Ignition delay time and methane time history in hydrogen-natural gas surrogate blends: A shock tube study

The pipeline transportation of hydrogen-blended natural gas offers an efficient large-scale solution while introducing new safety and technical challenges. This study investigates the combustion characteristics of hydrogen-natural gas blends, using pure methane and a 1% C₃H₈/99% CH₄ mixture as natural gas surrogates. Ignition delay times and methane time histories were measured in a shock tube for hydrogen–natural gas surrogate blends containing 10 %, 20 % and 30 % hydrogen (by mole fraction of the fuel component) at 1305–1729 K, 1 atm, and equivalence ratios of 0.5, 1.0 and 2.0. High-precision in-situ methane concentration data were obtained using 3175 nm laser absorption diagnostics. The results indicate that hydrogen addition significantly enhances methane consumption rate and overall reactivity. The Aramco Mech 3.0, NUIG Mech 1.3, FFCM-2, USC Mech Ⅱ and GRI Mech 3.0 kinetic models were evaluated against the present experimental data. The rate constants of three key reactions in the Aramco Mech 3.0, NUIG Mech 1.3, and FFCM-2 kinetic models were revised, resulting in simulation results that show improved agreement with the experimental data for ignition delay times and methane time histories. This study provides both experimental and modeling studies on the combustion characteristics of hydrogen-natural gas blends, contributing to the safe transportation and utilization of hydrogen.