Addressing safety challenges in renewable hydrogen production systems: Full-Field concentration construction of hydrogen leakage

Renewable hydrogen production systems offer zero carbon emissions and high energy efficiency, but hydrogen leakage resulting in flammable hydrogen-air mixtures presents safety challenges. Understanding the full-field concentration distribution of hydrogen leakage is critical for ensuring the safety of renewable hydrogen production systems. In this study, a precise and comprehensive characterization of the flow regime, spatial evolution, and full-field concentration distribution of hydrogen leakage jets under low-flow conditions are conducted. An experimental platform simulating low-flow hydrogen leakage scenarios in a containerized hydrogen production system is established, and high-resolution, real-time visual observations are conducted for hydrogen leaks at 1.52 bar through a 1 mm nozzle, with hydrogen concentrations ranging from 10 to 100 vol%. A transition from laminar to turbulent flow is identified and characterized, and a segmented model for hydrogen leakage-diffusion is established. A dominant oscillation at 24.98 Hz, associated with shear layer instabilities, is revealed using Fast Fourier Transform (FFT) analysis. A robust image processing and data reconstruction framework is developed to convert visual leak signatures into spatial hydrogen concentration fields. The concentration reconstructed results demonstrate high accuracy compared with the theoretical model: radial recognition accuracy reaches 98.41 % (below the transition point) and 94.56 % (above), with axial accuracy around 97.16 %.