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Parametric sensitivity analysis on the cold start process of a polymer electrolyte membrane fuel cell

Subzero start‐up of the polymer electrolyte membrane fuel cell (PEMFC) is one of the most challenging tasks to be solved before commercialization. During the subzero start‐up process, water generated in the oxygen reduction reaction at the cathode side of PEMFC is susceptible to freeze，which makes active sites covered by the ice and gases failed to reach the surface of the catalyst layer (CL), leading to a substantial decay and even ending up with a failure of the start‐up. Given that many factors affect the cold start process, the relative contribution of the essential factors on the cold start process is independently analyzed using first‐order finite‐difference sensitivity analysis from −20°C to −30°C. The effect of essential parameters on the cold start process is quantified. The investigated parameters include the ratio of bipolar plate (BP) thickness to that of the CL (RBP/CL), the starting voltage (Vini), stoichiometry ratios, inlet gas temperature (Tin), the porosity of the CL (εCL), initial membrane water content (λini), membrane thickness (θmem), the volume fraction of ionomer (ωCL) in CLs, and the heat capacity of the BP (ρcpBP). Results show that the cold start process is most sensitive to RBP/CL and λini. Significant improvement of cold start performance can be achieved by appropriately adjusting RBP/CL, λini, Tin, and εCL. Appropriately increasing the Vini also can be a method to improve cold start performance, especially for the cold start from −30°C. Besides, optimized ωCL in CLs, proper θmem, and lower ρcpBP can contribute to better performance, especially for the cold start from −20°C.