• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.60-66
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• 2001

Combustion using pure oxygen instead of air is an energy saving technology that can increase thermal efficiency by the improvement of burning rate and ultra high temperature flame, being used on the industrial spot. But information about it is not so enough yet. Flame figure, temperature distribution and emission concentration were measured with oxygen excess ratio and swirl number in a turbulent diffusion flame to investigate the combustion characteristics using pure oxygen. The results showed that flame figure became different as long as oxygen excess ratio varied and that concentration of NO and CO increased suddenly around ${\lambda}$=1.5.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1277-1284
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• 2005

The combustion characteristics of methane oxygen diffusion flames have been investigated to give basic information for designing industrial oxyfuel combustors. NOx reduction has become one of the most determining factors in the combustor design since the small amount of nitrogen is included from the current low cost oxygen production process. Flame lengths decreased with increasing fuel or oxygen velocity because of the enhancement of mixing effect. Correlation equation between flame length and turbulent kinetic energy was proposed. NOx concentration was reduced with increasing fuel or oxygen velocity because of the enhanced entrainment of the product gas into flame zone as well as the reduction of residence time in combustion zone.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.327-328
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• 2015

• Journal of the Korean Society of Combustion
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• v.22 no.2
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• pp.19-26
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• 2017

An experimental study investigates the flame response characteristics of jet-diffusion flame and premixed flame. The experiment was conducted while varying the amplitude. Flame lengths were quantified for OH chemiluminescence measurement and compared with the result of the flame transfer function. Flame length and flame velocity perturbation were normalized and compared with the result of the flame transfer function. The comparison results appear that velocity perturbation and flame length oscillation of premixed flame show linear behaviors on the other hand jet-diffusion flame, amplitudes are more thant 0.20, shows nonlinear behaviors of flame velocity perturbation and flame length oscillation.

• Journal of the Korean Society of Combustion
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• v.6 no.2
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• pp.23-28
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• 2001

In the present work, the effect of PDF selection and intermittency on the result of the numerical simulation are examined by the simulation of a turbulent methane-air jet diffusion flame. As to the PDFs, beta-function and clipped Gaussian are considered. Results for the pure mixing jet are compared with experimental results. Then, the turbulent flame is calculated for the same conditions and the results obtained for the several models are compared. It is found that the clipped Gaussian distribution coupled with consideration of intermittency recovers the experimental data very well. As to the reacting flow results, the main overall properties of the turbulent jet diffusion flame such as maximum flame temperature are less affected by the choice of the PDF. Flame height and NO emissions, on the contrary, appear to be significantly influenced.

• 한국연소학회:학술대회논문집
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• 2001.11a
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• pp.27-34
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• 2001

The soot formation characteristics have been studied experimentally in concentric co-flow ethylene/propane diffusion flames. Comparing to the homogeneously mixed propane/ethylene case, the increase of soot formation is observed when propane is supplied through the outer nozzle, while the decrease is observed when propane is supplied through the inner nozzle. The reaction path of PAHs formed from the pyrolysis process of propane is likely to be responsible to the observed difference. When propane is supplied through the outer nozzle, PAHs formed during the combustion process are easy to be exposed to the oxidization environment; however, when propane is supplied through the inner nozzle, PAHs are not likely to be oxidized and thus get involved in soot formation process. The synergistic effect in ethylene/propane diffusion flames is affected not only by the composition of mixture but also by the way of mixing.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.11-20
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• 1999

Acoustic pressure response and NO formation of hydrogen-air diffusion flames at various pressures are numerically studied by employing counterflow diffusion flame as a model flame let in turbulent flames in combustion chambers. The numerical results show that extinction strain rate increases linearly with pressure and then decreases, and increases again at high pressures. Thus, flames are classified into three pressure regimes. Such non-monotonic behavior is caused by the change in chemical kinetic behavior as pressure rises. Acoustic pressure response in each regime is investigated based on the Rayleigh criterion. At low pressures, pressure-rise causes the increase in flame temperature and chain branching/recombination reaction rates, resulting in increased heat release. Therefore, amplification in pressure oscillation is predicted. Similar phenomena are predicted at high pressures. At moderate pressures, weak amplification is predicted. Emission index of NO shows similar behaviors as to the peak-temperature variation with pressure.

• Journal of the Korean Society of Combustion
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• v.1 no.1
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• pp.11-18
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• 1996

The stabilization characteristics of diffusion flame formed behind a bluff body with fuel injection slits was experimentally investigated by varying main fuel injection angles and auxiliary fuel injection conditions. The flame stability limits, temperature and length of recirculation zone, direct and schlieren photographs of flames were measured in order to study the stabilization mechanism of the diffusion flame. The results of this investigation are as follows. The stability limits can be improved by the condition of the kind and quanity of the injected auxiliary fuel. The length and temperature decrease with injection of auxiliary fuel, and these phenomena are remarkable when LPG is injected into the recirculation zone. When the LPG is injected into the recirculation zone, flame remains sooty. Fluctuation of fuel and main stream is generated actively by air injection.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.25-31
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• 2002

For the better understanding of the stability of turbulent combustion, more researches on extinction and re-ignition are needed. Flame interactions in non-premixed flame have also not been greatly researched. We made a hybrid twin jet flame, the combinations of diffusion flame and partially-premixed diffusion flame, in a twin jet counterflow configuration. The extinction limits of a crossed twin jet counterflow have been extended in comparison with those of a one-dimensional counterflow because of flame interactions through heat transfer and joint ownership of various radicals. Besides, we have obtain ignition $Damk\"{o}hler$ number by experimental method without external ignition source using the extinction characteristic in a crossed twin jet counterflow flame. From results, we can identify the hysteresis between extinction and ignition $Damk\"{o}hler$ number in S-curve.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.122-131
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• 2020

To reduce emissions from coal-fired power plants, researchers focusing on coal and biomass co-firing technology. Biomass, with its carbon-neutral nature and lower quantities of nitrogen and sulfur compared with coals, has a positive impact on coal-fired power generation. Many studies on the combustion of biomass have been conducted, but the study on the combustion characteristics of biomass char is limited. FERPM predicts char combustion characteristics with high accuracy by introducing experimental data-based parameters of biomass char and has not yet been applied in numerical simulation. In this study, FERPM is numerically applied to char combustion of wood pellets representing wood-based biomass and the combustion characteristics are compared with the kinetic/diffusion limited model, intrinsic model, and diffusion limited model.