Experimental Research on Leakage and Diffusion Characteristics of Hydrogen-Blended Natural Gas Pipeline

Abstract The transportation of hydrogen through operational natural gas pipelines presents an economic solution for energy transition, yet introduces safety challenges due to hydrogen’s material compatibility risks and distinct leakage characteristics. While current studies often employ numerical simulations or simplified experimental setups with inert gases, these approaches fail to replicate actual pipeline operating conditions. This study develops an experimental system incorporating critical operational features as following: (1) Continuous gas supply with dynamic pressure regulation to maintain steady-state flow; (2) Make the leakage states configurable through replaceable pipeline sections; (3) Simultaneous monitoring of hydrogen and methane concentrations in spatial-temporal dimensions. Experimental results demonstrate differential dispersion patterns between hydrogen and methane under pressurized flow conditions, with hydrogen exhibiting faster vertical dispersion rates while methane shows a distinct ability of horizontal diffusion. The temporal analysis reveals pressure-dependent evolution of combustible gas clouds, showing nonlinear growth characteristics during sustained leakage. These findings enable the development of component-specific risk assessment models that account for the physical properties of the combustible gases. The experimental method provides a practical study framework for optimizing gas detection system layouts and updating integrity management protocols in repurposed natural gas infrastructure. This work advances the fundamental understanding of HBNG behavior during pipeline leakage events, offering implications for safety standard development in HBNG transportation systems.