Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale
Soot is an important component for heat transfer in combustion processes. However, it is also a harmful pollutant for humans, and strict emissions legislation motivates research on how to control soot formation and release. The formation of soot is known to be triggered by high temperature and high...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-01-01
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| Series: | Energies |
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| Online Access: | https://www.mdpi.com/1996-1073/13/1/191 |
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| author | Rikard Edland Thomas Allgurén Fredrik Normann Klas Andersson |
| author_facet | Rikard Edland Thomas Allgurén Fredrik Normann Klas Andersson |
| author_sort | Rikard Edland |
| collection | DOAJ |
| description | Soot is an important component for heat transfer in combustion processes. However, it is also a harmful pollutant for humans, and strict emissions legislation motivates research on how to control soot formation and release. The formation of soot is known to be triggered by high temperature and high pressure during combustion, and it is also strongly influenced by the local stoichiometry. The current study investigates how the formation of soot is affected by increasing the oxygen concentration in the oxidizer, since this affects both the temperature profile and partial pressures of reactants. The oxygen-to-fuel ratio is kept constant, i.e., the total flow rate of the oxidizer decreases with increasing oxygen concentration. Propane is combusted (80 kW<sub>th</sub>) while applying oxygen-enriched air, and in-flame measurements of the temperature and gas concentrations are performed and combined with available soot measurements. The results show that increasing the oxygen concentration in the oxidizer from 21% to 27% slightly increases soot formation, due to higher temperatures or the lower momentum of the oxidizer. At 30% oxygen, however, soot formation increases by orders of magnitude. Detailed reaction modeling is performed and the increase in soot formation is captured by the model. Both the soot inception rates and surface growth rates are significantly increased by the changes in combustion conditions, with the increase in soot inception being the most important. Under atmospheric conditions, there is a distinct threshold for soot formation at around 1200 °C for equivalence ratios >3. The increase in temperature, and the slower mixing that results from the lower momentum of the oxidizer, have the potential to push the combustion conditions over this threshold when the oxygen concentration is increased. |
| first_indexed | 2024-04-11T11:03:10Z |
| format | Article |
| id | doaj.art-9a9bbce7f47348c5a707f2f1d7119d05 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-11T11:03:10Z |
| publishDate | 2020-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-9a9bbce7f47348c5a707f2f1d7119d052022-12-22T04:28:29ZengMDPI AGEnergies1996-10732020-01-0113119110.3390/en13010191en13010191Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical ScaleRikard Edland0Thomas Allgurén1Fredrik Normann2Klas Andersson3Department of Space Earth and Environment, Division of Energy Technology, Chalmers University of Technology, 41296 Gothenburg, SwedenDepartment of Space Earth and Environment, Division of Energy Technology, Chalmers University of Technology, 41296 Gothenburg, SwedenDepartment of Space Earth and Environment, Division of Energy Technology, Chalmers University of Technology, 41296 Gothenburg, SwedenDepartment of Space Earth and Environment, Division of Energy Technology, Chalmers University of Technology, 41296 Gothenburg, SwedenSoot is an important component for heat transfer in combustion processes. However, it is also a harmful pollutant for humans, and strict emissions legislation motivates research on how to control soot formation and release. The formation of soot is known to be triggered by high temperature and high pressure during combustion, and it is also strongly influenced by the local stoichiometry. The current study investigates how the formation of soot is affected by increasing the oxygen concentration in the oxidizer, since this affects both the temperature profile and partial pressures of reactants. The oxygen-to-fuel ratio is kept constant, i.e., the total flow rate of the oxidizer decreases with increasing oxygen concentration. Propane is combusted (80 kW<sub>th</sub>) while applying oxygen-enriched air, and in-flame measurements of the temperature and gas concentrations are performed and combined with available soot measurements. The results show that increasing the oxygen concentration in the oxidizer from 21% to 27% slightly increases soot formation, due to higher temperatures or the lower momentum of the oxidizer. At 30% oxygen, however, soot formation increases by orders of magnitude. Detailed reaction modeling is performed and the increase in soot formation is captured by the model. Both the soot inception rates and surface growth rates are significantly increased by the changes in combustion conditions, with the increase in soot inception being the most important. Under atmospheric conditions, there is a distinct threshold for soot formation at around 1200 °C for equivalence ratios >3. The increase in temperature, and the slower mixing that results from the lower momentum of the oxidizer, have the potential to push the combustion conditions over this threshold when the oxygen concentration is increased.https://www.mdpi.com/1996-1073/13/1/191combustionflamesootoxygen-enrichmentpropane |
| spellingShingle | Rikard Edland Thomas Allgurén Fredrik Normann Klas Andersson Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale Energies combustion flame soot oxygen-enrichment propane |
| title | Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale |
| title_full | Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale |
| title_fullStr | Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale |
| title_full_unstemmed | Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale |
| title_short | Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale |
| title_sort | formation of soot in oxygen enriched turbulent propane flames at the technical scale |
| topic | combustion flame soot oxygen-enrichment propane |
| url | https://www.mdpi.com/1996-1073/13/1/191 |
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