• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.27-32
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• 2003

Diesel-Fueled HCCI(Homogeneous Charge Compression Ignition) Engine is an advanced combustion process explained as a premixed charge of diesel fuel and air is admitted into the cylinder and compression ignited. It has possibility to reduce NOx by spontaneous auto-ignition at multiple points that allows very lean combustion resulting in low combustion temperatures. Also PM could be reduced by the premixed combustion and no fuel-rich zones. But HCCI couldn't be realized because of the difficulties in vaporizing the diesel, control of combustion phase directly. To solve these problems, new fuel injection strategy, explained as the pilot fuel injection to promote ignition near TDC following the main fuel injection at the extremely advanced timing, is applied during the compression ratio is varied from 18.9:1 to 27.7:1 This is not a pilot fuel to promote the ignition but also the direct control method of the combustion phase. Experimental result shows the pilot fuel injection promote the ignition and the compression ignition of the HCCI engine is achieved as compression ratio becomes higher. Also there is an optimal pilot fuel injection timing for the HCCI combustion. NOx is reduced more than 90% compared to DI-Diesel case but PM and THC emission needs more investigation.

• 한국연소학회지
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• 제7권4호
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• pp.29-35
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• 2002

[$CO_2$] is a well-known greenhouse gas, which is the major source of global warming. Many researchers have studied to reduce $CO_2$ emission in combustion processes. The central method of low $CO_2$ emission is Oxygen/CxHy combustion. Theoretically Oxygen/CxHy combustion only produces $CO_2\;and\;H_2O$ and allows convenient recovery of $CO_2$. The combustion characteristics, flame stability, composition in the flame zone and temperature profile were studied experimentally for various compositions of oxidant by substituting $CO_2\;for\;N_2$ with the constant $O_2$ concentration. Results showed that flame became unstable due to the high heat capacity, low transport rate and strong radiation effect of $CO_2$ in comparison with those of $N_2$. The reaction zone was quenched and broadened, as the ratio of $CO_2\;to\;N_2$ was increased. The emission of NOx in flue gas decreased due to the decreased temperature of the reaction zone. As the conversion ratio of $CO_2\;to\;N_2$ was increased, the emission of CO and the higher temperature zone increased due to decrease of reaction rate by the a quenching effect.

• 한국연소학회지
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• 제9권1호
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• pp.11-17
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• 2004

The purposes of this study are to analyze nitrogen oxides(NOx) formation mechanism and to reduce abnormal NOx emissions in gas turbines. Industrial gas turbines emissions have potential to negative affect to the atmosphere in many different ways such as photochemical smog, acid rain and global warming. In conventional gas turbine combustors, one of the main pollutants such as nitrogen oxide(NOx) species, are principally formed from combustion process of fuel with oxygen in the primary combustion zone, and their emission levels are highly depend on peak temperatures in the combustor. In order to examine the characteristics and the effect of NOx formation, we used gas turbine of which commercial operating in Korea. From the examination, it has been found that NOx emissions are relatively high at low load(output) and during combustion mode change. Also, the effect of Air/Fuel ratio was considered. As the Air/Fuel ratio was increased in Lean-Lean mode, the NOx emission was decreased. The results of this study indicated that NOx emission levels are highly depend on peak temperature and pressure of combustion process in the combustor.

• 한국연소학회지
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• 제10권2호
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• pp.26-34
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• 2005

The performance of oxygen combustion with $CO_2$ feeding was investigated in a pyrex tube furnace. The inverse type multi-hole burner was used for improving mixing and wide operating range. It introduced oxygen, fuel, and oxygen, respectively, from center tube to outer tubes. Oxygen combustion characteristics with excess oxygen ratio, oxygen feeding ratio, and $CO_2$ feeding flow rate were studied to optimize the operating condition and to apply the oxygen combustion with recirculation of flue gas to a real furnace. This paper presents results on the effect of $CO_2$ feeding flow rate on the structure of the flames and concentrations of NO and CO emissions. The visible flame length was shortest due to well mixing between fuel and oxygen when the oxygen feeding ratio was 0.25. The NO emission was reduced drastically regardless of excess oxygen ratio when the $CO_2$ feeding flow rate was larger than 15 lpm. The CO emission is varied by changing the $CO_2$ feeding flow rate but the CO emission characteristics is highly affected by excess oxygen ratio. When the excess oxygen ratio is below $\lambda=1.1$, the CO emission increased as the $CO_2$ feeding flow rate increased.

• 대한기계학회논문집B
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• 제37권2호
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• pp.103-109
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• 2013

본 연구에서는 초소형 가스터빈 연소기에서의 수소/공기 연소에 대한 수치해석을 연소기 입구에서의 공급 유량 및 유체의 수소/공기 혼합비 변화에 대하여 수행하였다. 수치해석은 상용화 프로그램인 STAR-CCM 을 이용하였다. 유체의 공급 유량의 변화는 연소기 내 화염의 위치와 온도, 입구와 출구의 압력비 등에 상당한 영향을 주었다. 유체의 공급 유량이 증가할 때, 연소기 내의 화염은 점점 출구 방향으로 위치하였고, 화염의 온도 및 입구와 출구의 압력비는 단조적으로 증가하였다. 유체의 수소/공기 혼합비 변화는 화염의 위치에는 큰 영향을 주지 않았고, 이론공연 상태에서 연소실 내에 가장 높은 화염온도를 가졌다.

• 한국연소학회지
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• 제10권1호
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• pp.27-36
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• 2005

In this study, we investigated characteristics of a gas flow and a combustion property during the combustion of a RDF in a pyrolysis melting incinerator with disposal rate of 30 kg/hr. The RDF was pyrolyzed through the pyrolysis chamber at $600^{\circ}C$ of the chamber surface without oxygen condition. The pyrolysis gas was injected in the combustion chamber. It was burned by means of the staged combustion that was injecting secondary and tertiary air in the combustor. We measured the temperatures and the gas components in the combustion chamber while maintaining the air-fuel ratio of 1.3. Finally, we confirm that additional air injection, secondary and tertiary air ratio, was the most important factor to reduce NOx.

• 한국연소학회지
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• 제10권3호
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• pp.1-9
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• 2005

The characteristics of co-combustion of Korean anthracite and bituminous coal was determined in a TGA and a lab-scale CFB reactor. The combustion reactivity of Korean anthracite (E = 51.2 kcal/mol) was much lower than that of bituminous coal (E = 14.5 kcal/mol). As the addition amount of the bituminous coal into the anthracite was increased, the reactivity of the anthracite was found to be improved. The effluent rate of the emission gases from the CFB reactor was not changed appreciably when each coal burned. As the bituminous coal was added, however, the effluent rate of the emissions was increased. The unburned carbon in fly ash from the CFB reactor was decreased with increasing the ratio of bituminous coal in co-combustion. But as the ratio of the bituminous coal was larger than 40 %, the combustion reactivity was not increased any more.

• 한국연소학회지
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• 제16권2호
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• pp.9-15
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• 2011

Homogeneous charge compression ignition(HCCI) is the best concept able to provide low NOx and PM in diesel engine emissions. This new alternative combustion process is mainly controlled by chemical kinetics in comparison with the conventional combustion in internal combustion engine. In this paper, combustion characteristics of HCCI engine with suggested diesel surrogate(heptane/toluene mixture fuel) reaction mechanism were numerically investigated by heptane/toluene mixture ratio and EGR ratio. As results, the ignition timing became faster with increasing of heptane, and an initial oxidation and the ignition timing of the mixture fuel were affected by heptane and toluene, respectively.

• 한국자동차공학회논문집
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• 제24권3호
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• pp.358-364
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• 2016

The combustion and exhaust emission characteristics in a spark ignition (SI) engine with various test fuels (bioethanol - gasoline blends) and air-fuel ratio were investigated in this research. To investigate the influence of the excess air ratio and ethanol blends on the combustion characteristics such as the cylinder pressure, rate of heat release (ROHR), and fuel consumption rate were analyzed. In addition, the reduction effects of exhaust emissions such as carbon monoxide (CO), unburned hydrocarbon (HC), and oxides of nitrogen (NOx) were compared with those of neat gasoline fuel under the various excess-air ratios. The results showed that the peak combustion pressures and the ROHR of bioethanol fuel cases were slightly higher than those of gasoline fuel at all test ranges and fuel ratio. As compared with gasoline fuel (G100) at each given excess air ratio, BSFC of bio-ethanol was increased. The CO, HC, NOx emissions of bio-ethanol blends were lower than those of gasoline fuel under overall experimental conditions.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.341-345
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• 2005

본 논문은 액체로켓엔진용의 약 1.5MW급 터빈을 구동할 수 있고, 액체산소와 케로신을 추진제로 하는 연료과잉 영역에서 작동하는 실물형 가스발생기의 고압연소특성에 대한 것이다. 실물형 가스발생기 개발과정의 개략적인 과정, 연소시험 결과 분석에 따른 혼합비와 온도관계식, 연소가스의 물성치인 분자량 및 비열비 등에 대한 내용을 기술하였다. 혼합비에 따른 온도관계식을 고압에서 새롭게 얻을 수 있었으며 연소가스의 분자량 및 비열비를 수정하고 유량관계식을 통해 이들의 타당성을 확인하였다.