ScholarWorks@성균관대학교

초록

The increasing demand for sustainable and low-carbon energy alternatives has positioned ammonia-dimethyl ether (NH3/DME) mixtures as promising substitute fuels. Understanding their laminar combustion characteristics under medium to high-pressure conditions is essential for developing advanced combustion technologies. This study systematically investigated the laminar burning velocities (LBVs) of NH3/DME mixtures using an optical experimental platform. LBVs were measured across varying pressures (0.3–0.9 MPa), DME mole fractions (10 %–40 %), and equivalence ratios (Φ = 0.7–1.3) at the initial temperature of 393 K. Based on experimental LBV data, an optimized NH3/DME combustion mechanism was developed, enabling detailed kinetic analyses of the influences of DME mole fraction and pressure on combustion dynamics and emission characteristics. The results indicate that increasing DME mole fraction enhances LBV, though the rate slows when DME exceeds 20 %. This is because the inhibitory effect of ammonia on flame propagation weakens as DME becomes the dominant contributor to combustion energy. Additionally, the increase in DME leads to the reduction in Markstein length, which enhances thermal-diffusive instability. Increasing the initial pressure significantly decreases the LBV and intensifies hydrodynamic instability. The optimized mechanism performed excellently in predicting LBV. Kinetic analysis revealed that the reaction H + O2 = OH + O has the greatest impact on LBV. DME improves combustion performance and radical concentration by promoting reactions of carbon-containing species, while also enhancing the nitrogen oxidation pathway, resulting in increased NO emissions. Pressure has minimal effect on chain propagation but inhibits chain branching reactions, reducing overall reaction activity. These findings provide critical insights for the application of NH3/DME blended fuels and the optimization of high-pressure combustion technologies. © 2025

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