• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.253-259
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• 2006

The effect of DC electric fields on the flame extinction was investigated experimentally in counterflow configurations for the methane/oxygen/nitrogen diffusion flame. The electric fields was applied by connecting the high voltage and ground terminals to the upper and lower burners, respectively. In case of having electric fields, several modes of flame extinction was observed according to the electric field intensity and strain rate defined by the exit velocity. To visualize and characterize the flame structure and intensity, planar LIF technique was adopted for OH radicals. Consequently, several length scales, including the flame width, thickness, and height from the burner tip, were introduced to explain the various flame behaviors and to characterize the flame extinctions. It was found that the variation of flame width and the chemical reaction are strongly related to a critical electric field intensity, thus the various modes of diffusion flame extinction could be observed due to the electric fields.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.139-146
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• 2001

The experimental study was carried out for the diffusion flame characteristics of second stage combustor with the variations of temperature and supplying rate of hot exhaust gas from first stage combustor. It also examined the flame structure and NOx formation of the second stage combustor in which the fuel(natural gas) is supplying into the mixture of oxygen hot exhaust gas from first stage combustor. The results show that the increasement of temperature and flow rate of exhaust gas lead to increase the NOx up to 30ppm with 19% $O_2$ condition

• Journal of Environmental Science International
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• v.27 no.5
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• pp.309-317
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• 2018

In this study, a laser sheet technique and PLIF (Planar laser-induced fluorescence) are applied to a laboratory-scale pulverized coal burner of the open type, and the spatial relationship of the pulverized coal particle zone and the combustion reaction zone is examined by simultaneous measurement of Mie scattering and OH-LIF images. It is found that this technique can be used to investigate the spatial relationship of the combustion reaction zone and pulverized-coal particles in turbulent pulverized-coal flames without disturbing the combustion reaction field. In the upstream region, the combustion reaction occurs only in the periphery of the clusters where high-temperature burned gas of the methane pilot flame is entrained and oxygen supply is sufficient. In the downstream region, however, combustion reaction can be seen also within clusters of pulverized-coal particles, since the temperature of pulverized-coal particles rises, and the mixing with emitted volatile matter and ambient air is promoted.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.04a
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• pp.43-50
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• 2000

The flow field of a 1 Ton/Day entrained-flow gasifier constructed in KIER was numerical simulate in this paper. The standard $k-{\varepsilon}$ turbulence model and simple procedure was used with the Primitive-Variable methods during computation. In order to find the influence factors of the flow field which may have great effects on coal gasification process inside gasifier, difference geometry parameters at various operating conditions were studied by simulation methods. The calculation results show that the basic shape of the flow field is still parabolic even the oxygen gas is injected from the off-axis position. There exist an obvious external recirculation zone with a length less than 1.0m and a small internal recirculation region nears the inlet part. The flow field inside the new gasifier is nearly similar as that of the old 0.5T/D gasifier at same position if the design of burner remains unchanged.

• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.95-99
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• 2008

Halon was known as a cause of the ozone layer destruction. In 1987, it was designated as one of the ozone-layer-destroying materials in the Montreal Protocol. Therefore substitutes of Halon agent has been developed including inert gas extinguish system, which is one of the most widely used fire extinguishing system. This study intended to increase the efficiency of inert gas extinguishing agent by using inert gas additives. As IG-541 shows high extinguishing power, the experiment was performed to measure the effects of gaseous additives to it. Cup-burner fire extinguishing apparatus was used with n-Heptane fuel. Among many of pure inert gaseous agents, Helium showed the most excellent extinguishing power. When Helium was added to IG-541, fire extinguishing power was increased and the concentration of oxygen in chimney also risen. By adding Helium to IG-541, the effectiveness of inert gas fire extinguishing system is able to be increased.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.553-560
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• 2010

The characteristics of syngas-oxyfuel combustion has been investigated experimentally in the present study. Experimental measurements were conducted to aid a fundamental design of a syngas-oxyfuel combustor with a double coaxial burner configuration. To examine the effects of different syngas fuels on combustion characteristics, various fuel types are utilized such as commercial coal gases (Texaco, Shell), COG (cokes oven gas), and $CH_4$ as a main component of natural gas. $CO_2$ was added to the four fuel types as a diluent gas to reduce the flame temperature. The flame images and emission characteristics of NOx and CO were examined for various equivalence ratio and $CO_2$ dilution ratio. The results show that CO emission was rapidly increased as equivalence ratio approached the stoichiometry condition by reducing the amount of oxygen. As the $CO_2$ dilution increased, CO emission increased while NOx emission decreased due to reduced flame temperature. When the syngas-oxyfuel combustor is operated with 20~40% of $CO_2$ dilution ratio, the CO and NOx emission levels were kept below 50 ppm and 25 ppm, respectively, with a high concentration of $CO_2$ over 95 vol.% in exhaust gases.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.403-412
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• 2006

The effect of a wall temperature on the soot deposition process from a diffusion flame to a solid wall was investigated in a microgravity environment to attain in-situ observations of the process. The fuel for the flames was an ethylene ($C_2H_4$). The surrounding oxygen concentration was 35% with surrounding air temperatures of $T_a=600K$. In the study, three different wall temperatures. $T_w$=300, 600, 800K, were selected as major test conditions. Laser extinction was adopted to determine the soot volume fraction distribution between the flame and burner wall. The experimental results showed that the maximum soot volume fractions at $T_w$=300, 800 K were $8.8{\times}10^{-6},\;9.2{\times}10^{-6}$, respectively. However, amount of soot deposition on wall surface was decreased because of lower temperature gradient near the wall with increasing wall temperature. A numerical simulation was also performed to understand the motion of soot particles in the flame and the characteristics of the soot deposition to the wall. The results from the numerical simulation successfully predicted the differences in the motion of soot particles by different wall temperature near the burner surface and are in good agreement with observed soot behavior that is, the 'soot line', in microgravity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.9
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• pp.1175-1182
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• 2001

Chemical compositions of polydisperse SiO$_2$/TiO$_2$multicomponent aggregates were measured for different heights from the burner surface and different mobility diameters of aggregates. SiO$_2$/TiO$_2$multicomponent particles were generated in a hydrogen/oxygen coflow diffusion flame from two sets of precursors: TTIP(titanium tetraisopropoxide), TEOS(tetraethylorthosilicate). To maintain 1:1 mole ratio of TTIP:TEOS vapor, flow rate of carrier gas $N_2$was fixed at 0.6lpm for TTIP, at 0.1lpm for TEOS. In-situ sampling probe was used to supply particles into DMA(differential mobility analyzer) which was calibrated with using commercial DMA(TSI, model 3071A) and classifying monodisperse multicomponent particles. Classified monodisperse particles were collected with electrophoretic collector. The distributions of composition from particles to particle were determined using EDS(energy dispersive spectrometry) coupled with TEM(transmission electron microscope). The chemical(atomic) compositions of classified monodisperse particle were obtained for different heights; z=40mm, 60mm, 80mm. The results suggested that the chemical(atomic) composition of SiO$_2$decreased with the height from burner surface and the composition of SiO$_2$and TiO$_2$approached to the value of 1 to 1 fat downstream. It is also found that the composition of SiO$_2$decreases as the mobility diameter of aggregate increases.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.441-446
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• 2000

Chemical compositions of monodisperse $SiO_2/TiO_2$ multicomponent aggregates were measured for different heights from the burner surface and different mobility diameters of aggregates. $SiO_2/TiO_2$ multicomponent particles were generated in a hydrogen/oxygen coflow diffusion flame from two sets of precursors: TTIP (titanium tetraisopropoxide), TEOS(tetraethylorthosilicate). To maintain 1:1 mole ratio of TTIP:TEOS vapor theoretically, flow rate of carrier gas $N_2$ was fixed at 0.61pm for TTIP, at 0.11pm for TEOS. In situ sampling probe was used to supply particles into differential mobility analyzer(DMA) which was calibrated with using commercial DMA(TSI 3071A) and classifying monodisperse multicomponent particles. Classified particles were collected with electrophoretic collector. The distributions of composition from particle to particle were determined using EDS (energy dispersive spectrometry) coupled with TEM (transmission electron microscope). The chemical (atomic) compositions of classified monodisperse particle were obtained for different heights; z=40mm, 60mm, 80mm. The results suggested that the atomic composition of $SiO_2$ decreased with the height from burner surface and the composition of $SiO_2$ and $TiO_2$ approached to the value of 1 to 1 in far downstream. It is also found that the composition of $SiO_2$ decreases as the mobility diameter of aggregate increases.

• Polymer(Korea)
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• v.26 no.2
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• pp.200-208
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• 2002

Two-component polyurethane flame-retardant coatings were prepared by blending trichloro lactone modified polyesters (TAPTS) and isocyanate, Desmodur IL. Polycondensation reaction of trichlorobenzoic acid (TBA) as a flame-retardant component, and adipic acid with trimethylolpropane, polycaprolactone 0201, and 1,4-butanediol gave the corresponding TAPTs. The content of TBA was adjusted from 10 to 30 wt% in our experiment. It was found that various properties of these new flame-retardant coatings were comparable to other non-flame-retardant coatings. We also carried out three different tests for the measurement of flammability of flame -retardant coatings. The results of vertical burning test for the coatings containing more than 20 wt% of TBA were determined as 'no burn'. The results of flammability test for the coatings with 20 and 30 wt% of TBA contents indicated the limiting oxygen index (LOI) values of 25% and 27% respectively, which implied relatively good flame retardancy. They also showed the char length of 3.6-5.2 cm according to $45^{\circ}$ Meckel burner test, which can be classified as the first grade flame-retardant coatings.