Dinesh, KKJR;
Shalaby, H;
Luo, KH;
van Oijen, JA;
Thevenin, D;
(2017)
Heat release rate variations in high hydrogen content premixed syngas flames at elevated pressures: Effect of equivalence ratio.
International Journal of Hydrogen Energy
, 42
(10)
pp. 7029-7044.
10.1016/j.ijhydene.2016.11.205.
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Abstract
Three-dimensional direct numerical simulations with detailed chemistry were performed to investigate the effect of equivalence ratio on spatial variations of the heat release rate and flame markers of hydrogen/carbon monoxide syngas expanding spherical premixed flames under turbulent conditions at elevated pressures. The flame structures and the heat release rate were analysed and compared between fuel-lean, stoichiometric and fuel-rich centrally ignited spherical flames. The equivalence ratio changes the balance among thermo-diffusive effects, Darrieus–Landau instability and turbulence, leading to different flame dynamics and the heat release rate distribution, despite exhibiting similar cellular and wrinkling flames. The Darrieus–Landau instability is relatively insensitive to the equivalence ratio while the thermo-diffusive process is strongly affected by the equivalence ratio. As the thermo-diffusive effect increases as the equivalence ratio decreases, the fuel-lean flame is more unstable than the fuel-rich flame with the stoichiometric flame in between, under the joint effects of the thermo-diffusive instability and the Darrieus–Landau instability. The local heat release rate and curvature display a positive correlation for the lean flame, no correlation for the stoichiometric flame, and negative correlation for the rich flame. Furthermore, for the fuel-lean flame, the low and high heat release rate values are found in the negative and positive curvature zones, respectively, while for the fuel-rich flame, the opposite trends are found. It is found that heat release rate markers based on species concentrations vary strongly with changing equivalence ratio. The results suggest that the HCO, HO2 concentrations and product of OH and CH2O concentrations show good correlation with the local heat release rate for H2/CO premixed syngas-air stoichiometric flame under turbulent conditions at elevated pressures.
| Type: | Article |
|---|---|
| Title: | Heat release rate variations in high hydrogen content premixed syngas flames at elevated pressures: Effect of equivalence ratio |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.ijhydene.2016.11.205 |
| Publisher version: | http://doi.org/10.1016/j.ijhydene.2016.11.205 |
| 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: | Direct numerical simulation; Syngas combustion; Elevated pressure; Equivalence ratio; Heat release rate imaging; Flame markers |
| 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-pp.ucl.ac.uk/id/eprint/1557413 |
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