Hydrogen-Natural Gas Co-Blending: Performance Analysis with CFD and Static Mixers

The integration of hydrogen into natural gas infrastructure is a viable transitional strategy for decarbonizing energy systems without requiring major pipeline modifications. However, achieving uniform mixing of hydrogen and natural gas remains a significant challenge due to differences in gas properties. Additionally, poor mixing of hydrogen-natural gas blends can result in uneven flow distribution and pose potential safety risks. In this study, a T-junction pipeline model was developed, with hydrogen injected perpendicularly into a natural gas stream using computational fluid dynamics (CFD). Simulations were performed at a fixed natural gas flow velocity of 8 m/s, while varying hydrogen pipe diameters (0.1–0.4 m) and injection velocities (4–10 m/s) to evaluate the uniformity of the gas mixture. A Kenics-type static mixer was installed downstream of the injection point to assess its impact on blending performance. Results indicated that a hydrogen pipe diameter of 0.2 m and an injection velocity of 8–10 m/s yielded optimal blending, achieving a hydrogen blending ratio (HBR) of 20.00–23.81 % and a uniform hydrogen mole fraction distribution. The static mixer further improved blending quality, reducing the coefficient of variation (CoV) to 6.71 %. These results demonstrate the potential of CFD-guided optimization to ensure safe and efficient hydrogen–natural gas blending in the development of future energy networks.