Tian Yangyang, Tian Tongmu, Ren Gaofei, Zhang Jiaxin
College of Petroleum Engineering, Xi'an Shiyou University, Xi'an 710065, China.
Shaanxi Key Laboratory of Advanced Stimulation Technology for Oil & Gas Reservoirs, Xi'an 710065, China.
Materials (Basel). 2025 Apr 20;18(8):1879. doi: 10.3390/ma18081879.
As a cost-effective transitional strategy, the integrated utilization and transportation of hydrogen and natural gas have gained significant attention as a viable pathway toward carbon neutrality. However, hydrogen's low density, viscosity, and calorific value cause upward migration and accumulation in pipelines, raising embrittlement risks. Its high diffusion and leakage rates also pose significant safety challenges. To address hydrogen-natural gas blending challenges, achieving uniform mixing is crucial. This study systematically examines hydrogen-methane mixing in T-junction pipelines via numerical simulations, analyzing hydrogen mixing ratios (HMR: 10-25%) and methane flow rates (4-10 m/s) to assess flow and mixing dynamics. The coefficient of variation (COV) quantifies mixing uniformity with spatial and temporal analyses, optimizing hydrogen injection for rapid, homogeneous mixing. The key findings are as follows: (1) The uniform mixing length (the minimum axial distance required for the first pipeline cross-section to achieve 95% mixing uniformity) decreases inversely with the HMR, from 100 D to 20.875 D (D represents the pipeline diameter) as the HMR rises from 10% to 25%. (2) Analysis of initial uniform mixing time (defined as the duration required for the first pipeline cross-section to achieve 95% mixing uniformity) shows significant reduction with increasing HMR. While methane flow rate has a less pronounced effect, it nevertheless contributes to reducing the outlet uniform mixing time (defined as the time required to attain 95% mixing uniformity at the pipeline outlet). (3) A fundamental trade-off in engineering applications is established: increasing the HMR reduces mixing length but extends overall mixing time (difference between outlet and initial mixing times), while higher methane flow rates shorten overall mixing time at the cost of increased mixing length. The primary objective of this research is to elucidate the fundamental fluid dynamics of hydrogen-methane mixtures in T-junction pipelines, providing scientific insights for the safe and efficient operation of hydrogen-blended natural gas pipeline systems.
作为一种经济高效的过渡策略，氢气与天然气的综合利用和运输作为实现碳中和的可行途径已受到广泛关注。然而，氢气的低密度、低粘度和低热值导致其在管道中向上迁移和积聚，增加了脆化风险。其高扩散率和泄漏率也带来了重大安全挑战。为应对氢气 - 天然气混合的挑战，实现均匀混合至关重要。本研究通过数值模拟系统地研究了T型管道中氢气与甲烷的混合情况，分析了氢气混合比（HMR：10 - 25%）和甲烷流速（4 - 10 m/s），以评估流动和混合动力学。变异系数（COV）通过空间和时间分析来量化混合均匀性，优化氢气注入以实现快速、均匀的混合。主要研究结果如下：（1）均匀混合长度（第一个管道横截面达到95%混合均匀度所需的最小轴向距离）与HMR成反比，随着HMR从10%增加到25%，均匀混合长度从100D降至20.875D（D代表管道直径）。（2）对初始均匀混合时间（定义为第一个管道横截面达到95%混合均匀度所需的持续时间）的分析表明，随着HMR的增加，初始均匀混合时间显著减少。虽然甲烷流速的影响不太明显，但它有助于减少出口均匀混合时间（定义为在管道出口达到95%混合均匀度所需的时间）。（3）在工程应用中建立了一个基本的权衡关系：增加HMR会减少混合长度，但会延长整体混合时间（出口混合时间与初始混合时间之差），而较高的甲烷流速会以增加混合长度为代价缩短整体混合时间。本研究的主要目的是阐明T型管道中氢气 - 甲烷混合物的基本流体动力学，为掺氢天然气管道系统的安全高效运行提供科学见解。
