Investigation of the Laminar Burning Velocity and Exhaust Characteristics of Methane-Ammonia-Hydrogen Ternary Blends

Abstract Even though usage of hydrogen (H2) in the energy sector has gained a considerable amount of traction over the last decade, its high flame speed restricts its feasibility as a drop-in replacement for existing fuels in applications such as internal combustion engines and gas turbines. In order to address some potential issues, ammonia (NH3) can be used in conjunction with hydrogen, as its slow reaction kinetics offset that of H2 without compromising decarbonization efforts. However, simply replacing natural gas (primarily methane, CH4) with hydrogen/ammonia blends is not trivial due to compatibility issues associated with bulk combustion characteristics. In this study, methane-ammonia-hydrogen ternary blends are comprehensively investigated in terms of laminar burning velocity, flame morphology, stability, and emissions in order to understand transitional regimes between fossil-based approaches and carbon-free alternatives. This work presents the analysis of the combustion properties of different ammonia/methane/hydrogen blends at varied equivalence ratios in an optically accessible constant volume combustion chamber (CVCC) coupled with Z-type schlieren visualization. The emissions from each experimental trial were analyzed using a Fourier Transform Infrared (FTIR) Spectroscopy system for detailed speciation. Furthermore, a computational approach was implemented to validate the laminar burning velocity results using an established mechanism already tested for ternary blends.