• Title/Summary/Keyword: Fuel Lean Region

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The effect of water addition on combustion efficiency in premixed flame (물添加가 豫混合火焰의 燃燒效率에 미치는 影響)

  • 김성환;오신규;채재우
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.5
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    • pp.819-827
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    • 1987
  • The purpose of the present investigation is to examine the effect of water addition on combustion efficieny. In this research, fuel and additive water are injected into a burner in the form of vapors through separate needle valves, the flame temperature and concentrations of soot, CO and unburned hydrocarbons were measured in a premixed flame. The results are obtained to be: In the fuel lean region, the reduction rate of CO, soot and HC by water injection increases slightly, but there is no change in the combustion efficiency. On the other hand, in the fuel rich region, the reduction rate of CO, Soot and HC by water injection increases more than that of the fuel lean region. Accordingly, combustion efficiency increases.

Experimental Study on NOx Reduction and CO Emission by Fuel Lean Reburning Process (연료 희박 재연소 과정에 의한 NOx 저감 및 CO 발생에 대한 실험적 연구)

  • Lee, Chang-Yeop;Kim, Hak-Young;Baek, Seung-Wook;Kim, Se-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.3
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    • pp.216-223
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    • 2008
  • Reburning is a useful technology in reducing nitric oxide through injection of a secondary hydrocarbon fuel. In this paper, an experimental study has been conducted to evaluate the effect of fuel lean reburning on $NO_X/CO$ reduction in LPG flame. Experiments were performed in flames stabilized by a co-flow swirl burner, which was mounted at the bottom of the furnace. Tests were conducted using LPG gas as the reburn fuel as well as the main fuel. The effects of reburn fuel fraction and injection location of the reburn fuel were studied when the fuel lean reburning system was applied. The paper reports data on flue gas emissions and temperature distribution in the furnace for a wide range of experimental conditions. At steady state, temperature distribution and emission formation in the furnace have been measured and compared. This paper makes clear that in order to decrease both NOx and CO concentrations in the exhaust when the fuel lean reburning system was adapted, it is important that the control of some factors such as initial equivalence ratio, reburn fuel fraction and temperature of reburn fuel injection region. Also it shows the fuel lean reburning is also effective method to reduce NOx as much as reburning.

Study on the Characteristics of Performance and Exhaust Emissions of 3-Chamber GDI Engine (3-연소실형 GDI Engine의 성능 및 배기 배출물 특성에 관한 연구)

  • 김봉수;정남훈;진선호;배종욱
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.1
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    • pp.37-47
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    • 2002
  • Recently gasoline direct injection method has been applied to gasoline engine to reduce fuel consumption rate by controlling fuel air mixture on lean condition by means of stratified charging, and to reduce simultaneously. Pollutant emissions especially NOx and CO by lowering the combustion temperature. But difficulty of controling local fuel air ratio at ignition area in flammability limit unavoidably appeared, because it is merely controlled by injection timing with spatial and temporal distribution of fuel mixture. In this study, the authors devised a uniquely shaped combustion chamber so called three-chamber GDI engine, intended to keep the more reliable fuel air ratio at ignition area. The combustion chamber is divided into three regions. The first region is in the rich combustion division, where the fuel is injected from the fuel injection valve and ignited by the spark plug. The second region is in the lean combustion division, where the combustion gas from the rich combustion division flows out and burns on lean condition. And the last region is in the main combustion division ie in the cylinder, where the gas from the above two combustion divisions mixed together and completes the combustion during expansion stroke. They found that the stable range of operation of three-chamber GDI engine on low-load condition exists in the lean area of average equivalence ratio. And they also found that the reformed engine reveals less specific fuel consumption and less pollutant emissions compared with conventional carburettor type gasoline engine.

Analysis of Stratified Co-Flow Flames from Chemiluminescence Images (화염 발광 가시화를 이용한 성층화된 동축류 화염 특성 분석)

  • Ahn, Taekook;Nam, Younwoo;Lee, Wonnam
    • 한국연소학회:학술대회논문집
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    • 2012.04a
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    • pp.185-187
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    • 2012
  • The characteristics of stratified co-flow flames have been investigated from the flame chemiluminescence images. The fuel lean premixed flame could be stabilized with a fuel rich premixed flames that is generated with the supply of fuel through the inner nozzle. The penetration of outer region lean premixture into the fuel stream produced a lifted rich premixed flame at the center. Chemiluminescence images of OH, CH, and $C_2$ radicals indicated that the way of stratification of fuel/air mixture under various operating conditions.

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Effect of Enhanced Mixture Formation on the Combustion Characteristics in Gasoline Engine (가솔린 기관의 혼합기 형성 촉진이 연소 특성에 미치는 영향)

  • Lee, C.S.;Seo, Y.H.;Kim, M.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.5
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    • pp.56-63
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    • 1995
  • In this paper, the fuel atomization effect of a spark-ignition engine on the lean burn characteristics is studied. The fuel atomization is enhanced by heating the inside of the intake manifold with electric heater. Several operating parameters including cyclic variation are expressed against the air-fuel ratio from the experimental results. The fuel atomization gives much influence on the combustion stability. As the intake manifold is heated, the combustion duration decreased and the value of COV in the lean region as well as in the theoretical equivalence ratio became smaller than of not-heated.

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Lean Burn Characteristics in a Heavy Duty Liquid Phase LPG Injection SI Engine (대형 액상분사식 LPG 엔진의 희박연소특성에 관한 연구)

  • 오승묵;김창업;강건용;우영민;배충식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.4
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    • pp.1-11
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    • 2004
  • Combustion and fuel distribution characteristics of heavy duty engine with the liquid phase LPG injection(LPLI) were studied in a single cylinder engine, Swirl ratio were varied between 1.2, 2.3, and 3.4 following Ricardo swirl number(Rs) definition, Rs=2.3 showed the best results with lower cycle-by-cycle variation and shorter burning duration in the lean region while strong swirl(Rs=3.4) made these worse for combustion enhancement. Excessive swirl resulted in reverse effects due to high heat transfer and initial flame kernel quenching. Fuel injection timings were categorized with open valve injection(OVI) and closed valve injection(CVI). Open valve injection showed shorter combustion duration and extended lean limit. The formation of rich mixture in the spark plug vicinity was achieved by open valve injection. With higher swirl strength(Rs=3.4) and open valve injection, the cloud of fuel followed the flow direction and the radial air/fuel mixing was limited by strong swirl flow. It was expected that axial stratification was maintained with open-valve injection if the radial component of the swirling motion was stronger than the axial components. The axial fuel stratification and concentration were sensitive to fuel injection timing in case of Rs=3.4 while those were relatively independent of the injection timing in case of Rs=2.3.

The Characteristics of the Flame Propagation Velocity and Volume Integral of Reaction Rate with the Variation of Fuel Injection Velocity for a Liftoff Flame (부상화염에서 연료유량에 따른 화염전파속도와 체적연소반응속도의 변화 특성에 관한 연구)

  • Ha, Ji-Soo;Kim, Tae-Kwon;Park, Jeung
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.4
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    • pp.466-475
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    • 2009
  • A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of fuel injection velocity at the fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity, but its effect on the flame propagation velocity is not much greater under 4%. The increase of fuel injection velocity affects directly and linearly on the flame surface area in the fuel rich region and so enhances volume integral of reaction rate to accommodate the increment of fuel.

A Study on Lean Limit and Combustion Characteristics of Hydrogen Supplemented Gasoline Engine (수소첨가 가솔린기관의 희박한계 및 희박연소특성에 관한 연구)

  • Cho, Tae Hee;Kim, Chang Hyun;Lee, Jong Tai
    • Transactions of the Korean hydrogen and new energy society
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    • v.6 no.1
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    • pp.23-34
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    • 1995
  • In order to realize the ultra lean burn, the method of hydrogen supplement in gasoline engine has been examined and analyzed. A small quantity of hydrogen gas was supplied and mixed with gasoline fuel in the intake manifold. As the results, lean limit was extended to fuel-air equivalence ratio 0.35 which normal combustion was impossible by gasoline fuel. The NO and CO were remarkably decreased, and thermal efficiency and torque were increased. It was also found that by considering cycle variation, emission characteristics, torque and thermal efficiency, suitable operate region of hydrogen supplemented gasoline engine was equivalence ratio 0.5.

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The Effects of Injector and Swirler on the Flame Stability in a Model Combustor (모델연소기에서의 화염 안정화에 대한 분사기와 선회기의 영향)

  • Park, Seung-Hun;Lee, Dong-Hun;Bae, Choong-Sik
    • Journal of the Korean Society of Combustion
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    • v.3 no.2
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    • pp.13-27
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    • 1998
  • The optimization of frontal device including fuel nozzle and swirler is required to secure the mixing of fuel and air and the combustion stability leading the reduction of pollutant emissions and the increase of combustion efficiency in gas turbine combustor. The effects of injection nozzle and swirler on the flow field, spray characteristics and consequently the combustion stability, were experimentally investigated by measuring the velocity field, droplet sizes of fuel spray, lean combustion limit and the temperature field in the main combustion region. Flow fields and spray characteristics were measured with APV(Adaptive Phase Doppler Velocimetry) under atmospheric condition using kerosine fuel. Temperatures were measured by Pt-Pt13%Rh, R-type thermocouple which was 0.2mm thick. Spray and flame was visualized by ICCD(Intensified Charge Coupled Device) camera. It was found that the dual swirler resulted in the biggest recirculation zone with the highest reverse flow velocity at the central region, which lead the most stable combustion. The various combustion characteristics were observed as a function of the geometries of injector and swirler, that gave a tip for the better design of gas turbine combustor.

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Lean Combustion Characteristics with Hydrogen Addition in a LPG Fuelled Spark Ignition Engine (LPG엔진에서 수소연료 보조분사에 의한 희박연소특성 연구)

  • Oh, Seung-Mook;Kim, Chang-Up;Kang, Kern-Yong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.2
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    • pp.114-120
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    • 2006
  • The basic effects of hydrogen addition for engine performance and emission were investigated in single cylinder research engine. Seven commercial injectors were tested to choose a suitable injector for hydrogen injection prior to its engine implementation. The hydrogen fuel leakage and flow rate were evaluated for each injector and KN3-1(Keihin, CO.) showed the best performance for hydrogen fuel. At the higher excess air ratio(${\lambda}=1.7$, 2.0), the better combustion stability was found with hydrogen addition even though its effect was small at lower excess air ratio (${\lambda}=1.0$, 1.3). Stable operation of the engine was even guaranteed at ${\lambda}=2.0$, if the amount of hydrogen gas was near 15% of total energy. In the lean region, ${\lambda}>1.3$, thermal efficiency was improved slightly while it was not clearly observed at ${\lambda}=1.0$, 1.3. It is considered that, in some cases, high temperature environment due to hydrogen combustion caused further heat loss to surroundings. Except for ${\lambda}=1.0$, with larger amount of hydrogen addition, CO was reduced drastically but it was emitted more at the leaner region. Nitric oxides(NOx) was increased a little more with hydrogen addition at ${\lambda}=1.0$, 1.3. However, at ${\lambda}>1.3$ its relative amount of emission was low. In addition, the amount of NOx was continuously decreased with hydrogen addition, but, at ${\lambda}=2.0$ the amount of NOx was lowered to 1/100 of that of ${\lambda}=1.0$. THC emission was significantly increased as air/fuel ratio was raised to leaner region due to misfire and partial burn.