Unlocking clean gas with hydrogen: A combustion optimization study

Abstract

Combining hydrogen with natural gas, a hydrocarbon fuel, is seen as a critical step towards reaching net-zero emissions and creating a cleaner environment. To tackle climate change, major organizations like the U.S. Department of Energy, Energy Innovation, and the International Renewable Energy Agency are promoting the use of hydrogen blended with natural gas. This approach can potentially cut emissions in half compared to relying solely on natural gas. Using the Ansys 2022 R1 CHEMKIN tool, the study analyses combustion features in H2-CNG (compressed natural gas) -air mixtures, considering atmospheric conditions and operational parameters. Blending 50 % hydrogen with CNG results in significant changes, including an increase in laminar flame speed from 48.78 cm/s to 71.52 cm/s. As the hydrogen content in the CNG blend increases from 0 to 50 %, the concentration of free radicals like H, O, and OH rises by 42.86 %, 28.57 %, and 20.00 %, respectively, reaching these values at a 50 % hydrogen blend compared to pure CNG. NSGA-II multi-objective optimization identified that a 50 % hydrogen-blended CNG surpasses pure CNG in laminar flame speed and free radical generation. The research confirms that H2-CNG creates a promising fuel with several advantages. When combusted, H2-CNG mixtures exhibit superior characteristics, including potentially increased efficiency through increased free radical formation and laminar flame speed. This innovation has the potential to significantly reduce carbon footprint and contribute to achieving carbon neutrality goals. The cleaner and more efficient combustion properties of H2-CNG offer a compelling pathway for mitigating climate change.