Empirical lifetime prediction through deterioration evaluation of high-power PEMFC for railway vehicle applications

초록

As part of a carbon -neutral national policy, there has been an increasing demand for the development of an ecofriendly transportation system. Particularly, polymer electrolyte membrane fuel cells (PEMFCs) are being evaluated as suitable fuel cell railway vehicles that meet the requirements of moderate operating temperatures and high -power conditions. However, the different degradations that occur during cyclic load operation damage their performance. In this study, a high -power PEMFC unit (225 cm 2 ) was designed and fabricated to explore its longterm electrochemical characteristics before its application in railway vehicles. To solve the non -uniformity caused by the large area, the deterioration factors based on the progress of the cycle (change in the electrochemical properties and decrease in the electrochemical active surface area (ECSA)) were experimentally measured. A performance evaluation was conducted numerically based on the load cycle considering the operating conditions (temperature and flow rate) of the prototype railway vehicle. Further, an empirical largearea fuel cell numerical analysis model was constructed to improve the reliability of the current model by considering the parameters representing nonlinear deterioration characteristics. From the results, the maximum difference in power reduction rates after 2,000 cycles between the actual experimental results and numerical analysis results was approximately 11.6%. Finally, the performance was predicted under different conditions by predicting the Pt particle size through curve fitting and by applying the ECSA change based on the temperature, voltage, and humidity changes. When all the conditions were considered, the maximum power decreased by 79.4% when compared to numerical predictions after 2,000 cycles based on the experimental conditions of the prototype train. When a sensitivity analysis was conducted based on the simulation results, the temperature change in the fuel cell had the most significant influence on the reduction in the ECSA and the resulting decrease in the electrochemical power.

키워드