• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.25-27
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• 2012

In this paper, combustion process in the perforated silicon carbide(SiC) tube using a two dimensional approaches with GRI Mechanism 1.2 was investigated. The computational mesh structure which is divided into $60{\times}15$ and boundary conditions are set to constant mass flow rate at the inlet and constant pressure condition at the outlet respectively. Its result shows that the temperature on this peak was roughly 100K higher than the adiabatic flame temperature of 2223K for a free laminar flame at these conditions.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.23-33
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• 1999

A turbulent non-premixed ethylene flame, which was set up in a vertical wind tunnel, was examined to understand the effect of turbulent mixing on formations of soot and gaseous species in the flames. Temperature and velocity profiles were measured using uncoated thermocouples and LDV system. Gaseous samples were withdrawn by using a water cooled stainless iso-kinetic gas sampling probe. The samples for inorganic compounds and light hydrocarbons were collected with sampling bottles and were analyzed by a gas chromatography. The samples for aromatic hydrocarbons were collected on a sorbent tube and were analyzed on a GC/MS system. Some of main results were followed. CO and $CO_2$ were measured relatively in early part of flame and the concentration of CO was greater than that of $CO_2$ all over the early flame region due to the scavenging of the oxidizing species OH by soot particles. Aromatic hydrocarbons were measured at x/D=122 along the radial direction and main important species were benzene, xylene, toluene, styrene, indene, naphthalene. The peak points of these compounds occurred at r/D=0.8 apart from the center of flame, around in which the concentration of $C_2H_2$ decayed relatively rapidly from the maximum value.

• Journal of the Korean Society of Safety
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• v.26 no.1
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• pp.21-26
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• 2011

Extinction and ignition characteristics of $CH_4$-air counterflow diffusion flame were numerically investigated using a Flame-Controlling Method(FCM). A skeletal reaction mechanism, which adopts 17 species and 58 reactions, was used in the simulation. The extinction and ignition conditions of the $CH_4$-air diffusion flames were investigated with varying the global strain rate. Upper and middle branches of S-curve for the peak temperature in the inverse of the global strain rate space were obtained with the FCM. The structures of diffusion flames in the upper and middle branches of S-curve were compared. It was found that the global strain rate was not correlated with the local strain rate well in the low global strain rate region. It is expected that the FCM is very useful to obtaining the extinction and ignition condition of diffusion flame, such as fires.

• Textile Coloration and Finishing
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• v.34 no.4
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• pp.217-223
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• 2022

Flame-retardant finished silk fabrics could release carcinogenic formaldehyde resulting from the conventional finishing agents. New water-soluble cyclophosphazene derivative can be used as a formaldehyde-free flame retardant for the silk protein. Dichloro tetrakis{N-[3-dimethylamino)propyl]methacrylamido}cyclophosphazene(DCTDCP) can be cured by heat or UV irradiation as a durable flame retardant for the silk fabrics. Treatment conditions were optimized including curing temperature and time, finishing formulations, and UV energy. At the 30% DCTDCP application, peak HRR and THR decreased by 42.6% and 49.6% respectively compared to the pristine silk fabrics. Also char residue increased up to 48% from 11% indicating solid-phase retarding mechanism. The flame-retardant silk fabrics showed a LOI of 31.1 and the washed sample maintained a LOI of 26.8 even after ten laundering cycles.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.479-485
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• 1996

Volatile organic compounds are air pollutants exhausting from industrial process, evaporation of solvent, and so on. Most of VOCs are the combustible gas of low calorific value as it is diluted by air. The systems burning such a hazardous gas need to increase enthalpy in order to increase flame stability. In this study an incinerator with reciprocating flow in the honeycomb ceramic has been used for the experiment of VOCs control. By the reciprocating flow system, the enthalpy of combustion gas is effectively regenerated into the enthalpy increases of the combustible gas through the honeycomb ceramic, which provides a heat storage. The position of the reaction zone is strongly dependent on the parameters of mixture velocity and time frequency. Flame front is changed to the point where burning velocity is coincided with burning velocity in the honeycomb ceramic. In this system it is important that flame front should be located symmetrically at the center of honeycomb ceramic for the purpose of increasing the reaction rate at one point. Peak temperature becomes higher with decreasing time frequency, at which the flow direction is regularly reversed.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.79-84
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• 2004

For the non-premixed interacting jet flames, it has been reported that if eight small nozzles are arranged along the circle of 40 $^{\sim}$ 72 times the diameter of single jet, the flames are not extinguished over 2oom/s. In this research, experiments were extended to the partially premixed cases to reduce both flame temperature and NOx emission. Nine nozzles were used- eight was evenly located along the perimeter of the imaginary circle and one at the geometric centre. The space between nozzles, S, the equivalence ratio, ${\Phi}$, the exit velocity and the role of the jet from the centre nozzle were considered. Normally, flame was lifted and flame base was located inside the imaginary circle made by the nozzle. As nozzles went away from each other, blowout velocity increased and then decreased. The maximum blowout velocity diminished with the addition of air to the fuel stream. When the fuel and/or oxidizer were not fed through the centre nozzle, the maximum blowout velocity obtained by varying Sand ${\Phi}$ was around 160m/s. Optimum nozzle separation distance at which peak blowout velocity obtained also decreased with ${\Phi}$ decrease. Flame base became leaner as approaching to the blowout. It seemed that lots of air was supplied to the flame stabilizing region by the entrainment and partially premixing. To approve this idea and to enhance the blowout velocity, fuel was supplied to the centre region. With the small amount of fuel through the centre nozzle, partially premixed flame could be sustained till sonic velocities. It seemed that the stabilizing mechanism in partially premixed interacting flame was different from that of non-premixed case because one was stabilized by the fuel supply through the centre nozzle but the other destabilized.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.71-79
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• 2005

For the non-premixed interacting jet flames, it has been reported that if eight small nozzles are arranged along the circle of $40{\sim}72$ times the diameter of single jet, the flames are not extinguished even in 200m/s. In this research, experiments were extended to the partially premixed cases to reduce both flame temperature and NOx emission. Nine nozzles were used- eight was evenly located along the perimeter of the imaginary circle and one at the geometric centre. The space between nozzles, S, the equivalence ratio, ${\phi}$, the exit velocity and the role of the jet from the centre nozzle were considered. Normally, flame was lifted and flame base was located inside the imaginary circle made by the nozzle. As nozzles went away from each other, blowout velocity increased and then decreased. The maximum blowout velocity diminished with the addition of air to the fuel stream. When the fuel and/or oxidizer were not fed through the centre nozzle, the maximum blowout velocity obtained by varying S and ${\phi}$ was around 160m/s. Optimum nozzle separation distance at which peak blowout velocity obtained also decreased with ${\phi}$ decrease. Flame base became leaner as approaching to the blowout. It seemed that lots of air was supplied to the flame stabilizing region by the entrainment and partially premixing. To approve this idea and to enhance the blowout velocity, fuel was supplied to the centre region. With the small amount of fuel through the centre nozzle, partially premixed flame could be sustained till sonic velocities. It seemed that the stabilizing mechanism in partially premixed interacting flame was different from that of non-premixed case because one was stabilized by the fuel supply through the centre nozzle but the other destabilized.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1989-1998
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• 1995

Characteristics of the flame propagation for normal and abnormal combustion in hydrogen premixture in a cylindrical constant-volume combustion chamber are studied numerically. A detailed hydrogen oxidation kinetic mechanism, mixture transport properties and a model describing spark ignition process are used. The calculated pressure-time history of the stable deflagration wave propagation agrees well with the experiment. The ignition of the premixture in the unburned gas, initiated by the hot spot, causes a transition from deflagration to detonation under some initial temperature and pressure. Under the initial conditions with high temperature and pressure, excessive ignition energy initiates a strong blast wave and a detonation wave that follows. The chemical reaction in the detonation wave is much more vigorous than that in the deflagration wave and the peak pressure in the detonation wave is much higher than the equilibrium value.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.51-59
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• 2002

In this study, cycle simulation was performed to investigate the effect of EGR on combustion characteristics and emissions including NO and soot using a two-zone model in a DI diesel engine. The NO formation was well predicted for different EGR rate and temperature using a two-zone model. The oxygen in the inlet charge was replaced by CO$_2$ and H$_2$O with EGR. The reduction in the inlet charge oxygen resulted in very large reduction in NO level at the same inlet charge temperature. The effect of EGR was to reduce the burned gas temperature. When EGR was increased from 0% to 15%, the peak flame temperature was decreased by 50$\^{C}$ and it caused about 57% NO reduction. EGR caused increase of the overall inlet charge temperature which offset some of benefit of lower flame temperature resulting from O$_2$ displacement. Cooling the EGR was confirmed to provide additional benefits by lowering NO emission. It also reduced soot emission.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.45-52
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• 2010

The purpose of this study is application to flame retardant powder coating(FRPC) material consisting of ammonium polyphosphate(APP) and magnesium hydroxide($Mg(OH)_2$) as a halogen free flame retardant into thermoplastic resin(LDPE-g-MAH). For improvement of adhesion, LDPE-g-MAH was synthesized from low density polyethylene(LDPE) and maleic anhydride(MAH). The mechanical properties as melt flow index, pencil hardness, cross-hatch adhesion and impact resistance of FRPC were measured. Also, the limited oxygen index(LOI) values were measured 17.3vol%, 31.1vol% and 33.7vol% for LDPE-g-MAH, FRPC-3(APP 15wt%, $Mg(OH)_2$ 15wt%) and FRPC-5(APP 30 wt%), respectively. The thermo gravimetry/differential thermal analysis(TG/DTA) of FPRC-3 was observed endothermic peak at $340^{\circ}C$ and $450^{\circ}C$, it was confirmed predominant thermal stability though the wide temperature range by APP and $Mg(OH)_2$. It was showed V-0 grade for FRPC-3 and FRPC-4(APP 20wt%, $Mg(OH)_2$ 10wt%) that a char formation and drip suppressing effect, and combustion time reduced by UL94(vertical burning test). It was confirmed that flame retardancy was improved with the synergy effect because of char formation by APP and $Mg(OH)_2$.