Experimental and kinetic modeling study of the autoignition and oxidation of ammonia/ethane mixtures in a rapid compression machine and a jet-stirred reactor

Ignition delay times and speciation data of ammonia/ethane (NH3/C2H6) fuel blends were measured in a rapid compression machine (RCM) and in a jet-stirred reactor coupled with molecular beam mass spec-trometry (JSR-MBMS), respectively. Specifically, the RCM experiments were conducted at elevated pres-sures of 20 and 40 bar, intermediate temperatures between 890 and 1110 K, three equivalence ratios of 0.5, 1.0 and 2.0 and for three C2H6 mole fractions from 1% to 10%. Besides, the JSR measurements were conducted at atmospheric pressure, intermediate temperatures between 700 and 1180 K, three equiva-lence ratios of 0.5, 1.0 and 2.0 and three C2H6 mole fractions from 10% to 50%. The experimental re-sults demonstrate that adding C2H6 into NH3 leads to a more reactive mixture. A kinetic model from our recent work on ammonia/ethanol fuel blends (M. Li et al., Proc. Combust. Inst., 2022) has been up-dated and validated with the new data obtained in this work. The updated model (PTB-NH3/C2 mech) can reproduce the effects of ethane fraction and equivalence ratio on IDT/speciation and show an overall satisfactory agreement between experimental results and predictions. Based on the kinetic analyses, for all conditions investigated in this study, the generation of OH radicals from HO2 and H radicals domi-nates the characteristic of the auto-ignition process in the RCM and the NH3 consumption process in the JSR, respectively. Apart from that, the addition of ethane provides additional OH from a relatively low temperature (e.g., around 850 K in a JSR condition) and triggers the interactions between hydrocarbon and ammonia systems, e.g., the reactions of C2H6/C2H4/CH3 +NH2, which play an important role in the combustion of ammonia.& COPY; 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.