CFD simulation of pressurized Hydrogen jets in electrolyser systems using OpenFOAM

Water electrolysis using electrolysers is a key technology for sustainable hydrogen production and a promising pathway toward a hydrogen-based economy. However, the unique chemical and physical properties of hydrogen introduce significant safety challenges. Incident databases consistently identify pressurized hydrogen releases as among the most frequent and hazardous scenarios. Experimental investigations of such events in confined environments are fraught with risks and often fail to capture the rapid, transient evolution of these phenomena. In this context, Computational Fluid Dynamics (CFD) offers a powerful and safe alternative for analyzing high-pressure hydrogen releases, the associated dynamics and their impacts. This study focuses on examining both the structure of under-expanded hydrogen jets and their macro-evolution within a semi-confined industrial environment representative of facilities employing alkaline electrolysers. OpenFOAM, an open-source CFD platform, was selected for its versatility and capability in modeling complex flows. Multiple scenarios were analyzed, involving hydrogen releases through 1/2-inch, 1-inch, and 2-inch orifices at a pressure of 15 bar into air. The simulated mass flow rates closely align with theoretical maximum values derived from analytical formulations. For the 1/2-inch orifice scenario, the stable hydrogen release rate was predicted at 0.2328 kg/s, with rapid mixing forming a potentially flammable mixture in around 89% of the simulated domain within 0.08 seconds. This research highlights the critical role of the CFD in analyzing complex phenomena that are challenging to measure experimentally, such as high-pressure hydrogen releases. While short-cut methods can provide quick estimates, they often lack the accuracy, reproducibility, and ability to account for the specific geometric features of the context, frequently leading to overly conservative results. In contrast, CFD offers detailed, case-specific insights, making it an indispensable tool for improving safety and optimizing risk management in industrial hydrogen production settings.