Low-Temperature O-ring Leak Testing for High Pressure Hydrogen Gas Applications

초록

With the global shift towards clean energy, hydrogen fuel cell electric vehicles are considered promising alternatives to internal combustion engine vehicles. High-pressure hydrogen storage systems, operating at pressures up to 96.3 MPa, are now the preferred method for hydrogen refueling owing to their simplicity and fast refueling. However, such systems face significant safety challenges, particularly the risk of gas leakage through rubber O-rings under rapid temperature changes and high-pressure conditions. This study investigated the sealing performance of rubber O-rings under extremely low-temperature and high-pressure environments, which are encountered during hydrogen vehicle refueling. A custom testing apparatus was developed to simulate these conditions and accurately measure the leakage behavior of O-rings. Leakage was detected by visualizing detection liquids and tracking pressure reductions. This study identified three distinct leakage types, each with different failure mechanisms. One key finding is that a 10% reduction in contact force can substantially increase the likelihood of gas leakage, particularly under low-temperature conditions. This highlights the importance of maintaining sufficient and stable contact force to ensure sealing integrity. In addition, O-rings with lower glass transition temperatures ($T_g$) exhibited better sealing performance, indicating that selecting materials with lower $T_g$ is crucial for ensuring optimal performance in cold environments.

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