Effects of reactants/coolant non-uniform inflow on the cold start performance of PEMFC stack

• Published in: International journal of hydrogen energy 2020-05, Vol.45 (24), p.13469-13482
• Main Authors: Wei, Lin, Dafalla, Ahmed Mohmed, Jiang, Fangming
• Format: Article
• Language: English
• Subjects: Cold start; Coolant; Numerical model; Proton exchange membrane fuel cell
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2020.03.031

The failure at equally distributing reactants among different channels within the stack leads to uneven reaction and gas concentration distribution in the catalyst layers, which consequently impacts the performance and durability of proton exchange membrane fuel cell stacks (PEMFCs). A three-dimensional, transient, non-isothermal cold start model for PEMFCs with parallel flow-field configuration and coolant circulation is developed in this work to investigate the effects of non-uniform distribution of reactants/coolant inflow rates on the cold start process. The results show that the effect of non-uniform inflow on ice formation amount is obvious and that on the distribution uniformity of current density is apparent over the cold start survival time. Additionally, the simulation predictions show that the non-uniform initial membrane water content distribution due to the purge procedure can significantly increase the rate of ice growth and deteriorate the uniformity of current density distribution in the membrane. It is found that high stoichiometry operating condition is favorable to cold startup, but may result in drying in the membrane at regions close to the channel inlet side. As non-uniform inflow rates issue is inevitable in actual PEMFC stack operation conditions, our results demonstrate that the initial membrane water content and cathode stoichiometry ratio need to be identified to moderate the effects of reactants/coolant inflow maldistribution and to maintain a stable cold start performance for the PEMFC stack. •A 3D model for proton exchange membrane fuel cell cold start is presented.•The model is used to study the non-uniform inflow effects of reactants/coolant.•Obvious non-uniform inflow effects on ice formation and current density are seen.•Parametric study about membrane hydration and stoichiometry is also carried out.