• Title/Summary/Keyword: 화염 전 화학 반응

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Effect of N2 Diluent on Soot Formation Characteristics in Ethylene Diffusion Flames (에틸렌 확산화염 내 질소 혼합이 매연 생성 특성에 미치는 영향)

  • Jun-Soo Kim
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.4
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    • pp.356-362
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    • 2023
  • The risk of climate change has been long acknowledged, and ongoing efforts to overcome this issue, within the shipping sector, with the international maritime organization playing a central role. Conducting research on characteristics of soot formation is crucial to control its occurrence within the combustion process. In this study, the laser extinction method and chemical reaction numerical analysis were employed to examine the alterations in the state of chemical species associated with flame temperature, flame visual, and soot formation by mixing nitrogen, an inert gas, in the counterflow diffusion flame based on ethylene gas. The findings of the study suggest that as the mixing ratio of nitrogen increased, both the flame temperature and soot volume fraction decreased. Additionally, the area in which soot particles were distributed also decreased, and the volume fraction decrease rate declined when the mixing ratio increased by more than 30%. The mole fraction of the chemical species involved in soot growth also decreased. the chemical species associated with the HACA reaction were affected by variations in the hydrocarbon fuel ratio, and the chemical species related to the odd carbon path were confirmed to be affected by the flame temperature as well as the hydrocarbon fuel ratio.

A Study of the Temperature Elevation Due to the Pre-flame Reaction in a Spark-Ignition Engine Using CARS Technique (CARS 측정 기술을 이용한 스파크 점화 기관에서의 화염 전 화학 반응에 의한 온도 변화에 관한 연구)

  • 최인용;전광민;박철웅;한재원
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.9-16
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    • 2001
  • End-gas temperatures were measured using CARS technique in a conventional DOHC spark- ignition engine fueled with PRF80. The measured pressure data were analyzed using band pass filter method. The measured CARS temperatures were compared with adiabatic core temperatures calculated from measured pressures. Significant heating by pre-flame reaction in the end gas zone was observed in the late part of compression stroke under both knocking and non-knocking conditions. CARS temperatures measured at 10 crank angle degree before knock occurrence was higher than adiabatic core temperatures. These results indicate that there exist some exothermic reactions in low pressure and temperature region. CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached look. The temperature elevation due to the pre-flame reaction correlated better with CARS temperature than with cylinder pressure.

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Measurement of NO in Lean Burn and Soot Flame (희박화염과 매연화염의 NO 계측)

  • 손성민;고동섭;오승묵;강건용;김종욱
    • Proceedings of the Optical Society of Korea Conference
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    • 2001.02a
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    • pp.108-109
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    • 2001
  • 환경문제에 대한 인식이 높아지면서 각종 연소장치의 배출가스에 대한 규제치가 강화되고 있어서, 연소현상 연구는 연소효율 향상과 같은 경제적 측면뿐만이 아니라 환경오염의 해결 관점에서도 그 필요성이 요구되어, 이미 오래 전부터 연소과정의 연구가 활발하게 진행되어 왔다. 그러나 연소현상은 물리·화학적으로 빠르고 복잡한 반응과정을 수반하여 진행하므로, 레이저 분광학적 방법이 주로 계측수단으로 사용되고 있다. (중략)

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A Numerical Analysis of Flame Liftoff Height and Structure with the Variation of Velocity Profiles at the Nozzle Exit (연료노즐 출구에서의 속도 형상에 따른 부상화염 높이 및 화염구조에 관한 수치해석 연구)

  • Ha, Ji-Soo;Kim, Tae-Kwon;Park, Jeong
    • Journal of the Korean Institute of Gas
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    • v.12 no.4
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    • pp.21-28
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    • 2008
  • A numerical analysis is achieved to elucidate the behavior of lifted flames and characteristics of flow near flame zone according to the exit velocity of triple flame, Poiseuille and uniform distribution. For the cases of Poiseuille and uniform nozzle exit velocity, we reviewed previous results with the present numerical results and investigated characteristics of the flame structure near the flame zone comparing with liftoff height generalized by momentum flux. In addition, a close inquiry into the combustion flow characteristics near flame zone was made with the characteristics of velocity, pressure, temperature and chemical reaction. From nozzle to flame zone, center line velocity profile traced well with the velocity profile of typical cold jet flow, but very near the flame zone, this study examined phenomenon that flow velocity decreases very quickly before the flame zone and then increases very quickly after the flame zone. Because flame zone acts as a barrier at the flow region which is before the flame zone and accelerate the flow velocity when it pass through the flame zone. This phenomenon was not clarified previous cold jet flow.

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Modeling for Soot Formation Coupled with Detailed Chemistry in Laminar Pressurized Non-premixed Flames (층류 고압 비예혼합 화염에서 상세화학반응과 결합된 매연입자 생성 모델링)

  • Kim, Taehoon;Jeon, Sangtae;Kim, Yongmo
    • 한국연소학회:학술대회논문집
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    • 2012.11a
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    • pp.139-140
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    • 2012
  • In laminar non-premixed flame situation, the flamelet model is not suitable for simulating slow processor like soot and radiation. Thus in this study, we overcome this limitation by using the transient flamelet model. Also, for soot formation on laminar non-premixed flame, transient flamelet coupled with two-equation soot model has been adopted due to its inherent advantages in terms of accuracy and availability. Based on numerical results, the detailed discussion has been made for the precise structure and soot formation processes in the pressurized methane air flames.

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Anodic Oxidation of Potassium Iodide Solution (Ⅰ) (요오드화칼륨 수용액의 양극산화 (제1보))

  • Nam, Chong-Woo;Kim, Hark-Joon
    • Journal of the Korean Chemical Society
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    • v.17 no.5
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    • pp.378-384
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    • 1973
  • To investigate the mechanism of the reaction of electrolytic oxidation of iodide to iodate ions, polarization curves are determined in various kinds of solution using electrodeposited lead peroxide and platinum anodes. It was observed from the polarization curves that the limiting current is exists at concentration 1.5 M of potassium iodide, and these limiting current disappeared as potassium hydroxide was added up to concentration of 0.1 M. while in case of platinum anode, limiting current did not appear in dilute potassium iodide solution. These results are owing to the chemical reaction, $PbO_2+2I^{-}+2H^+{\to}PbO+I_2+H_{2}O$ ocurring at the surface of lead peroxide anode. Also, we studied to obtain the optimum conditions of electrolytic preparation of iodate from iodide solution using a cell without the diaphragm. The results are that; (a) addition of potassium dichromate at the anti-reducing agent is proper in concentration of 0.1 g/l, (b) electrolytic temperature is not so much effective in raising the current efficiency, (c) current efficiency is increased with current density, and (d) electrolysis is the most effective in weak alkaline solutions.

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