performance proton exchange membrane fuel cells

Abstract

To rationalize the layout of the fuel cell (FC) power system within the limited on-board space and enhance its volumetric power density, a novel honeycomb layout of the stack is designed in this study. This layout connects the individual FCs in the form of sidewalls, which reduces the longitudinal size by 59.5 % compared with the conventional stack with top and bottom terminals connected. To conduct a detailed comparison of the spatial distribution characteristics of physical quantities within each single FC in the two stack layouts, a three-dimensional multiphase non-isothermal model is developed, which focuses on the influence of the random microporous structure of the porous layer on the heat-mass transfer and the electrochemical reaction process, making the results more realistic. The results show that relative to the original stack, the novel stack layout shortens the inter-FC conductive path and increases the heat dissipation area. Therefore, the ohmic polarization region is extended and the concentration polarization region is shortened, which increased the peak power density by 5.1 %. The placement of single FCs strongly affects the spatial distribution of internal physical quantities and performance, with FCs placed at an angle of −30° to the horizontal having the best performance.