• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2175-2180
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• 2008

Oxy-fuel combustion has been gaining its significance as a means of migrating the green house effects. Some experimental measurements were conducted to investigate the characteristics of oxy-fuel combustion and to aid a fundamental design of a lab-scale oxy-fuel combustor with a coaxial burner. CO emission was measured along the combustor centerline while combustion of methane and oxygen diluted by CO2 took place. Substitution of CO2 with N2 indicates a possibility that some CO is formed by dissociation of CO2. Some parametric tests were also performed to see the mixing effects of reactant gases on CO emission by changing the gas injection velocity at the burner nozzles with various heat loads. The overall results indicate that CO emission was reduced when the reactants are injected at higher velocities of similar magnitude.

• 한국연소학회지
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• 제9권1호
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• pp.1-10
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• 2004

The results of a series of experiments executed by using two pilot-scale oxy-fuel burners are presented. The oxy-fuel burners are designed for maximum capacity of 50,000kcal/hr, 200,000kcal/hr and installed in the test furnace. The effects of turn-down ratio, excess oxygen ratio, nozzle exit velocity, injection angle, and swirl vane angle on the combustion characteristic are investigated. Temperature distributions are measured using R-type and Molybdenum sheathed C-type thermocouple at various points of the flame. The results showed that maximum temperature and mean temperature increase with the increase of turn-down ratio and momentum. The maximum flame temperature was increased about 35% compared to the case of equivalent air operated condition. In addition, optimum burner type, excess oxygen ratio and nozzle characteristics are obtained for this oxy-fuel glass melting furnace.

• 대한기계학회논문집B
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• 제32권7호
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• pp.504-512
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• 2008

The characteristics of nonpremixed oxy-fuel flame in a multi-jet burner were experimentally and numerically investigated. The overall flow rate of fuel and oxygen was fixed, and the oxygen feeding ratio (OFR) was varied by 0.25, 0.5, and 0.75. The results of numerical simulation were compared with the measured results which are temperature profile and direct flame observation. The probability density function (PDF) model was applied accounting to the description between turbulence and chemistry, and standard ${\kappa}-{\varepsilon}$ model was used for turbulent flow field. Equilibrium assumption is very reasonable due to fast chemistry of the oxy-fuel combustion. Thus, the equilibrium calculation based on Gibbs free energy minimization was guaranteed to generate the solution of the oxy-fuel combustion. The result was obtained by numerical simulation. The predicted radial temperature profiles were in good agreement with the measured results. The flame length was shorten and was intensified with the decrease of OFR because the mixture of fuel and oxidizer are fast mixed and burnt. The maximum temperature became lower as the OFR increased, as a consequence of large flame surface area.

• 대한기계학회논문집B
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• 제24권12호
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• pp.1662-1669
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• 2000

Various flame types are observed in a double concentric burner by varying equivalence ratio and flow rates in each tube. Observed flame types include bunsen-type flame, ring-shaped flame, outer lifted flame, inner lifted flame, and oscillatory lifted flame, The doman of existence of various flames is mapped with equivalence ratio and annular jet velocity. Each flame is investigated through direct photography and OH PLIF. As central air velocity increase, the blowout region is diminished and lifted oscillating flames are observed. Inner lifted flames are observed from bunsen flames or rich shaped flames by increasing central air velocity. For inner lifted flames, annular jet velocity, at flame liftoff decreases with increasing central air jet velocity. Axial velocity profile and temperature fie이 using LDV and CRS, respectively, for a typical inner lifted flame are also measured through which the role of tribrachial flame for stabilization in emphasized.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
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• pp.119-124
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• 2001

Propane coflow diffusion flames have been experimentally studied to investigate the liftoff and reattachment characteristics. Flame properties such as velocity and density distribution were measured by LDV and shadowgraphy, respectively. It is shown that as the velocity of coflowing air increases, liftoff velocity decreases nonlinearly in turbulent jets and linearly in laminar jets, while reattachment velocity decreases nonlinearly. Meanwhile, as inner nozzle tip thickness increases, liftoff velocity increases with the reattachment velocity nearly unchanged. Liftoff phenomena in these flames can be categorized into three classes as a function of coflow velocity, such as laminar liftoff, turbulent liftoff, and transient liftoff.

• 한국화재소방학회논문지
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• 제32권6호
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• pp.22-27
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• 2018

등유-산소 동축류 확산화염 버너에서 연료의 유량, 버너 외축에 공급되는 산화제의 온도, 불활성가스로 희석된 산화제의 특성이 화염 길이 변화 특성에 미치는 영향을 고찰해 보았다. 각 실험 조건에서 생성된 동축류 확산 화염은 쉴리렌 카메라를 이용하여 촬영한 뒤 디지털 이미징 프로세싱 기법을 적용하여 그 길이를 측정하였다. 실험결과를 통해 측정된 화염길이는 등유 연료의 유량과 산화제의 온도에 비례하여 증가하는 것을 확인할 수 있었다. 아울러, 산화제에 첨가되는 불활성가스의 희석량이 증가할수록 화염 길이는 증가하는 하였고, 특히 동일한 산소 농도에서 질소가스로 희석된 경우가 헬륨가스로 희석된 경우에 비해 화염길이가 큰 폭으로 증가하였다. 이는 유체의 점성 저항에 영향을 미치는 불활성가스의 희석이 화염 길이 변화에 영향을 미치는 주요 메카니즘이기 때문으로 판단된다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.70-75
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• 2004

The effect of electric fields on the stability of non-premixed laminar lifted flame in coflow jets has been investigated by applying high voltage alternative current (AC) to the nozzle of propane fuel. The stable lifted flame which exist in far field of jets, the liftoff height was not effected by applied voltage. This implies that the cold jet between the nozzle and flame base can be analyzed with the previous cold jet theory. Flame liftoff and reattachment velocities were also measured as function of applied voltage and frequency. The fuel jet velocity at flame liftoff and reattachment increased with increasing voltage, implying that the range of flame srability can be extended with the AC charging. However the liftoff velocity increased with frequency of AC charging on nozzle, whereas the reattachment velocity decreases with frequency. The liftoff and reattachment velocities were correlated linearly with voltage considering the effects of frequency.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.123-128
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• 2002

이중동축류 버너를 사용하여 에틸렌/프로판 및 에틸렌/메탄 혼합 연료의 매연생성 상승효과와 관련된 매연생성 메커니즘을 이해하기 위한 실험을 수행하였다. 매연체적분율, 광산란신호 및 PAH 형광신호를 측정한 결과 다음을 알 수 있었다. 에틸렌/프로판 혼합연료에서 연료공급 위치의 변화에 따른 매연생성특성의 변화는 대부분 synergistic 효과와 관련되는 것임을 알 수 있었다. 그러나 에틸렌/메탄 혼합연료의 경우 연료공급의 위치변화가 매연생성에 크게 영향을 주지 않았다. PAH 분포는 synergistic 효과에 의한 매연 생성 특성의 변화와 일관성이 없는 것이 관찰되었다. 따라서 synergistic 효과에 대한 PAH의 역할에 대한 이해가 필요함을 알 수 있었다.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.51-59
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• 2005

Co-flow laminar diffusion flames' temperature has been studied experimentally for ethylene$(C_2H_4)$ using a co-flow burner in order to investigate the characteristics of diffusion flame's temperature distribution. The temperature distributions in the flame were measured by rapid insertion of a R-type thermocouple. The measurement area was divided into three zones. 1st area was expect to created PAH zone, Il nd area was expect to form soot zone, which is known to generate most soot volume fraction, and III rd area was expect to from soot oxidization zone. Also The temperature along the flame y-axis as a fuel quantity was measured. As a results, we have measured temperature neglecting the effect of soot particles attached to the thermocouple junction, which is close to the nozzle and upstream zone has a unstable flow in co-flow diffusion flame and acquires that the flame y-axis temperature has a uniform temperature in the generated soot volume fraction zone(II nd).

• 대한기계학회논문집B
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• 제28권7호
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• pp.863-870
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• 2004

The temperature and soot particle measurement technique in a laminar diffusion flame has been studied to investigate the characteristics of soot particle with temperature using a co-flow burner. The temperature distribution in the flame were measured by rapid insertion of a R-type thermocouple and the soot particles by LEM/LIS techniques. In these measurement, soot volume fraction, number density and soot diameters were analyzed experimentally. As a results, the spacial distributions of particle volume fraction, soot diameter, and number density are mapped throughout the flame using the Rayleigh theory for the scattering of light by particles. A laser extinction method was used to measure the soot volume fraction and laser induced scattering method was used to measure the soot particle diameter and number density. Also, we measured temperature without the effect of soot particles attached to the thermocouple junction, which is close to the nozzle. In this result, we found that upstream zone has a unstable flowing in co-flow diffusion flame and the y-axis temperature of flame has a uniform temperature distribution in the most soot volume fraction zone.