• Title, Summary, Keyword: Premixed combustion

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Combustion and Emission Characteristics of Premixed Charge Compression Ignition Diesel Engine (예혼합 압축 착화 디젤 엔진의 연소 및 배기 특성)

  • Heo, Seong-Geun;Kim, Dac-Sik;Lee, Chang-Sik
    • 한국연소학회:학술대회논문집
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    • pp.187-192
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    • 2001
  • A homogeneous premixed charge compression ignition engine is experimentally investigated for the reduction of exhaust emissions in diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC and CO emissions were increased with the increase of premixed ratio. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

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Flame Stabilization and Structures in Narrow Combustion Space (좁은 연소공간에서의 화염 안정화와 화염구조)

  • Kim, Nam Il
    • 한국연소학회:학술대회논문집
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    • pp.159-162
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    • 2012
  • Combustion in a narrow space has been interested as a model of meso-scale combustors (or micro-combustors). Premixed flames have been used to overcome flame quenching in a narrow space and non-premixed flames have been used to improve flame stabilization. In this study, overall characteristics of premixed flame and non-premixed flame in narrow combustion spaces were reviewed. Various effects such as the flow velocity distribution, thermal interaction, enhanced mass diffusion were discussed and an eventual structure of the flame at the extinction limit was introduced.

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Effect of Premixed Fuel on the Combustion Characteristics of Premixed Charge Compression Ignition Engine (예혼합 연료에 따른 균일 예혼합 압축 착화 엔진의 연소특성)

  • Hwang, Jin-Woo;Kim, Dae-Sik;Rhyu, Youl;Lee, Ki-Hyung;Lee, Chang-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.1
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    • pp.49-54
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    • 2003
  • The purpose of this work is to investigate the effect of premixed fuel on the reduction of exhaust emissions in premixed charge compression ignition engine. The premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber. The pre-mixture is ignited by a small amount of diesel fuel directly injected into the cylinder. In the case of gasoline as a premixed fuel of the engine, $NO_x$ and smoke concentration of exhaust emissions were reduced compared with the conventional diesel engine. But in the event of diesel fuel for premixed fuel, the rate of smoke reduction was small compared with the case of gasoline as a premixed fuel. HC and CO emissions were increased at high premixed ratio in the case of two premixed fuels. The combustion characteristics of the engine such as the combustion pressure, the rate of heat release, and other characteristics are compared.

Analysis of Combustion Characteristics for a Homogeneous Charge Compression Ignition Engine with Load Condition (예혼합 압축착화 디젤엔진의 부하변동에 따른 연소특성 분석)

  • 장시웅;이기형;이창식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.1
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    • pp.17-23
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    • 2002
  • In order to reduce exhaust emissions from diesel engine under wide operating range, an experimental study based on a new concept of combustion called HCDC(Homogeneous Charge Diesel Combustion) was conducted. In this concept, most of the fuel is supplied as premixed homogeneous charge and the rest is directly injected into a cylinder to ignite. In this study we compared combustion characteristics of an HCDC engine with those of conventional diesel engines. At high premixed fuel ratio and high load range, it was observed that premixed combustion heat release rate was low and diffusion combustion duration was shorten. from this experiment, it was found that NOx is reduced by the lower maximum temperature and soot is reduced by rapid combustion during diffusion combustion phase.

Observation on Double-droplet Combustion Speed in Premixed Spray Flame (예혼합 분무화염내의 이중적 액적 연소속도에 관한 관찰)

  • Lee, Chi-Woo;Shim, Han-Sub
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.6
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    • pp.119-126
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    • 2004
  • In order to elucidate the modes of double-droplet combustion speed in premixed spray flame, the difference between flame propagation speed and droplet cluster disappearance speed are experimentally investigated using a premixed spray burner system, It was confirmed that flame speed concerned with premixed-mode combustion in the spray flame was approximately 2.0 m/s in average while mean disappearance speed of droplet clusters, which were dominated by diffusion-mode combustion in downstream of the flame, was evaluated as much as 0.45 m/s. It was clarified that both characteristics of premixed-mode and diffusion-mode combustion in spray flames are of much difference in nature, even though both speed, which are supposed to depend on local properties of the spray itself and flow conditions surrounding droplet clusters, are scattered in experiments.

Combustion Instability Mechanism of a Lean Premixed Gas Turbine Combustor

  • Seo, Seonghyeon
    • Journal of Mechanical Science and Technology
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    • v.17 no.6
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    • pp.906-913
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    • 2003
  • Lean premixed combustion has been considered as one of the promising solutions for the reduction of NOx emissions from gas turbines. However, unstable combustion of lean premixed flow becomes a real challenge on the way to design a reliable, highly efficient dry low NOx gas turbine combustor. Contrary to a conventional diffusion type combustion system, characteristics of premixed combustion significantly depend on a premixing degree of combusting flow. Combustion behavior in terms of stability has been studied in a model gas turbine combustor burning natural gas and air. Incompleteness of premixing is identified as significant perturbation source for inducing unstable combustion. Application of a simple convection time lag theory can only predict instability modes but cannot determine whether instability occurs or not. Low frequency perturbations are observed at the onset of instability and believed to initiate the coupling between heat release rate and pressure fluctuations.

Effects of Premixed Fuel and EGR on the Combustion and Emissions Characteristics of HCCI Diesel Engine (HCCI디젤엔진의 연소 및 배기 특성에 미치는 예혼합 연료와 EGR의 영향)

  • Yoon, Young-Hoon;Kim, Dae-Sik;Lee, Chang-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.9
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    • pp.1006-1012
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    • 2005
  • The effects of premixed fuels(diesel or n-heptane) and exhaust gas recirculation on combustion and exhaust emission characteristics in a DI diesel engine were experimentally investigated. To improve homogeneity of fuel-air mixture in the conventional diesel engine, the premixed fuel is injected by high pressure(5.5 MPa) into the premixing chamber prior to engine cylinder, And several additional systems such as an EGR system, air heating system and back pressure control system were equipped in the DI diesel engine. The results showed that premixed fuel-air mixture undergoes typical HCCI combustion prior to the combustion of DI diesel fuel. The ignition timing of HCCI combustion is delayed by application of EGR, and it also shows that HCCI combustion can be controlled by an EGR.

Effect of Premixing Condition on the Combustion and Emission Characteristics of HCCI Diesel Engine (균일 예혼합 압축 착화 디젤 엔진의 예혼합 조건 변화에 따른 연소 및 배기 특성)

  • Kim, Myung-Yoon;Hwang, Seok-Jun;Kim, Dae-Sik;Lee, Ki-Hyung;Lee, Chang-Sik
    • 한국연소학회:학술대회논문집
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    • pp.7-12
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    • 2003
  • The purpose of this work is to investigate the effect of premixing condition on the combustion and exhaust emission characteristics in a HCCI diesel engine. To form homogeneous charge before intake manifold, the premixed fuel is injected into premixed tank by GDI injection system and the premixed fuel is ignited by direct injected diesel fuel. But in the case of high intake air temperature, premixed fuel is auto-ignited before diesel combustion and soot emission is increased. In the case of light load condition, the BSFC is improved by intake air heating because increased air temperature promoted the combustion of premixed mixture. NOx and smoke concentration of exhaust emissions are reduced compared to conventional diesel engine. The combustion characteristics of the HCCI diesel engine such as combustion pressure, rate of heat release, and exhaust emission characteristics are discussed.

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A Basic Study on Combustion Noise of Premixed Flames in Sudden Expansion Channels (급속 확대 채널 예혼합 화염의 연소 소음 기초 연구)

  • Liu, Zhao;Kim, Nam Il
    • 한국연소학회:학술대회논문집
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    • pp.79-81
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    • 2012
  • Flame stabilization conditions and combustion noise characteristics induced by premixed flames in sudden expansion channels were experimentally investigated. Nozzle size and channel scale were varied continuously, and variation of flame behaviors was examined. Combustion noise was observed at specific configurational conditions, and their mechanism was investigated. This study will help understand premixed flame instability at the burner surface.

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Combustion Characteristics of Premixed Combustor using Nickel Based Metal Foam (니켈합금 Metal Foam을 적용한 예혼합 버너의 연소특성)

  • Lee, Pil Hyong;Hwang, Sang Soon;Kim, Jong Kwang
    • Journal of the Korean Society of Combustion
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    • v.22 no.2
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    • pp.42-49
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    • 2017
  • A premixed combustion has many advantages including low NOx and CO emission, high thermal efficiency and a small volume of combustor. This study focused on combustion characteristics in a premixed combustion burner using the nickel based metal foam. The results show that the blue flame is found to be very stable at heating load 6,300-25,200 kcal/h by implementing the proper nickel based metal foam and baffle plate. The premixed flame mode is changed into green flame, red flame, blue flame and lift off flame with decreasing equivalence ratio. NOx emission was measured 80 ppm(0% oxygen base) from 0.710 to 0.810 of equivalence ratio and CO emission is 90 ppm(0% oxygen base) under the same equivalence ratio. It is also found that the stable blue flame region in flame stability curve becomes wider with increasing the heat load.