Flame Propagation and Explosion Characteristics of Multi-component Natural Gas in a Low-pressure Hydrogen-doped Environment

Abstract Hydrogen is considered to be the most promising clean energy of the 21st century, and its development and application are conformed to ‘carbon peaking and carbon neutrality goals’. Hydrogen-doped natural gas pipelines, as the main means of transporting hydrogen energy, are normally laid through low-pressure areas. The influence of the low-pressure hydrogen-doped environment on the flame propagation and explosion characteristics of hydrogen-doped natural gas is not yet clear. To solve this problem, this paper configures real multi-component natural gas and experimentally obtains flame propagation as well as explosion hazard parameters for natural gas/H 2 /air mixtures. The tensile flame propagation velocity changes from a gradual decrease to a gradual increase with increasing tensile rate for increasing hydrogen content. The laminar burning velocity increases from 0.44 m/s to 0.66 m/s at 0.75 bar and from 0.49 m/s to 0.69 m/s at 0.50 bar. The increase in laminar burning velocity becomes more and more significant after the hydrogen content exceeds 20%. As the hydrogen content increases, the flame surface goes from smooth to cracked and gradually increases. Lewis number, flame thickness, Markstein length and critical destabilisation radius decrease with increasing hydrogen and increase with decreasing pressure. The flame stability shows the same trend. The explosion hazard of natural gas/H 2 /air is reinforced as the hydrogen content rises, and the reduction in pressure reduces the explosion overpressure by 70% and the flame temperature by 10%. The results of the current research could provide a scientific reference for the safe delivery of hydrogen-doped natural gas.