Development of a cylindrical burner comprising multiple pairs of opposing partially premixed or inverse diffusion flames

Kamal, M. M.

doi:10.1177/0957650915595177

Cited by 5 publications

(4 citation statements)

References 39 publications

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“…At the end, it is worthy to highlight that relative to the burner of opposing premixed flames with a crossflow of methane-air mixture, 13 the blowout velocity limit was currently extended by 26.1%. When it is compared to the burner of opposing nonpremixed methane-air flames with a cross-flow of air, 24 the flame length herein decreased by 35.9% and the Figure 10. Effect of the equivalence ratio, number of opposing jets, and jets' diameter-to-separation ratio on the exhaust NOx emissions (at MP ¼ 10.3%).…”

Section: Resultant Firing Limits and Nox Emissionsmentioning

confidence: 99%

“…At the end, it is worthy to highlight that relative to the burner of opposing premixed flames with a cross-flow of methane–air mixture, 13 the blowout velocity limit was currently extended by 26.1%. When it is compared to the burner of opposing nonpremixed methane–air flames with a cross-flow of air, 24 the flame length herein decreased by 35.9% and the combustion efficiency increased by 14.6% since the transport of active species becomes faster in the presence of a hydrogen diffusion flame. A future study can be commissioned for having the hydrogen normal diffusion flame stabilized prior to the injection of methane.…”

Section: Resultsmentioning

confidence: 99%

“…Based on the recent findings by Kamal, 24 introducing a cross-flow jet normal to the plane of the opposing jets at a velocity ratio [VR] enriches the strain rate by additional vortices in the vertical planes passing through the centerlines of each two opposing jets. This takes place either with dominant opposing flows (Figure 4 25 where the jet is deflected from its axis through large angles.…”

Section: Reactive Flow Features Of a Hydrogen Jet Normal To Opposing mentioning

confidence: 99%

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Combustion of a hydrogen jet normal to multiple pairs of opposing methane–air mixtures

Hamed

Hussin

Kamal

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part A:

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The combustion performance of a cylindrical burner accommodating up to six multiple pairs of opposing methane-air mixtures with a cross-flow of hydrogen was addressed. The cross-flow initially duplicated the stagnation impact and enriched the vortical structures. Aided by the resulting flow strain, the transport of heat and active species from the hydrogen oxidation zone to the methane reaction zones accelerated the combustion across the opposing premixed flames and reduced the peak temperature across the outer diffusion flame. Increasing the cross-flow/opposing jets' velocity ratio to 0.89 merged the two stagnation centers and maximized the shearing stress. By the slight increase in the velocity ratio to 1.07, the H and OH pools provided for methane combustion became closer to the ports such that a hydrogen/methane mass percent of 10.3% extended the stoichiometric blowout velocity from 28.3 to 35.7 m/s. Since the turbulent kinetic energy thus increased to 8.4 m 2 /s 2 , the firing intensity reached values as high as 48.2 MW/m 3. Not only was there a reduction in the residence time for NOx formation, but also the blowout velocity relative gain overrode the relative increase in the NOx formation rates such that the NOx emission index decreased to 17 g/MWhr. By the excessive increase in velocity ratio, the vortical structures shrank such that the NOx exponential increase became dominant above 21 ppm. With fuel-lean mixtures, the hydrogen was partially combusted by the excess air from the opposing flames but the blowout velocity decreased to 13.1 m/s at È ¼ 0.50. The hydrogen flame NOx emissions decreased by providing the excess air at larger jets' diameter/separation ratios, thus reducing the residence times for thermal NOx formation and simultaneously interrupting the prompt NOx formation. At the lean operational limit, tripling the number of opposing jets decreased the hydrogen flame length by 54% such that the NOx emissions decreased by 38.4%.

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Section: Resultant Firing Limits and Nox Emissionsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Reactive Flow Features Of a Hydrogen Jet Normal To Opposing mentioning

confidence: 99%

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Combustion of a hydrogen jet normal to multiple pairs of opposing methane–air mixtures

Hamed

Hussin

Kamal

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…They stimulated turbulent non-premixed combustion in the distributed reaction zone regime by enforcing multiple opposing fuel jets radially inward to be mixed with an air jet issuing vertically upward. More recently, Kamal 13 highlighted the duplication in the stagnation centers and the multiplication in the recirculation zones when multiple pairs of opposing jets are set with a cross-flow in a cylindrical burner to stabilize partially premixed or inverse diffusion flames. In the light of these previous works, the novelty of the current work is to utilize the multiple jets’ opposing flow field with a cross-flow in extending the stability limits of premixed flames and noticing the parametric effects of the number of opposing jets, their diameter, and axial separation.…”

Section: Introductionmentioning

confidence: 99%

Combustion via multiple pairs of opposing premixed flames with a cross-flow

Kamal

2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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A cylindrical burner accommodating stoichiometric fuel-air mixture combustion via multiple pairs of opposing jets and a cross-flow provided heat intensification and duplication of the stagnation impact for extending the firing limits and maximizing the power density. Six pairs of circumferentially opposing stoichiometric mixture jets sustained bulk injection velocities as high as 21.8 m/s and were associated with NOx emissions of 22 ppm, while emissions of 10 ppm were recorded upon reaching a lean limit equivalence ratio of 0.59. A stoichiometric mixture jet issuing perpendicular to the opposing jets at a momentum flux ratio of 0.3 increased the turbulence production rates to the extent that increased the maximum bulk injection velocity to 28.3 m/s and reduced the NOx emissions to 17 ppm. Since the recirculation zones between the two stagnation centers got compressed by increasing the momentum flux ratio to 0.8, the corresponding residence time reduction decreased the NOx emissions to 12 ppm. As the cross-flow mixture was made fuel-lean, dilution of the stoichiometric mixture by the fuel-lean mixture combustion products made it possible to get NOx emissions of single digit ppm. Emissions of 9 ppm resulted from using the cross-flow fuel-lean mixture jet due to compromising the flame stability limit extension and the temperature reduction in the post flame region. Such emissions, in turn, decreased to 4 ppm as the momentum flux ratio increased to 1.7 at which the stoichiometric mixture flames shrank into their ports. A minimum NOx emission index of 0.27 g/kg fuel was thus obtained at a volumetric heat release of 50.4 MW/m 3. The momentum flux ratio corresponding to merging the two stagnation zones was correlated with Reynolds and Froude numbers, the jets' separation as well as the density and viscosity values pertaining to the lean and stoichiometric mixtures' flame temperatures.

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