메탄 산소 연소에 있어서 화염 소화에 대한 연구
A Study on Flame Extinction in Oxymethane Combustion
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Oxy-methane nonpremixed flames diluted with CO2 were investigated to clarify impact of radiation heat loss and chemical effects of additional CO2 to oxidizer stream on flame extinction. Flame stability maps were presented with functional dependencies of critical diluents mole fraction upon global strain rate at several oxidizer stream temperatures in CH4-O2/N2, CH4-O2/CO2, and CH4-O2/CO2/N2 counterflow flames. The effects of radiation heat loss on the critical diluent mole fractions for flame extinction are not significant even at low strain rate in nonpremixed CH4-O2/N2 diffusion flame, whereas those are significant at low strain rate and are negligible at high strain rate (> 200 s-1) in CH4-O2/CO2 and CH4-O2/CO2/N2 counterflow flames. Chemical effects of additional CO2 to oxidizer stream on the flame extinction curves were appreciable in both CH4-O2/CO2 and CH4-O2/CO2/N2 flames. A scaling analysis based on asymptotic solution of stretched flame extinction was applied. A specific radical index, which could reflect the OH population in main reaction zone via controlling the mixture composition in the oxidizer stream, was identified to quantify the chemical kinetic contribution to flame extinction. A good correlation of predicted extinction limits to those calculated numerically were obtained via the ratio between radical indices and oxidizer Lewis numbers for the target and baseline flames. This offered an effective approach to estimate extinction strain rate of nonpremixed oxy-methane flames permitting air infiltration when the baseline flame was taken to nonpremixed CH4-O2/N2 flame.
Abstract
Oxy-methane nonpremixed flames diluted with CO2 were investigated to clarify impact of radiation heat loss and chemical effects of additional CO2 to oxidizer stream on flame extinction. Flame stability maps were presented with functional dependencies of critical diluents mole fraction upon global strain rate at several oxidizer stream temperatures in CH4-O2/N2, CH4-O2/CO2, and CH4-O2/CO2/N2 counterflow flames. The effects of radiation heat loss on the critical diluent mole fractions for flame extinction are not significant even at low strain rate in nonpremixed CH4-O2/N2 diffusion flame, whereas those are significant at low strain rate and are negligible at high strain rate (> 200 s-1) in CH4-O2/CO2 and CH4-O2/CO2/N2 counterflow flames. Chemical effects of additional CO2 to oxidizer stream on the flame extinction curves were appreciable in both CH4-O2/CO2 and CH4-O2/CO2/N2 flames. A scaling analysis based on asymptotic solution of stretched flame extinction was applied. A specific radical index, which could reflect the OH population in main reaction zone via controlling the mixture composition in the oxidizer stream, was identified to quantify the chemical kinetic contribution to flame extinction. A good correlation of predicted extinction limits to those calculated numerically were obtained via the ratio between radical indices and oxidizer Lewis numbers for the target and baseline flames. This offered an effective approach to estimate extinction strain rate of nonpremixed oxy-methane flames permitting air infiltration when the baseline flame was taken to nonpremixed CH4-O2/N2 flame.
참고문헌 (29)
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