Experimental Study on Gas Tightness of Fuel Cell Stacks Using Different Test Media 2022-01-5062

Gas leakage testing of fuel cell stacks is essential for ensuring safe and efficient performance. In many fuel cell stack gas leakage tests, nitrogen and helium are the most widely used test media. However, in some specific gas leakage tests of a fuel cell stack, it is not clear which kind of testing medium is better. This study aims to investigate the difference between gas leakage test results using nitrogen and helium, respectively, as the working medium, and then help us choose a suitable test medium. In this work, five types of leakage tests, namely, the three-chamber pressure holding, three-chamber total leakage, anode chamber pressure holding, anode-to-cathode crossover leakage, and anode-and-cathode-to-cooling chamber crossover leakage, were performed repeatedly on the same fuel cell stack using nitrogen and helium separately as the test medium. These five kinds of gas leakage tests are most frequently applied in the fuel cell field. The results of this study show that, for gas leakage tests involving gas molecules passing through a proton exchange membrane (PEM), the leak rates measured with nitrogen were significantly lower than those with helium. This phenomenon is attributed to the larger diameter of the nitrogen molecules than helium molecules. Therefore, for such leakage tests, it is recommended to use helium as the test medium to obtain more accurate test results.