• Journal of the Korean Society of Safety
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• v.23 no.4
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• pp.30-35
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• 2008

The present study has been conducted to examine the effect of grid resolution on the predicted results for electric cable fire using pyrolysis model in FDS(Fire Dynamics Simulator, version 5). The grid independent test for different grid resolutions has been performed for a PE coating cable and the grid resolution is defined by the non-dimensional characteristic length of fire and mean grid size. The calculated maximum heat release rate and mean flame spread rate were almost constant for higher grid resolution of 20${\sim}$25 and the computing time for the grid resolution takes approximately 20hours to solve flame propagation with pyrolysis model. The geometrical simplification of a electric cable dose not greatly affect on the maximum heat release rate and flame spread rate and the rectangular approximation of cable shape gives acceptable result comparing with the round cable with stepwise grid.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.12
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• pp.1041-1047
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• 2001

In this paper, reduction characteristics of the ac flashover voltage in the horizontal air gap of sphere-sphere/needle-needle electrode system were investigated when the combustion flame was present near the high-voltage electrodes. The voltage and current waveforms were measured, when the flashover is occurred, in order to examine the flashover polarity by flame. The reduction characteristics of ac flashover voltage were discussed with the thermal ionization process, the relative air density and the deflection phenomena in the shape of flames that changed by the corona wind and coulomb\`s force. As the results of an experimental investigation, It was found that the reduction of flashover voltages in sphere-sphere system, in comparison with the no-flame case, are 79.9 [%] for k=0, 82.9 [%] for k=0.5, 87.5 [%] for k=1.0, 85.0 [%] for h=0 [cm], 40.8 [%] for h=5 [cm] and 28.2 [%] for h=9 [cm] when ac voltage is applied.

• Fire Science and Engineering
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• v.27 no.6
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• pp.89-96
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• 2013

The purpose of this study is to check the fire origin and cause of the fire by observing the shape of the flame propagation in air-conditioner indoor unit through the fire tests. We supposed that the flame is spread from the surroundings to the top of the air-conditioner and ignited on top of the air-conditioner with n-heptane. And then repeated this experiment twice under the same conditions. After the ignition, refrigerant filled in air-conditioner and lubricating oil exploded with large explosion and flame having high temperature and pressure belched out rapidly due to bursting refrigerant pipe linked air-conditioner between 734 seconds and 559 seconds. After result of checking the combustion residue we found that almost all of that was lost except a part of the evaporator, motor and metal. The position of short-circuit traces of wiring for the air-conditioner ignited itself is similar to that of fire damage by external flame. Therefore, we verified that it is not certain to determine the ignition cause and point by only the shape of the combustion residues.

• Journal of the Korean Society of Combustion
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• v.14 no.4
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• pp.33-40
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• 2009

Waste Thermal Pyrolysis Melting process was proposed and has been studied in order to prevent air pollution by dioxin and fly ash generated from combustion process for disposal of waste. In this study, applicability as the fuel of diffusion burner of synthesis gas formed from Waste Thermal Pyrolysis process was addressed. Results showed that there is no big difference in the flame shape between MNDF and SNDF, and lift off was detected in MIDF but flame is more stable in SIDF which contains hydrogen with high combustion velocity as flow rate in first nozzle is increased. And radiation heat flux in inverse diffusion flame of synthesis gas was found to be more by 1.5 times than that in inverse diffusion flame of methane because of higher mole fraction of $CO_2$ with high emissivity in product gas.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.285-288
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• 2014

Experiments have been performed for the burners used in the non-oxidizing direct fired furnaces for the cold rolled plate to investigate the effect of fuel/air mixing patterns of the burner nozzle on flame shape, temperature and combustion gas concentration. CFD simulation has also been performed to investigate the mixing state of air-fuel for a nozzle mixing burner and a partially pre-mixing burner. A partially pre-mixing burner showed that flame temperature increased up to $26^{\circ}C$ on average compared than that of the nozzle mixing. It also showed that the mixing distance is important at the partially pre-mixing burner. Test results for a partially pre-mixing burner showed that the residual oxygen concentration and the volume ratio of $CO/CO_2$ of the flame were applicable to be used in field furnaces.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.233-234
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• 2014

Lean-rich combustion system was composed both fuel-lean and fuel-rich flame at once. Each of fuel-lean and fuel-rich combustion types to reduce Thermal $NO_x$ and obtain flame stability. This study was confirmed a stability of flame through variation of flame shape that EGR was applied and compared the emission characteristics of EGR lean-rich combustion system to normal premixed combustion system at real condition to review a utility of the system. As a result, emission index of $NO_x$ and CO generated from EGR lean-rich combustion system at global equivalence ratio is 0.85 just half level($NO_x$ 0.31 g/kg, CO 0.08g/kg) compared to the amount generated from normal premixed combustion system at equivalence ratio is 0.78.

• Elastomers and Composites
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• v.52 no.1
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• pp.27-34
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• 2017

In this experiment, blends of ethylene vinyl acetate rubber (EVM) with a vinyl acetate (VA) content greater than 40 wt% and ethylene propylene rubber (EPM) were prepared by mechanical mixing; a number of parameters of the blends, including oil resistance, morphological and dynamic mechanical properties and flame retardancy, were subsequently measured. In the $100^{\circ}C$ oil resistance test, both the ammonium polyphosphate/dipentaerythritol/expandable graphite (APP/DPER/EG) and aluminum hydroxide (ATH) flame retardant systems showed an increase in volume change with increasing EPM content. For the ATH system, the dispersion shape was coarse and aggregation was observed. The results of a dynamic mechanical test showed slightly higher E' and E'' for the APP/DPER/EG flame retardant system when compared to the single ATH system. For both the APP/DPER/EG and ATH systems, the limited oxygen index (LOI) tests performed at increasing content of EPM showed a LOI value higher than 30, indicating excellent flame resistance.

• Journal of the Korean Society of Combustion
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• v.14 no.1
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• pp.19-24
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• 2009

A novel low NOx oil burner of 0.7 MW (for a 1 ton steam/hr industrial boiler) was designed and tested to investigate the combustion characteristics through in-flame measurement and flue gas analysis. Flame shape was observed by CCD camera and $CH^*/{C_2}^*$ radical distribution in the flame were observed, along with measurement of flue gas composition such as NOx and CO, for various heat inputs, excess airs and pressure of the fuel spary nozzles. The flame showed the two-zone structure: fuel-rich and fuel-lean zone, which was very favorable for the low-NOx combustion, and the NOx emission for haevy oil combustion was significantly reduced to < 150 ppm at 4 % $O_2$, compared with the NOx level of a conventional heavy oil burner.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.680-685
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• 2000

Investigation on ignition and flame propagation of pyrolyzing fuel in a cylindrical enclosure is accomplished. The pyrolyzing fuel of cylindrical shape is located in an outer cylinder sustained at high-temperature. Due to gravity, the buoyancy motion is inevitably incurred in the enclosure and this affects the flame initiation and propagation behavior. The radiative heat transfer plays an important role since a high temperature difference is involved in the problem. Numerical studies have been performed over overheat ratio, and vertical fuel eccentricity. The location of flame onset is affected by the vertical eccentricity of inner pyrolyzing fuel as well as thermal conditions applied.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.597-602
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• 2012

Flame deflector is an important plan item for protecting propulsion system model, test facility, and life. This study suggests the way of flame deflector design in test facility evaluating performance of 75 ton and 300ton PSM. The flame deflector height was designed as 30m using a slope way in establishment location of facility. The flame deflector suitability was considered according to the shape of open and closed type. Also the cooling duct was made as modeling in accordance with core and side injection type.