• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.149-156
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• 2006

Structure of edge flame established in a mixing layer, formed between two uniformly flowing pure $CH_4$ and pure $O_2$ streams, is numerically investigated by employing a detailed methane-oxidation mechanism. The numerical results exhibited the most outstanding distinction of using pure oxygen in the fuel-rich premixed-flame front, through which the carbon-containing compound is found to leak mainly in the form of CO instead of HC compounds, contrary to the rich $CH_4-air$ premixed flames in which $CH_4$ as well as $C_2H_m$ leakage can occur. Moreover, while passing through the rich premixed flame, a major route for CO production, in addition to the direct $CH_4$ decomposition, is found to be $C_2H_m$ compound formation followed by their decomposition into CO. Beyond the rich premixed flame front, CO is further oxidized into $CO_2$ in a broad diffusion-flame-like reaction zone located around moderately fuel-rich side of the stoichiometric mixture by the OH radical from the fuel-lean premixed-flame front. Since the secondary CO production through $C_2H_m$ decomposition has a relatively strong reaction intensity, an additional heat-release branch appears and the resulting heat-release profile can no longer be seen as a tribrachial structure.

• 한국연소학회지
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• 제14권2호
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• pp.1-9
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• 2009

New way to effectively capture $CO_2$ in coal fired power plant is the combustion of coal using oxy-fuel technology. Combustion characteristics of Minco sub-bituminous coal at oxy-fuel conditions using TGA and drop tube furnace (DTF) were included activation energy about the char burnout, volatile yield and combustion efficiency of raw coal, the porosity of pyrolyzed char and fusion temperature of by-product ash. TGA result shows that the effect of $CO_2$ on combustion kinetics reduces activation energy by approximately 7 kJ/mol at air oxygen level(21% $O_2$) and decreases the burning time by approximately 16%. The results from DTF indicated similar combustion efficiency under $O_2/CO_2$ and $O_2/N_2$ atmospheres for equivalent $O_2$ concentration whereas high combustion efficiency under $O_2/N_2$ than $O_2/CO_2$ was obtained for high temperature of more than $1,100^{\circ}C$. Overall coal burning rate under $O_2/CO_2$ is decreased due to the lower rate of oxygen diffusion into coal surface through the $CO_2$ rich boundary layer. By-product ash produced under $O_2/CO_2$ and $O_2/N_2$ was similar IDT in irrelevant to $O_2$ concentration and atmospheres gas during the coal combustion.

• 한국연소학회지
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• 제21권1호
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• pp.1-7
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• 2016

This study was performed to provide the basic information of the combustion, CO and $NO_X$ characteristics of biodiesel in accordance with equivalence ratio. The closed homogeneous reactor model used for the analysis. The analysis conditions were set to 900 K of the initial temperature, 20 atm of initial pressure and equivalence ratio was changes from 0.6 to 1.4. The results of analysis were predicted and compared in terms of combustion temperature, combustion pressure, CO and $NO_X$ emissions. The results of combustion characteristics showed that ignition delay was decreased and the combustion temperature and combustion pressure was increased in accordance with equivalence ratio. CO emission was decreased in lean condition(${\Phi}$ < 1.0), however, CO emission was increased in rich condition(${\Phi}$ > 1.0) because oxygen supply insufficient. $NO_X$ emission showed the largest amount in condition 0.8 of equivalence ratio because the oxygen concentration was sufficient.

• 한국추진공학회지
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• 제17권3호
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• pp.67-75
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• 2013

케로신-액체산소 로켓 엔진에 적용되는 산화제 과잉 예연소기의 냉각 성능 확인을 위한 수치 해석을 수행하였다. 예연소기 1차 연소구역을 상사하기 위하여 분사기 배열에 따른 혼합비를 바탕으로 연소가스 물성치를 계산하였고, 냉각제로서 채널을 흐르는 산소의 물성치는 실제기체 조건에 대하여 적용하였으며, 1차 연소구역과 냉각제로 쓰인 액체산소의 혼합과정은 다상혼합모델을 적용하였다. 수치 해석으로 계산된 결과를 연소시험과 비교하였으며, 이를 통하여 재생냉각 채널과 연소실에서의 물성 등을 정량적으로 파악할 수 있었다.

• 한국추진공학회지
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• 제17권2호
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• pp.122-127
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• 2013

고성능 폐회로 액체로켓엔진 시스템에 적용되는 산화제 과잉 예연소기 내에서 발생하는 연소 압력 섭동 데이터에 대한 분석 결과를 수록하였다. 연소실험은 두 단계의 압력 값을 순차적으로 형성하였는데 상대적으로 저압 조건에서만 78 Hz의 특성 주파수를 갖는 자발적인 압력 섭동이 발생하였다. 이와 같은 연소 불안정은 bulk mode에 해당하는 것으로 판단된다. 압력 섭동의 세기는 rms 기준으로 연소실 정압 대비 13.3%에 해당하며, 설계압 구간(19.3 MPa)에서는 매우 안정적인 모습을 보였다. 이와 같은 bulk mode는 연소실 내부에서 특성 압력파의 위상차가 없이 전체 공간에서 압력이 증가와 감소를 반복하는 것으로 Helmholtz 공진기와 비슷한 특성을 보이는 것으로 판단된다.

• 한국항공우주학회지
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• 제34권10호
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• pp.56-60
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• 2006

액체 로켓 엔진용 가스발생기 개발을 위해서는 추진제 O/F ratio에 따른 연소 가스의 열역학적 물성치 예측이 필수적이다. 본 연구에서는 액체산소/Jet A-1 조합의 연료 과농 가스발생기의 실 추진제 연소 시험을 통해 O/F ratio 변화에 따른 연소 생성 가스의 온도를 계측하였다. 또한 연소실 내 동압 섭동 측정 및 정압 측정 결과를 이용하여 비열비, 가스 상수, 정압 비열과 같은 연소 가스의 열역학적 물성치를 간접적으로 산출해내었다. 본 실험값은 화학평형코드 결과를 통해 구한 보간 계수를 이용한 예측 결과와 비교해보았을 때 동일한 경향 및 유사한 값을 가지는 것으로 밝혀졌으며 이는 보간 계수 예측 방법이 설계 도구로 충분히 적용 가능하다는 결과를 확인하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
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• pp.153-160
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• 2001

The combustion test used DTF was performed to obtain the characteristics of NOx emission and reduction. In this test, major factor of NOx emission was a stoichiometric air ratio. At the onset of combustion to be rich oxygen, NOx was produced rapidly. Optimum condition for NOx reduction was formed under about AR:0.7 in the combustion test of Alaska coal. Investigations were undertaken with 200KW(th) test combustor. In combustion test, the major variables were coal feed ratio of center/outer, stoichiometric air ratio at the onset of combustion. The lowest NOx emission, 182ppm(6% O2 base), was achieved at about AR:0.6 of the first combustion stage with low NOx burner. Also, unburned carbon content of char collected in this combustion condition was about 1wt%.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.83-88
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• 2003

Measurements on the combustion characteristics of dimethyl ether(DME:$CH_3$O$CH_3$) as compared with LPC in constant volume combustion chamber have been conducted. The DME is a good alternative fuel having oxygen component in fuel. To elucidate the combustion characteristics of dimethyl ether as a fuel, the combustion pressures, combustion durations, and pollutants(NOx, $CO_2$, CO) are measured with equivalence ratios(Ø), and initial Pressures of fuel-air mixture. In the case of DME, the NOx concentration peaks in leu flame Ø = 0.85~0.9, and $CO_2$ concentration peaks at Ø=1.1, while the CO concentration abruptly rises at the condition of fuel-rich mixtures.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.97-100
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• 2011

액체로켓엔진의 점화는 그 시퀀스가 대단히 중요하며 시퀀스에 따라 엔진에 손상이 갈 수도 있다. 따라서 시동 시 hard start가 일어나지 않도록 많은 연구가 이루어지고 있다. 액체로켓의 점화 방법은 점화성 연료를 많이 사용하며 그 중 TEAL 역시 대기 중의 산소과 접촉하면 발화되는 자연발화 물질이다. TEAL을 사용하는 점화방법은 케로신-액체산소 엔진의 주요한 점화방식 중의 하나이나 아직까지 국내에서는 다단연소사이클 산화제 과잉 예연소기에 TEAL을 사용하여 점화 시험을 실시한 경험이 거의 없기 때문에 본격적인 시험에 앞서 이를 예측해 보고자 한다.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.300-310
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• 1999

A constant-volume combustion chamber is developed to measure the burnt gas temperature over the wide ranges of equivalence ratio from 1.5 to 2.7 and pressure from 0.1 to 2.7 and pressure from 0.1 to 6 MPa by two-color method. The combustion temperature is also calculated by the conventional two-region model. The premixed fuel rich propane-oxygen-inert gas mixtures under high pressures are simultaneously ignited by eight spark plugs located on the circumference of combustion chamber with 45 degree intervals. The eight converging flames compress the end gases to high pressures. The transmissiv-ity in the chamber center during the final stage of combustion at the highest pressure is measured by in situ laser extinction method. Comparisons are made with the combustion temperatures between two-color method and two-region model. It is found that the burnt gas temperature mea-sured by two-color method is higher than that calculated by two-region model because of being the negative temperature gradient on the calculation and the temperature distribution of light path-length on the measurement and the burnt gas temperature for the turbulent combustion is higher than that of the laminar combustion under the same conditions because the heat loss for turbulent combustion is lower due to the shorter combustion period.