Effects of CO2-H2O dilution on the characteristics of CH4-air-O2 flames

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Submitted on 25 Apr 2019

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Effects of CO2-H2O dilution on the characteristics of CH4-air-O2 flames

H. Zaidaoui, T. Boushaki, J.C. Sautet, C Chauveau, I. Gökalp

To cite this version:

H. Zaidaoui, T. Boushaki, J.C. Sautet, C Chauveau, I. Gökalp. Effects of CO2-H2O dilution on the characteristics of CH4-air-O2 flames. 9th European Combustion Meeting, Apr 2019, Lisboa, Portugal. �hal-02110516�

Effects of CO

₂

-H

₂

O dilution on the characteristics

of CH

₄

-air-O

₂

flames

H. Zaidaoui

1,2,

*, T. Boushaki

1,2

, J.C. Sautet

3

, C. Chauveau

1

, I. Gökalp

1

1

_{ICARE CNRS, 1C Avenue of scientific research, 45071 Orléans Cedex 2, France}

2

_{Orléans University, GTE, IUT, 45067 Orléans cedex 2, France}

3

_{Normandie University, CORIA UMR 6614, 76801 Saint Etienne du Rouvray, France}

*

hajar.zaidaoui@cnrs-orleans.fr

Context and objectives

 Study of non-premixed turbulent flames stabilized by a swirler

 Control of pollutant emissions / emissions standards

 Improve performances of combustion plants



Investigations on flame characteristics

 Effects of oxygen enrichment

 Effects of steam and CO

dilution

 Effects of swirl intensity

Numerical calculations

Experimental study

H2O dilution, %vol

740 760 780 800 820 840 860 0 5 10 15 20 25 30 35 40 45 50 0 4 8 12 16 20 Exhaust G as T emp erature, T( K) NO x (p pm ), CO (100*ppm )

CO2 dilution, %vol

NOx CO EGT

• Freely propagating methane-air flames.

• One-dimensional premixed flame.

• GRI-mech 3.0 mechanism.

• Atmospheric pressure and 300K.

• Equivalence ratio : from 0.8 to 1.2

• Oxygen enrichment : from 21% to 30%vol.

• Dilution : (0-20%vol) for both CO

and H

O.

The numerical computations were

conducted with COSILAB software

-3 -2 -1 0 1 2 3 4 5 6 -60 -40 -20 0 20 40 60 A xial v elocit y (m /s) Position (mm) 0 0,5 1 1,5 2 2,5 -60 -40 -20 0 20 40 60 A xial v elocit y RMS (m /s) Position (mm) Without dilution With CO2 dilution With H2O dilution

Without dilution CO₂ dilution H₂O dilution

 Coaxial swirl burner

_{ OH* chemiluminescence}

_{ Laser Doppler Anemometry}

Acknowledgments

:

The authors are grateful for the financial support of this work provided by the French Government's Investissement d'Avenir

program: LABEX CAPRYSSES, under GrantANR-11-LABX-0006-01.

NO_X and CO emissions and exhaust gas temperature are reported as a function of H₂O and CO₂ dilution. Case: Sn = 0.8, ɸ = 0.8, and 25% oxygen enriched methane/air mixture at atmospheric pressure.

→ Effect of CO₂ dilution is stronger than that of

steam dilution.

OH* intensity distributions of methane/air swirling flames diluted by CO₂, H₂O and EGR, in the case of 21% O₂, for Sn=0.8 and ɸ=0.8.

→ The flame becomes taller and unsettled with dilution. → CO₂ has greater effect on the flame lift-off heights.

Flame lengths as a function of CO₂ and H₂O diluted for 25% oxygen enriched methane/air mixture for Sn=1.4 and ɸ=0.8.

→ EGR dilution increases lift-off heights about 60% compared to the case without dilution.

→ The flame becomes much taller with CO₂ dilution.

Axial velocity and RMS profiles at z=30mm with & without CO₂ and water vapor dilution for Sn=1.4 and ɸ=0.8.

→ With CO₂ and H₂O dilution, the maximum velocity is higher and the flow is narrower.

→ Root Mean Squares are higher in the case of dilution.

- With O

: notable increase in flame temperature and laminar burnig velocity.