• Title/Summary/Keyword: Unburned Hydrocarbon

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A Study on Direct Injection Stratified Charge Combustion with Spark Ignition in Constant Volume Bomb (정적 용기내의 직접분사식 스파크 점화 성층 연소에 관한 연구)

  • Hong, M.S.;Kim, K.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.5
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    • pp.30-40
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    • 1994
  • The direct-injection stratified-charge engine has the advantages of higher thermal efficiency and less CO and $NO_x$ emission levels than conventional spark ignition engines. However, its actual utilization is prevented by high unburned hydrocarbon emission levels during light-load operations. In this paper, fundamental studies were carried out using a pancake type constant volume bomb. The effects of intensification of local premixing by tangential and radial fuel injection were examined experimentally. Unburned hydrocarbon emission levels with radial fuel injection were shown to be lower than those of tangential fuel injection cases. The stratification and mixing process of fuel jet and combustion process were observed by schlieren photography.

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Measurement of HC Concentration near Spark Plug and Combustion Analysis (스파크플러그 주위의 HC 농도 측정 및 연소특성 분석)

  • 조한승;송해박;이종화;이귀영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.2
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    • pp.212-219
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    • 1998
  • Unburned hydrocarbon is a key contributor to both the fuel economy and emissions of automotive engine. Cyclic variation of HC emission is of importance, especially during throttle transients. The real time measurement of hydrocarbon is particularly important to obtain a better understanding of the mechanisms for combustion and emissions, especially during cold start and throttle transient condition. This paper reports the cycle resolved measurement technique of unburned hydrocarbons to quantify rapid changes of in-cylinder concentration in the vicinity of spark plug by using the Fast Response Flame Ionization Detector(FRFID). While this instrument actually measures fuel concentration, its results can be indicative of the AFR behaviour. In order to understand the rapid change of hydrocarbons with cylinder pressure, it is necessary to study the response time delay of the system, including the time associated with gas transportation to FID. And signal from FRFID is correlated with cylinder pressure data to relate changes in mixture preparation to the classic analysis, such as indicated mean effective(IMEF) and ignition delay, etc.

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Prediction Modeling of Unburned Hydrocarbon Oxidation in the Exhaust Port of a Propane-Fueled SI Engine (프로판 엔진의 배기 포트에서 탄화수소 산화 예측을 위한 모델링)

  • 이형승;박종범;최회명;민경덕;김응서
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.2
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    • pp.33-40
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    • 2000
  • In order to investigate the exhaust structure and secondary oxidation of unburned hydrocarbon (HC) in the exhaust port, a numerical simulation was performed with 3-dimensional flow model and oxidation mechanism optimized for port oxidation. To predict the exhaust and oxidation process with consideration of flow, mixing, and temperature, 3-dimensional flow model and HC oxidation model were used with a commercial computational program, STAR-CD. The flow model were with moving grid for valve motion, which could predict the change of flow field with respect to valve lift. Optimization was performed to predict the HC oxidation with temperature range of 1200~1500K, low HC and oxygen concentration, existence of intermediate species, as typical in port oxidation. The constructed model could predict the port oxidation process with oxidation degree of 14~48% according to the engine operation conditions.

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Exhaust Emissions Reduction using Unburned Exhaust Gas Ignition Technology and Hydrocarbon Adsorber (미연 배기가스 점화 기술과 탄화수소 흡착기를 이용한 배기저감)

  • Kim, C.S.;Chun, J.Y.;Choi, J.W.;Kim, D.S.;Lee, Y.S.;Kim, I.T.;Ohm, I.Y.;Cho, Y.S.
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.150-155
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    • 2000
  • Exhaust emissions from vehicles are the main source of air pollution. Many researchers are trying to find the way of reducing vehicle emissions, especially in the cold transient period of the FTP-75 test. In this study, UEGI (Unburned Exhaust Gas Ignition) technology, warming up the close-coupled catalytic converter (CCC) by igniting the unburned exhaust mixture using two glow plugs installed in the upstream of the catalyst, was developed. It was applied to an exhaust system with a hydrocarbon adsorber to ensure an effective reduction of HC emission during the cold start period. Results showed that the CCC reaches the light-off temperature (LOT) in a shorter time compared with the baseline exhaust system, and HC and CO emissions are reduced significantly during the cold start.

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Piston Crevice Hydrocarbon Oxidation During Expansion Process in an SI Engine

  • Kyoungdoug Min;Kim, Sejun
    • Journal of Mechanical Science and Technology
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    • v.17 no.6
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    • pp.888-895
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    • 2003
  • Combustion chamber crevices in SI engines are identified as the largest contributors to the engine-out hydrocarbon emissions. The largest crevice is the piston ring-pack crevice. A numerical simulation method was developed, which would allow to predict and understand the oxidation process of piston crevice hydrocarbons. A computational mesh with a moving grid to represent the piston motion was built and a 4-step oxidation model involving seven species was used. The sixteen coefficients in the rate expressions of 4-step oxidation model are optimized based on the results from a study on the detailed chemical kinetic mechanism of oxidation in the engine combustion chamber. Propane was used as the fuel in order to eliminate oil layer absorption and the liquid fuel effect. Initial conditions of the burned gas temperature and in-cylinder pressure were obtained from the 2-zone cycle simulation model. And the simulation was carried out from the end of combustion to the exhaust valve opening for various engine speeds, loads, equivalence ratios and crevice volumes. The total hydrocarbon (THC) oxidation in the crevice during the expansion stroke was 54.9% at 1500 rpm and 0.4 bar (warmed-up condition). The oxidation rate increased at high loads, high swirl ratios, and near stoichiometric conditions. As the crevice volume increased, the amount of unburned HC left at EVO (Exhaust Valve Opening) increased slightly.

Hydrocarbon Speciation in Low Temperature Diesel Combustion (저온 디젤 연소에서 발생하는 탄화수소 종 분석)

  • Han, Man-Bae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.4
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    • pp.417-422
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    • 2010
  • Low temperature diesel combustion was achieved via a combination of late injection timing ($8.5^{\circ}$ CA BTDC to $0.5^{\circ}$ CA BTDC) and heavy exhaust gas recirculation (37% to 48%) with ultra low sulfur Swedish diesel fuel in a 1.7L common rail direct injection diesel engine. When injection timing is retarded at a certain exhaust gas recirculation rate, the particulate matter and nitrogen oxides decease simultaneously, while the hydrocarbon and carbon monoxide increase. Hydrocarbon speciation by gas chromatography using a flame ionization detector reveals that the ratio of partially burned hydrocarbon, i.e., mainly alkenes increase as the injection timing is retarded and exhaust gas recirculation is increased. The two most abundant hydrocarbon species are ethene which is a representative species of partially burned hydrocarbons, and n-undecane, which is a representative species of unburned hydrocarbons. They may be used as surrogate hydrocarbon species for performing a bench flow reactor test for catalyst development.

Emission Reduction using Unburned Exhaust Gas Ignition (미연배기가스 점화 기술을 이용한 배기저감)

  • 김득상;강봉균;양창석;조용석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.3
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    • pp.39-47
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    • 2003
  • UEGI (Unburned Exhaust Gas Ignition) is an alternative method for fast light-off of a catalyst. It ignites the unburned exhaust mixture using two glow plugs installed in the upstream of the close-coupled catalysts. In addition, a hydrocarbon adsorber was applied to the UEGI, for more effective reduction of HC emission. Engine bench tests show that the CCC reaches the light-off temperature laster than the baseline exhaust system and HC and CO emissions are reduced significantly during the cold start. From the vehicle test, it was observed that a few amount of HC emission was reduced even the catalysts were aged. It is expected to develop a solution kit applicable to a new vehicle or used one, to meet the emission regulation

The Misfire Detection by the Exhaust Pressure Ascent Rate (배기 압력 상승률에 의한 실화 검출)

  • 김세웅;최미호;심국상
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.2
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    • pp.1-7
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    • 2003
  • This paper proposes a method to detect misfired cylinders by the exhaust pressure ascent rate. The misfire is generated by faults of electric system or faults of fuel delivery system. It is one of the abnormal combustions. Therefore, it increases the unburned hydrocarbon and the carbon monoxide and affects a bad influence to the 3-way catalyst. The misfire causes to decrease the power of the engine and increase the consumption of the fuel. Early detection and correction of the misfired cylinders can prevent these unusual phenomena. The misfired cylinders can be detected by the comparison of exhaust pressure ascent rate during each cycle. The exhaust pressure ascent rate is defined as pressure rise per time. Our experimental results showed that the proposed method is effective in the detection of the misfired cylinders on a gasoline engine regardless loads and revolutions of the engine.

The Reduction of Unburned Hydrocarbons on the Direct-Injection Stratified-Charge Combustion Method by Hydrogen Addition (직접분사 성층연소방식에서 수소 첨가에 의한 미연 탄화수소의 저감)

  • 홍명석;김경석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.4
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    • pp.46-57
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    • 1996
  • The direct injection stratified charge(DISC) engine enhances the fuel tolerance and the antiknock tendency. This enhanc3d antiknock tendency allows use of a higher compression ratio which results in higher thermal efficiency. But its actual utilization is prevented by high emission combustion time and wall quenching will be the main causes of increasing unburned hydrocarbons in DISC system. In order to solve this problem, small aount of hydrogen was added to the charging air or injected fuel. The effects of hydrogen addition were examined experimentally by radial fuel injection using a pancake-type constant volume bomb. In case of the hydrogen addition to the charge of air, the combustion the amount of hydrogen. In case of the hydrogen addition to the fuel, the combustion pressure was significantly increased.

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Analysis of Heat Quantity in CNG Direct Injection Bomb(1) : Homogeneous Charge (CNG 직접분사식 연소기에서의 열량해석(1) :균질급기)

  • 최승환;전충환;장영준
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.2
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    • pp.17-23
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    • 2004
  • A cylindrical constant volume combustion bomb is used to investigate the combustion characteristics and to analyze the heat quantity of homogeneous charge methane-air mixture under various initial pressures, excess air ratios and ignition times. As the overall pressure increase, the values of maximum combustion pressure, maximum heat release rate and cumulative heat release have been increased. But it is not very meaningful to compare with some values such as maximum combustion pressure, maximum heat release rate and cumulative heat release for different overall pressure due to the different heat energy of supplied fuel. So the each value is needed to be compared with normalized value, which is divided by the entered fuel energy. To analyze the heat quantity, some definitions including the CHR ratio, the UHC ratio and the HL ratio are needed and are calculated. As the overall pressure increase, the CHR ratios and the UHC ratios have been decreased, while the HL ratios have been increased. The CHR ratio of 300 ms has the higher value than that of 10000ms, and the HL ratios of 300 ms have a lower value.