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A validated numerical framework for hydrogen-enriched combustion in a micro gas turbine combustor

par Piscopo, Alessandro ;Yousefzad Farrokhi, Farshid ;Giuntini, Lorenzo ;De Paepe, Ward;Parente, Alessandro
Référence Fuel, 428, page (140209)
Publication A Paraître, 2027-01-15

Article révisé par les pairs

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Résumé :

The transition toward carbon-neutral energy systems has increased interest in carbon-free fuels, with hydrogen emerging as a key candidate for low-emission power generation. In this context, micro gas turbines (mGTs) represent an attractive solution due to their operational flexibility and suitability for decentralised heat and power production in energy systems with a high share of variable renewable sources. MGTs burn mainly natural gas, resulting in CO2 production. To reduce these emissions, natural gas can be replaced by hydrogen. However, the transition from methane to hydrogen is not straightforward and requires careful investigation. Hydrogen combustion introduces specific challenges related to its high reactivity, including increased risks of flashback, autoignition, and elevated NOx emissions in burners originally designed for methane. To this end, a partially premixed 20 kW th mGT combustor of a 3.2 kW e machine was investigated. Various experimental set points were available, ranging from pure methane to 50%volH2, including Exhaust Gas Recirculation (EGR) with a valve opening between 0% and 85%. Computational Fluid Dynamics (CFD) simulations were employed to evaluate the impact of hydrogen addition to the fuel. The numerical model was validated against experimental data, as it accurately predicted the concentrations of different species (CO2, O2, CO, and NOx) over a broad range of operating conditions, demonstrating the validity of the adopted computational approach. The validated numerical framework was then used to extrapolate toward unexplored operating conditions, extending from 50% H2 to pure hydrogen combustion. The results highlighted the need for future geometry adaptations to prevent damage to the swirler at hydrogen contents exceeding 90%, as ignition was predicted to occur upstream of the combustion chamber. Finally, a kinetic analysis of the CFD results indicated that NO formation is predominantly governed by thermal pathways, with hydrogen enrichment accelerating the chemistry and altering the NO formation process.