• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.73-78
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• 2006

The lifted oscillating flame has been studied using experiments of inverse diffusion flames that the air jet injected into a methane background. To find out the characteristics of inverse diffusion flames, fundamentally flame stabilized diagram is investigated with various air and fuel jet velocities. It has five regions - flame extinction, stable attached flame, anchored flame, liftoff flame and blow off region. In inverse diffusion flame, lifted flames were observed near the blow off region. As long as flames lift off, flames oscillate by periods. In this oscillating lifted flame region, the frequency of 1 and under were observed in various air and methane jet velocities. Characteristics of lifted flames are also examined by using the ICCD direct image. And intensity of flame chemiluminescence is very different in rising and falling period from photographs. For the present, it is predicted that the changes of flame structure are related with flame oscillation, but more experiments will be needed to make clear the phenomenon.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.31-45
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• 2001

The effect of adding carbon dioxide to methane-air flame was investigated experimentally. Measurements included extinction limits, flame temperature and photographic investigation of flame. A diffusion flame was stabilized between counterflowing streams of methane diluted with carbon dioxide and air diluted with carbon dioxide. Extinction limits and temperature for such flames were measured over a wide parametric range and were compared with those for other flames that fuel or oxidant was diluted with nitrogen or argon. The experimental results indicate that extinction phenomena can be explained by thermal effect and as an amount of carbon dioxide in fuel or oxidant increases, greatly as compared with other flames flame-temperature falls and flame-thickness is reduced.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.63-68
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• 2007

An experimental study was carried out to investigate gasification process of wood sawdust in the 1-dimensional downdraft fixed bed gasifier. The preheated air which was used oxidizer and steam were used as a gasifying agent. The downdraft fixed bed gasifier obtains more amount of hydrogen and methane by increasing residence time of supplied air. The operating parameters, the supplied air temperature and steam were used. The oxidizer temperature was varied from 500K to 620K and vapor was added. The gasification process was monitored by measuring temperature at three position near the biomass using R-type thermocouples and the syngas composition was analyzed by gas chromatograph. We get the sample gas at the end of gasifier and it was eonugh time to finishing the chemical reaction. Finally, the amount of hydrogen and methane were increased widely as increasing the oxidizer temperature and adding steam.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.325-328
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• 2012

Radiation effects on the partially premixed methane flames diluted with water vapor in the air stream were numerically investigated. OPPDIF code and GRI-v3.0 were used in the numerical simulation. Adiabatic condition was compared with two different radiation models, optically-thin and WSGGM models. It was found that the radiation effect on the flame structure for the equivalence ratio (${\Phi}$) of 2.5 was less than ${\Phi}=1.5$. Extinction limit was not affected significantly, however, local flame structure was markedly influenced by the radiation models as increasing the water vapor concentration.

• Journal of Mechanical Science and Technology
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• v.16 no.2
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• pp.262-269
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• 2002

The effects of velocity boundary conditions on the structure of methane-air nonpremixed counterflow flames were investigated by two-dimensional numerical simulation. Two low global strain rates, 12 s$\^$-1/ and 20 s$\^$-1/, were considered for comparison with measurements. Buoyancy was conformed to have strong effects on the flame structure at a low global strain rate. It was shown that the location where a top hat velocity profile was imposed is sensitive to the flame structure, and that the computed temperature along the centerline agrees well with the measurements when plug flow was imposed at the inner surface of the screen nearest the duct exit.

• Journal of Hydrogen and New Energy
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• v.15 no.3
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• pp.244-249
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• 2004

Pd catalyst have been used in hydrogenation, oxidation, and low temperature combustion reaction. Recently, it has been candidated as a possible reagents in the partial oxidation of methanol reformers of the fuel cell. Pd catalysts, even though it is very precious and expensive, catalytic functioning is good, but it still need to be improved in the matter of durability and low catalytic activity after calcination. In this study, we synthesize the improved Pd catalyst and study their chemical functioning.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.185-193
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• 2003

Basic flow fields of two dimensional V flames were examined as a preliminary work to study the instability of premixed flame with vorticity generation. Laminar premixed propane and methane flame were anchored by electrically heated wire to make two dimensional V flames. Flow fields were measured mainly by PIV(Particle Image Velocimetray) and the results were compared with those obtained by LDV(Laser Doppler Velocimetry) to confirm their reliability. Because the curvatures of V flames are so small, V flames were locally assumed to be inclined planar flames in gravitational field. The measured flow fields were locally compared with those of analytical solutions, which showed the qualitatively similar results. In downstream region, the vorticity fields were nearly constant except region near the center line, which support the assumption of locally one dimensional flame. Besides it was tried to find experimentally the similarity of flow fields in downstream region. Finally, stability diagram of propane and methane flames were drawn for the equivalence ratio less than one and the wide range of mean velocity.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.13-16
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• 2012

The interaction between methane and hydrogen premixed flames with the different equivalence ratio and global strain rate was investigated numerically in one-dimensional counterflow field. The OPPDIF code and GRI-v3.0 were used to simulate the interacting flames. Overall trends in the maximum heat release rates of $CH_4{^-}$ and $H_2$-side flame were examined with the variation of $a_g$. The interaction mode of the flames were classified according to the equivalence ratios and Lewis numbers of each flame and global strain rate.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.11-17
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• 2002

The first-order conditional moment closure (CMC) model is applied to $CH_4$/Air turbulent jet diffusion flames(Sandia Flame D, E and F). The flow and mixing fields are calculated by fast chemistry assumption and a beta function pdf for mixture fraction. Reacting scalar fields are calculated by elliptic CMC formulation. The results for Flame D show reasonable agreement with the measured conditional mean temperature and mass fractions of major species, although with discrepancy on the fuel rich side. The discrepancy tends to increase as the level of local extinction increases. Second-order CMC may be needed for better prediction of these near-extinction flames.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.144-148
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• 2006

Characteristics of a plasma reactor for partial oxidation of methane, especially focused on the role and effectiveness of plasma chemistry, is investigated. Partial oxidation of methane is investigated using a rotating arc which is a three dimensional version of a typical glidingarc. The rotating arc has both the characteristics of equilibrium and non-equilibrium plasma. Non-equilibrium characteristics of the rotating gliding arc can be increased by rotating an elongated arc string attached at both the tip of inner electrode and the edge of outer electrode. In this way, plasma chemistry can be enhanced and hydrogen selectivity can reach almost 100% that is much higher than thermal equilibrium condition. As a result, the present study enables the strategic approach of the plasma reforming process by means of appropriate reactor design to maximize plasma effect and resulting in maximized reaction efficiency.