• Fire Science and Engineering
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• v.25 no.2
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• pp.126-131
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• 2011

This study is intended to understand mass loss rate and air entrainment rate of the whirl fire by height of fire source. Liquid fuels were methanol and n-Heptane which are used in many studies of whirl fire. Size of vessel was 100 mm ${\times}$ 100 mm ${\times}$ 50 mm and the vessel was made by stainless steel. When height of fire source changed from 0 cm to 30 cm, air entrainment rate showed the fastest in case of 0 cm. And in the same height of fire source, average and maximum air entrainment rate showed the fastest in 30 cm of anemometer. From the results of whirl fire for methanol and n-Heptane, mass loss rate and air entrainment rate of n-Heptane was found to faster 1.33 to 1.58 times and 4.38 to 5.44 times compared with methanol, respectively. Consequently, mass loss rate and air entrainment rate in whirl fire was able to identified decrease as height of fire source increases and the higher the heating value, increases the that's value.

• Fire Science and Engineering
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• v.26 no.3
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• pp.73-78
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• 2012

This study is intended to understand flame behavior of pool and whirl fire by height of fire source. Liquid fuel was methanol which is used in many studies for pool and whirl fire. Size of vessel was $100{\times}100{\times}50$ and the vessel was made by stainless steel. Combustion time, mass loss rate, flame temperature, flame height and air entrainment rate from the outside to flame were measured, and flame behavior was visualized with video camera. Based on the experiment, it was found that combustion characteristics by height of fire source got a more effect on whirl fire than pool fire.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.114-122
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• 1999

Reignition as special cases of acoustic pressure responses of flame are numerically studied by employing methanol droplet flame as a laminar flamelet. Quasi-steady flame responses occur in the range of small amplitude, low frequency oscillation. Reignition phenomena can occur when, by increasing the frequency of large amplitude acoustic pressure, the magnitude of characteristic acoustic time is the same order of that of characteristic reaction time of flames. And more increasing of amplitude of acoustic pressure induces the direct extinction of flame. Flame can sustain its own intensity even under the steady extinction temperature in case of high frequency acoustic oscillation, and this tendency is remarkable with increasing frequency. Reignition regime with respect to amplitude and frequency of acoustic pressure doesn't exist in low frequency($10^2$ Hz, in this study), but broadens with frequency of acoustic pressure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4671-4676
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• 2010

This study is intended to understand flame behavior of the pool fire by height of fire source. Liquid fuels were methanol and n-Heptane which are used in many studies of pool fire. Size of vessel was $100mm{\times}100mm{\times}50mm$ and the vessel was made by stainless steel. Combustion time, mass loss rate, flame temperature, flame height and air entrainment rate from the outside to flame were measured, and flame behavior was visualized with video camera. Based on the experiment, it was found that combustion characteristics of pool fire was decreased according to increase of height of fire source because entrainment volume of relative cold air was increased from the outside to flame.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.389-396
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• 1994

It is very important to clarify the ignition and flame propagation processes of methanol fuel in the Spark-ignition engine. High speed Schlieren photography and pressure trace analyses were used to study on combustion characteristics of methanol fuel in a constant volume chamber. Methanol-air mixtures equivalence rations from lean limit to 1.4 were ignited at initial pressure (0.1, 0.3, 0.5 MPa), temperature (313 343, 373 K) and ignition energy (40, 180 mJ). As the result of this study, we verified the characteristics such as ignition delay, effective thermal efficiency, flame propagation velocity, lean limit, ignitability and combustion duration. Obatained results are as follows. (1) The time to 10% reach of maximum pressure was 40-50% of the total combustion duration for this experimental condition hardly affected by equivalence ratio. (2) The Effective thermal efficiency, as calculated from maximum pressure was the highest when the mixture was slightly lean $({\phi} 0.8-0.9)$ and maximum pressure was the highest when the mixiture was slightly rich $({\phi} 1.2-1.2).$

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.37-42
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• 2001

This paper computes the bluff-body stabilized jet and flame. This study numerically investigates the nonpremixed $C_{2}H_{4}-air$ jet for the nonreacting case and the nonpremixed $CH_{3}OH-air$ turbulent flames for the reacting case using the laminar flamelet model on modified KIVA2 code. And this study predicts $NO_{x}$ formation characteristics using Eulerian Particle Flamelet Model. In the present study, the turbulent combustion model is applied to analyze both nonreacting and reacting case. And both standard $k-{\varepsilon}$ model and modified $k-{\varepsilon}$ model are used in nonreacting case. Calculations are compared with experimental data in terms of velocity, mixture fraction, mixture fraction Root Mean Square and Temperature. The present model correctly predicts the essential features of flame structures and $NO_{x}$ formation characteristics in the bluff-body stabilized flames.

• Resources Recycling
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• v.16 no.5
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• pp.41-45
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• 2007

Tetramethylorthosilicate (TMOS) and silica nanopowder were synthesized from the waste silicon sludge containing 15% weight of silicon powder. TMOS, a precursor of silica nanopowder, was firstly prepared from the waste silicon sludge by catalytic chemical reaction. The maximum recovery of the TMOS was 100% after 5 hrs regardless of reaction temperature above $130^{\circ}C$. But the initial reaction rate became faster while the reaction temperature was higher than $150^{\circ}C$. As the methanol feedrate Increased from 0.8 ml/min to 1.4 ml/min, the yield of reaction was not varied after 3 hrs. Then, silica nanopowder was synthesized from the synthesized TMOS by flame spray pyrolysis. The morphology of as-prepared silica nanopowder was spherical and non-aggregated. The average particle diameters ranged from 9 nm to 30 nm and were in proportional to the precursor feed rate, and precursor concentration.