Oxidation of H2/CO2 mixtures and effect of hydrogen initial concentration on the combustion of CH4 and CH4/CO2 mixtures: Experiments and modeling

Cong, Tanh Le; Dagaut, Philippe

doi:10.1016/j.proci.2008.05.079

Cited by 60 publications

(29 citation statements)

References 20 publications

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“…This is contrary to previous literatures, which instead show that the role of CO 2 is to inhibit CH 4 oxidation in a dilute flow reactor (6,9) . The details of our findings will be discussed later.…”

Section: Journal Of Thermal Science and Technologycontrasting

confidence: 99%

“…Therefore, CH 4 is often the focus of O 2 /CO 2 combustion studies. Many studies have reported that CO 2 is not inert but participates in chemical reactions in its gas phase primarily through the reaction CO 2 + H = CO + OH (R1) (5)(6)(7)(8)(9)(10)(11)(12)(13) .…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

“…The effect of R1 on the combustion process has been extensively studied (5)(6)(7)(8)(9)(10)(11)(12)(13) , and some studies have shown that CO 2 inhibits the oxidation of CH 4 because of the competition between reactions R1 and H + O 2 = O + OH (R3), the main chain branching reaction in the combustion process in a dilute flow reactor (7,10) . In contrast, our previous paper shows the role of CO 2 was to advance CH 4 oxidation during fuel-rich O 2 /CO 2 combustion where the concentrations of reactants were high because R3 became insignificant under fuel-rich condition, and R1 produced an abundance of OH radicals that were more active than the H radicals in hydrocarbon reactions in the specific temperature range (12,13) .…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

“…R1 is not the only reaction in which CO 2 plays a role. Hydrocarbon radicals are able to react with CO 2 (5) , and some reactions are enhanced by CO 2 because of higher third body efficiencies for CO 2 than for those for N 2 (6,10) . However, the above chemical role of CO 2 in CH 4 oxidation has not been systematically investigated in fuel-rich O 2 /CO 2 combustion under various air ratios.…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

“…H + CH 3 (+M) → CH 4 (+M) (R5) Several studies have shown that high levels of CO 2 reduce the amount of H radicals through R1 reaction, lowering the rate of formation of chain carriers via R3 reaction (5)(6)(7)(8)(9)(10) .…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

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Experimental and Kinetic Studies of Chemical Role of CO2 in Hydrocarbon Oxidation during Fuel-Rich O2/CO2 Combustion

Watanabe

Kiatpanachart

Okazaki

2013

JTST

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Experimental and kinetic studies of the chemical role of CO 2 in hydrocarbon reactions were conducted in a fuel-rich CH 4 flat flame with air ratios varying from 0.60 to 0.74. Unburned hydrocarbons (CH 4 , C 2 H 2 , C 2 H 4 , and C 2 H 6 ) in O 2 /CO 2 combustion were found to be lower than those in air combustion. The differences in the CH 4 oxidation characteristics between the air and O 2 /CO 2 combustion were caused by the chemical role of CO 2 in the reaction R1 (CO 2 + H → CO + OH), R2 (CH 2 (S) + CO 2 → CH 2 O + CO), and higher third body efficiencies of CO 2 at an air ratio (= 0.62 where the concentrations of reactants were high. The role of CO 2 in R1, R2, and the higher third body efficiencies of CO 2 decreased the rate of CH 4 oxidation during the early stage of combustion, where O 2 was present. Even though R2 did not directly compete with the main chain branching reaction R3 (H + O 2 → H + OH) for H radicals, like R1 did, R2 changed the hydrocarbon reaction pathway, thereby decreasing the rate of R4 (CH 3 + HO 2 → CH 3 O + OH) which had negative sensitivity in CH 4 oxidation. However, we found that R1 and R2 advance CH 4 oxidation in the last stage of combustion where O 2 was mostly consumed. This is attributed to the fact that the reactions R1 and R2 were able to advance without the presence of O 2 , and that R1 produced OH radicals that were active in hydrocarbon oxidation in the specific temperature range and R2 enhanced hydrocarbon oxidation when the rate of R4 was insignificant. Although R1 was the dominant reaction to reduce unburned hydrocarbons in the O 2 /CO 2 combustion, the role of R2 was significant at  = 0.62. Meanwhile, when the air ratio was 0.74 where concentrations of reactants were relatively low, the chemical role of CO 2 is to only decrease the rate of CH 4 oxidation due to the presence of an excessive amount of O 2 .

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Section: Journal Of Thermal Science and Technologycontrasting

confidence: 99%

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

See 3 more Smart Citations

Experimental and Kinetic Studies of Chemical Role of CO2 in Hydrocarbon Oxidation during Fuel-Rich O2/CO2 Combustion

Watanabe

Kiatpanachart

Okazaki

2013

JTST

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Impact of Oxygen Enrichment and CO2–H2O Dilution on Stability and Pollutant Emissions of Non-Premixed Swirling Turbulent Flames

Boushaki

Zaidaoui

Chakchak

et al. 2023

Flow Turbulence Combust

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The aim of this work is to investigate the effect of exhaust gas recirculation (EGR: water vapor and CO2), with and without O2 enrichment, on non-premixed turbulent flames stabilized on a swirl burner. The motivations include CO2 capture applications using O2 and CO2, combustion of biogas that contains CO2 and the use of EGR or H2O in certain industrial applications to reduce pollutant emissions. Experiments were carried out on a coaxial swirl burner placed in a combustion chamber of 25 kW of nominal power. The oxidant (air-O2, +H2O, +CO2) is introduced in the annular part though a swirler. The fuel (CH4) is fed though the central tube and injected radially at the exit section. The study focused on laminar burning velocity, pollutant emissions, flame stability, and flow fields measurements with different fractions of O2, H2O and CO2 in the mixture. The fraction of diluents varied from 0 to 20%, O2 concentration from 21 to 25% (in vol.) and the swirl number from 0.8 to 1.4. Different measurements were recorded: OH* chemiluminescence to locate the flame front, Stereo-PIV to analyze the flow field, pollutant emissions analysis (NOx and CO) and temperatures in the combustion chamber. Results show that dilution significantly influences flame characteristics. Dilution increases the lift-off height and reduces flame stability especially with high fractions (16-20%). O2 enrichment decreases lift-off height and enhances flame stability. Increase dilution reduces NOx and increases CO emissions. Stereo-PIV measurements highlight the turbulent coherent structure of the swirling flow and the effect of dilution on axial and tangential velocities. The effect of dilution on the underlying laminar burning velocity were determined by 1D calculation using COSILAB with GRI3.0 mechanism.

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Coupled chemical effects of carbon dioxide and hydrogen additions on premixed lean dimethyl ether flames

Pan

Liu

2016

Sci. China Technol. Sci.

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Oxidation of H2/CO2 mixtures and effect of hydrogen initial concentration on the combustion of CH4 and CH4/CO2 mixtures: Experiments and modeling

Cited by 60 publications

References 20 publications

Experimental and Kinetic Studies of Chemical Role of CO<sub>2</sub> in Hydrocarbon Oxidation during Fuel-Rich O<sub>2</sub>/CO<sub>2</sub> Combustion

Experimental and Kinetic Studies of Chemical Role of CO<sub>2</sub> in Hydrocarbon Oxidation during Fuel-Rich O<sub>2</sub>/CO<sub>2</sub> Combustion

Impact of Oxygen Enrichment and CO2–H2O Dilution on Stability and Pollutant Emissions of Non-Premixed Swirling Turbulent Flames

Coupled chemical effects of carbon dioxide and hydrogen additions on premixed lean dimethyl ether flames

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