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Abstract : Flameless combustion is an innovating combustion mode in the domain of the energy savings and pollutants emissions reducing, which is not yet fully explained. The aim of this study is to characterize its mechanisms from experimental investigations. Complementary, an experimental facility has been built at laboratory scale. The unique characteristics of this facility are the possible easy change of one of combustion chamber dimensions while keeping same other operating conditions. First part of the study has been performed at semi-industrial scale. Several in-flame measurements have been performed to characterize the flame stabilisation mode, reactive zone structure, the flue gas recirculation and its effect on combustion and NOx emissions. Different parameters (thermal input, air temperature, wall temperature, excess air ratio, flame confinement) have been changed in order to characterize their effects on flameless combustion regime.
Results show that the flame can be divided in two zones. Whereas the main reaction occurs when central air and external natural gas high velocity jets merge, a first reactive zone is also observed in the internal recirculation zone, assuring flame stabilization. Flue gas recirculation is also pointed out and quantified from in-flame measurements. Re-entrained in the main flow, these recirculating gases induce large dilution in the main reactive region where CO concentration and temperature remain at low levels. Nitrogen oxides are mainly produced by the thermal NO process. Moreover, a reduction mechanism in the flame of recirculating NO can be observed. The parametric study shows that if the changing of the thermal input has not effect on the combustion regime, the flameless combustion is achievable with no preheated air. However, an increase of excess air ratio increase reduces the reactive zone dilution by inert gas. For highs excess air ratio, we can observe a third reaction zone in the external part of the natural gas jets.
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Contributor : Eric Masson Connect in order to contact the contributor
Submitted on : Tuesday, November 29, 2005 - 6:52:43 PM
Last modification on : Tuesday, October 19, 2021 - 4:14:03 PM
Long-term archiving on: : Friday, November 25, 2016 - 9:51:11 AM


  • HAL Id : tel-00011087, version 2


Eric Masson. ETUDE EXPERIMENTALE DES CHAMPS DYNAMIQUES ET SCALAIRES DE LA COMBUSTION SANS FLAMME. Energie électrique. INSA de Rouen, 2005. Français. ⟨tel-00011087v2⟩



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