Xu, Y;
Mao, Q;
Wang, Y;
Luo, KH;
Zhou, L;
Wang, Z;
Wei, H;
(2023)
Role of ammonia addition on polycyclic aromatic hydrocarbon growth: A ReaxFF molecular dynamics study.
Combustion and Flame
, 250
, Article 112651. 10.1016/j.combustflame.2023.112651.
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Abstract
Ammonia (NH3), one of the most promising carbon-free fuels, has received great research interest. In particular, NH3 is often blended with hydrocarbon fuels to achieve desired combustion characteristics. However, NH3 addition could affect soot formation, which has not been adequately understood. In this study, the effect of NH3 on the growth of polycyclic aromatic hydrocarbons (PAHs) is investigated with the reactive force field molecule dynamics (ReaxFF MD) simulations and quantum chemistry calculations. The simulation results indicate that NH3 addition slows down the growth of large carbon-containing species in the C2H4/O2 system. Novel path with HCN addition is discovered in the PAH growth, which inhibits the PAH growth compared to the conventional Hydrogen-Abstraction-Carbon-Addition (HACA) path via C2H2 addition. Moreover, quantum chemical calculations verified the rationality of this addition path and explained its inhibition on PAH growth by calculating the heat of reactions and reaction energy barriers. According to the present study, NH3 also has an inhibitory effect on both the HCN addition path and C2H2 addition path by providing H atoms to promote the generation of PAH radicals back to PAH molecules, and this effect is more significant for the C2H2 addition path. Results from the study provide a fundamental insight for the inhibition of PAH growth due to the NH3 addition from an atomistic insight, which helps to improve the understanding of the combustion of blends of NH3 and hydrocarbon fuels.
| Type: | Article |
|---|---|
| Title: | Role of ammonia addition on polycyclic aromatic hydrocarbon growth: A ReaxFF molecular dynamics study |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.combustflame.2023.112651 |
| Publisher version: | https://doi.org/10.1016/j.combustflame.2023.112651 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Ammonia, PAHs, Molecule dynamics, Quantum chemistry, HACA pathway, Soot, Carbon-free |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10166768 |
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