Optimization of self-cold start for PEM fuel cell with serpentine flow field based on three-dimensional transient model: synergy of initial conditions and start-up strategies

The rapid self-cold start of proton exchange membrane fuel cells (PEMFCs) at extremely low temperatures remains a major bottleneck for commercial applications. In this study, a three-dimensional transient self-cold start model is developed to numerically investigate the effects of initial conditions and startup strategies on self-cold start characteristics, and innovatively reveals the key to optimizing the startup strategies. The results indicate that initial conditions significantly impact the self-cold start characteristics, with initial current density playing a critical role in balancing heat generation and ice formation rates. High membrane water content reduces hydration capacity, leading to rapid freezing, the ice volume fraction in catalytic layer increases by 31.3 %. Ice distribution exhibits a trend where more ice accumulates at the edges while the central region remains relatively less, with ice primarily forming in the catalyst layer and significantly more in cathode than in anode. PEMFCs struggle to achieve a successful self-cold start at −30 °C, and the maximum survival time is 181 s. The coordinated control of ramp rate and step interval time is key to optimizing ice/thermal distribution, and the number of steps must be properly matched with the step intervals. These insights provide new ideas for optimizing the cold start strategies.