A numerical investigation of hydrogen blending effects on pressure regulators and compressors in natural gas pipeline networks

The present study numerically investigates the hydraulic and thermodynamic impacts of hydrogen (H₂) blending (0-100%) on pressure regulators and compressors within a South Korean high-pressure natural gas (NG) transmission pipeline. To solve the network flow while capturing thermodynamic property variations of H₂NG, we adopt the Linear-Pressure Analog method coupled with the GERG-2008 equation of state. For pressure regulators, the decreased Joule-Thomson coefficient of H₂NG mixtures reduces preheating energy, suggesting that current thermal management strategies should be re-evaluated. In addition, the increased volumetric flow rate elevates the required flow coefficient (C_g), potentially exceeding maximum capacities and requiring equipment replacement. For compressors, the lower density and compressibility of H₂ increase power consumption and weaken the ability to redistribute flow, thereby reducing overall network controllability. These results suggest that operating strategies for both regulators and compressors must be reassessed to ensure reliable operation of high-pressure networks under H₂ blending scenarios.