• 대한기계학회논문집B
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• 제24권10호
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• pp.1351-1358
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• 2000

Two dimensional aerosol dynamics considering the effects of particle generation, coagulation, thermophoresis, sintering and convection has been studied to obtain the growth of non-spherical silica particles in conjunction with determining flame temperature by performing combustion analysis of premixed flat flame. Heat and mass transfer analysis includes 16 species, 29 chemical reaction steps together with oxidation and hydrolysis of SiCl4. The effect of radiation heat loss has also been included. The predictions of flame temperatures and the evolution of particle size distributions were in a reasonable agreement with the existing experimental data.

• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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• pp.267-271
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• 2009

The Marine Environment Protection Committee(MEPC) which is the IMO's specialized committee on marine pollution related matters deals with GHG related issues to discuss and compile possible approaches on technical, operational and market based measures to address GHG emissions from ships. The nitrous oxide($N_2O$) which remains generally in the atmosphere for around 114 years is one of the green house gases. The global warming potential of $N_2O$ is 310 times than $CO_2$ in the given period 100 years. It seems that the $N_2O$ formation is influenced by the nitrogen compound contained in the fuel which is named as "Fuel N" during the combustion process or the NOx, SOx and $H_2O$ through the emission gases before exhausted into the atmosphere. This paper has carried out an experimental study of the $N_2O$ concentration profiles by the change of $NH_3$ flows in the planner premixed combustion with using $C_3H_8$ and air.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.54-59
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• 2001

OH radical concentration have been measured in a methane-air partially premixed flames using PLIF. Excitation lines were selected $Q_{1}(6)$ branch, (1,0) band. The system is consisted of Nd:YAG laser, dye laser and frequency doubler to make pump beam for OH radical. On the direct photographs, flame height increases as fuel flow rate and equivalence ratio increase. And on the PLIF images, OH radical is distributed from premixed flame front to nonpremixed flame front through the flame structure with all equivalence ratio. OH overall concentrations increase with equivalence ratio. At the stoichiometric equivalence ratio, the peak of OH radical concentration exists strongly near the inner cone. As equivalence ratio is changed to richer, OH radical distribution goes thinly and the peak is increased as longitudinal direction. As the flow goes to the downstream, OH radical concentration decreases and broadens, because OH radical reacts with another species after OH formation at the initial oxidization. This phenomenon resembles radial distribution. At the l00cc fuel flowrate, the radial peak of OH radical exists from x/R=l.0 to 1.5.

• Journal of Advanced Marine Engineering and Technology
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• 제13권4호
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• pp.33-39
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• 1989

A turbulent premixed flames of layer formed between burned hot gas and unburned mixture were investigated by means of schlieren photograph with fluctuations of temperature and ion current. The combustion intensity between burned hot gas and shear layer was higher than the intensity between unburned mixture and shear layer. A wrinkled laminar flame and flamelet were appeared at downstream to exist and distributed reaction zone was at upstream as a result of analyzed probability density functions of temperature fluctuation. The initial combustion intensity of reaction zone of eddy between burned hot gas and shear layer was higher than that of final, flowing downstream, and vice versa between unburned mixture and shear layer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.65-70
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• 2001

OH radical and NOx have been measured in a methane-air partially premixed flame using PLIF technique to define preheated air combustion characteristics. The temperature of mixture is determined by 300K, 400K, 600K and 800K below the auto-ignition temperature respectively. Flame height increases as equivalence ratio increased. As initial enthalpy is supplied, the radius of flame was increased and much amount of yellow flame in rich equivalence ratio was observed. This is due to the faster burning velocity. Also initial oxidization begins earlier as the initial temperature of mixture increased. It means that height of premixed flame front decreased. This phenomenon can be observed OH PLIF image. The qualitative analysis of OH concentration in the PLIF image shows that overall OH concentration increases with equivalence ratio and the initial temperature of mixture increased. At the preheating temperature goes up, axial gradient of OH concentration is less steep than that of lower temperature condition. This may identify that combustion reacts continuously, so preheated air combustion can evade the local heating and make high temperature indiscriminately in the overall reaction zone.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.33-44
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• 1997

연소상태의 온도를 이동하면서 측정할 수 있는 광대역 코헤런트 반스톡스 라만 분광기를 제작하였다. 분광기의 온도 측정 정확도를 향상시키기 위하여 무모드레이저를 제작하여 스톡스광으로 사용하였다. 이동형 CARS 분광기에 적합하도록 CARS신호 측정용 단색기를 제작하여 분광기 내부에 설치 하였다. CARS 분광기의 온도 측정의 정확도를 알아보려고 흑연관 전기로를 이용하여 표준 복사온도계와 CARS 분광기로 측정한 온도의 차이를 측정하였다. 장치의 온도 정확도는 1000 K - 2400 K 사이의 온도영역에서 2%이내 였다. 무모드 색소레이저의 출력 스펙트럼의 시간에 따른 안정도를 측정하여 온도측정에 미치는 오차를 조사한 결과 1500 K에서 5 시간 동안 1.5 %이내 였다. 평면 화염 버너에서 프로판공기 예혼합 화염의 온도 분포를 측정하여 이 장치의 응용 가능성을 확인하였다.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.171-178
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• 2006

The performance in the practical combustion system including reciprocating engines and gas turbine combustors is being much governed by turbulent reacting flow that is often analyzed by both a laminar flamelets concept and flame interaction. The characteristics of laminar flame interaction have been investigated numerically to provide basic understanding of wrinkled turbulent flames under concentration interaction resulting from inhomogeneity in fuel-air mixing, especially focused on the transition of flame characteristics such as diffusion flame, partially premixed diffusion flame, and triple-layer flame by the variation in the degree of premixedness. The extinction stretch rates to the premixedness have also been obtained in this paper. The boundary defining the regime of the existence of triple-layer flames as functions of both stretch rate and premixedness has been determined which agrees well with previously reported experiment measuring OH radical concentration peaks based on PLIF.

• 에너지공학
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• 제11권1호
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• pp.10-17
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• 2002

본 연구에서는 콘덴싱 가스보일러의 NOx와 CO 배출농도를 줄이기 위한 방안으로 원통형 버너와 열교환기를 평면으로 모사한 평면 버너와 열교환기를 제작하여 버너와 열교환기 거리에 따른 배기 특성을 검토하였다. 그리고 평면 버너 실험에서 도출한 거리에 따라 직경이 다른 3종류의 원통형 버너를 제작하여 각각의 화염 안정성과 배기 특성, 효율 등을 검토하였다. 위와 같은 연구결과에 의해 최적화된 버너를 응축 가스 보일러에 장착히여 LNG와 LPG를 연료로 사용하여 보일러에 대한 종합성능, 즉 화염 안정성, 난방효율 및 배기 특성 등을 검토하여 다음과 같은 결론을 얻었다. 난방부하 20,000kca/hr에 적합한 다공 예혼합 원통형 버너의 최적 제원을 결정하였으며, 이 버너는 당량비 0.68~0.85부근에서 turn-down ratio가 약 5 : 1 정도로 비례제어에 적합하였다. 그리고 보일러의 종합성능을 검토한 결과 난방부하 20,000 kcal/hr로 운전할 경우 LNG, LPG 모두 난방효율 97%(저위 발열량 기준)를 달성할 수 있었고 NOx와 CO 배출농도(O$_2$=0%, wet basis)는 LNG의 경우 각각 26 ppm과 85 ppm, LPG의 경우 각각 41 ppm과 113 ppm 정도로 매우 양호하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.97-106
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• 2004

Stability of laminar premixed planar flames inclined in gravitational field which generate vorticity is asymptotically examined. The flame structure is resolved by a large activation energy asymptotics and a long wave approximation. The coupling between hydrodynamics and diffusion processes is included and near-unity Lewis number is assumed. The results show that as the flame is more inclined from the horizontal plane it becomes more unstable due to not only the decrease of stabilizing effect of gravity but also the increase of destabilizing effect of rotational flow. The obtained dispersion relation involves the Prandtl number and shows the destabilizing effect of viscosity. The analysis predicts that the phase velocity of unstable flame wave depends on not only the flame angle but also the Lewis number. For relatively short wave disturbances, still much larger than flame thickness, the most unstable wavelength is nearly independent on the flame angle and the flame can be stabilized by gravity and diffusion mechanism.

• 한국연소학회지
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• 제9권4호
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• pp.9-21
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• 2004

Stability of laminar premixed planar flames inclined in the gravitational field is asymptotically examined. The flame structure is resolved by a large activation energy asymptotics and a long wave approximation. The coupling between hydrodynamics and diffusion processes is included and near-unity Lewis number is assumed. The results show that as the flame is more inclined from the horizontal plane it becomes more unstable due to not only the decrease of stabilizing effect of gravity but also the increase of destabilizing effect of rotational flow. The obtained dispersion relation involves the Prandtl number and shows the destabilizing effect of viscosity. The analysis predicts that the phase velocity of unstable flame wave depends on not only the flame angle but also the Lewis number. For relatively short wave disturbances, still much larger than flame thickness, the most unstable wavelength is nearly independent on the flame angle and the flame can be stabilized by gravity and diffusion mechanism.