Investigation on mixing characteristics of hydrogen and natural gas fuel based on SMX static mixer

Hydrogen, as a carbon-free fuel, is significantly for replacing fossil fuels and reaching the ultimate goal of carbon neutrality, and is commonly expected to play a major role in future energy supply. Blending hydrogen into natural gas pipeline networks for end-user consumption as a means of delivering pure hydrogen to the market which not only improves the utilization rate of hydrogen energy, but also reduces the cost of hydrogen transportation. A three-dimensional model of the blending the natural gas and hydrogen with SMX mixing elements is developed to obtain homogeneous mixed gas injected into the natural gas pipeline network. The Reynolds-averaged Navier-Stokes (RANS) method is employed to investigate the flow physics in the static mixer, which was verified by experiments. The numerical results are in good agreement with the experimental data. Based on the static mixer model, the coupling relationship between mixing performance and the crucial parameters including the number of mixing elements, operating conditions and hydrogen blending volume fraction is analyzed in detail, and a compromise design scheme is proposed under the studied conditions to improve the mixing performance of natural gas and hydrogen.