Numerical Analysis on Flow and Heat Transfer Performance of High-Pressure Hydrogen/Methane Mixtures in Horizontal Pipelines.

Blending hydrogen with natural gas is necessary before fully transitioning to pure hydrogen energy. This approach also offers a practical way to reduce carbon emissions. High-pressure hydrogen/methane mixtures are the study object, and the flow and heat transfer performance inside horizontal pipelines are investigated through numerical analysis. General flow and heat transfer trends for the mixture components are identified across varying mole fractions, mass flow rates, ambient temperatures, and operating pressures. The results indicate that the addition of hydrogen reduces frictional resistance. When the molar fraction of hydrogen varies within the range of 5% to 30%, the maximum reduction in the friction factor is 1.03%. At a hydrogen molar fraction of 15%, the operating pressures of 10 and 12 MPa significantly influence convective heat transfer. Specific heat slightly decreases with increasing pressure. A new empirical correlation for thermal properties is proposed, predicting friction factor data with an error of less than ±10% and Nusselt number data with an error of less than ±20%.