• Journal of the Korean Wood Science and Technology
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• 제36권2호
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• pp.1-8
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• 2008

This study was performed to evaluate the burning characteristics of wood-based materials and the effect of surface treatment of fire retardant using cone calorimeter. Four types of wood-based materials, such as Plywood, Oriented Strand Board (OSB), Particle Board (PB) and Medium Density Fiberboard (MDF), were tested at a constant heat flux of $50kW/m^2$ to investigate the time to ignition, mass loss rate, heat release rate, effective heat of combustion, etc. In addition, each type of wood-based material was tested at the same heat flux after fire retardant treatment on the surface to evaluate the effect of this treatment on the burning characteristics. The surface treatment of fire retardant, by the amount of $110g/m^2$, delayed the time to ignition almost twice. However, it was indicated that heat release rate, mass loss rate, and effective heat of combustion were not significantly affected by fire retardants treatment for all types of wood-based materials.

• 대한기계학회논문집
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• 제17권12호
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• pp.3187-3195
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• 1993

Combustion of liquid-fuelled combustion in a high-temperature vitiated-air stream was studied. The mathematical formulation comprise the application of Eulerian conservation equation to the gas phase and Lagrangian equation of droplet motion. The latter is coupled with a droplet-tracking technique (PSI-CELL Model) which regard the droplet phase as a source of mass, momentum, and energy to the gaseous phase. Reaction rate is determined by taking into account the Arrhenius reaction rate based on a single-step reaction mechanism. The calculated profiles show somewhat uncertainess at the upstream, but bases data for designing the combustor followed by 2-phase flow were obtained.

• 한국연소학회지
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• 제20권2호
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• pp.46-53
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• 2015

The relationship between mass transfer and reaction within the washcoat is investigated in a monolith type micro-scale Pt-catalytic combustor. Nondimensionalized balance equation of butane is applied in a simplified washcoat geometry having the shape of slab. Both Thiele modulus and effectiveness factor are considered to compare reaction rate and diffusion rate according to the operation temperature and the diameter of alumina nano-pores. The effect of reaction becomes stronger as the temperature increases, while the effect of diffusion becomes relatively dominant as the diameter of nano-pores increases. From the analysis of butane distribution within the washcoat, design criterion for the thickness of washcoat is discussed.

• Journal of Mechanical Science and Technology
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• 제20권9호
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• pp.1436-1448
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• 2006

This paper describes the effects of injection rate shaping on the combustion, fuel consumption and emission of $NO_x$ and soot of a medium duty diesel engine. The focus is on the influence of four different injection rate shapes, square type 1, square type 2, boot and ramp, with a variation of maximum injection pressure and start of injection (SOI). The experiments were carried out on a 1 liter single cylinder research diesel engine equipped with an amplifier-piston common rail injection system, allowing the adjustment of the injection pressure during the injection event and thus injection rate as desired. Two strategies to maintain the injected fuel mass constant were followed. One where rate shaping is applied at constant injection duration with different peak injection pressure and one strategy where rate shaping is applied at a constant peak injection pressure, but with variable injection duration. Injection rate shaping was found to have a large effect on the premixed and diffusion combustion, a significant influence on $NO_x$ emissions and depending on the followed strategy, moderate or no influence on soot emission. Only small effects on indicated fuel consumption were found.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.152-156
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• 2007

로켓 엔진에서 연소챔버 내의 압력섭동에 의해 발생되는 추진제 유량변동에 대한 현상을 파악하는 것은 매우 중요하다. 이를 위해 압력섭동이 발생되었을 때 유량변동의 측정에 대한 정량화를 수행하였다. 오리피스 내의 유동의 속도를 알기 위해 오리피스 내의 압력을 측정한 후 이론식에 입각하여 속도를 풀었고, 액막두에 측정장치를 이용하여 오리피스 내에서의 면적을 측정하였다. 정상상태에서의 속도 및 유량을 분석값과 비교한 결과, 매우 작은 오차내에서 일치함을 알 수 있었다. 따라서, 본 연구에서 도출된 이론식을 바탕으로 비정상상태에서의 유량 변동 측정을 수행하는데 큰 역할을 할 수 있을 것이다.

• Asian Journal of Atmospheric Environment
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• 제6권1호
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• pp.67-72
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• 2012

The chemical characterization of water-soluble organic carbon in ash emitted from a coal combustion boiler has not been reported yet. A total of 5 ash samples were collected from the outlet of an electrostatic precipitator in a commercial 500 MW coal-fired power plant, with their chemical characteristics investigated. XAD7HP resin was used to quantify the hydrophilic and hydrophobic water-soluble organic carbons (WSOC), which are the fractions of WSOC that penetrate and remain on the resin column, respectively. Calibration results indicate that the hydrophilic fraction includes aliphatic dicarboxylic acids and carbonyls (<4 carbons), amines and saccharides, while the hydrophobic fraction includes aliphatic dicarboxylic acids (>4-5 carbons), phenols, aromatic acids, cyclic acid and humic acid. The average mass of the WSOC in the ash samples was found to depend on the bituminous coal type being burned, and ranged from 163 to 259 ${\mu}g$ C/g of ash, which corresponds to 59-96 mg C of WSOC/kg of coal combusted. The WSOC mass accounted for 0.02-0.03 wt% of the used ash sample mass. Based on the flow rate of flue gas produced from the combustion of the blended coals in the 500 MW coal combustion boiler, it was estimated that the WSOC particles were emitted to the atmosphere at flow rates of 4.6-7.2 g C/hr. The results also indicated that the hydrophilic WSOC fraction in the coal burned accounted for 64-82% of the total WSOC, which was 2-4 times greater than the mass of the hydrophobic WSOC fraction.

• 한국산업융합학회 논문집
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• 제18권4호
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• pp.197-206
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• 2015

Recently the automobile engine has been developed in achieving the high performance, fuel economy, and emission reduction. In a conventional spark ignition engine the fuel and air are mixed together in the intake system, inducted through the intake valve into the cylinder, and then compressed. Under normal operating conditions, the combustion is initiated towards the end of the compression stroke at the spark plug by an electric discharge. Following inflammation, a flame develops and propagates through this premixed fuel-air mixture. Therefore the state of mixture is very important in the combustion and emission characteristics. In this study the combustion and emission characteristics were tested and analyzed with changing the mixture composition and engine operating parameters in order to improve the combustion and performance in engine.

• 대한기계학회논문집B
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• 제31권3호
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• pp.292-299
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• 2007

In gas turbine technology, the flame stability is inherently greater in conventional diffusion type combustion over a wider range fuel to oxidizer ratio. However, premixed type combustion which has narrow flame stability region, is widely used due to environmental reason. It has been observed in experiments that combustion instability of low frequency (${\sim}10Hz$) results from the modulation of equivalence ratio at fuel injection hole when a pressure fluctuation propagates upwards along the channel of the burner under an unchoked fuel flow condition. In this study, a commercial program was used to determine how the fuel flow rate changed with respect to the pressure, velocity of the fuel flow and the mass fraction in a choked and an unchoked condition. The calculation focuses on the upstream of the dump plane to know how the forced pressure with the fuel injection conditions affects the modulation of the equivalence ratio. Therefore, it is found that pressure fluctuation leads to oscillation of mass flow rate and then results in equivalence ratio modulation under the unchoked fuel flow condition.

• 한국화재소방학회논문지
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• 제22권5호
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• pp.72-78
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• 2008

본 연구에서는 EPS 샌드위치 패널 심재에 대한 일정한 외부 복사열에 의한 질량감소속도와 열방출특성을 분석하였다. 일정한 외부 복사열원에 노출된 EPS 샌드위치 패널 심재의 질량감소속도와 열방출특성을 분석하기 위해 3가지 Type의 시료를 사용하였으며, 연소열을 측정하기 위해 Oxygen bomb calorimeter를 질량감소속도와 열방출특성을 분석하기 위해 Mass loss calorimeter를 사용하였다. 질량감소속도와 열방출 특성을 분석하기 위해 $100mm{\times}100mm{\times}50mm$ 크기의 시료를 사용하였다. 연구결과 50 kW/$m^2$의 외부복사열원에서 평균질량감소속도는 Type A와 B의 경우 각각 2.7 g/$m^2s$, 2.8 g/$m^2s$로 비슷한 경향을 나타낸 반면, Type C는 2.3 g/$m^2s$로 상대적으로 낮게 나타났으며, 평균열방출속도는 Type B와 C의 경우 각각 47.19 kW/$m^2$, 50.06 kW/$m^2$으로 큰 차이가 없었으나, Type A는 58.23 kW/$m^2$으로 상대적으로 높게 나타났다. 열방출특성의 결과를 캐나다 분류체계에 적용할 경우 Type A와 C의 경우 C-3등급, Type B의 경우 C-2등급으로 분류되었다. 향후 콘칼로리미터법을 이용한 샌드위치 패널 심재에 대한 열방출율 특성과의 비교연구가 필요할 것으로 판단된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.524-527
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• 2004

Hybrid rocket had many advantage with compared to solid and liquid rockets. However, the engines have not yet been used in practical rocket systems, due mainly to the disadvantage of hybrid combustion, such as low fuel regression rate. In this study, lab-scale hybrid motor was designed and manufactured. And the methods of regression rate improvement were considered. Test firings with thrusts up to 300 N were conducted with GOX and transparent PMMA. Thrust was calculated with the pressure of the combustion chamber and the regression rate was measured in with variation of oxidizer flow rate. The regression rates showed a strong dependency on GOX mass flux. The frequency analysis technique of the bulk-mode oscillation of motor was applied to a hybrid rocket motor and was based on the principle that this frequency was inversely proportional to the square root of the chamber volume. Several problems and solutions of operating hybrid rocket were presented.