Optimizing energy efficiency in hydrogen-blended natural gas pipelines: Evaluating the impact of hydrogen ratio on calorific value and Wobbe index

Integrating hydrogen into natural gas has emerged as a promising strategy to reduce greenhouse gas emissions and support the transition toward a cleaner energy future without requiring the replacement of existing natural gas infrastructure. This study investigates the effects of varying hydrogen concentrations on the hydraulic and thermal properties of the mixture to identify an optimal blending ratio using established industrial calculation methods. A computational fluid dynamics (CFD) model was then employed to predict pressure losses for the optimum hydrogen-blended natural gas (HBNG) mixture. Validation against analytical calculations showed good agreement, with a mean relative error of 3.99% across different pipeline lengths, well within the recommended 5% threshold. The results indicate that a 20% hydrogen blend provides the best balance between energy efficiency and performance. Under standard conditions of 25 °C and 1 atm, this HBNG mixture exhibits a density of 0.536 kg/m3, a viscosity of 1.066 × 10−5 Pa s, a lower heating value (LHV) of 29.24 MJ/m3, a Wobbe Index of 50.851 MJ/m3, and an energy flow rate of 17.25 TJ/h. Further investigation was conducted on HBNG pressure loss over varying pipeline lengths from 10 m to 80 m. A correlation between HBNG pressure loss and pipeline length was established, expressed as ΔP = 0.0548L.