Thesis Defence: Mixing Hydrogen into Natural Gas Distribution Pipelines

Arash Jalil Khabbazi, supervised by Dr. Sunny Ri Li, will defend their dissertation titled “Mixing Hydrogen into Natural Gas Distribution Pipelines” in partial fulfillment of the requirements for the degree of Master of Applied Science in Mechanical Engineering.

An abstract for Arash Jalil Khabbazi’s thesis is included below.

Defences are open to all members of the campus community as well as the general public. Please email sunny.li@ubc.ca to receive the Zoom link for this defence.

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ABSTRACT

Hydrogen, as the most promising alternative power source, has the potential to minimize greenhouse gas (GHG) emissions. Through power-to-gas (PtG) technology, it is feasible to use hydrogen and store or transport surplus electricity generated by renewable energy sources, such as wind or solar. Therefore, blending certain percentages of hydrogen into the existing natural gas pipeline infrastructure can greatly decrease the carbon intensity of current gas grids while also promoting a more sustainable and decarbonized energy system. Nevertheless, the significant density contrast of almost eight to nine times between hydrogen and natural gas introduces a challenge as buoyant hydrogen tends to stratify and become trapped near the top wall once injected via a Tee junction.In this study, the hydrogen blending into distribution natural gas pipelines using Tee junctions is numerically investigated, and the mixing homogeneity length is quantified through the coefficient of variation of the hydrogen mole fraction. The effect of side flow jet intensity on turbulent mixing in a low-pressure system is first looked into by altering the secondary pipe diameter while maintaining the same flow rate. Furthermore, the differences between vertical top-side, horizontal, and vertical bottom-side injection designs are studied. The ideal and real gas equations of state (EoS) scenarios are next investigated in the intermediate-pressure case. Overall, a larger secondary flow jet intensity results in a shorter mixing homogeneity length, as investigated in the low-pressure case. This is shortened even further if the secondary flow penetrates deep into the primary flow without getting trapped near the top wall from its beginning. Vertical injection from the bottom also results in a mixing homogeneity length that is roughly four times shorter than horizontal injection and five times shorter than vertical top-side injection. When industry standards are followed, injecting from the bottom definitely outperforms other injection setups. Furthermore, using real gas EoS, such as Soave-Redlich-Kwong, becomes crucial when the operating pressure rises, resulting in a longer mixing homogeneity length.