Study of internal performance of commercial-size fuel cell stack with 3D multi-physical model and high resolution current mapping

Abstract

The inhomogeneous spatial reaction distributions over the large-scale active area of proton exchange membrane fuel cell stack are critical to the system energy efficiency and lifetime for the automotive applications. In this work, a commercial-size fuel cell stack of 406 cm2 active area is designed with asymmetric reactants flow fields for fuel cell vehicles. To understand the internal performance of the fuel cell, a segmented device with 396 segments is well designed based on the multi-layered printed circuit board technology for high resolution current mapping of the presented stack. Validated by the segmented fuel cell measurements, a 3D multi-physical large-scale model is developed to analyze the detailed distributions of current density, water content and temperature inside the fuel cell stack under different operating conditions. In the counter-flow operation of hydrogen and air, the lowest current density consistently locates around anode inlet while the mid portion of the active area near cathode inlet performs the best. Increasing the air stoichiometric ratio significantly improves the uniformity of current density distribution and the overall performance. The local flow field structures of Cross-flow configurations apparently enhance the in-plane temperature uniformity than the Parallel-flow ones. With the combination of current mapping and coupled modeling, both the distribution trends and local details of internal performance could be analyzed comprehensively to bridge the gap between the stack design and energy efficiency performance.