• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1043-1050
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• 2010

Fuel stratification and thermal stratification occur in the HCCI combustion chamber on a microscopic scale. They affect the ignition and combustion processes. In this study, the effect of the inhomogeneity in the mixture gas on the HCCI combustion process was investigated. Two-dimensional chemiluminescence images were captured using a framing camera to evaluate the flame structure. DME was used as the test fuel. First, the effect of inhomogeneity in the fuel distribution in the premixture was investigated for the four-stroke optically accessible engine. Then, by comparing the combustion of the homogeneous mixture in the rapid compression machine, which does not contain any residual gas, with the combustion in the four-stroke engine, the effect of inhomogeneity in temperature due to the residual gas was analyzed. The results showed that a time lag appears spatially in combustion under inhomogeneous conditions in the four-stroke engine. The spatial variation in the combustion without the residual gas in the rapid compression machine is less than that in the combustion in the four-stroke engine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.247-250
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• 2009

The catalytic combustor has the advantage of stable combustion under very lean conditions with low emissions of $NO_x$, CO and unburned hydrocarbon(UHC). Notwithstanding these advantages, the commercial application of the catalytic combustion has been delayed due to the complicated reaction process. For the stable operation of catalytic combustor, study on the combustion characteristics of the catalytic combustor is needed. So, in this study, numerical study on the propane combustion characteristics of the catalytic combustor with Pd-based catalyst is performed.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.127-132
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• 1999

우리나라의 도시폐기물 소각로는 화격자 위에 폐기물을 공급하고 화격자 밑에서 공기를 공급하는 스토커식 소각로를 대부분 채택하고 있다. 이러한 스토커 소각로 연소실내에서는 매우 복잡한 연소현상이 발생하는데, 연소실로 투입된 쓰레기는 먼저 건조부에서 수분의 건조가 일어나고, 화격자의 구동에 의해 쓰레기가 혼합 및 이송되면서 열분해, 가스화, 가연성분의 탈휘발화 및 연소, 일부 고정탄소의 표면연소 등의 반응이 일어난다. 그리고 1,2차 연소실에서는 휘발분 및 비산된 고체의 연소가 일어나는데, 이때 대류 및 복사열전달 등의 복잡한 현상을 수반하는 유동장이 형성된다. 더욱이 불균질한 특성을 갖는 쓰레기층 내에서의 복잡한 현상으로 인하여 발생하는 경계조건 설정의 불확실성으로 연소실내의 연소 현상을 전산해석하는 데에는 상당한 어려움이 있다.(중략)

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.188-190
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• 2012

고전단력을 갖도록 개발된 Homogenizer를 이용해 IFO 380cst Bunker-C 시료를 미립화 및 균질화하는 전처리를 시행하였다. 전처리된 시료의 슬러지 저감효과를 확인하기위하여 유청정기(oil purifier)를 이용하였고, 실험결과 약 13% 가량 슬러지 생성이 감소하는 것을 확인하였다. 또한, 전처리 후 유청정기를 통과한 시료를 실제 보일러 시스템에서 연소시켜 연소 성능 특성을 확인한 결과 CO가 감소하는 경향을 확인하였다. 선박운항비용 분석을 통해 U.L.C.C 기준 연 8,800만원 가량의 연료비 절감 효과가 있을 것으로 추정된다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.584-590
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• 2012

In this study, we have conducted a work on homogenizer development which is operated by high shearing force generated by stator and rotor inside it. To investigate the performance for homogenization and atomization of homogenizer, Bunker-C (IFO 380 cSt) was used as a fuel for experiment. Pre-treatment of bunker-C was carried out with homogenizer developed in this study. Oil purifier was used to investigate effect of oil sludge reduction after pre-treatment. Experimental result showed that the amount of sludge of fuel oil after pre-treatment with homogenizer has decreased by 13 %. To confirm combustion efficiency, Bunker-C which have pre-treatment with homogenizer and purified after are burned in boiler system. The result showed that CO concentration in exhaust gas was decreased. These results mean that if the homogenizer which is developed in this study for marine fuel oil is applied on real vessels, oil costs and operating costs can be reduced.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.48-57
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• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of homogeneous charge methane-air mixture under various initial pressure, excess air ratio and ignition times in quiescent mixture. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer and flame propagation acquired by ICCD camera were used to investigate the effect of initial pressure, excess air ratio and ignition times on pressure, combustion duration, flame speed and burning velocity. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to near 0 value gradually after 3 seconds. Combustion duration, flame speed and burning velocity were observed to be promoted with excess air ratio of 1.1, lower initial pressure and ignition time of 300ms.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.319-321
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• 2014

The homogeneity and the long term stability for HCNG(CNG composed of about 20 % hydrogen) have been studied. The homogeneity by using ANOVA shows that the HCNG mixing gas is homogeneous ; the relative uncertainty of homogeneity is 0.0375 %. The long term stability for HCNG mixing gas by using F-test and t-test shows that HCNG mixing gas is stable ; the relative uncertainty of the long term stability is 0.0682 % for seven months.

• Journal of the Korean Society of Combustion
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• v.13 no.3
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• pp.9-16
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• 2008

In this study, a cylindrical constant volume combustion chamber is used to investigate the flow and combustion characteristics of methane-air homogeneous mixture under various initial charge pressure, excess air ratios and ignition times. The flame and burning speed, mean gas speed are calculated by numerical analysis to analyze the combustion characteristics. It is found that the mean gas velocity during combustion has the maximum value around 300 ms and then decreased gradually on the condition of 10000 ms, and that the combustion duration is shorten and flame speed and burning velocity have the highest value under the conditions of an excess air ratio 1.1, an initial charge pressure of 0.2 MPa and an ignition time of 300 ms in the present study. And, the initial pressure and burning speed are in inverse proportion, so that it is in agreement with Strehlow who presented that the initial pressure and burning speed are in inverse proportion when the burning speed is under 50cm/s.

• Journal of the Korean Society of Combustion
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• v.11 no.2
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• pp.28-36
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• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.518-524
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• 2013

In this study, we conducted a study on characteristics of exhaust gas emissions from boiler when water-bunker oil mixed by homogenizer was burned in boiler. The results showed that NOx concentration and CO concentration of the homogenized bunker oil was decreased by 19% and 54% compared to pure bunker oil pretreatment was not being performed. And, in the case of water-bunker A oil, the NOx concentration was decreased with increasing water mixing ratio in bunker A oil. In particular, the NOx concentration in exhaust gas of 20 %water-80 %bunker A oil decrease by 45 % compared with pure bunker-A. However, the CO concentration in exhaust gas of 20 %water-80 %bunker A oil shows irregular changes. This means that the mixing of water more than a certain amount can cause a decrease in combustion performance. From this result, it can be found that critical mixing ratio of water in bunker A oil for normal combustion is 15% in this study. Deposition amount of soot that is collected in the vicinity of the chimney was decreased with increasing water mixing ratio.