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Study of hydrogen stratification phenomena in hydrogen-blended natural gas pipelines.

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Bibliographic Details
Title:	Study of hydrogen stratification phenomena in hydrogen-blended natural gas pipelines.
Authors:	Su, Yue¹ (AUTHOR), Li, Jingfa^1,2 (AUTHOR) lijingfa@bipt.edu.cn, Yu, Bo² (AUTHOR), Wang, Xiaofeng³ (AUTHOR), Pu, Ming³ (AUTHOR), Wang, Weiqiang¹ (AUTHOR), Zhang, Boxuan¹ (AUTHOR)
Source:	Renewable Energy: An International Journal. Nov2025, Vol. 253, pN.PAG-N.PAG. 1p.
Subject Terms:	Hydrogen, Natural gas, Mathematical models, Chemical derivatives, Gas dynamics, Thermodynamics, Pipeline transportation
Abstract:	The potential re-stratification of uniformly mixed hydrogen-blended natural gas (HBNG) under the influence of gravity during pipeline transportation remains a contentious issue in the industry. This study addresses this issue by considering the extreme condition of a shutdown pipeline. Based on the principle of minimum energy in thermodynamics and by integrating different gas equations of state (EoS) to calculate the Helmholtz free energy and chemical potential, a mathematical model is proposed for describing the concentration distribution of HBNG along the height direction under gravity during pipeline shutdown conditions. Furthermore, a mathematical formula for calculating hydrogen concentration in the gravity direction is derived from the ideal gas EoS, along with an efficient calculation method based on the Peng-Robinson (PR) EoS and the concept of defect correction. The study analyzes the impacts of pipeline elevation differences, hydrogen blending ratios (HBR), and temperatures on the degree of hydrogen stratification. The results indicate that in engineering practice, except for extreme elevation differences or extremely low temperatures, the stratification of hydrogen in HBNG does not need to be considered for the uniformly mixed HBNG. This study theoretically clarifies the current disputes about the stratification phenomenon of HBNG and holds significant implications for the safe transportation of HBNG pipelines. [ABSTRACT FROM AUTHOR]
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Database:	GreenFILE

Description
Abstract:	The potential re-stratification of uniformly mixed hydrogen-blended natural gas (HBNG) under the influence of gravity during pipeline transportation remains a contentious issue in the industry. This study addresses this issue by considering the extreme condition of a shutdown pipeline. Based on the principle of minimum energy in thermodynamics and by integrating different gas equations of state (EoS) to calculate the Helmholtz free energy and chemical potential, a mathematical model is proposed for describing the concentration distribution of HBNG along the height direction under gravity during pipeline shutdown conditions. Furthermore, a mathematical formula for calculating hydrogen concentration in the gravity direction is derived from the ideal gas EoS, along with an efficient calculation method based on the Peng-Robinson (PR) EoS and the concept of defect correction. The study analyzes the impacts of pipeline elevation differences, hydrogen blending ratios (HBR), and temperatures on the degree of hydrogen stratification. The results indicate that in engineering practice, except for extreme elevation differences or extremely low temperatures, the stratification of hydrogen in HBNG does not need to be considered for the uniformly mixed HBNG. This study theoretically clarifies the current disputes about the stratification phenomenon of HBNG and holds significant implications for the safe transportation of HBNG pipelines. [ABSTRACT FROM AUTHOR]
ISSN:	09601481
DOI:	10.1016/j.renene.2025.123603