Extrapolated 20-30 atm Laminar Burning Speeds of Hydrogen-Enriched Natural Gas and Ammonia Mixtures From Empirical Correlations

Abstract Hydrogen-containing fuels (e.g., ammonia and hydrogen) are an alternative to reduce CO2 emissions from electricity generation. Ammonia and hydrogen are increasingly added to natural gas combustion systems, including gas turbines [1, 2], to achieve this goal. Several studies exist on the combustion of these fuels in the literature at relatively lower pressures and most near atmospheric pressure. However, fundamental data on flame and burning characteristics are challenging to obtain at higher pressures relevant to gas turbines. The present study sought to identify the flame speeds and laminar burning speeds (LBS) of pure and hydrogen (H2) enhanced natural gas (NG) and ammonia (NH3) fuels at high pressure (20–30 atm) using mathematical correlations derived from experimental constant volume LBS calculations using an initial pressure of 10 atm. The correlations identified to determine the high-pressure LBS for the aforementioned fuels are discussed and presented for the advancement of the combustion literature as they relate to sustainable fuel implementation to turbomachinery systems, which operate at the elevated pressure settings presented here. The results of this work illustrate the significance of pressure on reaction dynamics via elevated LBS calculations across the equivalence ratio spectrum (ф = 0.7–1.3). H2 dilution revealed further LBS enhancement for all mixtures across the equivalence ratio range, primarily at stoichiometry for H2-diluted NG and in the lean region for H2-diluted NH3. The mathematical methods for high-pressure LBS calculation presented here introduce a benchmark for future experimental validation and a baseline for potential theoretical formulations currently under development. Current work also provides crucial validation data needed for developing and refining combustion chemical kinetic mechanisms for these fuels.