Characterizing the instability limits of turbulent, premixed combustion using CO2-diluted, oxy-methane/hydrogen mixtures
(2026) Fuel : the science and technology of fuel and energy — Vol. 415, n° 138466, p. 12 (2026)
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- Abstract
- This study investigates the combustion instability limits of CO2-diluted oxy-methane/hydrogen mixtures in a spark ignition engine through a combined experimental and numerical approach. Two experimental campaigns were conducted at constant fuel mean effective pressure and maximum brake torque spark timing. In each campaign, either the oxidizer composition was varied while the fuel mixture remained fixed, or vice versa. These experiments were designed to provide insight into combustion phenomena across a broad spectrum of fuel and oxidizer mixtures representing a wide range of thermophysical properties, and to explore regimes not typically encountered in reciprocating engines operated with air. Over the series of tested conditions, the pronounced thermal quenching effect of CO2 causes a shift in the cyclic energy balance. While the replacement of N2 with CO2 in the oxidizer causes a reduction in thermal efficiency, proportionally more heat is distributed to the combustion chamber gases, suggesting a combined heat and power application, which in principle could produce zero NOx, would be most appropriate for this concept. The experimental results were then used to extend the theory of premixed, turbulent combustion to the CO2-diluted oxy-fuel regime. The interaction between turbulent flame propagation and the in-cylinder mixture was further analyzed using predictive modeling and compared to established theories of premixed, turbulent combustion. The results demonstrate that the dilution limit of oxy-CH4/H2 combustion based on theoretical predictions correlates strongly with experimental measurements of combustion instability, even in cases when the engine operation appears to deviate from the flamelet regime.
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Citations
Daese, M., Contino, F., & Lacey, J. (2026). Characterizing the instability limits of turbulent, premixed combustion using CO2-diluted, oxy-methane/hydrogen mixtures. Fuel : the science and technology of fuel and energy, 415(138466), 12. https://doi.org/10.1016/j.fuel.2026.138466 (Original work published 2026)