Investigation of Stratification Behaviour in Hydrogen-Methane Blends in Domestic Gas Piping Systems

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Hydrogen (H2) energy is recognized as a clean energy source and has become an important component for attaining net-zero energy systems by 2050 as per the Paris Agreement. By utilizing existing transport and distribution infrastructure, an expedient pathway for increased use of H2 energy by modern-day society is to blend H2 with Natural Gas (NG). With this approach, hydrogen generated through Power-to-Gas (P2G) is either injected into the existing Natural Gas (NG) transmission and distribution network or injected into pure hydrogen transmission and distribution systems. In doing this, the electrical utility system becomes more closely integrated with the NG transmission and distribution system. Given that NG transmission and distribution systems already exist, injection of H2/NG blends into NG piping systems offers a low-cost method for achieving both energy storage and increased integration of H2 energy into society. This research investigation will examine the flow of gas mixtures with strong component density differences in both horizontal and vertical domestic gas piping sections where the flow Reynolds number ranges from zero up to Reynolds numbers slightly greater than the laminar-to-turbulent transition Reynolds number (~2,200). The fluid dynamic processes within these systems will also be investigated during a leak event in order to better understand the behavior of H2/NG mixtures within a pipe during a leak event and the influence of component density difference on odorant concentration in the leaked gas. Numerical modeling of horizontal flow, vertical flow, and horizontal flow with a leak will be performed and used to examine the evolution of gas mixtures with position and time, and concentration profiles within pipe sections during a wide range of flow events. This research is important to ensure the safety of H2/NG blends in NG distribution systems, enabling increased integration of H2 energy as one method to attain 2050 net-zero targets.