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| Investigation on Laminar Burning Characteristics of Ammonia/Hydrogen under Water Vapor Dilution |
| DOI：10.13949/j.cnki.nrjgc.2024.06.005 |
| Key Words:ammonia/hydrogen/water combustion constant volume combustionbomb laminar flame speed chemical kinetics analysis |
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| Abstract:The mechanism of the influence of water vapor dilution （0~50%） on the combustion characteristics of NH3/H2 was investigated under the conditions of initial pressure of 101.3 kPa， chemical equivalence ratio of 0.8~1.4 and hydrogen blending ratio of 0.3~0.7， by the method of a constant volume combustion bomb experiment together with the method of one-dimensional laminar premixed flame numerical calculation. The results show that the laminar flame speed of NH3/H2 first increased and then decreased with the increase of equivalence ratio， with a peak appearing around 1.2 equivalence ratio. As the dilution ratio of water vapor increased， the laminar flame speed of NH3/H2 decreased linearly， and its peak shift towards the equivalence ratio of 1.1， and the sensitivity affected by the equivalence ratio decreased. The chemical kinetic analysis result shows that the dilution effect has the greatest impact among different physical and chemical effects of water vapor. The branch chain reactions such as R1， R3， and R68 promote laminar flame propagation， while branch chain reactions such as R16， R58， and R60 have the opposite effect. A higher water dilution ratio increases the sensitivity coefficient of critical branch chain reactions to laminar flame speed， and the growth trend of sensitivity coefficient continues to increase. With the increase of the water dilution ratio， the molar fractions of free radicals such as NO， N2O， OH in the reaction zone significantly decrease， leading to a decrease in the laminar flame speed of NH3/H2. |
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