Effects of Endplate Assembly on Cold Start Performance of Proton Exchange Membrane Fuel Cell Stacks

A proton exchange membrane fuel cell (PEMFC) stack has two endplate assemblies (EAs) to stabilize the multilayered structure and distribute the preload evenly on each cell. Thermal inertia of and heat loss through the EA are crucial factors for developing novel thermal and water management strategies for PEMFC stacks. Herein, a 3D multidisciplinary transient model is established to assess the effects of EAs on the cold start performance of PEMFC stacks. The underlying mechanism linked to the EA effects is revealed through the analysis of temperature distribution, current density distribution, ice formation, and water balance calculation. The predicted results show that the EA has a significant impact on temperature and ice distributions in the end cell, thus negatively affecting the end cell performance. It is found that the smaller water diffusivity caused by the lower temperature in end cells results in more ice accumulation in the middle of cathode catalyst layer (CCL). The temperature of the end cells is greatly influenced by the thermal mass of the bus plate. For a low start-up temperature of -30 degrees C, the impact of EA becomes more significant and the end cell is completely filled up by ice and therefore shuts down.