Numerical investigation of key factors influencing the mixing performance of static mixers for hydrogen-blended natural gas

Blending hydrogen into existing natural gas pipelines has emerged as a pivotal strategy for the efficient transportation of hydrogen. Static mixers, as the core components in such pipelines, play a critical role in achieving uniform hydrogen-blended natural gas mixing. In this study, numerical simulations were employed to investigate the effects of operational conditions and structural parameters on the mixing uniformity and pressure drop of the gases within static mixers. A systematic analysis was performed to evaluate the effects of the hydrogen blending ratio (HBR), inlet flow velocity, operating pressure, and the geometric configuration of the mixing elements. Results demonstrate that, among the factors investigated, the geometry of the mixing elements exerts the most significant impact on mixing performance. Increasing the HBR, inlet flow velocity, or operating pressure were found to enhance the mixing uniformity. Furthermore, increasing the number of mixing elements and optimizing their configuration can enhance mixing performance but also leads to a higher pressure drop. Therefore, engineering applications must balance mixing performance with energy efficiency. This study provides a theoretical foundation for the development of high-efficiency static mixers for hydrogen-blended natural gas systems.