• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.606-611
• /
• 2008

The objective of the present study is to actively control the flame oscillation in the experimental lean premixed methane burner by the phase-controlled sound waves. The authors propose the methodology of generating the phase-controlled sound waves by directly sensing the preferential frequency and generating the sensor-triggered sound waves with fixed optimum phase difference with the flame oscillation. The real-time controller is implemented in the present study, and the combustion noise reduction is achieved. The reduction is 20dB at peak frequency and 13dB in the OASPL.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
• /
• pp.123-125
• /
• 2012

In this study, combustion characteristics for 20t/h water tube boilers are studied. The burner by applying The fuel staging technology, the air staging technology, the partially premixed technology, the separated flame technology and the flame inner recirculation technology was designed. This study was to determine the combustion characteristics for the three types of burners. It is found that the result of flame temperature measurement is less than $1300^{\circ}C$ at the all flame region. also, emissions of NOx and CO are found to be 15.8 ppm and 18.9 ppm, respectively.

• 한국연소학회:학술대회논문집
• /
• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
• /
• pp.195-200
• /
• 2003

A two-dimensional "twin-jet counterflow" burner has been designed for the better understanding of the stability of turbulent flames. This flow system enables one to systematically investigate various effects on non-premixed flames, including the effects of curvature, negative strain, and non-premixed flame interactions. The objective of this study is comparing characteristics of extinction of non-premixed methane flames with that of non-premixed propane flames investigated previously. The extinction limit of non-premixed methane and propane flames can be extended compare to that for the conventional counterflow non-premixed flame because of the existence of petal shaped flame and have same structure. The hysteresis in transition between the petal shaped flame and the curved two-wing flames could be observed. We could find differences between non-premixed methane flame and non-premixe propane flame such as the position of one wing extinction and the regime of one wing extinction.

• Journal of Advanced Marine Engineering and Technology
• /
• 제35권4호
• /
• pp.397-405
• /
• 2011

친환경 대체에너지의 한 분야인 수소에너지는 물의 전기분해와 화석연료의 개질을 통해 얻어 진다. PEMFC용 개질기에 적용 가능한 난류예혼합 방식의 메탈화이버 플랫버너를 제작하였다. 공급열 량에 따른 연소영역의 평균온도분포와 CO, HC, $CO_2$ 및 $O_2$등 각종 화학종의 평균농도로 플랫버너의 화염구조 및 특성을 조사하여 개질기 적용 가능성을 확인하였다. 그리고 PIV 유동실험결과와 유동수 치해석 결과를 비교 분석하여 차후 PEMFC용 개질기 개발에 있어 수치해석을 적용하기 위한 기초연구를 진행하였다.

• 한국연소학회지
• /
• 제15권3호
• /
• pp.8-14
• /
• 2010

Fuel processing systems which convert fuel into rich gas (such as stream reforming, partial oxidation, autothermal reforming) need high temperature environment ($600{\sim}1,000^{\circ}$). Generally, anode-off gas or mixture of anode-off gas and LNG is used as input gas of fuel reformer. In order to make efficient and low emission burner system for fuel reformer, it is necessary to elucidate the combustion and emission characteristic of fuel reformer burner. The purpose of this study is to develop a porous premixed flat ceramic burner that can be used for 1~5 kW fuel cell reformer. Ceramic burner experiments using natural gas, hydrogen gas, anode off gas, mixture of natural gas & anode off gas were carried out respectively to investigate the flame characteristics by heating capacity and equivalence ratio. Results show that the stable flat flames can be established for natural gas, hydrogen gas, anode off gas and mixture of natural gas & anode off gas as reformer fuel in the porous ceramic burner. For all of fuels, their burning velocities become smaller as the equivalence ratio goes to the lean mixture ratio, and a lift-off occurs at lean limit. Flame length in hydrogen and anode off gas became longer with increasing the heat capacity. In particular, the blue surface flame is found to be very stable at a very lean equivalence ratio at heat capacity and different fuels. The exhausted NOx and CO measurement shows that the blue surface flame represents the lowest NOx and CO emissions since it remains very stable at a lean equivalence ratio.

• 한국자동차공학회논문집
• /
• 제12권6호
• /
• pp.119-126
• /
• 2004

In order to elucidate the modes of double-droplet combustion speed in premixed spray flame, the difference between flame propagation speed and droplet cluster disappearance speed are experimentally investigated using a premixed spray burner system, It was confirmed that flame speed concerned with premixed-mode combustion in the spray flame was approximately 2.0 m/s in average while mean disappearance speed of droplet clusters, which were dominated by diffusion-mode combustion in downstream of the flame, was evaluated as much as 0.45 m/s. It was clarified that both characteristics of premixed-mode and diffusion-mode combustion in spray flames are of much difference in nature, even though both speed, which are supposed to depend on local properties of the spray itself and flow conditions surrounding droplet clusters, are scattered in experiments.

• 대한기계학회논문집B
• /
• 제35권9호
• /
• pp.933-938
• /
• 2011

본 연구는 비예혼합화염보다 화염길이가 짧고 당량비 조절을 통해 NOx 및 CO 배출량을 제어할 수 있는 예혼합방식의 버너를 설치하고, 버너와 열교환기 사이의 거리가 각각 30, 40, 50mm인 3종의 열교환기에 대해 당량비를 변화시킬 때 NOx 및 CO의 배출특성을 비교하고 열교환기의 열전달특성을 검토한 것이다. 실험결과 버너와 열교환기의 거리변화와 관계없이 당량비가 증가할수록 화염온도가 높아져 NOx 및 CO 배출량도 증가한다. 또한 CO 배출량은 버너와 열교환기 사이의 거리가 가까울수록 높게 나타난다. 본 실험범위에서 A type 열교환기(버너와 열교환기 사이 거리 30 cm)를 당량비 0.75(CO 94.5ppm, NOx 11.2ppm, 효율 84.1%)에서 운전하는 것이 최적조건으로 나타났다.

• 대한기계학회논문집B
• /
• 제34권5호
• /
• pp.547-552
• /
• 2010

본 연구에서는 VIStA(Vortex Inertial Staged Air) 버너를 개조하여 관류보일러에 적용하였다. 개조는 크게 2가지 부분에서 이루어 졌는데, 먼저 원형에서 채택한 예혼합 연소 방식을 사용상 편의와 안전을 위해 비예혼합방식으로 변경하였다. 연소 방식의 변경에 따라 공기 1차, 2차에 별도의 송풍기를 사용하던 공급 방식도 변경하여 본 연구에서는 하나의 송풍기로부터 공기를 공급받아 댐퍼를 통하여 1, 2차 연소실에 분할하여 공기를 공급하도록 하였다. 본 연구에서는 질소 산화물(NOx)의 생성을 억제하는 최적의 운전 조건을 찾기 위하여 전체 공기비 및 1, 2차 연소실로의 공기 분배 비율에 따른 NOx 생성 특성을 관찰하였다. 본 연구에서 산업용 보일러에 적용하기 위해 개조한 비예혼합 방식의 VIStA 버너를 설치한 결과, 기존의 일반 버너에 비해 균일한 화염을 얻었고 질소 산화물을 최대 20%까지 줄일 수 있는 것을 확인하였다.

• 대한기계학회논문집B
• /
• 제29권3호
• /
• pp.376-383
• /
• 2005

In the paper we investigate characteristics of a transitional behavior from a premixed flame to a triple flame in a lifted flame according to the change of equivalence ratio. In previous study, we showed that the stabilized laminar lifted flame regime is categorized by regimes of premixed flame, triple flame and critical flame. A gas-chromatograph is used to measure concentration field, a smoke-wire system is used to measure streak line, and a PIV system is used to measure velocity field in lifted flame. In the visualization experiment of smoke wire, the flow divergence and redirection reappeared in premixed flame as well as triple flame. Thus we cannot express the flame front of lifted flame has a behavior of triple flame with only flow divergence and redirection. In PIV measurement, flow velocity for those three flames has minimum value at the tip of flame front. To differentiate triple flame and premixed flame, $\Phi$ value of partially premixed fraction is employed. The partially premixed fraction $\Phi$ was constant in premixed flame. In critical flame small gradient appears over the whole regime. In triple flame, typical diffusion flame shape is obtained as parabolic distribution type due to diffusion flame trailing.

• 한국연소학회지
• /
• 제6권1호
• /
• pp.1-6
• /
• 2001

To evaluate the effect of lobed structure on pollutant emission, an experimental study examines NOx and CO emissions associated with four burner geometries, such as a conventional circular burner and three lobed ones. Rapid mixing allowed by the lobed burner to produce lean premixed flames, with narrower flame stability diagram than for the conventional circular one. Conventional circular burner of wide and uniform burner rim has an advantage of flame stabilization. Correlation on fuel discharge velocity for flame blowout should be included a variable related to the wall effect of the burner. NOx emission reduces by about 5% at the burner with lobed structure in fuel discharge side compared to conventional circular one. This is due to lower flame temperatures through flame elongation and increased radiative heat losses, caused by partially luminous flame in flame front. Meanwhile, at the burner with lobed structure in air discharge side and both fuel and air discharge sides, NOx emission somewhat increases with reduced radiative heat losses in spite of flame elongation. Therefore, the rapid mixing by lobed structure does not always have an advantage on NOx reduction.