• Title/Summary/Keyword: Combustion Conditions

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The Experimental Study on the Low-temperature Combustion Characteristics of DME Fuel in a Compression Ignition Engine

  • Yoon, Seung Hyun
    • Journal of ILASS-Korea
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    • v.22 no.4
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    • pp.190-196
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    • 2017
  • The aim of this work is to investigate the combustion and exhaust emission characteristics of low-temperature combustion (LTC) at various EGR test conditions using a single cylinder common-rail diesel engine. In high EGR rate combustion mode with DME fuel, 30% (${\Phi}=0.61$) and 50% (${\Phi}=0.86$) of EGR were respectively examined, and then the combustion, exhaust emissions, nano-particle characteristics of each cases were measured. From these results, it revealed that The ignition delay and combustion duration are prolonged as the increase of EGR rate. In addition, at an advanced injection timing (BTDC $30^{\circ}$), ignition delays were fairly increased because the dilution effect of EGR and also low charge in-cylinder temperature created a lean mixture, thus decreased the peak release rate.

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.

Numerical Analysis of Combustion Characteristics during Combustion Mode Change of a Low NOx Utility Gas Turbine (발전용 저 NOx 가스터빈의 연소모드 변환시기의 연소특성 전산해석)

  • Jeong, Jai-Mo;Chung, Jae-Hwa;Park, Jung-Kyu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.6
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    • pp.127-134
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    • 2004
  • Three-dimensional numerical investigations are carried out to understand the combustion characteristics inside a DLN(dry low NOx) utility gas turbine combustor during the combustion mode change period by applying transient fuel flow rates in fuel supply system as numerical boundary conditions. The numerical solution domain comprises the complex combustor liner including cooling air holes, three types of fuel nozzles, a swirl vane, and a venturi. Detailed three-dimensional flow and temperature fields before and after combustion mode changeover have been analyzed. The results may be useful for further studies on the unfavorable phenomena, such as flashback or thermal damage of combustor parts when the combustion mode changes.

COMBUSTION CHARACTERISTICS AND HEAT FLUX DISTRIBUTION OF PREMIXED PROPANE MIXTURE IN A CONSTANT VOLUME COMBUSTION CHAMBER

  • PARK K. S.
    • International Journal of Automotive Technology
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    • v.6 no.2
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    • pp.79-85
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    • 2005
  • This work is to investigate the surface heat flux and combustion characteristics of premixed propane mixture in a constant volume chamber. The experiment of heat flux and combustion characteristics of premixed propane mixture are performed with various equivalence ratio and initial pressure conditions. Based on the experimental results, it is found that the maximum instantaneous temperature is increased with the increase of initial pressure in the chamber. There are significant differences in the burning velocity of premixed propane mixture at different measuring points in the constant volume combustion chamber. A]so, the trends of temperature difference at each measuring points are similar to the burning velocity in the combustion chamber. It is concluded that the total heat loss during the combustion period is affected by the equivalence ratio and the initial condition of fuel-air mixture.

Combustion stability assessment of muti-injector using simulant propellant in LRE (모의 추진제를 이용한 액체로켓엔진용 다중 분사기의 연소안정성 평가 방법)

  • Seo Seonghyeon;Song Joo-Young;Seol Woo-Seok;Lee Kwang-Jin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.10a
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    • pp.229-234
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    • 2004
  • The objective of the present study is to conduct model combustion tests for double swirl coaxial injectors to identify their combustion stability characteristics. Gaseous oxygen and mixture of methane and propane have been used as simulant propellants. Two model chambers tuned to the If acoustic resonance mode of a full-scale thrust chamber were manufactured to be used as a combustion cylinder. The main idea of the experiment is that the mixing mechanism is considered as a dominant factor significantly affecting combustion instability in a full-scale thrust chamber. Self-excited dynamic pressure values in a model chamber show different combustion stability zones with respect to a recess number. Upon test results, couplings between combustion conditions and the IT acoustic resonance mode become strengthened with the increase of a recess length.

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An Experimental Research on Performance and Emission Characteristics of Direct-Injection Diesel Engines with Annular Two-stage Combustion Chamber (환상 2단연소실을 갖는 직접분사식 디젤기관의 성능 및 배출물 특성에 관한 실험적 연구)

  • Kim, D.H.;Bae, J.U.
    • Journal of Power System Engineering
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    • v.7 no.4
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    • pp.12-18
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    • 2003
  • Various measures have been tried to reduce the NOx emission from diesel engine, but with partial success because the mechanisms of NOx and PM formations appear to have trade-off relation between each other. Therefore it has been known to be difficult to reduce NOx emission and PM emission simultaneously. Two stage combustion method i,e. a combustion process which has rich combustion stage and lean combustion stage one by one, has been developed successfully to reduce NOx formation in the continuous combustion chambers such as in the boilers. But until yet it is not successful to apply the same method in intermittent combustion chamber like in the diesel engine cylinder, as it was, only several research works were carried out. In this study, devised was a uniquely shaped combustion chamber with reformed piston crown intended to keep fuel-rich condition during early stage of combustion and fuel-lean condition during next stage. It was found that the NOx emission decreased significantly at various conditions of operation with the two stage combustion type engines of PR20 type, but other values such as smoke, CO and specific fuel consumption deteriorated as usual.

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Investigation of Combustion Strategy for Commercialization of Low Temperature Diesel Combustion Engine (저온연소엔진 실용화를 위한 연소전략에 대한 연구)

  • Shim, Euijoon;Han, Youngdeok;Shin, Seunghyup;Kim, Duksang;Kwon, Sangil
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.6
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    • pp.120-127
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    • 2014
  • Robustness and controllability are the key factors in internal combustion engine commercialization. This study focuses on the combustion strategy to commercialize the low temperature diesel combustion technology. Various LTC combustion methods such as PPCI, MK and highly diluted mixing controlled LTC were conducted on 6.0L heavy duty diesel engine. To find the best feasible LTC strategy, emission level, fuel consumption and combustion safety during the combustion mode change were considered. Experiments were carried out under various engine operating conditions; engine speed & load, EGR level, injection timing. Finally, this study suggests realizable LTC combustion strategy; moderate EGR level and slight early injection are possible to considerably lower PM, NOx emission and expand LTC operating range up to 50% load without CO and HC emission.

Comparison of Combustion Characteristics with Combustion Strategy and Excess Air Ratio Change in a Lean-burn LPG Direct Injection Engine (직접분사식 LPG 엔진의 연소전략 및 공기과잉률 변화에 따른 연소특성 비교)

  • Cho, Seehyeon;Park, Cheolwoong;Oh, Seungmook;Yoon, Junkyu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.6
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    • pp.96-103
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    • 2014
  • Liquefied Petroleum Gas(LPG) has attracted attention as a alternative fuel. The lean-burn LPG direct injection engine is a promising technology because it has an advantage of lower harmful emissions. This study aims to investigate the effect of combustion strategy and excess air ratio on combustion and emission characteristics in lean-burn LPG direct injection engine. Fuel consumption and combustion stability were measured with change of the ignition timing and injection timing at various air/fuel ratio conditions. The lean combustion characteristics were evaluated as a function of the excess air ratio with the single injection and multiple injection strategy. Furthermore, the feasibility of lean operation with stratified mixture was assessed when comparing the combustion and emission characteristics with premixed lean combustion.

COMBUSTION CHARACTERISTICS OF INHOMOGENEOUS METHANE-AIR MIXTURE IN A CONSTANT VOLUME COMBUSTION CHAMBER

  • Choi, S.H.;Jeon, C.H.;Chang, Y.J.
    • International Journal of Automotive Technology
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    • v.5 no.3
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    • pp.181-188
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    • 2004
  • A cylindrical constant-volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of an inhomogeneous charge methane-air mixture under several parameters such as stratified pattern, initial charge pressure, ignition time and the excess air ratio of the initial charge mixture. Flow characteristics including mean velocity and turbulence intensity were analyzed by a hot-wire anemometer. The combustion pressure development, measured by a piezo-electric pressure transducer, was used to investigate the effect of initial charge pressure, excess air ratio and ignition times on combustion pressure and combustion duration. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to near-zero value at 3000 ms. For the stratified patterns, the combustion rate under the rich injection (RI) condition was the fastest. Under the initial charge conditions, the second mixture was accompanied by an increase in the combustion rate, and that the higher the mass which is added in the second stage injection, the faster the combustion rate.

Prediction of Biodiesel Combustion, CO and NOX Emission Characteristics in Accordance with Equivalence Ratio (당량비 변화에 따른 바이오디젤 연소 및 CO, NOX 생성 특성 예측)

  • Lim, Young Chan;Suh, Hyun Kyu
    • Journal of the Korean Society of Combustion
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    • v.21 no.1
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    • pp.1-7
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    • 2016
  • This study was performed to provide the basic information of the combustion, CO and $NO_X$ characteristics of biodiesel in accordance with equivalence ratio. The closed homogeneous reactor model used for the analysis. The analysis conditions were set to 900 K of the initial temperature, 20 atm of initial pressure and equivalence ratio was changes from 0.6 to 1.4. The results of analysis were predicted and compared in terms of combustion temperature, combustion pressure, CO and $NO_X$ emissions. The results of combustion characteristics showed that ignition delay was decreased and the combustion temperature and combustion pressure was increased in accordance with equivalence ratio. CO emission was decreased in lean condition(${\Phi}$ < 1.0), however, CO emission was increased in rich condition(${\Phi}$ > 1.0) because oxygen supply insufficient. $NO_X$ emission showed the largest amount in condition 0.8 of equivalence ratio because the oxygen concentration was sufficient.