An experimental study of stable and unstable operation range in a two-layer porous burner
| Autor: | Mohammad Javad Omidi, Mohsen Davazdah Emami |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Fluid Flow and Transfer Processes
Length scale Materials science 020209 energy 02 engineering and technology Condensed Matter Physics Combustion Instability Adiabatic flame temperature Flashback 020401 chemical engineering 0202 electrical engineering electronic engineering information engineering medicine Combustor 0204 chemical engineering Composite material medicine.symptom Porosity Porous medium |
| Zdroj: | Heat and Mass Transfer. 55:1627-1639 |
| ISSN: | 1432-1181 0947-7411 |
| DOI: | 10.1007/s00231-018-02541-6 |
| Popis: | In this study, the stable and unstable (flashback phenomenon) performance of a two-part porous burner has been evaluated experimentally. The aim of this research is to reach an ultra-lean combustion, and investigate the performance of a porous burner at such condition. Moreover, it is essential to evaluate the conditions that lead to instability (flashback phenomenon) to prevent flashback in a practical porous burner. The stability of the flame and the flashback phenomenon have been evaluated by changing operating parameters such as equivalence ratio, firing rate, the length scale of the porous and the burner’s structure (foam or bead). Results show that a stable flame prevails in the range of equivalence ratios of 0.35–0.45. The flame is formed in the vicinity of the interface between the two porous media in all the cases. The flame moves to the downstream by reducing the equivalence ratio. Moreover, the maximum temperature of the flame increases by increasing the equivalence ratio and decreasing the balls’ diameter. As equivalence ratio approaches unity, the flashback time decreases. According to the achieved results, the porosity of the media has a great influence on both the flashback time and the temperature profile. The amount of radiation heat-transfer to upstream increases by increasing the balls’ diameter downstream of the burner. Experiments show that the flame temperature for the foams and the beads is not the same due to structural differences. The amount of the excess air has a significant effect on the amount of CO such that the concentration of CO reduces by reducing the equivalence ratio in the specific range of the experiment. The NOx concentration is negligible in all the experiments due to the low temperature of the burner. |
| Databáze: | OpenAIRE |
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